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<span id="1000">1000</span>
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<span id="1003">1003</span>
<span id="1004">1004</span>
<span id="1005">1005</span>
<span id="1006">1006</span>
<span id="1007">1007</span>
<span id="1008">1008</span>
<span id="1009">1009</span>
<span id="1010">1010</span>
<span id="1011">1011</span>
<span id="1012">1012</span>
<span id="1013">1013</span>
<span id="1014">1014</span>
<span id="1015">1015</span>
<span id="1016">1016</span>
<span id="1017">1017</span>
<span id="1018">1018</span>
<span id="1019">1019</span>
<span id="1020">1020</span>
<span id="1021">1021</span>
<span id="1022">1022</span>
<span id="1023">1023</span>
<span id="1024">1024</span>
<span id="1025">1025</span>
<span id="1026">1026</span>
<span id="1027">1027</span>
<span id="1028">1028</span>
<span id="1029">1029</span>
<span id="1030">1030</span>
<span id="1031">1031</span>
<span id="1032">1032</span>
<span id="1033">1033</span>
<span id="1034">1034</span>
<span id="1035">1035</span>
<span id="1036">1036</span>
<span id="1037">1037</span>
<span id="1038">1038</span>
<span id="1039">1039</span>
<span id="1040">1040</span>
<span id="1041">1041</span>
<span id="1042">1042</span>
<span id="1043">1043</span>
<span id="1044">1044</span>
<span id="1045">1045</span>
<span id="1046">1046</span>
<span id="1047">1047</span>
<span id="1048">1048</span>
<span id="1049">1049</span>
<span id="1050">1050</span>
<span id="1051">1051</span>
<span id="1052">1052</span>
<span id="1053">1053</span>
<span id="1054">1054</span>
<span id="1055">1055</span>
<span id="1056">1056</span>
<span id="1057">1057</span>
<span id="1058">1058</span>
<span id="1059">1059</span>
<span id="1060">1060</span>
<span id="1061">1061</span>
<span id="1062">1062</span>
<span id="1063">1063</span>
<span id="1064">1064</span>
<span id="1065">1065</span>
<span id="1066">1066</span>
<span id="1067">1067</span>
<span id="1068">1068</span>
<span id="1069">1069</span>
<span id="1070">1070</span>
<span id="1071">1071</span>
<span id="1072">1072</span>
<span id="1073">1073</span>
<span id="1074">1074</span>
<span id="1075">1075</span>
<span id="1076">1076</span>
<span id="1077">1077</span>
<span id="1078">1078</span>
<span id="1079">1079</span>
<span id="1080">1080</span>
<span id="1081">1081</span>
<span id="1082">1082</span>
<span id="1083">1083</span>
<span id="1084">1084</span>
</pre><pre class="rust">
<span class="kw">use</span> <span class="kw">crate</span><span class="ident">::read_u8</span>;
<span class="kw">use</span> <span class="ident">error</span>::{<span class="ident">Error</span>, <span class="prelude-ty">Result</span>, <span class="ident">UnsupportedFeature</span>};
<span class="kw">use</span> <span class="ident">huffman</span>::{<span class="ident">fill_default_mjpeg_tables</span>, <span class="ident">HuffmanDecoder</span>, <span class="ident">HuffmanTable</span>};
<span class="kw">use</span> <span class="ident">marker::Marker</span>;
<span class="kw">use</span> <span class="ident">parser</span>::{<span class="ident">AdobeColorTransform</span>, <span class="ident">AppData</span>, <span class="ident">CodingProcess</span>, <span class="ident">Component</span>, <span class="ident">Dimensions</span>, <span class="ident">EntropyCoding</span>, <span class="ident">FrameInfo</span>,
<span class="ident">parse_app</span>, <span class="ident">parse_com</span>, <span class="ident">parse_dht</span>, <span class="ident">parse_dqt</span>, <span class="ident">parse_dri</span>, <span class="ident">parse_sof</span>, <span class="ident">parse_sos</span>, <span class="ident">IccChunk</span>,
<span class="ident">ScanInfo</span>};
<span class="kw">use</span> <span class="ident">upsampler::Upsampler</span>;
<span class="kw">use</span> <span class="ident">std::cmp</span>;
<span class="kw">use</span> <span class="ident">std::io::Read</span>;
<span class="kw">use</span> <span class="ident">std::mem</span>;
<span class="kw">use</span> <span class="ident">std::ops::Range</span>;
<span class="kw">use</span> <span class="ident">std::sync::Arc</span>;
<span class="kw">use</span> <span class="ident">worker</span>::{<span class="ident">RowData</span>, <span class="ident">PlatformWorker</span>, <span class="ident">Worker</span>};
<span class="kw">pub</span> <span class="kw">const</span> <span class="ident">MAX_COMPONENTS</span>: <span class="ident">usize</span> <span class="op">=</span> <span class="number">4</span>;
<span class="kw">static</span> <span class="ident">UNZIGZAG</span>: [<span class="ident">u8</span>; <span class="number">64</span>] <span class="op">=</span> [
<span class="number">0</span>, <span class="number">1</span>, <span class="number">8</span>, <span class="number">16</span>, <span class="number">9</span>, <span class="number">2</span>, <span class="number">3</span>, <span class="number">10</span>,
<span class="number">17</span>, <span class="number">24</span>, <span class="number">32</span>, <span class="number">25</span>, <span class="number">18</span>, <span class="number">11</span>, <span class="number">4</span>, <span class="number">5</span>,
<span class="number">12</span>, <span class="number">19</span>, <span class="number">26</span>, <span class="number">33</span>, <span class="number">40</span>, <span class="number">48</span>, <span class="number">41</span>, <span class="number">34</span>,
<span class="number">27</span>, <span class="number">20</span>, <span class="number">13</span>, <span class="number">6</span>, <span class="number">7</span>, <span class="number">14</span>, <span class="number">21</span>, <span class="number">28</span>,
<span class="number">35</span>, <span class="number">42</span>, <span class="number">49</span>, <span class="number">56</span>, <span class="number">57</span>, <span class="number">50</span>, <span class="number">43</span>, <span class="number">36</span>,
<span class="number">29</span>, <span class="number">22</span>, <span class="number">15</span>, <span class="number">23</span>, <span class="number">30</span>, <span class="number">37</span>, <span class="number">44</span>, <span class="number">51</span>,
<span class="number">58</span>, <span class="number">59</span>, <span class="number">52</span>, <span class="number">45</span>, <span class="number">38</span>, <span class="number">31</span>, <span class="number">39</span>, <span class="number">46</span>,
<span class="number">53</span>, <span class="number">60</span>, <span class="number">61</span>, <span class="number">54</span>, <span class="number">47</span>, <span class="number">55</span>, <span class="number">62</span>, <span class="number">63</span>,
];
<span class="doccomment">/// An enumeration over combinations of color spaces and bit depths a pixel can have.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Copy</span>, <span class="ident">Debug</span>, <span class="ident">PartialEq</span>)]</span>
<span class="kw">pub</span> <span class="kw">enum</span> <span class="ident">PixelFormat</span> {
<span class="doccomment">/// Luminance (grayscale), 8 bits</span>
<span class="ident">L8</span>,
<span class="doccomment">/// RGB, 8 bits per channel</span>
<span class="ident">RGB24</span>,
<span class="doccomment">/// CMYK, 8 bits per channel</span>
<span class="ident">CMYK32</span>,
}
<span class="kw">impl</span> <span class="ident">PixelFormat</span> {
<span class="doccomment">/// Determine the size in bytes of each pixel in this format</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">pixel_bytes</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="ident">usize</span> {
<span class="kw">match</span> <span class="self">self</span> {
<span class="ident">PixelFormat::L8</span> <span class="op">=</span><span class="op">></span> <span class="number">1</span>,
<span class="ident">PixelFormat::RGB24</span> <span class="op">=</span><span class="op">></span> <span class="number">3</span>,
<span class="ident">PixelFormat::CMYK32</span> <span class="op">=</span><span class="op">></span> <span class="number">4</span>,
}
}
}
<span class="doccomment">/// Represents metadata of an image.</span>
<span class="attribute">#[<span class="ident">derive</span>(<span class="ident">Clone</span>, <span class="ident">Copy</span>, <span class="ident">Debug</span>, <span class="ident">PartialEq</span>)]</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">ImageInfo</span> {
<span class="doccomment">/// The width of the image, in pixels.</span>
<span class="kw">pub</span> <span class="ident">width</span>: <span class="ident">u16</span>,
<span class="doccomment">/// The height of the image, in pixels.</span>
<span class="kw">pub</span> <span class="ident">height</span>: <span class="ident">u16</span>,
<span class="doccomment">/// The pixel format of the image.</span>
<span class="kw">pub</span> <span class="ident">pixel_format</span>: <span class="ident">PixelFormat</span>,
}
<span class="doccomment">/// JPEG decoder</span>
<span class="kw">pub</span> <span class="kw">struct</span> <span class="ident">Decoder</span><span class="op"><</span><span class="ident">R</span><span class="op">></span> {
<span class="ident">reader</span>: <span class="ident">R</span>,
<span class="ident">frame</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">FrameInfo</span><span class="op">></span>,
<span class="ident">dc_huffman_tables</span>: <span class="ident">Vec</span><span class="op"><</span><span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">HuffmanTable</span><span class="op">></span><span class="op">></span>,
<span class="ident">ac_huffman_tables</span>: <span class="ident">Vec</span><span class="op"><</span><span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">HuffmanTable</span><span class="op">></span><span class="op">></span>,
<span class="ident">quantization_tables</span>: [<span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">Arc</span><span class="op"><</span>[<span class="ident">u16</span>; <span class="number">64</span>]<span class="op">></span><span class="op">></span>; <span class="number">4</span>],
<span class="ident">restart_interval</span>: <span class="ident">u16</span>,
<span class="ident">color_transform</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">AdobeColorTransform</span><span class="op">></span>,
<span class="ident">is_jfif</span>: <span class="ident">bool</span>,
<span class="ident">is_mjpeg</span>: <span class="ident">bool</span>,
<span class="ident">icc_markers</span>: <span class="ident">Vec</span><span class="op"><</span><span class="ident">IccChunk</span><span class="op">></span>,
<span class="comment">// Used for progressive JPEGs.</span>
<span class="ident">coefficients</span>: <span class="ident">Vec</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">i16</span><span class="op">></span><span class="op">></span>,
<span class="comment">// Bitmask of which coefficients has been completely decoded.</span>
<span class="ident">coefficients_finished</span>: [<span class="ident">u64</span>; <span class="ident">MAX_COMPONENTS</span>],
}
<span class="kw">impl</span><span class="op"><</span><span class="ident">R</span>: <span class="ident">Read</span><span class="op">></span> <span class="ident">Decoder</span><span class="op"><</span><span class="ident">R</span><span class="op">></span> {
<span class="doccomment">/// Creates a new `Decoder` using the reader `reader`.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">new</span>(<span class="ident">reader</span>: <span class="ident">R</span>) <span class="op">-</span><span class="op">></span> <span class="ident">Decoder</span><span class="op"><</span><span class="ident">R</span><span class="op">></span> {
<span class="ident">Decoder</span> {
<span class="ident">reader</span>: <span class="ident">reader</span>,
<span class="ident">frame</span>: <span class="prelude-val">None</span>,
<span class="ident">dc_huffman_tables</span>: <span class="macro">vec!</span>[<span class="prelude-val">None</span>, <span class="prelude-val">None</span>, <span class="prelude-val">None</span>, <span class="prelude-val">None</span>],
<span class="ident">ac_huffman_tables</span>: <span class="macro">vec!</span>[<span class="prelude-val">None</span>, <span class="prelude-val">None</span>, <span class="prelude-val">None</span>, <span class="prelude-val">None</span>],
<span class="ident">quantization_tables</span>: [<span class="prelude-val">None</span>, <span class="prelude-val">None</span>, <span class="prelude-val">None</span>, <span class="prelude-val">None</span>],
<span class="ident">restart_interval</span>: <span class="number">0</span>,
<span class="ident">color_transform</span>: <span class="prelude-val">None</span>,
<span class="ident">is_jfif</span>: <span class="bool-val">false</span>,
<span class="ident">is_mjpeg</span>: <span class="bool-val">false</span>,
<span class="ident">icc_markers</span>: <span class="ident">Vec::new</span>(),
<span class="ident">coefficients</span>: <span class="ident">Vec::new</span>(),
<span class="ident">coefficients_finished</span>: [<span class="number">0</span>; <span class="ident">MAX_COMPONENTS</span>],
}
}
<span class="doccomment">/// Returns metadata about the image.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// The returned value will be `None` until a call to either `read_info` or `decode` has</span>
<span class="doccomment">/// returned `Ok`.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">info</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">ImageInfo</span><span class="op">></span> {
<span class="kw">match</span> <span class="self">self</span>.<span class="ident">frame</span> {
<span class="prelude-val">Some</span>(<span class="kw-2">ref</span> <span class="ident">frame</span>) <span class="op">=</span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">pixel_format</span> <span class="op">=</span> <span class="kw">match</span> <span class="ident">frame</span>.<span class="ident">components</span>.<span class="ident">len</span>() {
<span class="number">1</span> <span class="op">=</span><span class="op">></span> <span class="ident">PixelFormat::L8</span>,
<span class="number">3</span> <span class="op">=</span><span class="op">></span> <span class="ident">PixelFormat::RGB24</span>,
<span class="number">4</span> <span class="op">=</span><span class="op">></span> <span class="ident">PixelFormat::CMYK32</span>,
<span class="kw">_</span> <span class="op">=</span><span class="op">></span> <span class="macro">panic!</span>(),
};
<span class="prelude-val">Some</span>(<span class="ident">ImageInfo</span> {
<span class="ident">width</span>: <span class="ident">frame</span>.<span class="ident">output_size</span>.<span class="ident">width</span>,
<span class="ident">height</span>: <span class="ident">frame</span>.<span class="ident">output_size</span>.<span class="ident">height</span>,
<span class="ident">pixel_format</span>: <span class="ident">pixel_format</span>,
})
},
<span class="prelude-val">None</span> <span class="op">=</span><span class="op">></span> <span class="prelude-val">None</span>,
}
}
<span class="doccomment">/// Returns the embeded icc profile if the image contains one.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">icc_profile</span>(<span class="kw-2">&</span><span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span><span class="op">></span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">marker_present</span>: [<span class="prelude-ty">Option</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">IccChunk</span><span class="op">></span>; <span class="number">256</span>] <span class="op">=</span> [<span class="prelude-val">None</span>; <span class="number">256</span>];
<span class="kw">let</span> <span class="ident">num_markers</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">icc_markers</span>.<span class="ident">len</span>();
<span class="kw">if</span> <span class="ident">num_markers</span> <span class="op">=</span><span class="op">=</span> <span class="number">0</span> <span class="op">&&</span> <span class="ident">num_markers</span> <span class="op"><</span> <span class="number">256</span> {
<span class="kw">return</span> <span class="prelude-val">None</span>;
}
<span class="comment">// check the validity of the markers</span>
<span class="kw">for</span> <span class="ident">chunk</span> <span class="kw">in</span> <span class="kw-2">&</span><span class="self">self</span>.<span class="ident">icc_markers</span> {
<span class="kw">if</span> <span class="ident">usize::from</span>(<span class="ident">chunk</span>.<span class="ident">num_markers</span>) <span class="op">!</span><span class="op">=</span> <span class="ident">num_markers</span> {
<span class="comment">// all the lengths must match</span>
<span class="kw">return</span> <span class="prelude-val">None</span>;
}
<span class="kw">if</span> <span class="ident">chunk</span>.<span class="ident">seq_no</span> <span class="op">=</span><span class="op">=</span> <span class="number">0</span> {
<span class="kw">return</span> <span class="prelude-val">None</span>;
}
<span class="kw">if</span> <span class="ident">marker_present</span>[<span class="ident">usize::from</span>(<span class="ident">chunk</span>.<span class="ident">seq_no</span>)].<span class="ident">is_some</span>() {
<span class="comment">// duplicate seq_no</span>
<span class="kw">return</span> <span class="prelude-val">None</span>;
} <span class="kw">else</span> {
<span class="ident">marker_present</span>[<span class="ident">usize::from</span>(<span class="ident">chunk</span>.<span class="ident">seq_no</span>)] <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">chunk</span>);
}
}
<span class="comment">// assemble them together by seq_no failing if any are missing</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">data</span> <span class="op">=</span> <span class="ident">Vec::new</span>();
<span class="comment">// seq_no's start at 1</span>
<span class="kw">for</span> <span class="kw-2">&</span><span class="ident">chunk</span> <span class="kw">in</span> <span class="ident">marker_present</span>.<span class="ident">get</span>(<span class="number">1</span>..<span class="op">=</span><span class="ident">num_markers</span>)<span class="question-mark">?</span> {
<span class="ident">data</span>.<span class="ident">extend_from_slice</span>(<span class="kw-2">&</span><span class="ident">chunk</span><span class="question-mark">?</span>.<span class="ident">data</span>);
}
<span class="prelude-val">Some</span>(<span class="ident">data</span>)
}
<span class="doccomment">/// Tries to read metadata from the image without decoding it.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// If successful, the metadata can be obtained using the `info` method.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">read_info</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Result</span><span class="op"><</span>()<span class="op">></span> {
<span class="self">self</span>.<span class="ident">decode_internal</span>(<span class="bool-val">true</span>).<span class="ident">map</span>(<span class="op">|</span><span class="kw">_</span><span class="op">|</span> ())
}
<span class="doccomment">/// Configure the decoder to scale the image during decoding.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// This efficiently scales the image by the smallest supported scale</span>
<span class="doccomment">/// factor that produces an image larger than or equal to the requested</span>
<span class="doccomment">/// size in at least one axis. The currently implemented scale factors</span>
<span class="doccomment">/// are 1/8, 1/4, 1/2 and 1.</span>
<span class="doccomment">///</span>
<span class="doccomment">/// To generate a thumbnail of an exact size, pass the desired size and</span>
<span class="doccomment">/// then scale to the final size using a traditional resampling algorithm.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">scale</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">requested_width</span>: <span class="ident">u16</span>, <span class="ident">requested_height</span>: <span class="ident">u16</span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Result</span><span class="op"><</span>(<span class="ident">u16</span>, <span class="ident">u16</span>)<span class="op">></span> {
<span class="self">self</span>.<span class="ident">read_info</span>()<span class="question-mark">?</span>;
<span class="kw">let</span> <span class="ident">frame</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">frame</span>.<span class="ident">as_mut</span>().<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="ident">idct_size</span> <span class="op">=</span> <span class="kw">crate</span><span class="ident">::idct::choose_idct_size</span>(<span class="ident">frame</span>.<span class="ident">image_size</span>, <span class="ident">Dimensions</span>{ <span class="ident">width</span>: <span class="ident">requested_width</span>, <span class="ident">height</span>: <span class="ident">requested_height</span> });
<span class="ident">frame</span>.<span class="ident">update_idct_size</span>(<span class="ident">idct_size</span>)<span class="question-mark">?</span>;
<span class="prelude-val">Ok</span>((<span class="ident">frame</span>.<span class="ident">output_size</span>.<span class="ident">width</span>, <span class="ident">frame</span>.<span class="ident">output_size</span>.<span class="ident">height</span>))
}
<span class="doccomment">/// Decodes the image and returns the decoded pixels if successful.</span>
<span class="kw">pub</span> <span class="kw">fn</span> <span class="ident">decode</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span><span class="op">></span> {
<span class="self">self</span>.<span class="ident">decode_internal</span>(<span class="bool-val">false</span>)
}
<span class="kw">fn</span> <span class="ident">decode_internal</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>, <span class="ident">stop_after_metadata</span>: <span class="ident">bool</span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span><span class="op">></span> {
<span class="kw">if</span> <span class="ident">stop_after_metadata</span> <span class="op">&&</span> <span class="self">self</span>.<span class="ident">frame</span>.<span class="ident">is_some</span>() {
<span class="comment">// The metadata has already been read.</span>
<span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="ident">Vec::new</span>());
}
<span class="kw">else</span> <span class="kw">if</span> <span class="self">self</span>.<span class="ident">frame</span>.<span class="ident">is_none</span>() <span class="op">&&</span> (<span class="ident">read_u8</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">reader</span>)<span class="question-mark">?</span> <span class="op">!</span><span class="op">=</span> <span class="number">0xFF</span> <span class="op">|</span><span class="op">|</span> <span class="ident">Marker::from_u8</span>(<span class="ident">read_u8</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">reader</span>)<span class="question-mark">?</span>) <span class="op">!</span><span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">Marker::SOI</span>)) {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Format</span>(<span class="string">"first two bytes are not an SOI marker"</span>.<span class="ident">to_owned</span>()));
}
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">previous_marker</span> <span class="op">=</span> <span class="ident">Marker::SOI</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">pending_marker</span> <span class="op">=</span> <span class="prelude-val">None</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">worker</span> <span class="op">=</span> <span class="prelude-val">None</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">scans_processed</span> <span class="op">=</span> <span class="number">0</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">planes</span> <span class="op">=</span> <span class="macro">vec!</span>[<span class="ident">Vec::new</span>(); <span class="self">self</span>.<span class="ident">frame</span>.<span class="ident">as_ref</span>().<span class="ident">map_or</span>(<span class="number">0</span>, <span class="op">|</span><span class="ident">frame</span><span class="op">|</span> <span class="ident">frame</span>.<span class="ident">components</span>.<span class="ident">len</span>())];
<span class="kw">loop</span> {
<span class="kw">let</span> <span class="ident">marker</span> <span class="op">=</span> <span class="kw">match</span> <span class="ident">pending_marker</span>.<span class="ident">take</span>() {
<span class="prelude-val">Some</span>(<span class="ident">m</span>) <span class="op">=</span><span class="op">></span> <span class="ident">m</span>,
<span class="prelude-val">None</span> <span class="op">=</span><span class="op">></span> <span class="self">self</span>.<span class="ident">read_marker</span>()<span class="question-mark">?</span>,
};
<span class="kw">match</span> <span class="ident">marker</span> {
<span class="comment">// Frame header</span>
<span class="ident">Marker::SOF</span>(..) <span class="op">=</span><span class="op">></span> {
<span class="comment">// Section 4.10</span>
<span class="comment">// "An image contains only one frame in the cases of sequential and</span>
<span class="comment">// progressive coding processes; an image contains multiple frames for the</span>
<span class="comment">// hierarchical mode."</span>
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">frame</span>.<span class="ident">is_some</span>() {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Unsupported</span>(<span class="ident">UnsupportedFeature::Hierarchical</span>));
}
<span class="kw">let</span> <span class="ident">frame</span> <span class="op">=</span> <span class="ident">parse_sof</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">reader</span>, <span class="ident">marker</span>)<span class="question-mark">?</span>;
<span class="kw">let</span> <span class="ident">component_count</span> <span class="op">=</span> <span class="ident">frame</span>.<span class="ident">components</span>.<span class="ident">len</span>();
<span class="kw">if</span> <span class="ident">frame</span>.<span class="ident">is_differential</span> {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Unsupported</span>(<span class="ident">UnsupportedFeature::Hierarchical</span>));
}
<span class="kw">if</span> <span class="ident">frame</span>.<span class="ident">coding_process</span> <span class="op">=</span><span class="op">=</span> <span class="ident">CodingProcess::Lossless</span> {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Unsupported</span>(<span class="ident">UnsupportedFeature::Lossless</span>));
}
<span class="kw">if</span> <span class="ident">frame</span>.<span class="ident">entropy_coding</span> <span class="op">=</span><span class="op">=</span> <span class="ident">EntropyCoding::Arithmetic</span> {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Unsupported</span>(<span class="ident">UnsupportedFeature::ArithmeticEntropyCoding</span>));
}
<span class="kw">if</span> <span class="ident">frame</span>.<span class="ident">precision</span> <span class="op">!</span><span class="op">=</span> <span class="number">8</span> {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Unsupported</span>(<span class="ident">UnsupportedFeature::SamplePrecision</span>(<span class="ident">frame</span>.<span class="ident">precision</span>)));
}
<span class="kw">if</span> <span class="ident">component_count</span> <span class="op">!</span><span class="op">=</span> <span class="number">1</span> <span class="op">&&</span> <span class="ident">component_count</span> <span class="op">!</span><span class="op">=</span> <span class="number">3</span> <span class="op">&&</span> <span class="ident">component_count</span> <span class="op">!</span><span class="op">=</span> <span class="number">4</span> {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Unsupported</span>(<span class="ident">UnsupportedFeature::ComponentCount</span>(<span class="ident">component_count</span> <span class="kw">as</span> <span class="ident">u8</span>)));
}
<span class="comment">// Make sure we support the subsampling ratios used.</span>
<span class="kw">let</span> <span class="kw">_</span> <span class="op">=</span> <span class="ident">Upsampler::new</span>(<span class="kw-2">&</span><span class="ident">frame</span>.<span class="ident">components</span>, <span class="ident">frame</span>.<span class="ident">image_size</span>.<span class="ident">width</span>, <span class="ident">frame</span>.<span class="ident">image_size</span>.<span class="ident">height</span>)<span class="question-mark">?</span>;
<span class="self">self</span>.<span class="ident">frame</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">frame</span>);
<span class="kw">if</span> <span class="ident">stop_after_metadata</span> {
<span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="ident">Vec::new</span>());
}
<span class="ident">planes</span> <span class="op">=</span> <span class="macro">vec!</span>[<span class="ident">Vec::new</span>(); <span class="ident">component_count</span>];
},
<span class="comment">// Scan header</span>
<span class="ident">Marker::SOS</span> <span class="op">=</span><span class="op">></span> {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">frame</span>.<span class="ident">is_none</span>() {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Format</span>(<span class="string">"scan encountered before frame"</span>.<span class="ident">to_owned</span>()));
}
<span class="kw">if</span> <span class="ident">worker</span>.<span class="ident">is_none</span>() {
<span class="ident">worker</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">PlatformWorker::new</span>()<span class="question-mark">?</span>);
}
<span class="kw">let</span> <span class="ident">frame</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">frame</span>.<span class="ident">clone</span>().<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="ident">scan</span> <span class="op">=</span> <span class="ident">parse_sos</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">reader</span>, <span class="kw-2">&</span><span class="ident">frame</span>)<span class="question-mark">?</span>;
<span class="kw">if</span> <span class="ident">frame</span>.<span class="ident">coding_process</span> <span class="op">=</span><span class="op">=</span> <span class="ident">CodingProcess::DctProgressive</span> <span class="op">&&</span> <span class="self">self</span>.<span class="ident">coefficients</span>.<span class="ident">is_empty</span>() {
<span class="self">self</span>.<span class="ident">coefficients</span> <span class="op">=</span> <span class="ident">frame</span>.<span class="ident">components</span>.<span class="ident">iter</span>().<span class="ident">map</span>(<span class="op">|</span><span class="ident">c</span><span class="op">|</span> {
<span class="kw">let</span> <span class="ident">block_count</span> <span class="op">=</span> <span class="ident">c</span>.<span class="ident">block_size</span>.<span class="ident">width</span> <span class="kw">as</span> <span class="ident">usize</span> <span class="op">*</span> <span class="ident">c</span>.<span class="ident">block_size</span>.<span class="ident">height</span> <span class="kw">as</span> <span class="ident">usize</span>;
<span class="macro">vec!</span>[<span class="number">0</span>; <span class="ident">block_count</span> <span class="op">*</span> <span class="number">64</span>]
}).<span class="ident">collect</span>();
}
<span class="comment">// This was previously buggy, so let's explain the log here a bit. When a</span>
<span class="comment">// progressive frame is encoded then the coefficients (DC, AC) of each</span>
<span class="comment">// component (=color plane) can be split amongst scans. In particular it can</span>
<span class="comment">// happen or at least occurs in the wild that a scan contains coefficient 0 of</span>
<span class="comment">// all components. If now one but not all components had all other coefficients</span>
<span class="comment">// delivered in previous scans then such a scan contains all components but</span>
<span class="comment">// completes only some of them! (This is technically NOT permitted for all</span>
<span class="comment">// other coefficients as the standard dictates that scans with coefficients</span>
<span class="comment">// other than the 0th must only contain ONE component so we would either</span>
<span class="comment">// complete it or not. We may want to detect and error in case more component</span>
<span class="comment">// are part of a scan than allowed.) What a weird edge case.</span>
<span class="comment">//</span>
<span class="comment">// But this means we track precisely which components get completed here.</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">finished</span> <span class="op">=</span> [<span class="bool-val">false</span>; <span class="ident">MAX_COMPONENTS</span>];
<span class="kw">if</span> <span class="ident">scan</span>.<span class="ident">successive_approximation_low</span> <span class="op">=</span><span class="op">=</span> <span class="number">0</span> {
<span class="kw">for</span> (<span class="kw-2">&</span><span class="ident">i</span>, <span class="ident">component_finished</span>) <span class="kw">in</span> <span class="ident">scan</span>.<span class="ident">component_indices</span>.<span class="ident">iter</span>().<span class="ident">zip</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">finished</span>) {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">coefficients_finished</span>[<span class="ident">i</span>] <span class="op">=</span><span class="op">=</span> <span class="op">!</span><span class="number">0</span> {
<span class="kw">continue</span>;
}
<span class="kw">for</span> <span class="ident">j</span> <span class="kw">in</span> <span class="ident">scan</span>.<span class="ident">spectral_selection</span>.<span class="ident">clone</span>() {
<span class="self">self</span>.<span class="ident">coefficients_finished</span>[<span class="ident">i</span>] <span class="op">|</span><span class="op">=</span> <span class="number">1</span> <span class="op"><</span><span class="op"><</span> <span class="ident">j</span>;
}
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">coefficients_finished</span>[<span class="ident">i</span>] <span class="op">=</span><span class="op">=</span> <span class="op">!</span><span class="number">0</span> {
<span class="kw-2">*</span><span class="ident">component_finished</span> <span class="op">=</span> <span class="bool-val">true</span>;
}
}
}
<span class="kw">let</span> (<span class="ident">marker</span>, <span class="ident">data</span>) <span class="op">=</span> <span class="self">self</span>.<span class="ident">decode_scan</span>(<span class="kw-2">&</span><span class="ident">frame</span>, <span class="kw-2">&</span><span class="ident">scan</span>, <span class="ident">worker</span>.<span class="ident">as_mut</span>().<span class="ident">unwrap</span>(), <span class="kw-2">&</span><span class="ident">finished</span>)<span class="question-mark">?</span>;
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">data</span>) <span class="op">=</span> <span class="ident">data</span> {
<span class="kw">for</span> (<span class="ident">i</span>, <span class="ident">plane</span>) <span class="kw">in</span> <span class="ident">data</span>.<span class="ident">into_iter</span>().<span class="ident">enumerate</span>().<span class="ident">filter</span>(<span class="op">|</span><span class="kw-2">&</span>(<span class="kw">_</span>, <span class="kw-2">ref</span> <span class="ident">plane</span>)<span class="op">|</span> <span class="op">!</span><span class="ident">plane</span>.<span class="ident">is_empty</span>()) {
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">coefficients_finished</span>[<span class="ident">i</span>] <span class="op">=</span><span class="op">=</span> <span class="op">!</span><span class="number">0</span> {
<span class="ident">planes</span>[<span class="ident">i</span>] <span class="op">=</span> <span class="ident">plane</span>;
}
}
}
<span class="ident">pending_marker</span> <span class="op">=</span> <span class="ident">marker</span>;
<span class="ident">scans_processed</span> <span class="op">+</span><span class="op">=</span> <span class="number">1</span>;
},
<span class="comment">// Table-specification and miscellaneous markers</span>
<span class="comment">// Quantization table-specification</span>
<span class="ident">Marker::DQT</span> <span class="op">=</span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">tables</span> <span class="op">=</span> <span class="ident">parse_dqt</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">reader</span>)<span class="question-mark">?</span>;
<span class="kw">for</span> (<span class="ident">i</span>, <span class="kw-2">&</span><span class="ident">table</span>) <span class="kw">in</span> <span class="ident">tables</span>.<span class="ident">iter</span>().<span class="ident">enumerate</span>() {
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">table</span>) <span class="op">=</span> <span class="ident">table</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">unzigzagged_table</span> <span class="op">=</span> [<span class="number">0u16</span>; <span class="number">64</span>];
<span class="kw">for</span> <span class="ident">j</span> <span class="kw">in</span> <span class="number">0</span> .. <span class="number">64</span> {
<span class="ident">unzigzagged_table</span>[<span class="ident">UNZIGZAG</span>[<span class="ident">j</span>] <span class="kw">as</span> <span class="ident">usize</span>] <span class="op">=</span> <span class="ident">table</span>[<span class="ident">j</span>];
}
<span class="self">self</span>.<span class="ident">quantization_tables</span>[<span class="ident">i</span>] <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">Arc::new</span>(<span class="ident">unzigzagged_table</span>));
}
}
},
<span class="comment">// Huffman table-specification</span>
<span class="ident">Marker::DHT</span> <span class="op">=</span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">is_baseline</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">frame</span>.<span class="ident">as_ref</span>().<span class="ident">map</span>(<span class="op">|</span><span class="ident">frame</span><span class="op">|</span> <span class="ident">frame</span>.<span class="ident">is_baseline</span>);
<span class="kw">let</span> (<span class="ident">dc_tables</span>, <span class="ident">ac_tables</span>) <span class="op">=</span> <span class="ident">parse_dht</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">reader</span>, <span class="ident">is_baseline</span>)<span class="question-mark">?</span>;
<span class="kw">let</span> <span class="ident">current_dc_tables</span> <span class="op">=</span> <span class="ident">mem::replace</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">dc_huffman_tables</span>, <span class="macro">vec!</span>[]);
<span class="self">self</span>.<span class="ident">dc_huffman_tables</span> <span class="op">=</span> <span class="ident">dc_tables</span>.<span class="ident">into_iter</span>()
.<span class="ident">zip</span>(<span class="ident">current_dc_tables</span>.<span class="ident">into_iter</span>())
.<span class="ident">map</span>(<span class="op">|</span>(<span class="ident">a</span>, <span class="ident">b</span>)<span class="op">|</span> <span class="ident">a</span>.<span class="ident">or</span>(<span class="ident">b</span>))
.<span class="ident">collect</span>();
<span class="kw">let</span> <span class="ident">current_ac_tables</span> <span class="op">=</span> <span class="ident">mem::replace</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">ac_huffman_tables</span>, <span class="macro">vec!</span>[]);
<span class="self">self</span>.<span class="ident">ac_huffman_tables</span> <span class="op">=</span> <span class="ident">ac_tables</span>.<span class="ident">into_iter</span>()
.<span class="ident">zip</span>(<span class="ident">current_ac_tables</span>.<span class="ident">into_iter</span>())
.<span class="ident">map</span>(<span class="op">|</span>(<span class="ident">a</span>, <span class="ident">b</span>)<span class="op">|</span> <span class="ident">a</span>.<span class="ident">or</span>(<span class="ident">b</span>))
.<span class="ident">collect</span>();
},
<span class="comment">// Arithmetic conditioning table-specification</span>
<span class="ident">Marker::DAC</span> <span class="op">=</span><span class="op">></span> <span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Unsupported</span>(<span class="ident">UnsupportedFeature::ArithmeticEntropyCoding</span>)),
<span class="comment">// Restart interval definition</span>
<span class="ident">Marker::DRI</span> <span class="op">=</span><span class="op">></span> <span class="self">self</span>.<span class="ident">restart_interval</span> <span class="op">=</span> <span class="ident">parse_dri</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">reader</span>)<span class="question-mark">?</span>,
<span class="comment">// Comment</span>
<span class="ident">Marker::COM</span> <span class="op">=</span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">_comment</span> <span class="op">=</span> <span class="ident">parse_com</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">reader</span>)<span class="question-mark">?</span>;
},
<span class="comment">// Application data</span>
<span class="ident">Marker::APP</span>(..) <span class="op">=</span><span class="op">></span> {
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">data</span>) <span class="op">=</span> <span class="ident">parse_app</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">reader</span>, <span class="ident">marker</span>)<span class="question-mark">?</span> {
<span class="kw">match</span> <span class="ident">data</span> {
<span class="ident">AppData::Adobe</span>(<span class="ident">color_transform</span>) <span class="op">=</span><span class="op">></span> <span class="self">self</span>.<span class="ident">color_transform</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">color_transform</span>),
<span class="ident">AppData::Jfif</span> <span class="op">=</span><span class="op">></span> {
<span class="comment">// From the JFIF spec:</span>
<span class="comment">// "The APP0 marker is used to identify a JPEG FIF file.</span>
<span class="comment">// The JPEG FIF APP0 marker is mandatory right after the SOI marker."</span>
<span class="comment">// Some JPEGs in the wild does not follow this though, so we allow</span>
<span class="comment">// JFIF headers anywhere APP0 markers are allowed.</span>
<span class="comment">/*
if previous_marker != Marker::SOI {
return Err(Error::Format("the JFIF APP0 marker must come right after the SOI marker".to_owned()));
}
*/</span>
<span class="self">self</span>.<span class="ident">is_jfif</span> <span class="op">=</span> <span class="bool-val">true</span>;
},
<span class="ident">AppData::Avi1</span> <span class="op">=</span><span class="op">></span> <span class="self">self</span>.<span class="ident">is_mjpeg</span> <span class="op">=</span> <span class="bool-val">true</span>,
<span class="ident">AppData::Icc</span>(<span class="ident">icc</span>) <span class="op">=</span><span class="op">></span> <span class="self">self</span>.<span class="ident">icc_markers</span>.<span class="ident">push</span>(<span class="ident">icc</span>),
}
}
},
<span class="comment">// Restart</span>
<span class="ident">Marker::RST</span>(..) <span class="op">=</span><span class="op">></span> {
<span class="comment">// Some encoders emit a final RST marker after entropy-coded data, which</span>
<span class="comment">// decode_scan does not take care of. So if we encounter one, we ignore it.</span>
<span class="kw">if</span> <span class="ident">previous_marker</span> <span class="op">!</span><span class="op">=</span> <span class="ident">Marker::SOS</span> {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Format</span>(<span class="string">"RST found outside of entropy-coded data"</span>.<span class="ident">to_owned</span>()));
}
},
<span class="comment">// Define number of lines</span>
<span class="ident">Marker::DNL</span> <span class="op">=</span><span class="op">></span> {
<span class="comment">// Section B.2.1</span>
<span class="comment">// "If a DNL segment (see B.2.5) is present, it shall immediately follow the first scan."</span>
<span class="kw">if</span> <span class="ident">previous_marker</span> <span class="op">!</span><span class="op">=</span> <span class="ident">Marker::SOS</span> <span class="op">|</span><span class="op">|</span> <span class="ident">scans_processed</span> <span class="op">!</span><span class="op">=</span> <span class="number">1</span> {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Format</span>(<span class="string">"DNL is only allowed immediately after the first scan"</span>.<span class="ident">to_owned</span>()));
}
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Unsupported</span>(<span class="ident">UnsupportedFeature::DNL</span>));
},
<span class="comment">// Hierarchical mode markers</span>
<span class="ident">Marker::DHP</span> <span class="op">|</span> <span class="ident">Marker::EXP</span> <span class="op">=</span><span class="op">></span> <span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Unsupported</span>(<span class="ident">UnsupportedFeature::Hierarchical</span>)),
<span class="comment">// End of image</span>
<span class="ident">Marker::EOI</span> <span class="op">=</span><span class="op">></span> <span class="kw">break</span>,
<span class="kw">_</span> <span class="op">=</span><span class="op">></span> <span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Format</span>(<span class="macro">format!</span>(<span class="string">"{:?} marker found where not allowed"</span>, <span class="ident">marker</span>))),
}
<span class="ident">previous_marker</span> <span class="op">=</span> <span class="ident">marker</span>;
}
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">frame</span>.<span class="ident">is_none</span>() {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Format</span>(<span class="string">"end of image encountered before frame"</span>.<span class="ident">to_owned</span>()));
}
<span class="kw">let</span> <span class="ident">frame</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">frame</span>.<span class="ident">as_ref</span>().<span class="ident">unwrap</span>();
<span class="comment">// If we're decoding a progressive jpeg and a component is unfinished, render what we've got</span>
<span class="kw">if</span> <span class="ident">frame</span>.<span class="ident">coding_process</span> <span class="op">=</span><span class="op">=</span> <span class="ident">CodingProcess::DctProgressive</span> <span class="op">&&</span> <span class="self">self</span>.<span class="ident">coefficients</span>.<span class="ident">len</span>() <span class="op">=</span><span class="op">=</span> <span class="ident">frame</span>.<span class="ident">components</span>.<span class="ident">len</span>() {
<span class="kw">for</span> (<span class="ident">i</span>, <span class="ident">component</span>) <span class="kw">in</span> <span class="ident">frame</span>.<span class="ident">components</span>.<span class="ident">iter</span>().<span class="ident">enumerate</span>() {
<span class="comment">// Only dealing with unfinished components</span>
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">coefficients_finished</span>[<span class="ident">i</span>] <span class="op">=</span><span class="op">=</span> <span class="op">!</span><span class="number">0</span> {
<span class="kw">continue</span>;
}
<span class="kw">let</span> <span class="ident">quantization_table</span> <span class="op">=</span> <span class="kw">match</span> <span class="self">self</span>.<span class="ident">quantization_tables</span>[<span class="ident">component</span>.<span class="ident">quantization_table_index</span>].<span class="ident">clone</span>() {
<span class="prelude-val">Some</span>(<span class="ident">quantization_table</span>) <span class="op">=</span><span class="op">></span> <span class="ident">quantization_table</span>,
<span class="prelude-val">None</span> <span class="op">=</span><span class="op">></span> <span class="kw">continue</span>,
};
<span class="comment">// Get the worker prepared</span>
<span class="kw">if</span> <span class="ident">worker</span>.<span class="ident">is_none</span>() {
<span class="ident">worker</span> <span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">PlatformWorker::new</span>()<span class="question-mark">?</span>);
}
<span class="kw">let</span> <span class="ident">worker</span> <span class="op">=</span> <span class="ident">worker</span>.<span class="ident">as_mut</span>().<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="ident">row_data</span> <span class="op">=</span> <span class="ident">RowData</span> {
<span class="ident">index</span>: <span class="ident">i</span>,
<span class="ident">component</span>: <span class="ident">component</span>.<span class="ident">clone</span>(),
<span class="ident">quantization_table</span>,
};
<span class="ident">worker</span>.<span class="ident">start</span>(<span class="ident">row_data</span>)<span class="question-mark">?</span>;
<span class="comment">// Send the rows over to the worker and collect the result</span>
<span class="kw">let</span> <span class="ident">coefficients_per_mcu_row</span> <span class="op">=</span> <span class="ident">usize::from</span>(<span class="ident">component</span>.<span class="ident">block_size</span>.<span class="ident">width</span>) <span class="op">*</span> <span class="ident">usize::from</span>(<span class="ident">component</span>.<span class="ident">vertical_sampling_factor</span>) <span class="op">*</span> <span class="number">64</span>;
<span class="kw">for</span> <span class="ident">mcu_y</span> <span class="kw">in</span> <span class="number">0</span>..<span class="ident">frame</span>.<span class="ident">mcu_size</span>.<span class="ident">height</span> {
<span class="kw">let</span> <span class="ident">row_coefficients</span> <span class="op">=</span> {
<span class="kw">let</span> <span class="ident">offset</span> <span class="op">=</span> <span class="ident">usize::from</span>(<span class="ident">mcu_y</span>) <span class="op">*</span> <span class="ident">coefficients_per_mcu_row</span>;
<span class="self">self</span>.<span class="ident">coefficients</span>[<span class="ident">i</span>][<span class="ident">offset</span> .. <span class="ident">offset</span> <span class="op">+</span> <span class="ident">coefficients_per_mcu_row</span>].<span class="ident">to_vec</span>()
};
<span class="ident">worker</span>.<span class="ident">append_row</span>((<span class="ident">i</span>, <span class="ident">row_coefficients</span>))<span class="question-mark">?</span>;
}
<span class="ident">planes</span>[<span class="ident">i</span>] <span class="op">=</span> <span class="ident">worker</span>.<span class="ident">get_result</span>(<span class="ident">i</span>)<span class="question-mark">?</span>;
}
}
<span class="ident">compute_image</span>(<span class="kw-2">&</span><span class="ident">frame</span>.<span class="ident">components</span>, <span class="ident">planes</span>, <span class="ident">frame</span>.<span class="ident">output_size</span>, <span class="self">self</span>.<span class="ident">is_jfif</span>, <span class="self">self</span>.<span class="ident">color_transform</span>)
}
<span class="kw">fn</span> <span class="ident">read_marker</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">Marker</span><span class="op">></span> {
<span class="kw">loop</span> {
<span class="comment">// This should be an error as the JPEG spec doesn't allow extraneous data between marker segments.</span>
<span class="comment">// libjpeg allows this though and there are images in the wild utilising it, so we are</span>
<span class="comment">// forced to support this behavior.</span>
<span class="comment">// Sony Ericsson P990i is an example of a device which produce this sort of JPEGs.</span>
<span class="kw">while</span> <span class="ident">read_u8</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">reader</span>)<span class="question-mark">?</span> <span class="op">!</span><span class="op">=</span> <span class="number">0xFF</span> {}
<span class="comment">// Section B.1.1.2</span>
<span class="comment">// All markers are assigned two-byte codes: an X’FF’ byte followed by a</span>
<span class="comment">// byte which is not equal to 0 or X’FF’ (see Table B.1). Any marker may</span>
<span class="comment">// optionally be preceded by any number of fill bytes, which are bytes</span>
<span class="comment">// assigned code X’FF’.</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">byte</span> <span class="op">=</span> <span class="ident">read_u8</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">reader</span>)<span class="question-mark">?</span>;
<span class="comment">// Section B.1.1.2</span>
<span class="comment">// "Any marker may optionally be preceded by any number of fill bytes, which are bytes assigned code X’FF’."</span>
<span class="kw">while</span> <span class="ident">byte</span> <span class="op">=</span><span class="op">=</span> <span class="number">0xFF</span> {
<span class="ident">byte</span> <span class="op">=</span> <span class="ident">read_u8</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">reader</span>)<span class="question-mark">?</span>;
}
<span class="kw">if</span> <span class="ident">byte</span> <span class="op">!</span><span class="op">=</span> <span class="number">0x00</span> <span class="op">&&</span> <span class="ident">byte</span> <span class="op">!</span><span class="op">=</span> <span class="number">0xFF</span> {
<span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="ident">Marker::from_u8</span>(<span class="ident">byte</span>).<span class="ident">unwrap</span>());
}
}
}
<span class="kw">fn</span> <span class="ident">decode_scan</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>,
<span class="ident">frame</span>: <span class="kw-2">&</span><span class="ident">FrameInfo</span>,
<span class="ident">scan</span>: <span class="kw-2">&</span><span class="ident">ScanInfo</span>,
<span class="ident">worker</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">PlatformWorker</span>,
<span class="ident">finished</span>: <span class="kw-2">&</span>[<span class="ident">bool</span>; <span class="ident">MAX_COMPONENTS</span>])
<span class="op">-</span><span class="op">></span> <span class="prelude-ty">Result</span><span class="op"><</span>(<span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">Marker</span><span class="op">></span>, <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span><span class="op">></span><span class="op">></span>)<span class="op">></span> {
<span class="macro">assert!</span>(<span class="ident">scan</span>.<span class="ident">component_indices</span>.<span class="ident">len</span>() <span class="op"><</span><span class="op">=</span> <span class="ident">MAX_COMPONENTS</span>);
<span class="kw">let</span> <span class="ident">components</span>: <span class="ident">Vec</span><span class="op"><</span><span class="ident">Component</span><span class="op">></span> <span class="op">=</span> <span class="ident">scan</span>.<span class="ident">component_indices</span>.<span class="ident">iter</span>()
.<span class="ident">map</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">i</span><span class="op">|</span> <span class="ident">frame</span>.<span class="ident">components</span>[<span class="ident">i</span>].<span class="ident">clone</span>())
.<span class="ident">collect</span>();
<span class="comment">// Verify that all required quantization tables has been set.</span>
<span class="kw">if</span> <span class="ident">components</span>.<span class="ident">iter</span>().<span class="ident">any</span>(<span class="op">|</span><span class="ident">component</span><span class="op">|</span> <span class="self">self</span>.<span class="ident">quantization_tables</span>[<span class="ident">component</span>.<span class="ident">quantization_table_index</span>].<span class="ident">is_none</span>()) {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Format</span>(<span class="string">"use of unset quantization table"</span>.<span class="ident">to_owned</span>()));
}
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">is_mjpeg</span> {
<span class="ident">fill_default_mjpeg_tables</span>(<span class="ident">scan</span>, <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">dc_huffman_tables</span>, <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">ac_huffman_tables</span>);
}
<span class="comment">// Verify that all required huffman tables has been set.</span>
<span class="kw">if</span> <span class="ident">scan</span>.<span class="ident">spectral_selection</span>.<span class="ident">start</span> <span class="op">=</span><span class="op">=</span> <span class="number">0</span> <span class="op">&&</span>
<span class="ident">scan</span>.<span class="ident">dc_table_indices</span>.<span class="ident">iter</span>().<span class="ident">any</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">i</span><span class="op">|</span> <span class="self">self</span>.<span class="ident">dc_huffman_tables</span>[<span class="ident">i</span>].<span class="ident">is_none</span>()) {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Format</span>(<span class="string">"scan makes use of unset dc huffman table"</span>.<span class="ident">to_owned</span>()));
}
<span class="kw">if</span> <span class="ident">scan</span>.<span class="ident">spectral_selection</span>.<span class="ident">end</span> <span class="op">></span> <span class="number">1</span> <span class="op">&&</span>
<span class="ident">scan</span>.<span class="ident">ac_table_indices</span>.<span class="ident">iter</span>().<span class="ident">any</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">i</span><span class="op">|</span> <span class="self">self</span>.<span class="ident">ac_huffman_tables</span>[<span class="ident">i</span>].<span class="ident">is_none</span>()) {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Format</span>(<span class="string">"scan makes use of unset ac huffman table"</span>.<span class="ident">to_owned</span>()));
}
<span class="comment">// Prepare the worker thread for the work to come.</span>
<span class="kw">for</span> (<span class="ident">i</span>, <span class="ident">component</span>) <span class="kw">in</span> <span class="ident">components</span>.<span class="ident">iter</span>().<span class="ident">enumerate</span>() {
<span class="kw">if</span> <span class="ident">finished</span>[<span class="ident">i</span>] {
<span class="kw">let</span> <span class="ident">row_data</span> <span class="op">=</span> <span class="ident">RowData</span> {
<span class="ident">index</span>: <span class="ident">i</span>,
<span class="ident">component</span>: <span class="ident">component</span>.<span class="ident">clone</span>(),
<span class="ident">quantization_table</span>: <span class="self">self</span>.<span class="ident">quantization_tables</span>[<span class="ident">component</span>.<span class="ident">quantization_table_index</span>].<span class="ident">clone</span>().<span class="ident">unwrap</span>(),
};
<span class="ident">worker</span>.<span class="ident">start</span>(<span class="ident">row_data</span>)<span class="question-mark">?</span>;
}
}
<span class="kw">let</span> <span class="ident">is_progressive</span> <span class="op">=</span> <span class="ident">frame</span>.<span class="ident">coding_process</span> <span class="op">=</span><span class="op">=</span> <span class="ident">CodingProcess::DctProgressive</span>;
<span class="kw">let</span> <span class="ident">is_interleaved</span> <span class="op">=</span> <span class="ident">components</span>.<span class="ident">len</span>() <span class="op">></span> <span class="number">1</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">dummy_block</span> <span class="op">=</span> [<span class="number">0i16</span>; <span class="number">64</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">huffman</span> <span class="op">=</span> <span class="ident">HuffmanDecoder::new</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">dc_predictors</span> <span class="op">=</span> [<span class="number">0i16</span>; <span class="ident">MAX_COMPONENTS</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">mcus_left_until_restart</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">restart_interval</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">expected_rst_num</span> <span class="op">=</span> <span class="number">0</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">eob_run</span> <span class="op">=</span> <span class="number">0</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">mcu_row_coefficients</span> <span class="op">=</span> <span class="ident">Vec::with_capacity</span>(<span class="ident">components</span>.<span class="ident">len</span>());
<span class="kw">if</span> <span class="op">!</span><span class="ident">is_progressive</span> {
<span class="kw">for</span> (<span class="kw">_</span>, <span class="ident">component</span>) <span class="kw">in</span> <span class="ident">components</span>.<span class="ident">iter</span>().<span class="ident">enumerate</span>().<span class="ident">filter</span>(<span class="op">|</span><span class="kw-2">&</span>(<span class="ident">i</span>, <span class="kw">_</span>)<span class="op">|</span> <span class="ident">finished</span>[<span class="ident">i</span>]) {
<span class="kw">let</span> <span class="ident">coefficients_per_mcu_row</span> <span class="op">=</span> <span class="ident">component</span>.<span class="ident">block_size</span>.<span class="ident">width</span> <span class="kw">as</span> <span class="ident">usize</span> <span class="op">*</span> <span class="ident">component</span>.<span class="ident">vertical_sampling_factor</span> <span class="kw">as</span> <span class="ident">usize</span> <span class="op">*</span> <span class="number">64</span>;
<span class="ident">mcu_row_coefficients</span>.<span class="ident">push</span>(<span class="macro">vec!</span>[<span class="number">0i16</span>; <span class="ident">coefficients_per_mcu_row</span>]);
}
}
<span class="comment">// 4.8.2</span>
<span class="comment">// When reading from the stream, if the data is non-interleaved then an MCU consists of</span>
<span class="comment">// exactly one block (effectively a 1x1 sample).</span>
<span class="kw">let</span> (<span class="ident">mcu_horizontal_samples</span>, <span class="ident">mcu_vertical_samples</span>) <span class="op">=</span> <span class="kw">if</span> <span class="ident">is_interleaved</span> {
<span class="kw">let</span> <span class="ident">horizontal</span> <span class="op">=</span> <span class="ident">components</span>.<span class="ident">iter</span>().<span class="ident">map</span>(<span class="op">|</span><span class="ident">component</span><span class="op">|</span> <span class="ident">component</span>.<span class="ident">horizontal_sampling_factor</span> <span class="kw">as</span> <span class="ident">u16</span>).<span class="ident">collect</span>::<span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="kw">_</span><span class="op">></span><span class="op">></span>();
<span class="kw">let</span> <span class="ident">vertical</span> <span class="op">=</span> <span class="ident">components</span>.<span class="ident">iter</span>().<span class="ident">map</span>(<span class="op">|</span><span class="ident">component</span><span class="op">|</span> <span class="ident">component</span>.<span class="ident">vertical_sampling_factor</span> <span class="kw">as</span> <span class="ident">u16</span>).<span class="ident">collect</span>::<span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="kw">_</span><span class="op">></span><span class="op">></span>();
(<span class="ident">horizontal</span>, <span class="ident">vertical</span>)
} <span class="kw">else</span> {
(<span class="macro">vec!</span>[<span class="number">1</span>], <span class="macro">vec!</span>[<span class="number">1</span>])
};
<span class="comment">// This also affects how many MCU values we read from stream. If it's a non-interleaved stream,</span>
<span class="comment">// the MCUs will be exactly the block count.</span>
<span class="kw">let</span> (<span class="ident">max_mcu_x</span>, <span class="ident">max_mcu_y</span>) <span class="op">=</span> <span class="kw">if</span> <span class="ident">is_interleaved</span> {
(<span class="ident">frame</span>.<span class="ident">mcu_size</span>.<span class="ident">width</span>, <span class="ident">frame</span>.<span class="ident">mcu_size</span>.<span class="ident">height</span>)
} <span class="kw">else</span> {
(<span class="ident">components</span>[<span class="number">0</span>].<span class="ident">block_size</span>.<span class="ident">width</span>, <span class="ident">components</span>[<span class="number">0</span>].<span class="ident">block_size</span>.<span class="ident">height</span>)
};
<span class="kw">for</span> <span class="ident">mcu_y</span> <span class="kw">in</span> <span class="number">0</span>..<span class="ident">max_mcu_y</span> {
<span class="kw">if</span> <span class="ident">mcu_y</span> <span class="op">*</span> <span class="number">8</span> <span class="op">></span><span class="op">=</span> <span class="ident">frame</span>.<span class="ident">image_size</span>.<span class="ident">height</span> {
<span class="kw">break</span>;
}
<span class="kw">for</span> <span class="ident">mcu_x</span> <span class="kw">in</span> <span class="number">0</span>..<span class="ident">max_mcu_x</span> {
<span class="kw">if</span> <span class="ident">mcu_x</span> <span class="op">*</span> <span class="number">8</span> <span class="op">></span><span class="op">=</span> <span class="ident">frame</span>.<span class="ident">image_size</span>.<span class="ident">width</span> {
<span class="kw">break</span>;
}
<span class="kw">if</span> <span class="self">self</span>.<span class="ident">restart_interval</span> <span class="op">></span> <span class="number">0</span> {
<span class="kw">if</span> <span class="ident">mcus_left_until_restart</span> <span class="op">=</span><span class="op">=</span> <span class="number">0</span> {
<span class="kw">match</span> <span class="ident">huffman</span>.<span class="ident">take_marker</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">reader</span>)<span class="question-mark">?</span> {
<span class="prelude-val">Some</span>(<span class="ident">Marker::RST</span>(<span class="ident">n</span>)) <span class="op">=</span><span class="op">></span> {
<span class="kw">if</span> <span class="ident">n</span> <span class="op">!</span><span class="op">=</span> <span class="ident">expected_rst_num</span> {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Format</span>(<span class="macro">format!</span>(<span class="string">"found RST{} where RST{} was expected"</span>, <span class="ident">n</span>, <span class="ident">expected_rst_num</span>)));
}
<span class="ident">huffman</span>.<span class="ident">reset</span>();
<span class="comment">// Section F.2.1.3.1</span>
<span class="ident">dc_predictors</span> <span class="op">=</span> [<span class="number">0i16</span>; <span class="ident">MAX_COMPONENTS</span>];
<span class="comment">// Section G.1.2.2</span>
<span class="ident">eob_run</span> <span class="op">=</span> <span class="number">0</span>;
<span class="ident">expected_rst_num</span> <span class="op">=</span> (<span class="ident">expected_rst_num</span> <span class="op">+</span> <span class="number">1</span>) <span class="op">%</span> <span class="number">8</span>;
<span class="ident">mcus_left_until_restart</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">restart_interval</span>;
},
<span class="prelude-val">Some</span>(<span class="ident">marker</span>) <span class="op">=</span><span class="op">></span> <span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Format</span>(<span class="macro">format!</span>(<span class="string">"found marker {:?} inside scan where RST{} was expected"</span>, <span class="ident">marker</span>, <span class="ident">expected_rst_num</span>))),
<span class="prelude-val">None</span> <span class="op">=</span><span class="op">></span> <span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Format</span>(<span class="macro">format!</span>(<span class="string">"no marker found where RST{} was expected"</span>, <span class="ident">expected_rst_num</span>))),
}
}
<span class="ident">mcus_left_until_restart</span> <span class="op">-</span><span class="op">=</span> <span class="number">1</span>;
}
<span class="kw">for</span> (<span class="ident">i</span>, <span class="ident">component</span>) <span class="kw">in</span> <span class="ident">components</span>.<span class="ident">iter</span>().<span class="ident">enumerate</span>() {
<span class="kw">for</span> <span class="ident">v_pos</span> <span class="kw">in</span> <span class="number">0</span>..<span class="ident">mcu_vertical_samples</span>[<span class="ident">i</span>] {
<span class="kw">for</span> <span class="ident">h_pos</span> <span class="kw">in</span> <span class="number">0</span>..<span class="ident">mcu_horizontal_samples</span>[<span class="ident">i</span>] {
<span class="kw">let</span> <span class="ident">coefficients</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">is_progressive</span> {
<span class="kw">let</span> <span class="ident">block_y</span> <span class="op">=</span> (<span class="ident">mcu_y</span> <span class="op">*</span> <span class="ident">mcu_vertical_samples</span>[<span class="ident">i</span>] <span class="op">+</span> <span class="ident">v_pos</span>) <span class="kw">as</span> <span class="ident">usize</span>;
<span class="kw">let</span> <span class="ident">block_x</span> <span class="op">=</span> (<span class="ident">mcu_x</span> <span class="op">*</span> <span class="ident">mcu_horizontal_samples</span>[<span class="ident">i</span>] <span class="op">+</span> <span class="ident">h_pos</span>) <span class="kw">as</span> <span class="ident">usize</span>;
<span class="kw">let</span> <span class="ident">block_offset</span> <span class="op">=</span> (<span class="ident">block_y</span> <span class="op">*</span> <span class="ident">component</span>.<span class="ident">block_size</span>.<span class="ident">width</span> <span class="kw">as</span> <span class="ident">usize</span> <span class="op">+</span> <span class="ident">block_x</span>) <span class="op">*</span> <span class="number">64</span>;
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">coefficients</span>[<span class="ident">scan</span>.<span class="ident">component_indices</span>[<span class="ident">i</span>]][<span class="ident">block_offset</span>..<span class="ident">block_offset</span> <span class="op">+</span> <span class="number">64</span>]
} <span class="kw">else</span> <span class="kw">if</span> <span class="ident">finished</span>[<span class="ident">i</span>] {
<span class="comment">// Because the worker thread operates in batches as if we were always interleaved, we</span>
<span class="comment">// need to distinguish between a single-shot buffer and one that's currently in process</span>
<span class="comment">// (for a non-interleaved) stream</span>
<span class="kw">let</span> <span class="ident">mcu_batch_current_row</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">is_interleaved</span> {
<span class="number">0</span>
} <span class="kw">else</span> {
<span class="ident">mcu_y</span> <span class="op">%</span> <span class="ident">component</span>.<span class="ident">vertical_sampling_factor</span> <span class="kw">as</span> <span class="ident">u16</span>
};
<span class="kw">let</span> <span class="ident">block_y</span> <span class="op">=</span> (<span class="ident">mcu_batch_current_row</span> <span class="op">*</span> <span class="ident">mcu_vertical_samples</span>[<span class="ident">i</span>] <span class="op">+</span> <span class="ident">v_pos</span>) <span class="kw">as</span> <span class="ident">usize</span>;
<span class="kw">let</span> <span class="ident">block_x</span> <span class="op">=</span> (<span class="ident">mcu_x</span> <span class="op">*</span> <span class="ident">mcu_horizontal_samples</span>[<span class="ident">i</span>] <span class="op">+</span> <span class="ident">h_pos</span>) <span class="kw">as</span> <span class="ident">usize</span>;
<span class="kw">let</span> <span class="ident">block_offset</span> <span class="op">=</span> (<span class="ident">block_y</span> <span class="op">*</span> <span class="ident">component</span>.<span class="ident">block_size</span>.<span class="ident">width</span> <span class="kw">as</span> <span class="ident">usize</span> <span class="op">+</span> <span class="ident">block_x</span>) <span class="op">*</span> <span class="number">64</span>;
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">mcu_row_coefficients</span>[<span class="ident">i</span>][<span class="ident">block_offset</span>..<span class="ident">block_offset</span> <span class="op">+</span> <span class="number">64</span>]
} <span class="kw">else</span> {
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">dummy_block</span>[..]
};
<span class="kw">if</span> <span class="ident">scan</span>.<span class="ident">successive_approximation_high</span> <span class="op">=</span><span class="op">=</span> <span class="number">0</span> {
<span class="ident">decode_block</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">reader</span>,
<span class="ident">coefficients</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">huffman</span>,
<span class="self">self</span>.<span class="ident">dc_huffman_tables</span>[<span class="ident">scan</span>.<span class="ident">dc_table_indices</span>[<span class="ident">i</span>]].<span class="ident">as_ref</span>(),
<span class="self">self</span>.<span class="ident">ac_huffman_tables</span>[<span class="ident">scan</span>.<span class="ident">ac_table_indices</span>[<span class="ident">i</span>]].<span class="ident">as_ref</span>(),
<span class="ident">scan</span>.<span class="ident">spectral_selection</span>.<span class="ident">clone</span>(),
<span class="ident">scan</span>.<span class="ident">successive_approximation_low</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">eob_run</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">dc_predictors</span>[<span class="ident">i</span>])<span class="question-mark">?</span>;
}
<span class="kw">else</span> {
<span class="ident">decode_block_successive_approximation</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">reader</span>,
<span class="ident">coefficients</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">huffman</span>,
<span class="self">self</span>.<span class="ident">ac_huffman_tables</span>[<span class="ident">scan</span>.<span class="ident">ac_table_indices</span>[<span class="ident">i</span>]].<span class="ident">as_ref</span>(),
<span class="ident">scan</span>.<span class="ident">spectral_selection</span>.<span class="ident">clone</span>(),
<span class="ident">scan</span>.<span class="ident">successive_approximation_low</span>,
<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">eob_run</span>)<span class="question-mark">?</span>;
}
}
}
}
}
<span class="comment">// Send the coefficients from this MCU row to the worker thread for dequantization and idct.</span>
<span class="kw">for</span> (<span class="ident">i</span>, <span class="ident">component</span>) <span class="kw">in</span> <span class="ident">components</span>.<span class="ident">iter</span>().<span class="ident">enumerate</span>() {
<span class="kw">if</span> <span class="ident">finished</span>[<span class="ident">i</span>] {
<span class="comment">// In the event of non-interleaved streams, if we're still building the buffer out,</span>
<span class="comment">// keep going; don't send it yet. We also need to ensure we don't skip over the last</span>
<span class="comment">// row(s) of the image.</span>
<span class="kw">if</span> <span class="op">!</span><span class="ident">is_interleaved</span> <span class="op">&&</span> (<span class="ident">mcu_y</span> <span class="op">+</span> <span class="number">1</span>) <span class="op">*</span> <span class="number">8</span> <span class="op"><</span> <span class="ident">frame</span>.<span class="ident">image_size</span>.<span class="ident">height</span> {
<span class="kw">if</span> (<span class="ident">mcu_y</span> <span class="op">+</span> <span class="number">1</span>) <span class="op">%</span> <span class="ident">component</span>.<span class="ident">vertical_sampling_factor</span> <span class="kw">as</span> <span class="ident">u16</span> <span class="op">></span> <span class="number">0</span> {
<span class="kw">continue</span>;
}
}
<span class="kw">let</span> <span class="ident">coefficients_per_mcu_row</span> <span class="op">=</span> <span class="ident">component</span>.<span class="ident">block_size</span>.<span class="ident">width</span> <span class="kw">as</span> <span class="ident">usize</span> <span class="op">*</span> <span class="ident">component</span>.<span class="ident">vertical_sampling_factor</span> <span class="kw">as</span> <span class="ident">usize</span> <span class="op">*</span> <span class="number">64</span>;
<span class="kw">let</span> <span class="ident">row_coefficients</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">is_progressive</span> {
<span class="comment">// Because non-interleaved streams will have multiple MCU rows concatenated together,</span>
<span class="comment">// the row for calculating the offset is different.</span>
<span class="kw">let</span> <span class="ident">worker_mcu_y</span> <span class="op">=</span> <span class="kw">if</span> <span class="ident">is_interleaved</span> {
<span class="ident">mcu_y</span>
} <span class="kw">else</span> {
<span class="comment">// Explicitly doing floor-division here</span>
<span class="ident">mcu_y</span> <span class="op">/</span> <span class="ident">component</span>.<span class="ident">vertical_sampling_factor</span> <span class="kw">as</span> <span class="ident">u16</span>
};
<span class="kw">let</span> <span class="ident">offset</span> <span class="op">=</span> <span class="ident">worker_mcu_y</span> <span class="kw">as</span> <span class="ident">usize</span> <span class="op">*</span> <span class="ident">coefficients_per_mcu_row</span>;
<span class="self">self</span>.<span class="ident">coefficients</span>[<span class="ident">scan</span>.<span class="ident">component_indices</span>[<span class="ident">i</span>]][<span class="ident">offset</span> .. <span class="ident">offset</span> <span class="op">+</span> <span class="ident">coefficients_per_mcu_row</span>].<span class="ident">to_vec</span>()
} <span class="kw">else</span> {
<span class="ident">mem::replace</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">mcu_row_coefficients</span>[<span class="ident">i</span>], <span class="macro">vec!</span>[<span class="number">0i16</span>; <span class="ident">coefficients_per_mcu_row</span>])
};
<span class="ident">worker</span>.<span class="ident">append_row</span>((<span class="ident">i</span>, <span class="ident">row_coefficients</span>))<span class="question-mark">?</span>;
}
}
}
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">marker</span> <span class="op">=</span> <span class="ident">huffman</span>.<span class="ident">take_marker</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> <span class="self">self</span>.<span class="ident">reader</span>)<span class="question-mark">?</span>;
<span class="kw">while</span> <span class="kw">let</span> <span class="prelude-val">Some</span>(<span class="ident">Marker::RST</span>(<span class="kw">_</span>)) <span class="op">=</span> <span class="ident">marker</span> {
<span class="ident">marker</span> <span class="op">=</span> <span class="self">self</span>.<span class="ident">read_marker</span>().<span class="ident">ok</span>();
}
<span class="kw">if</span> <span class="ident">finished</span>.<span class="ident">iter</span>().<span class="ident">any</span>(<span class="op">|</span><span class="kw-2">&</span><span class="ident">c</span><span class="op">|</span> <span class="ident">c</span>) {
<span class="comment">// Retrieve all the data from the worker thread.</span>
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">data</span> <span class="op">=</span> <span class="macro">vec!</span>[<span class="ident">Vec::new</span>(); <span class="ident">frame</span>.<span class="ident">components</span>.<span class="ident">len</span>()];
<span class="kw">for</span> (<span class="ident">i</span>, <span class="kw-2">&</span><span class="ident">component_index</span>) <span class="kw">in</span> <span class="ident">scan</span>.<span class="ident">component_indices</span>.<span class="ident">iter</span>().<span class="ident">enumerate</span>() {
<span class="kw">if</span> <span class="ident">finished</span>[<span class="ident">i</span>] {
<span class="ident">data</span>[<span class="ident">component_index</span>] <span class="op">=</span> <span class="ident">worker</span>.<span class="ident">get_result</span>(<span class="ident">i</span>)<span class="question-mark">?</span>;
}
}
<span class="prelude-val">Ok</span>((<span class="ident">marker</span>, <span class="prelude-val">Some</span>(<span class="ident">data</span>)))
}
<span class="kw">else</span> {
<span class="prelude-val">Ok</span>((<span class="ident">marker</span>, <span class="prelude-val">None</span>))
}
}
}
<span class="kw">fn</span> <span class="ident">decode_block</span><span class="op"><</span><span class="ident">R</span>: <span class="ident">Read</span><span class="op">></span>(<span class="ident">reader</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">R</span>,
<span class="ident">coefficients</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> [<span class="ident">i16</span>],
<span class="ident">huffman</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">HuffmanDecoder</span>,
<span class="ident">dc_table</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">HuffmanTable</span><span class="op">></span>,
<span class="ident">ac_table</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">HuffmanTable</span><span class="op">></span>,
<span class="ident">spectral_selection</span>: <span class="ident">Range</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span>,
<span class="ident">successive_approximation_low</span>: <span class="ident">u8</span>,
<span class="ident">eob_run</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">u16</span>,
<span class="ident">dc_predictor</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">i16</span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Result</span><span class="op"><</span>()<span class="op">></span> {
<span class="macro">debug_assert_eq!</span>(<span class="ident">coefficients</span>.<span class="ident">len</span>(), <span class="number">64</span>);
<span class="kw">if</span> <span class="ident">spectral_selection</span>.<span class="ident">start</span> <span class="op">=</span><span class="op">=</span> <span class="number">0</span> {
<span class="comment">// Section F.2.2.1</span>
<span class="comment">// Figure F.12</span>
<span class="kw">let</span> <span class="ident">value</span> <span class="op">=</span> <span class="ident">huffman</span>.<span class="ident">decode</span>(<span class="ident">reader</span>, <span class="ident">dc_table</span>.<span class="ident">unwrap</span>())<span class="question-mark">?</span>;
<span class="kw">let</span> <span class="ident">diff</span> <span class="op">=</span> <span class="kw">match</span> <span class="ident">value</span> {
<span class="number">0</span> <span class="op">=</span><span class="op">></span> <span class="number">0</span>,
<span class="number">1</span>..<span class="op">=</span><span class="number">11</span> <span class="op">=</span><span class="op">></span> <span class="ident">huffman</span>.<span class="ident">receive_extend</span>(<span class="ident">reader</span>, <span class="ident">value</span>)<span class="question-mark">?</span>,
<span class="kw">_</span> <span class="op">=</span><span class="op">></span> {
<span class="comment">// Section F.1.2.1.1</span>
<span class="comment">// Table F.1</span>
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Format</span>(<span class="string">"invalid DC difference magnitude category"</span>.<span class="ident">to_owned</span>()));
},
};
<span class="comment">// Malicious JPEG files can cause this add to overflow, therefore we use wrapping_add.</span>
<span class="comment">// One example of such a file is tests/crashtest/images/dc-predictor-overflow.jpg</span>
<span class="kw-2">*</span><span class="ident">dc_predictor</span> <span class="op">=</span> <span class="ident">dc_predictor</span>.<span class="ident">wrapping_add</span>(<span class="ident">diff</span>);
<span class="ident">coefficients</span>[<span class="number">0</span>] <span class="op">=</span> <span class="kw-2">*</span><span class="ident">dc_predictor</span> <span class="op"><</span><span class="op"><</span> <span class="ident">successive_approximation_low</span>;
}
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">index</span> <span class="op">=</span> <span class="ident">cmp::max</span>(<span class="ident">spectral_selection</span>.<span class="ident">start</span>, <span class="number">1</span>);
<span class="kw">if</span> <span class="ident">index</span> <span class="op"><</span> <span class="ident">spectral_selection</span>.<span class="ident">end</span> <span class="op">&&</span> <span class="kw-2">*</span><span class="ident">eob_run</span> <span class="op">></span> <span class="number">0</span> {
<span class="kw-2">*</span><span class="ident">eob_run</span> <span class="op">-</span><span class="op">=</span> <span class="number">1</span>;
<span class="kw">return</span> <span class="prelude-val">Ok</span>(());
}
<span class="comment">// Section F.1.2.2.1</span>
<span class="kw">while</span> <span class="ident">index</span> <span class="op"><</span> <span class="ident">spectral_selection</span>.<span class="ident">end</span> {
<span class="kw">if</span> <span class="kw">let</span> <span class="prelude-val">Some</span>((<span class="ident">value</span>, <span class="ident">run</span>)) <span class="op">=</span> <span class="ident">huffman</span>.<span class="ident">decode_fast_ac</span>(<span class="ident">reader</span>, <span class="ident">ac_table</span>.<span class="ident">unwrap</span>())<span class="question-mark">?</span> {
<span class="ident">index</span> <span class="op">+</span><span class="op">=</span> <span class="ident">run</span>;
<span class="kw">if</span> <span class="ident">index</span> <span class="op">></span><span class="op">=</span> <span class="ident">spectral_selection</span>.<span class="ident">end</span> {
<span class="kw">break</span>;
}
<span class="ident">coefficients</span>[<span class="ident">UNZIGZAG</span>[<span class="ident">index</span> <span class="kw">as</span> <span class="ident">usize</span>] <span class="kw">as</span> <span class="ident">usize</span>] <span class="op">=</span> <span class="ident">value</span> <span class="op"><</span><span class="op"><</span> <span class="ident">successive_approximation_low</span>;
<span class="ident">index</span> <span class="op">+</span><span class="op">=</span> <span class="number">1</span>;
}
<span class="kw">else</span> {
<span class="kw">let</span> <span class="ident">byte</span> <span class="op">=</span> <span class="ident">huffman</span>.<span class="ident">decode</span>(<span class="ident">reader</span>, <span class="ident">ac_table</span>.<span class="ident">unwrap</span>())<span class="question-mark">?</span>;
<span class="kw">let</span> <span class="ident">r</span> <span class="op">=</span> <span class="ident">byte</span> <span class="op">></span><span class="op">></span> <span class="number">4</span>;
<span class="kw">let</span> <span class="ident">s</span> <span class="op">=</span> <span class="ident">byte</span> <span class="op">&</span> <span class="number">0x0f</span>;
<span class="kw">if</span> <span class="ident">s</span> <span class="op">=</span><span class="op">=</span> <span class="number">0</span> {
<span class="kw">match</span> <span class="ident">r</span> {
<span class="number">15</span> <span class="op">=</span><span class="op">></span> <span class="ident">index</span> <span class="op">+</span><span class="op">=</span> <span class="number">16</span>, <span class="comment">// Run length of 16 zero coefficients.</span>
<span class="kw">_</span> <span class="op">=</span><span class="op">></span> {
<span class="kw-2">*</span><span class="ident">eob_run</span> <span class="op">=</span> (<span class="number">1</span> <span class="op"><</span><span class="op"><</span> <span class="ident">r</span>) <span class="op">-</span> <span class="number">1</span>;
<span class="kw">if</span> <span class="ident">r</span> <span class="op">></span> <span class="number">0</span> {
<span class="kw-2">*</span><span class="ident">eob_run</span> <span class="op">+</span><span class="op">=</span> <span class="ident">huffman</span>.<span class="ident">get_bits</span>(<span class="ident">reader</span>, <span class="ident">r</span>)<span class="question-mark">?</span>;
}
<span class="kw">break</span>;
},
}
}
<span class="kw">else</span> {
<span class="ident">index</span> <span class="op">+</span><span class="op">=</span> <span class="ident">r</span>;
<span class="kw">if</span> <span class="ident">index</span> <span class="op">></span><span class="op">=</span> <span class="ident">spectral_selection</span>.<span class="ident">end</span> {
<span class="kw">break</span>;
}
<span class="ident">coefficients</span>[<span class="ident">UNZIGZAG</span>[<span class="ident">index</span> <span class="kw">as</span> <span class="ident">usize</span>] <span class="kw">as</span> <span class="ident">usize</span>] <span class="op">=</span> <span class="ident">huffman</span>.<span class="ident">receive_extend</span>(<span class="ident">reader</span>, <span class="ident">s</span>)<span class="question-mark">?</span> <span class="op"><</span><span class="op"><</span> <span class="ident">successive_approximation_low</span>;
<span class="ident">index</span> <span class="op">+</span><span class="op">=</span> <span class="number">1</span>;
}
}
}
<span class="prelude-val">Ok</span>(())
}
<span class="kw">fn</span> <span class="ident">decode_block_successive_approximation</span><span class="op"><</span><span class="ident">R</span>: <span class="ident">Read</span><span class="op">></span>(<span class="ident">reader</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">R</span>,
<span class="ident">coefficients</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> [<span class="ident">i16</span>],
<span class="ident">huffman</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">HuffmanDecoder</span>,
<span class="ident">ac_table</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="kw-2">&</span><span class="ident">HuffmanTable</span><span class="op">></span>,
<span class="ident">spectral_selection</span>: <span class="ident">Range</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span>,
<span class="ident">successive_approximation_low</span>: <span class="ident">u8</span>,
<span class="ident">eob_run</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">u16</span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Result</span><span class="op"><</span>()<span class="op">></span> {
<span class="macro">debug_assert_eq!</span>(<span class="ident">coefficients</span>.<span class="ident">len</span>(), <span class="number">64</span>);
<span class="kw">let</span> <span class="ident">bit</span> <span class="op">=</span> <span class="number">1</span> <span class="op"><</span><span class="op"><</span> <span class="ident">successive_approximation_low</span>;
<span class="kw">if</span> <span class="ident">spectral_selection</span>.<span class="ident">start</span> <span class="op">=</span><span class="op">=</span> <span class="number">0</span> {
<span class="comment">// Section G.1.2.1</span>
<span class="kw">if</span> <span class="ident">huffman</span>.<span class="ident">get_bits</span>(<span class="ident">reader</span>, <span class="number">1</span>)<span class="question-mark">?</span> <span class="op">=</span><span class="op">=</span> <span class="number">1</span> {
<span class="ident">coefficients</span>[<span class="number">0</span>] <span class="op">|</span><span class="op">=</span> <span class="ident">bit</span>;
}
}
<span class="kw">else</span> {
<span class="comment">// Section G.1.2.3</span>
<span class="kw">if</span> <span class="kw-2">*</span><span class="ident">eob_run</span> <span class="op">></span> <span class="number">0</span> {
<span class="kw-2">*</span><span class="ident">eob_run</span> <span class="op">-</span><span class="op">=</span> <span class="number">1</span>;
<span class="ident">refine_non_zeroes</span>(<span class="ident">reader</span>, <span class="ident">coefficients</span>, <span class="ident">huffman</span>, <span class="ident">spectral_selection</span>, <span class="number">64</span>, <span class="ident">bit</span>)<span class="question-mark">?</span>;
<span class="kw">return</span> <span class="prelude-val">Ok</span>(());
}
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">index</span> <span class="op">=</span> <span class="ident">spectral_selection</span>.<span class="ident">start</span>;
<span class="kw">while</span> <span class="ident">index</span> <span class="op"><</span> <span class="ident">spectral_selection</span>.<span class="ident">end</span> {
<span class="kw">let</span> <span class="ident">byte</span> <span class="op">=</span> <span class="ident">huffman</span>.<span class="ident">decode</span>(<span class="ident">reader</span>, <span class="ident">ac_table</span>.<span class="ident">unwrap</span>())<span class="question-mark">?</span>;
<span class="kw">let</span> <span class="ident">r</span> <span class="op">=</span> <span class="ident">byte</span> <span class="op">></span><span class="op">></span> <span class="number">4</span>;
<span class="kw">let</span> <span class="ident">s</span> <span class="op">=</span> <span class="ident">byte</span> <span class="op">&</span> <span class="number">0x0f</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">zero_run_length</span> <span class="op">=</span> <span class="ident">r</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">value</span> <span class="op">=</span> <span class="number">0</span>;
<span class="kw">match</span> <span class="ident">s</span> {
<span class="number">0</span> <span class="op">=</span><span class="op">></span> {
<span class="kw">match</span> <span class="ident">r</span> {
<span class="number">15</span> <span class="op">=</span><span class="op">></span> {
<span class="comment">// Run length of 16 zero coefficients.</span>
<span class="comment">// We don't need to do anything special here, zero_run_length is 15</span>
<span class="comment">// and then value (which is zero) gets written, resulting in 16</span>
<span class="comment">// zero coefficients.</span>
},
<span class="kw">_</span> <span class="op">=</span><span class="op">></span> {
<span class="kw-2">*</span><span class="ident">eob_run</span> <span class="op">=</span> (<span class="number">1</span> <span class="op"><</span><span class="op"><</span> <span class="ident">r</span>) <span class="op">-</span> <span class="number">1</span>;
<span class="kw">if</span> <span class="ident">r</span> <span class="op">></span> <span class="number">0</span> {
<span class="kw-2">*</span><span class="ident">eob_run</span> <span class="op">+</span><span class="op">=</span> <span class="ident">huffman</span>.<span class="ident">get_bits</span>(<span class="ident">reader</span>, <span class="ident">r</span>)<span class="question-mark">?</span>;
}
<span class="comment">// Force end of block.</span>
<span class="ident">zero_run_length</span> <span class="op">=</span> <span class="number">64</span>;
},
}
},
<span class="number">1</span> <span class="op">=</span><span class="op">></span> {
<span class="kw">if</span> <span class="ident">huffman</span>.<span class="ident">get_bits</span>(<span class="ident">reader</span>, <span class="number">1</span>)<span class="question-mark">?</span> <span class="op">=</span><span class="op">=</span> <span class="number">1</span> {
<span class="ident">value</span> <span class="op">=</span> <span class="ident">bit</span>;
}
<span class="kw">else</span> {
<span class="ident">value</span> <span class="op">=</span> <span class="op">-</span><span class="ident">bit</span>;
}
},
<span class="kw">_</span> <span class="op">=</span><span class="op">></span> <span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Format</span>(<span class="string">"unexpected huffman code"</span>.<span class="ident">to_owned</span>())),
}
<span class="kw">let</span> <span class="ident">range</span> <span class="op">=</span> <span class="ident">Range</span> {
<span class="ident">start</span>: <span class="ident">index</span>,
<span class="ident">end</span>: <span class="ident">spectral_selection</span>.<span class="ident">end</span>,
};
<span class="ident">index</span> <span class="op">=</span> <span class="ident">refine_non_zeroes</span>(<span class="ident">reader</span>, <span class="ident">coefficients</span>, <span class="ident">huffman</span>, <span class="ident">range</span>, <span class="ident">zero_run_length</span>, <span class="ident">bit</span>)<span class="question-mark">?</span>;
<span class="kw">if</span> <span class="ident">value</span> <span class="op">!</span><span class="op">=</span> <span class="number">0</span> {
<span class="ident">coefficients</span>[<span class="ident">UNZIGZAG</span>[<span class="ident">index</span> <span class="kw">as</span> <span class="ident">usize</span>] <span class="kw">as</span> <span class="ident">usize</span>] <span class="op">=</span> <span class="ident">value</span>;
}
<span class="ident">index</span> <span class="op">+</span><span class="op">=</span> <span class="number">1</span>;
}
}
<span class="prelude-val">Ok</span>(())
}
<span class="kw">fn</span> <span class="ident">refine_non_zeroes</span><span class="op"><</span><span class="ident">R</span>: <span class="ident">Read</span><span class="op">></span>(<span class="ident">reader</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">R</span>,
<span class="ident">coefficients</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> [<span class="ident">i16</span>],
<span class="ident">huffman</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">HuffmanDecoder</span>,
<span class="ident">range</span>: <span class="ident">Range</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span>,
<span class="ident">zrl</span>: <span class="ident">u8</span>,
<span class="ident">bit</span>: <span class="ident">i16</span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span> {
<span class="macro">debug_assert_eq!</span>(<span class="ident">coefficients</span>.<span class="ident">len</span>(), <span class="number">64</span>);
<span class="kw">let</span> <span class="ident">last</span> <span class="op">=</span> <span class="ident">range</span>.<span class="ident">end</span> <span class="op">-</span> <span class="number">1</span>;
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">zero_run_length</span> <span class="op">=</span> <span class="ident">zrl</span>;
<span class="kw">for</span> <span class="ident">i</span> <span class="kw">in</span> <span class="ident">range</span> {
<span class="kw">let</span> <span class="ident">index</span> <span class="op">=</span> <span class="ident">UNZIGZAG</span>[<span class="ident">i</span> <span class="kw">as</span> <span class="ident">usize</span>] <span class="kw">as</span> <span class="ident">usize</span>;
<span class="kw">if</span> <span class="ident">coefficients</span>[<span class="ident">index</span>] <span class="op">=</span><span class="op">=</span> <span class="number">0</span> {
<span class="kw">if</span> <span class="ident">zero_run_length</span> <span class="op">=</span><span class="op">=</span> <span class="number">0</span> {
<span class="kw">return</span> <span class="prelude-val">Ok</span>(<span class="ident">i</span>);
}
<span class="ident">zero_run_length</span> <span class="op">-</span><span class="op">=</span> <span class="number">1</span>;
}
<span class="kw">else</span> <span class="kw">if</span> <span class="ident">huffman</span>.<span class="ident">get_bits</span>(<span class="ident">reader</span>, <span class="number">1</span>)<span class="question-mark">?</span> <span class="op">=</span><span class="op">=</span> <span class="number">1</span> <span class="op">&&</span> <span class="ident">coefficients</span>[<span class="ident">index</span>] <span class="op">&</span> <span class="ident">bit</span> <span class="op">=</span><span class="op">=</span> <span class="number">0</span> {
<span class="kw">if</span> <span class="ident">coefficients</span>[<span class="ident">index</span>] <span class="op">></span> <span class="number">0</span> {
<span class="ident">coefficients</span>[<span class="ident">index</span>] <span class="op">+</span><span class="op">=</span> <span class="ident">bit</span>;
}
<span class="kw">else</span> {
<span class="ident">coefficients</span>[<span class="ident">index</span>] <span class="op">-</span><span class="op">=</span> <span class="ident">bit</span>;
}
}
}
<span class="prelude-val">Ok</span>(<span class="ident">last</span>)
}
<span class="kw">fn</span> <span class="ident">compute_image</span>(<span class="ident">components</span>: <span class="kw-2">&</span>[<span class="ident">Component</span>],
<span class="kw-2">mut</span> <span class="ident">data</span>: <span class="ident">Vec</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span><span class="op">></span>,
<span class="ident">output_size</span>: <span class="ident">Dimensions</span>,
<span class="ident">is_jfif</span>: <span class="ident">bool</span>,
<span class="ident">color_transform</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">AdobeColorTransform</span><span class="op">></span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span><span class="op">></span> {
<span class="kw">if</span> <span class="ident">data</span>.<span class="ident">is_empty</span>() <span class="op">|</span><span class="op">|</span> <span class="ident">data</span>.<span class="ident">iter</span>().<span class="ident">any</span>(<span class="ident">Vec::is_empty</span>) {
<span class="kw">return</span> <span class="prelude-val">Err</span>(<span class="ident">Error::Format</span>(<span class="string">"not all components have data"</span>.<span class="ident">to_owned</span>()));
}
<span class="kw">if</span> <span class="ident">components</span>.<span class="ident">len</span>() <span class="op">=</span><span class="op">=</span> <span class="number">1</span> {
<span class="kw">let</span> <span class="ident">component</span> <span class="op">=</span> <span class="kw-2">&</span><span class="ident">components</span>[<span class="number">0</span>];
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">decoded</span>: <span class="ident">Vec</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span> <span class="op">=</span> <span class="ident">data</span>.<span class="ident">remove</span>(<span class="number">0</span>);
<span class="kw">let</span> <span class="ident">width</span> <span class="op">=</span> <span class="ident">component</span>.<span class="ident">size</span>.<span class="ident">width</span> <span class="kw">as</span> <span class="ident">usize</span>;
<span class="kw">let</span> <span class="ident">height</span> <span class="op">=</span> <span class="ident">component</span>.<span class="ident">size</span>.<span class="ident">height</span> <span class="kw">as</span> <span class="ident">usize</span>;
<span class="kw">let</span> <span class="ident">size</span> <span class="op">=</span> <span class="ident">width</span> <span class="op">*</span> <span class="ident">height</span>;
<span class="kw">let</span> <span class="ident">line_stride</span> <span class="op">=</span> <span class="ident">component</span>.<span class="ident">block_size</span>.<span class="ident">width</span> <span class="kw">as</span> <span class="ident">usize</span> <span class="op">*</span> <span class="ident">component</span>.<span class="ident">dct_scale</span>;
<span class="comment">// if the image width is a multiple of the block size,</span>
<span class="comment">// then we don't have to move bytes in the decoded data</span>
<span class="kw">if</span> <span class="ident">usize::from</span>(<span class="ident">output_size</span>.<span class="ident">width</span>) <span class="op">!</span><span class="op">=</span> <span class="ident">line_stride</span> {
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">buffer</span> <span class="op">=</span> <span class="macro">vec!</span>[<span class="number">0u8</span>; <span class="ident">width</span>];
<span class="comment">// The first line already starts at index 0, so we need to move only lines 1..height</span>
<span class="kw">for</span> <span class="ident">y</span> <span class="kw">in</span> <span class="number">1</span>..<span class="ident">height</span> {
<span class="kw">let</span> <span class="ident">destination_idx</span> <span class="op">=</span> <span class="ident">y</span> <span class="op">*</span> <span class="ident">width</span>;
<span class="kw">let</span> <span class="ident">source_idx</span> <span class="op">=</span> <span class="ident">y</span> <span class="op">*</span> <span class="ident">line_stride</span>;
<span class="comment">// We could use copy_within, but we need to support old rust versions</span>
<span class="ident">buffer</span>.<span class="ident">copy_from_slice</span>(<span class="kw-2">&</span><span class="ident">decoded</span>[<span class="ident">source_idx</span>..][..<span class="ident">width</span>]);
<span class="kw">let</span> <span class="ident">destination</span> <span class="op">=</span> <span class="kw-2">&</span><span class="kw-2">mut</span> <span class="ident">decoded</span>[<span class="ident">destination_idx</span>..][..<span class="ident">width</span>];
<span class="ident">destination</span>.<span class="ident">copy_from_slice</span>(<span class="kw-2">&</span><span class="ident">buffer</span>);
}
}
<span class="ident">decoded</span>.<span class="ident">resize</span>(<span class="ident">size</span>, <span class="number">0</span>);
<span class="prelude-val">Ok</span>(<span class="ident">decoded</span>)
}
<span class="kw">else</span> {
<span class="ident">compute_image_parallel</span>(<span class="ident">components</span>, <span class="ident">data</span>, <span class="ident">output_size</span>, <span class="ident">is_jfif</span>, <span class="ident">color_transform</span>)
}
}
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"rayon"</span>)]</span>
<span class="kw">fn</span> <span class="ident">compute_image_parallel</span>(<span class="ident">components</span>: <span class="kw-2">&</span>[<span class="ident">Component</span>],
<span class="ident">data</span>: <span class="ident">Vec</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span><span class="op">></span>,
<span class="ident">output_size</span>: <span class="ident">Dimensions</span>,
<span class="ident">is_jfif</span>: <span class="ident">bool</span>,
<span class="ident">color_transform</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">AdobeColorTransform</span><span class="op">></span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span><span class="op">></span> {
<span class="kw">use</span> <span class="ident">rayon::prelude</span>::<span class="kw-2">*</span>;
<span class="kw">let</span> <span class="ident">color_convert_func</span> <span class="op">=</span> <span class="ident">choose_color_convert_func</span>(<span class="ident">components</span>.<span class="ident">len</span>(), <span class="ident">is_jfif</span>, <span class="ident">color_transform</span>)<span class="question-mark">?</span>;
<span class="kw">let</span> <span class="ident">upsampler</span> <span class="op">=</span> <span class="ident">Upsampler::new</span>(<span class="ident">components</span>, <span class="ident">output_size</span>.<span class="ident">width</span>, <span class="ident">output_size</span>.<span class="ident">height</span>)<span class="question-mark">?</span>;
<span class="kw">let</span> <span class="ident">line_size</span> <span class="op">=</span> <span class="ident">output_size</span>.<span class="ident">width</span> <span class="kw">as</span> <span class="ident">usize</span> <span class="op">*</span> <span class="ident">components</span>.<span class="ident">len</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">image</span> <span class="op">=</span> <span class="macro">vec!</span>[<span class="number">0u8</span>; <span class="ident">line_size</span> <span class="op">*</span> <span class="ident">output_size</span>.<span class="ident">height</span> <span class="kw">as</span> <span class="ident">usize</span>];
<span class="ident">image</span>.<span class="ident">par_chunks_mut</span>(<span class="ident">line_size</span>)
.<span class="ident">with_max_len</span>(<span class="number">1</span>)
.<span class="ident">enumerate</span>()
.<span class="ident">for_each</span>(<span class="op">|</span>(<span class="ident">row</span>, <span class="ident">line</span>)<span class="op">|</span> {
<span class="ident">upsampler</span>.<span class="ident">upsample_and_interleave_row</span>(<span class="kw-2">&</span><span class="ident">data</span>, <span class="ident">row</span>, <span class="ident">output_size</span>.<span class="ident">width</span> <span class="kw">as</span> <span class="ident">usize</span>, <span class="ident">line</span>);
<span class="ident">color_convert_func</span>(<span class="ident">line</span>);
});
<span class="prelude-val">Ok</span>(<span class="ident">image</span>)
}
<span class="attribute">#[<span class="ident">cfg</span>(<span class="ident">not</span>(<span class="ident">feature</span><span class="op">=</span><span class="string">"rayon"</span>))]</span>
<span class="kw">fn</span> <span class="ident">compute_image_parallel</span>(<span class="ident">components</span>: <span class="kw-2">&</span>[<span class="ident">Component</span>],
<span class="ident">data</span>: <span class="ident">Vec</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span><span class="op">></span>,
<span class="ident">output_size</span>: <span class="ident">Dimensions</span>,
<span class="ident">is_jfif</span>: <span class="ident">bool</span>,
<span class="ident">color_transform</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">AdobeColorTransform</span><span class="op">></span>) <span class="op">-</span><span class="op">></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="ident">Vec</span><span class="op"><</span><span class="ident">u8</span><span class="op">></span><span class="op">></span> {
<span class="kw">let</span> <span class="ident">color_convert_func</span> <span class="op">=</span> <span class="ident">choose_color_convert_func</span>(<span class="ident">components</span>.<span class="ident">len</span>(), <span class="ident">is_jfif</span>, <span class="ident">color_transform</span>)<span class="question-mark">?</span>;
<span class="kw">let</span> <span class="ident">upsampler</span> <span class="op">=</span> <span class="ident">Upsampler::new</span>(<span class="ident">components</span>, <span class="ident">output_size</span>.<span class="ident">width</span>, <span class="ident">output_size</span>.<span class="ident">height</span>)<span class="question-mark">?</span>;
<span class="kw">let</span> <span class="ident">line_size</span> <span class="op">=</span> <span class="ident">output_size</span>.<span class="ident">width</span> <span class="kw">as</span> <span class="ident">usize</span> <span class="op">*</span> <span class="ident">components</span>.<span class="ident">len</span>();
<span class="kw">let</span> <span class="kw-2">mut</span> <span class="ident">image</span> <span class="op">=</span> <span class="macro">vec!</span>[<span class="number">0u8</span>; <span class="ident">line_size</span> <span class="op">*</span> <span class="ident">output_size</span>.<span class="ident">height</span> <span class="kw">as</span> <span class="ident">usize</span>];
<span class="kw">for</span> (<span class="ident">row</span>, <span class="ident">line</span>) <span class="kw">in</span> <span class="ident">image</span>.<span class="ident">chunks_mut</span>(<span class="ident">line_size</span>)
.<span class="ident">enumerate</span>() {
<span class="ident">upsampler</span>.<span class="ident">upsample_and_interleave_row</span>(<span class="kw-2">&</span><span class="ident">data</span>, <span class="ident">row</span>, <span class="ident">output_size</span>.<span class="ident">width</span> <span class="kw">as</span> <span class="ident">usize</span>, <span class="ident">line</span>);
<span class="ident">color_convert_func</span>(<span class="ident">line</span>);
}
<span class="prelude-val">Ok</span>(<span class="ident">image</span>)
}
<span class="kw">fn</span> <span class="ident">choose_color_convert_func</span>(<span class="ident">component_count</span>: <span class="ident">usize</span>,
<span class="ident">_is_jfif</span>: <span class="ident">bool</span>,
<span class="ident">color_transform</span>: <span class="prelude-ty">Option</span><span class="op"><</span><span class="ident">AdobeColorTransform</span><span class="op">></span>)
<span class="op">-</span><span class="op">></span> <span class="prelude-ty">Result</span><span class="op"><</span><span class="kw">fn</span>(<span class="kw-2">&</span><span class="kw-2">mut</span> [<span class="ident">u8</span>])<span class="op">></span> {
<span class="kw">match</span> <span class="ident">component_count</span> {
<span class="number">3</span> <span class="op">=</span><span class="op">></span> {
<span class="comment">// http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/JPEG.html#Adobe</span>
<span class="comment">// Unknown means the data is RGB, so we don't need to perform any color conversion on it.</span>
<span class="kw">if</span> <span class="ident">color_transform</span> <span class="op">=</span><span class="op">=</span> <span class="prelude-val">Some</span>(<span class="ident">AdobeColorTransform::Unknown</span>) {
<span class="prelude-val">Ok</span>(<span class="ident">color_convert_line_null</span>)
}
<span class="kw">else</span> {
<span class="prelude-val">Ok</span>(<span class="ident">color_convert_line_ycbcr</span>)
}
},
<span class="number">4</span> <span class="op">=</span><span class="op">></span> {
<span class="comment">// http://www.sno.phy.queensu.ca/~phil/exiftool/TagNames/JPEG.html#Adobe</span>
<span class="kw">match</span> <span class="ident">color_transform</span> {
<span class="prelude-val">Some</span>(<span class="ident">AdobeColorTransform::Unknown</span>) <span class="op">=</span><span class="op">></span> <span class="prelude-val">Ok</span>(<span class="ident">color_convert_line_cmyk</span>),
<span class="prelude-val">Some</span>(<span class="kw">_</span>) <span class="op">=</span><span class="op">></span> <span class="prelude-val">Ok</span>(<span class="ident">color_convert_line_ycck</span>),
<span class="prelude-val">None</span> <span class="op">=</span><span class="op">></span> <span class="prelude-val">Err</span>(<span class="ident">Error::Format</span>(<span class="string">"4 components without Adobe APP14 metadata to indicate color space"</span>.<span class="ident">to_owned</span>())),
}
},
<span class="kw">_</span> <span class="op">=</span><span class="op">></span> <span class="macro">panic!</span>(),
}
}
<span class="kw">fn</span> <span class="ident">color_convert_line_null</span>(<span class="ident">_data</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> [<span class="ident">u8</span>]) {
}
<span class="kw">fn</span> <span class="ident">color_convert_line_ycbcr</span>(<span class="ident">data</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> [<span class="ident">u8</span>]) {
<span class="kw">for</span> <span class="ident">chunk</span> <span class="kw">in</span> <span class="ident">data</span>.<span class="ident">chunks_exact_mut</span>(<span class="number">3</span>) {
<span class="kw">let</span> (<span class="ident">r</span>, <span class="ident">g</span>, <span class="ident">b</span>) <span class="op">=</span> <span class="ident">ycbcr_to_rgb</span>(<span class="ident">chunk</span>[<span class="number">0</span>], <span class="ident">chunk</span>[<span class="number">1</span>], <span class="ident">chunk</span>[<span class="number">2</span>]);
<span class="ident">chunk</span>[<span class="number">0</span>] <span class="op">=</span> <span class="ident">r</span>;
<span class="ident">chunk</span>[<span class="number">1</span>] <span class="op">=</span> <span class="ident">g</span>;
<span class="ident">chunk</span>[<span class="number">2</span>] <span class="op">=</span> <span class="ident">b</span>;
}
}
<span class="kw">fn</span> <span class="ident">color_convert_line_ycck</span>(<span class="ident">data</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> [<span class="ident">u8</span>]) {
<span class="kw">for</span> <span class="ident">chunk</span> <span class="kw">in</span> <span class="ident">data</span>.<span class="ident">chunks_exact_mut</span>(<span class="number">4</span>) {
<span class="kw">let</span> (<span class="ident">r</span>, <span class="ident">g</span>, <span class="ident">b</span>) <span class="op">=</span> <span class="ident">ycbcr_to_rgb</span>(<span class="ident">chunk</span>[<span class="number">0</span>], <span class="ident">chunk</span>[<span class="number">1</span>], <span class="ident">chunk</span>[<span class="number">2</span>]);
<span class="kw">let</span> <span class="ident">k</span> <span class="op">=</span> <span class="ident">chunk</span>[<span class="number">3</span>];
<span class="ident">chunk</span>[<span class="number">0</span>] <span class="op">=</span> <span class="ident">r</span>;
<span class="ident">chunk</span>[<span class="number">1</span>] <span class="op">=</span> <span class="ident">g</span>;
<span class="ident">chunk</span>[<span class="number">2</span>] <span class="op">=</span> <span class="ident">b</span>;
<span class="ident">chunk</span>[<span class="number">3</span>] <span class="op">=</span> <span class="number">255</span> <span class="op">-</span> <span class="ident">k</span>;
}
}
<span class="kw">fn</span> <span class="ident">color_convert_line_cmyk</span>(<span class="ident">data</span>: <span class="kw-2">&</span><span class="kw-2">mut</span> [<span class="ident">u8</span>]) {
<span class="kw">for</span> <span class="ident">chunk</span> <span class="kw">in</span> <span class="ident">data</span>.<span class="ident">chunks_exact_mut</span>(<span class="number">4</span>) {
<span class="ident">chunk</span>[<span class="number">0</span>] <span class="op">=</span> <span class="number">255</span> <span class="op">-</span> <span class="ident">chunk</span>[<span class="number">0</span>];
<span class="ident">chunk</span>[<span class="number">1</span>] <span class="op">=</span> <span class="number">255</span> <span class="op">-</span> <span class="ident">chunk</span>[<span class="number">1</span>];
<span class="ident">chunk</span>[<span class="number">2</span>] <span class="op">=</span> <span class="number">255</span> <span class="op">-</span> <span class="ident">chunk</span>[<span class="number">2</span>];
<span class="ident">chunk</span>[<span class="number">3</span>] <span class="op">=</span> <span class="number">255</span> <span class="op">-</span> <span class="ident">chunk</span>[<span class="number">3</span>];
}
}
<span class="comment">// ITU-R BT.601</span>
<span class="kw">fn</span> <span class="ident">ycbcr_to_rgb</span>(<span class="ident">y</span>: <span class="ident">u8</span>, <span class="ident">cb</span>: <span class="ident">u8</span>, <span class="ident">cr</span>: <span class="ident">u8</span>) <span class="op">-</span><span class="op">></span> (<span class="ident">u8</span>, <span class="ident">u8</span>, <span class="ident">u8</span>) {
<span class="kw">let</span> <span class="ident">y</span> <span class="op">=</span> <span class="ident">y</span> <span class="kw">as</span> <span class="ident">f32</span>;
<span class="kw">let</span> <span class="ident">cb</span> <span class="op">=</span> <span class="ident">cb</span> <span class="kw">as</span> <span class="ident">f32</span> <span class="op">-</span> <span class="number">128.0</span>;
<span class="kw">let</span> <span class="ident">cr</span> <span class="op">=</span> <span class="ident">cr</span> <span class="kw">as</span> <span class="ident">f32</span> <span class="op">-</span> <span class="number">128.0</span>;
<span class="kw">let</span> <span class="ident">r</span> <span class="op">=</span> <span class="ident">y</span> <span class="op">+</span> <span class="number">1.40200</span> <span class="op">*</span> <span class="ident">cr</span>;
<span class="kw">let</span> <span class="ident">g</span> <span class="op">=</span> <span class="ident">y</span> <span class="op">-</span> <span class="number">0.34414</span> <span class="op">*</span> <span class="ident">cb</span> <span class="op">-</span> <span class="number">0.71414</span> <span class="op">*</span> <span class="ident">cr</span>;
<span class="kw">let</span> <span class="ident">b</span> <span class="op">=</span> <span class="ident">y</span> <span class="op">+</span> <span class="number">1.77200</span> <span class="op">*</span> <span class="ident">cb</span>;
<span class="comment">// TODO: Rust has defined float-to-int conversion as saturating,</span>
<span class="comment">// which is exactly what we need here. However, as of this writing</span>
<span class="comment">// it still hasn't reached the stable channel.</span>
<span class="comment">// This can be simplified to `(r + 0.5) as u8` without any clamping</span>
<span class="comment">// as soon as our MSRV reaches the version that has saturating casts.</span>
<span class="comment">// The version without explicit clamping is also noticeably faster.</span>
(<span class="ident">clamp_to_u8</span>((<span class="ident">r</span> <span class="op">+</span> <span class="number">0.5</span>) <span class="kw">as</span> <span class="ident">i32</span>) <span class="kw">as</span> <span class="ident">u8</span>,
<span class="ident">clamp_to_u8</span>((<span class="ident">g</span> <span class="op">+</span> <span class="number">0.5</span>) <span class="kw">as</span> <span class="ident">i32</span>) <span class="kw">as</span> <span class="ident">u8</span>,
<span class="ident">clamp_to_u8</span>((<span class="ident">b</span> <span class="op">+</span> <span class="number">0.5</span>) <span class="kw">as</span> <span class="ident">i32</span>) <span class="kw">as</span> <span class="ident">u8</span>)
}
<span class="kw">fn</span> <span class="ident">clamp_to_u8</span>(<span class="ident">value</span>: <span class="ident">i32</span>) <span class="op">-</span><span class="op">></span> <span class="ident">i32</span> {
<span class="kw">let</span> <span class="ident">value</span> <span class="op">=</span> <span class="ident">std::cmp::max</span>(<span class="ident">value</span>, <span class="number">0</span>);
<span class="ident">std::cmp::min</span>(<span class="ident">value</span>, <span class="number">255</span>)
}
</pre></div>
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