ironpress 1.4.4

Pure Rust HTML/CSS/Markdown to PDF converter with layout engine, LaTeX math, tables, images, custom fonts, and streaming output. No browser, no system dependencies.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228

use super::*;

pub(super) struct ShapedTextRender<'a> {
    origin: PdfPoint,
    font_size: f32,
    layout_to_text_scale: f32,
    text_y_axis: f32,
    font: &'a TtfFont,
    shaped: &'a crate::text::ShapedRun,
    prepared_font: Option<&'a PreparedCustomFont>,
    /// Extra advance (in PDF text-space units) to insert after each space
    /// cluster (U+0020).  Carries CSS `word-spacing` plus the per-space
    /// `text-align: justify` stretch.  Type0 / Identity-H text ignores the
    /// PDF `Tw` operator (it only applies to single-byte code 32), so this
    /// must be baked into the TJ array as a negative adjustment instead.
    word_spacing: f32,
    letter_spacing: f32,
    /// Synthetic-italic shear (the text-matrix `c` term): a face with no genuine
    /// italic gets an algorithmic oblique slant (CSS Fonts 4 `font-synthesis:
    /// style`). 0 = upright. Matches Skia/Chrome's synthetic skew (0.25).
    shear: f32,
    scale_x: f32,
}

impl<'a> ShapedTextRender<'a> {
    pub(super) fn new(
        origin: PdfPoint,
        font_size: f32,
        font: &'a TtfFont,
        shaped: &'a crate::text::ShapedRun,
        prepared_font: Option<&'a PreparedCustomFont>,
        text_space: PdfContentSpace,
    ) -> Self {
        Self {
            origin: text_space.point(origin),
            font_size: font.adjusted_font_size(text_space.length(font_size)),
            layout_to_text_scale: text_space.length(1.0),
            text_y_axis: text_space.y_axis(),
            font,
            shaped,
            prepared_font,
            word_spacing: 0.0,
            letter_spacing: 0.0,
            shear: 0.0,
            scale_x: 1.0,
        }
    }

    pub(super) const fn with_word_spacing(mut self, word_spacing: f32) -> Self {
        self.word_spacing = word_spacing * self.layout_to_text_scale;
        self
    }

    pub(super) const fn with_letter_spacing(mut self, letter_spacing: f32) -> Self {
        self.letter_spacing = letter_spacing * self.layout_to_text_scale;
        self
    }

    pub(super) const fn with_shear(mut self, shear: f32) -> Self {
        // `c` controls the physical horizontal displacement of glyph tops. The
        // text matrix's `d` term and the surrounding PageCss transform already
        // account for the Y-axis direction; reflecting `c` as well reverses the
        // visible oblique direction.
        self.shear = shear;
        self
    }

    /// Extra TJ adjustment (thousandths of an em / text-space units) to add
    /// after `glyph` when it is a space cluster.  A positive `Tj` number moves
    /// the cursor left, so the returned adjustment is negative in order to
    /// *widen* the gap after the space.
    fn space_tj_adjustment(&self, glyph: &crate::text::ShapedGlyph) -> f32 {
        if self.word_spacing == 0.0 {
            return 0.0;
        }
        if glyph.unicode.as_slice() == [0x0020] {
            -(self.word_spacing * 1000.0 / self.font_size.max(f32::EPSILON))
        } else {
            0.0
        }
    }

    pub(super) fn has_complex_offsets(&self) -> bool {
        self.shaped
            .glyphs
            .iter()
            .any(|glyph| glyph.x_offset != 0.0 || glyph.y_offset != 0.0)
    }

    fn encode_glyph(&self, glyph_id: u16) -> String {
        self.prepared_font.map_or_else(
            || encode_pdf_hex_glyph(glyph_id),
            |prepared_font| prepared_font.encode_glyph(glyph_id),
        )
    }
}

pub(crate) fn append_pdf_tj_adjustment(content: &mut String, adjustment: f32) {
    if adjustment != 0.0 {
        content.push(' ');
        content.push_str(&format_pdf_number(adjustment));
    }
}

fn sfnt_has_table(data: &[u8], tag: &[u8; 4]) -> bool {
    let base = if data.len() >= 16 && &data[0..4] == b"ttcf" {
        let first_offset = u32::from_be_bytes([data[12], data[13], data[14], data[15]]) as usize;
        if first_offset >= data.len() {
            return false;
        }
        first_offset
    } else {
        0
    };
    if data.len() < base + 12 {
        return false;
    }
    let num_tables = u16::from_be_bytes([data[base + 4], data[base + 5]]) as usize;
    let dir_end = base + 12 + num_tables.saturating_mul(16);
    if dir_end > data.len() {
        return false;
    }
    (0..num_tables).any(|i| &data[base + 12 + i * 16..base + 16 + i * 16] == tag)
}

pub(crate) fn sfnt_has_cff_outlines(data: &[u8]) -> bool {
    sfnt_has_table(data, b"CFF ") || sfnt_has_table(data, b"CFF2")
}

pub(super) fn append_positioned_shaped_text(content: &mut String, render: ShapedTextRender<'_>) {
    let mut cursor_x = render.origin.x;
    let last_idx = render.shaped.glyphs.len().saturating_sub(1);
    for (idx, glyph) in render.shaped.glyphs.iter().enumerate() {
        let draw_x = cursor_x + glyph.x_offset * render.layout_to_text_scale;
        let draw_y =
            render.origin.y + glyph.y_offset * render.layout_to_text_scale * render.text_y_axis;
        let encoded = render.encode_glyph(glyph.glyph_id);
        content.push_str(&format!(
            "{} 0 {} {} {} {} Tm\n",
            format_pdf_number(render.scale_x),
            format_pdf_number(render.shear),
            format_pdf_number(render.text_y_axis),
            format_pdf_number(draw_x),
            format_pdf_number(draw_y),
        ));
        content.push_str(&format!("<{encoded}> Tj\n"));
        cursor_x += glyph.x_advance * render.layout_to_text_scale;
        if idx < last_idx {
            cursor_x += render.letter_spacing;
        }
        // Identity-H ignores the PDF `Tw` operator, so widen the gap after
        // each space cluster by advancing the cursor manually.
        if render.word_spacing != 0.0 && glyph.unicode.as_slice() == [0x0020] {
            cursor_x += render.word_spacing;
        }
    }
}

/// Emit a top-to-bottom shaped run one glyph at a time.
///
/// PDF Type0 text does not have a vertical writing mode in this renderer, so
/// each glyph receives the exact vertical OpenType origin selected by the
/// shaper.  Unlike horizontal `TJ`, the cursor advances on Y between glyphs.
pub(super) fn append_positioned_vertical_shaped_text(
    content: &mut String,
    origin: PdfPoint,
    shaped: &crate::text::VerticalShapedRun,
    prepared_font: Option<&PreparedCustomFont>,
) {
    let mut cursor_y = origin.y;
    for glyph in &shaped.glyphs {
        let encoded = prepared_font.map_or_else(
            || encode_pdf_hex_glyph(glyph.glyph_id),
            |font| font.encode_glyph(glyph.glyph_id),
        );
        content.push_str(&format!(
            "1 0 0 1 {} {} Tm\n",
            format_pdf_number(origin.x + glyph.x_offset),
            format_pdf_number(cursor_y + glyph.y_offset),
        ));
        content.push_str(&format!("<{encoded}> Tj\n"));
        cursor_y += glyph.y_advance;
    }
}

pub(super) fn append_tj_shaped_text(content: &mut String, render: ShapedTextRender<'_>) {
    content.push_str(&format!(
        "{} 0 {} {} {} {} Tm\n",
        format_pdf_number(render.scale_x),
        format_pdf_number(render.shear),
        format_pdf_number(render.text_y_axis),
        format_pdf_number(render.origin.x),
        format_pdf_number(render.origin.y),
    ));
    content.push('[');

    let mut first = true;
    let last_idx = render.shaped.glyphs.len().saturating_sub(1);
    for (idx, glyph) in render.shaped.glyphs.iter().enumerate() {
        if !first {
            content.push(' ');
        }
        first = false;

        let encoded = render.encode_glyph(glyph.glyph_id);
        content.push('<');
        content.push_str(&encoded);
        content.push('>');

        let nominal_advance = render
            .font
            .glyph_width_scaled(glyph.glyph_id, render.font_size);
        let advance_adjustment = glyph.x_advance * render.layout_to_text_scale - nominal_advance;
        // Fold the shaper advance/kerning delta together with any extra
        // inter-word spacing (CSS word-spacing + justify stretch) for space
        // clusters, so a single TJ number carries both.
        let kern_adjustment = -(advance_adjustment * 1000.0 / render.font_size.max(f32::EPSILON));
        let letter_adjustment = if idx < last_idx {
            -(render.letter_spacing * 1000.0 / render.font_size.max(f32::EPSILON))
        } else {
            0.0
        };
        let tj_adjustment = kern_adjustment + render.space_tj_adjustment(glyph) + letter_adjustment;
        append_pdf_tj_adjustment(content, tj_adjustment);
    }

    content.push_str("] TJ\n");
}