cranpose_ui_graphics/
image.rs

1//! Image bitmap primitives used by render backends.
2
3use crate::{BlendMode, Color, Size};
4use std::hash::{Hash, Hasher};
5use std::sync::atomic::{AtomicU64, Ordering};
6use std::sync::Arc;
7use thiserror::Error;
8
9static NEXT_IMAGE_BITMAP_ID: AtomicU64 = AtomicU64::new(1);
10
11/// Errors returned while constructing an [`ImageBitmap`].
12#[derive(Debug, Clone, PartialEq, Eq, Error)]
13pub enum ImageBitmapError {
14    #[error("image dimensions must be greater than zero")]
15    InvalidDimensions,
16    #[error("image dimensions are too large")]
17    DimensionsTooLarge,
18    #[error("pixel data length mismatch: expected {expected} bytes, got {actual}")]
19    PixelDataLengthMismatch { expected: usize, actual: usize },
20}
21
22/// Immutable RGBA image data used by UI primitives and render backends.
23#[derive(Clone, Debug)]
24pub struct ImageBitmap {
25    id: u64,
26    width: u32,
27    height: u32,
28    pixels: Arc<[u8]>,
29}
30
31/// Simple image color filter model.
32#[derive(Clone, Copy, Debug, PartialEq)]
33pub enum ColorFilter {
34    /// Compose-style tint using `BlendMode::SrcIn`.
35    Tint(Color),
36    /// Explicit per-channel modulation (multiply behavior).
37    Modulate(Color),
38    /// 4x5 color matrix in row-major order.
39    ///
40    /// Rows map output RGBA channels, columns map input RGBA plus constant term:
41    /// `out = M * [r, g, b, a, 1]`.
42    Matrix([f32; 20]),
43}
44
45impl ColorFilter {
46    /// Creates a Compose-style tint filter (`SrcIn`).
47    pub fn tint(color: Color) -> Self {
48        Self::Tint(color)
49    }
50
51    /// Creates an explicit modulation filter that multiplies channels by `color`.
52    pub fn modulate(color: Color) -> Self {
53        Self::Modulate(color)
54    }
55
56    /// Creates a filter from a 4x5 color matrix.
57    pub fn matrix(matrix: [f32; 20]) -> Self {
58        Self::Matrix(matrix)
59    }
60
61    pub fn compose(self, next: ColorFilter) -> ColorFilter {
62        ColorFilter::Matrix(compose_color_matrices(self.as_matrix(), next.as_matrix()))
63    }
64
65    pub fn as_matrix(self) -> [f32; 20] {
66        match self {
67            Self::Tint(tint) => [
68                0.0,
69                0.0,
70                0.0,
71                tint.r(),
72                0.0, // R' = A * tint.r
73                0.0,
74                0.0,
75                0.0,
76                tint.g(),
77                0.0, // G' = A * tint.g
78                0.0,
79                0.0,
80                0.0,
81                tint.b(),
82                0.0, // B' = A * tint.b
83                0.0,
84                0.0,
85                0.0,
86                tint.a(),
87                0.0, // A' = A * tint.a
88            ],
89            Self::Modulate(modulate) => [
90                modulate.r(),
91                0.0,
92                0.0,
93                0.0,
94                0.0, // R' = R * modulate.r
95                0.0,
96                modulate.g(),
97                0.0,
98                0.0,
99                0.0, // G' = G * modulate.g
100                0.0,
101                0.0,
102                modulate.b(),
103                0.0,
104                0.0, // B' = B * modulate.b
105                0.0,
106                0.0,
107                0.0,
108                modulate.a(),
109                0.0, // A' = A * modulate.a
110            ],
111            Self::Matrix(matrix) => matrix,
112        }
113    }
114
115    pub fn apply_rgba(self, rgba: [f32; 4]) -> [f32; 4] {
116        apply_color_matrix(self.as_matrix(), rgba)
117    }
118
119    pub fn supports_gpu_vertex_modulation(self) -> bool {
120        matches!(self, Self::Modulate(_))
121    }
122
123    pub fn gpu_vertex_tint(self) -> Option<[f32; 4]> {
124        match self {
125            Self::Modulate(tint) => Some([tint.r(), tint.g(), tint.b(), tint.a()]),
126            _ => None,
127        }
128    }
129
130    pub fn blend_mode(self) -> BlendMode {
131        match self {
132            Self::Tint(_) => BlendMode::SrcIn,
133            Self::Modulate(_) => BlendMode::Modulate,
134            Self::Matrix(_) => BlendMode::SrcOver,
135        }
136    }
137}
138
139fn apply_color_matrix(matrix: [f32; 20], rgba: [f32; 4]) -> [f32; 4] {
140    let r = rgba[0];
141    let g = rgba[1];
142    let b = rgba[2];
143    let a = rgba[3];
144    [
145        (matrix[0] * r + matrix[1] * g + matrix[2] * b + matrix[3] * a + matrix[4]).clamp(0.0, 1.0),
146        (matrix[5] * r + matrix[6] * g + matrix[7] * b + matrix[8] * a + matrix[9]).clamp(0.0, 1.0),
147        (matrix[10] * r + matrix[11] * g + matrix[12] * b + matrix[13] * a + matrix[14])
148            .clamp(0.0, 1.0),
149        (matrix[15] * r + matrix[16] * g + matrix[17] * b + matrix[18] * a + matrix[19])
150            .clamp(0.0, 1.0),
151    ]
152}
153
154fn compose_color_matrices(first: [f32; 20], second: [f32; 20]) -> [f32; 20] {
155    let mut composed = [0.0f32; 20];
156    for row in 0..4 {
157        let row_base = row * 5;
158        let s0 = second[row_base];
159        let s1 = second[row_base + 1];
160        let s2 = second[row_base + 2];
161        let s3 = second[row_base + 3];
162        let s4 = second[row_base + 4];
163
164        composed[row_base] = s0 * first[0] + s1 * first[5] + s2 * first[10] + s3 * first[15];
165        composed[row_base + 1] = s0 * first[1] + s1 * first[6] + s2 * first[11] + s3 * first[16];
166        composed[row_base + 2] = s0 * first[2] + s1 * first[7] + s2 * first[12] + s3 * first[17];
167        composed[row_base + 3] = s0 * first[3] + s1 * first[8] + s2 * first[13] + s3 * first[18];
168        composed[row_base + 4] =
169            s0 * first[4] + s1 * first[9] + s2 * first[14] + s3 * first[19] + s4;
170    }
171    composed
172}
173
174impl ImageBitmap {
175    /// Creates a bitmap from tightly packed RGBA8 pixels.
176    pub fn from_rgba8(width: u32, height: u32, pixels: Vec<u8>) -> Result<Self, ImageBitmapError> {
177        Self::from_rgba8_slice(width, height, &pixels)
178    }
179
180    /// Creates a bitmap from tightly packed RGBA8 pixels.
181    pub fn from_rgba8_slice(
182        width: u32,
183        height: u32,
184        pixels: &[u8],
185    ) -> Result<Self, ImageBitmapError> {
186        if width == 0 || height == 0 {
187            return Err(ImageBitmapError::InvalidDimensions);
188        }
189        let expected = (width as usize)
190            .checked_mul(height as usize)
191            .and_then(|value| value.checked_mul(4))
192            .ok_or(ImageBitmapError::DimensionsTooLarge)?;
193
194        if pixels.len() != expected {
195            return Err(ImageBitmapError::PixelDataLengthMismatch {
196                expected,
197                actual: pixels.len(),
198            });
199        }
200
201        Ok(Self {
202            id: NEXT_IMAGE_BITMAP_ID.fetch_add(1, Ordering::Relaxed),
203            width,
204            height,
205            pixels: Arc::from(pixels),
206        })
207    }
208
209    /// Stable bitmap identity used by caches.
210    pub fn id(&self) -> u64 {
211        self.id
212    }
213
214    /// Width in pixels.
215    pub fn width(&self) -> u32 {
216        self.width
217    }
218
219    /// Height in pixels.
220    pub fn height(&self) -> u32 {
221        self.height
222    }
223
224    /// Returns the raw RGBA8 pixel data.
225    pub fn pixels(&self) -> &[u8] {
226        &self.pixels
227    }
228
229    /// Returns intrinsic size in logical units.
230    pub fn intrinsic_size(&self) -> Size {
231        Size {
232            width: self.width as f32,
233            height: self.height as f32,
234        }
235    }
236}
237
238impl PartialEq for ImageBitmap {
239    fn eq(&self, other: &Self) -> bool {
240        self.id == other.id
241    }
242}
243
244impl Eq for ImageBitmap {}
245
246impl Hash for ImageBitmap {
247    fn hash<H: Hasher>(&self, state: &mut H) {
248        self.id.hash(state);
249    }
250}
251
252#[cfg(test)]
253mod tests {
254    use super::*;
255
256    #[test]
257    fn from_rgba8_accepts_valid_data() {
258        let bitmap = ImageBitmap::from_rgba8(2, 1, vec![255, 0, 0, 255, 0, 255, 0, 255])
259            .expect("valid bitmap");
260
261        assert_eq!(bitmap.width(), 2);
262        assert_eq!(bitmap.height(), 1);
263        assert_eq!(bitmap.pixels().len(), 8);
264    }
265
266    #[test]
267    fn from_rgba8_rejects_zero_dimensions() {
268        let err = ImageBitmap::from_rgba8(0, 2, vec![]).expect_err("must fail");
269        assert_eq!(err, ImageBitmapError::InvalidDimensions);
270    }
271
272    #[test]
273    fn from_rgba8_rejects_wrong_pixel_length() {
274        let err = ImageBitmap::from_rgba8(2, 2, vec![0; 15]).expect_err("must fail");
275        assert_eq!(
276            err,
277            ImageBitmapError::PixelDataLengthMismatch {
278                expected: 16,
279                actual: 15,
280            }
281        );
282    }
283
284    #[test]
285    fn from_rgba8_slice_accepts_valid_data() {
286        let pixels = [255u8, 0, 0, 255];
287        let bitmap = ImageBitmap::from_rgba8_slice(1, 1, &pixels).expect("valid bitmap");
288        assert_eq!(bitmap.pixels(), &pixels);
289    }
290
291    #[test]
292    fn ids_are_unique() {
293        let a = ImageBitmap::from_rgba8(1, 1, vec![0, 0, 0, 255]).expect("bitmap a");
294        let b = ImageBitmap::from_rgba8(1, 1, vec![0, 0, 0, 255]).expect("bitmap b");
295        assert_ne!(a.id(), b.id());
296    }
297
298    #[test]
299    fn intrinsic_size_matches_dimensions() {
300        let bitmap = ImageBitmap::from_rgba8(3, 4, vec![255; 3 * 4 * 4]).expect("bitmap");
301        assert_eq!(bitmap.intrinsic_size(), Size::new(3.0, 4.0));
302    }
303
304    #[test]
305    fn tint_filter_multiplies_channels() {
306        let filter = ColorFilter::modulate(Color::from_rgba_u8(128, 255, 64, 128));
307        let tinted = filter.apply_rgba([1.0, 0.5, 1.0, 1.0]);
308        assert!((tinted[0] - (128.0 / 255.0)).abs() < 1e-5);
309        assert!((tinted[1] - 0.5).abs() < 1e-5);
310        assert!((tinted[2] - (64.0 / 255.0)).abs() < 1e-5);
311        assert!((tinted[3] - (128.0 / 255.0)).abs() < 1e-5);
312    }
313
314    #[test]
315    fn tint_constructor_matches_variant() {
316        let color = Color::from_rgba_u8(10, 20, 30, 40);
317        assert_eq!(ColorFilter::tint(color), ColorFilter::Tint(color));
318    }
319
320    #[test]
321    fn tint_filter_uses_src_in_behavior() {
322        let filter = ColorFilter::tint(Color::from_rgba_u8(255, 128, 0, 128));
323        let tinted = filter.apply_rgba([0.2, 0.4, 0.8, 0.25]);
324        assert!((tinted[0] - 0.25).abs() < 1e-5);
325        assert!((tinted[1] - (0.25 * 128.0 / 255.0)).abs() < 1e-5);
326        assert!(tinted[2].abs() < 1e-5);
327        assert!((tinted[3] - (0.25 * 128.0 / 255.0)).abs() < 1e-5);
328    }
329
330    #[test]
331    fn matrix_filter_transforms_channels() {
332        let matrix = [
333            1.0, 0.0, 0.0, 0.0, 0.1, // R + 0.1
334            0.0, 0.5, 0.0, 0.0, 0.0, // G * 0.5
335            0.0, 0.0, 0.0, 1.0, 0.0, // A -> B
336            0.0, 0.0, 0.0, 1.0, 0.0, // A passthrough
337        ];
338        let filter = ColorFilter::matrix(matrix);
339        let transformed = filter.apply_rgba([0.2, 0.6, 0.9, 0.4]);
340        assert!((transformed[0] - 0.3).abs() < 1e-5);
341        assert!((transformed[1] - 0.3).abs() < 1e-5);
342        assert!((transformed[2] - 0.4).abs() < 1e-5);
343        assert!((transformed[3] - 0.4).abs() < 1e-5);
344    }
345
346    #[test]
347    fn filter_compose_applies_in_order() {
348        let first = ColorFilter::modulate(Color::from_rgba_u8(128, 255, 255, 255));
349        let second = ColorFilter::tint(Color::from_rgba_u8(255, 0, 0, 255));
350        let chained = first.compose(second);
351        let direct_second = second.apply_rgba(first.apply_rgba([0.8, 0.4, 0.2, 0.5]));
352        let composed = chained.apply_rgba([0.8, 0.4, 0.2, 0.5]);
353        assert!((direct_second[0] - composed[0]).abs() < 1e-5);
354        assert!((direct_second[1] - composed[1]).abs() < 1e-5);
355        assert!((direct_second[2] - composed[2]).abs() < 1e-5);
356        assert!((direct_second[3] - composed[3]).abs() < 1e-5);
357    }
358}
cranpose_ui_graphics/image.rs

cranpose_ui_graphics/
image.rs
