tex_packer_core/
compositing.rs

1use image::{Rgba, RgbaImage};
2
3#[derive(Clone, Copy, Debug)]
4pub struct BlitRect {
5    pub x: u32,
6    pub y: u32,
7    pub w: u32,
8    pub h: u32,
9}
10
11impl BlitRect {
12    pub fn new(x: u32, y: u32, w: u32, h: u32) -> Self {
13        Self { x, y, w, h }
14    }
15}
16
17#[derive(Clone, Copy, Debug)]
18pub struct BlitOptions {
19    pub rotated: bool,
20    pub extrude: u32,
21    pub outlines: bool,
22}
23
24/// Blit a sub-rectangle from `src` into `canvas` at destination (dx, dy),
25/// optionally rotated 90° clockwise, then apply pixel extrusion around the
26/// blitted content area and optional red outlines for debugging.
27///
28/// - (sx, sy, sw, sh): source rectangle within `src`
29/// - (dx, dy): destination top-left in `canvas` where content area begins
30/// - rotated: if true, rotate 90° CW during blit
31/// - extrude: number of pixels to extrude around the content
32/// - outlines: if true, draw a red 1px outline around the content area
33pub fn blit_rgba(
34    src: &RgbaImage,
35    canvas: &mut RgbaImage,
36    dst: BlitRect,
37    src_rect: BlitRect,
38    options: BlitOptions,
39) {
40    let (cw, ch) = canvas.dimensions();
41    let BlitRect {
42        x: dx,
43        y: dy,
44        w: _,
45        h: _,
46    } = dst;
47    let BlitRect {
48        x: sx,
49        y: sy,
50        w: sw,
51        h: sh,
52    } = src_rect;
53    let BlitOptions {
54        rotated,
55        extrude,
56        outlines,
57    } = options;
58
59    // destination (rendered) size may differ when rotated
60    let (rw, rh) = if rotated { (sh, sw) } else { (sw, sh) };
61
62    // main blit
63    for yy in 0..rh {
64        for xx in 0..rw {
65            let (ix, iy) = if rotated {
66                (sx + yy, sy + (sh - 1 - xx))
67            } else {
68                (sx + xx, sy + yy)
69            };
70            if dx + xx < cw && dy + yy < ch {
71                let px = *src.get_pixel(ix, iy);
72                canvas.put_pixel(dx + xx, dy + yy, px);
73            }
74        }
75    }
76
77    if outlines {
78        // red outline on frame bounds
79        let red = Rgba([255, 0, 0, 255]);
80        for xx in 0..rw {
81            if dx + xx < cw && dy < ch {
82                canvas.put_pixel(dx + xx, dy, red);
83            }
84            let by = dy + rh.saturating_sub(1);
85            if dx + xx < cw && by < ch {
86                canvas.put_pixel(dx + xx, by, red);
87            }
88        }
89        for yy in 0..rh {
90            if dx < cw && dy + yy < ch {
91                canvas.put_pixel(dx, dy + yy, red);
92            }
93            let rx = dx + rw.saturating_sub(1);
94            if rx < cw && dy + yy < ch {
95                canvas.put_pixel(rx, dy + yy, red);
96            }
97        }
98    }
99
100    if extrude > 0 {
101        // edges
102        for e in 1..=extrude {
103            // top row
104            if dy >= e && dy < ch {
105                for xx in 0..rw {
106                    if dx + xx < cw {
107                        let p = *canvas.get_pixel(dx + xx, dy);
108                        if dy >= e {
109                            canvas.put_pixel(dx + xx, dy - e, p);
110                        }
111                    }
112                }
113            }
114            // bottom row
115            if dy + rh - 1 < ch && dy + rh - 1 + e < ch {
116                for xx in 0..rw {
117                    if dx + xx < cw {
118                        let p = *canvas.get_pixel(dx + xx, dy + rh - 1);
119                        canvas.put_pixel(dx + xx, dy + rh - 1 + e, p);
120                    }
121                }
122            }
123            // left col
124            if dx >= e && dx < cw {
125                for yy in 0..rh {
126                    if dy + yy < ch {
127                        let p = *canvas.get_pixel(dx, dy + yy);
128                        canvas.put_pixel(dx - e, dy + yy, p);
129                    }
130                }
131            }
132            // right col
133            if dx + rw - 1 < cw && dx + rw - 1 + e < cw {
134                for yy in 0..rh {
135                    if dy + yy < ch {
136                        let p = *canvas.get_pixel(dx + rw - 1, dy + yy);
137                        canvas.put_pixel(dx + rw - 1 + e, dy + yy, p);
138                    }
139                }
140            }
141        }
142        // corners (copy the corner pixel) with bounds guards
143        let c00 = if dx < cw && dy < ch {
144            *canvas.get_pixel(dx, dy)
145        } else {
146            Rgba([0, 0, 0, 0])
147        };
148        let c10 = if dx + rw > 0 && dx + rw - 1 < cw && dy < ch {
149            *canvas.get_pixel(dx + rw - 1, dy)
150        } else {
151            Rgba([0, 0, 0, 0])
152        };
153        let c01 = if dx < cw && dy + rh > 0 && dy + rh - 1 < ch {
154            *canvas.get_pixel(dx, dy + rh - 1)
155        } else {
156            Rgba([0, 0, 0, 0])
157        };
158        let c11 = if dx + rw > 0 && dx + rw - 1 < cw && dy + rh > 0 && dy + rh - 1 < ch {
159            *canvas.get_pixel(dx + rw - 1, dy + rh - 1)
160        } else {
161            Rgba([0, 0, 0, 0])
162        };
163        if dx >= 1 && dy >= 1 {
164            for ex in 1..=extrude {
165                for ey in 1..=extrude {
166                    if dx >= ex && dy >= ey {
167                        canvas.put_pixel(dx - ex, dy - ey, c00);
168                    }
169                }
170            }
171        }
172        if dy >= 1 && dx + rw - 1 < cw {
173            for ex in 1..=extrude {
174                for ey in 1..=extrude {
175                    if dy >= ey && dx + rw - 1 + ex < cw {
176                        canvas.put_pixel(dx + rw - 1 + ex, dy - ey, c10);
177                    }
178                }
179            }
180        }
181        if dx >= 1 && dy + rh - 1 < ch {
182            for ex in 1..=extrude {
183                for ey in 1..=extrude {
184                    if dx >= ex && dy + rh - 1 + ey < ch {
185                        canvas.put_pixel(dx - ex, dy + rh - 1 + ey, c01);
186                    }
187                }
188            }
189        }
190        if dx + rw - 1 < cw && dy + rh - 1 < ch {
191            for ex in 1..=extrude {
192                for ey in 1..=extrude {
193                    if dx + rw - 1 + ex < cw && dy + rh - 1 + ey < ch {
194                        canvas.put_pixel(dx + rw - 1 + ex, dy + rh - 1 + ey, c11);
195                    }
196                }
197            }
198        }
199    }
200}
tex_packer_core/compositing.rs

tex_packer_core/
compositing.rs
