72 lines
2.4 KiB
Rust
Executable File
72 lines
2.4 KiB
Rust
Executable File
/// Write a single palette index. Out-of-bounds coordinates are silently ignored.
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#[allow(dead_code)]
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pub fn set_pixel(dst: &mut [u8], dst_w: usize, x: i32, y: i32, color: u8) {
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let dst_h = (dst.len() / dst_w) as i32;
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if x < 0 || x >= dst_w as i32 || y < 0 || y >= dst_h {
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return;
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}
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dst[dst_w * y as usize + x as usize] = color;
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}
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/// Copy a rectangle out of `src` into a new Vec (for building sprites/glyphs).
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#[allow(dead_code)]
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pub fn extract(src: &[u8], src_w: usize, x: usize, y: usize, w: usize, h: usize) -> Vec<u8> {
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let mut out = vec![0u8; w * h];
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for row in 0..h {
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let s = src_w * (y + row) + x;
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let d = w * row;
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out[d..d + w].copy_from_slice(&src[s..s + w]);
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}
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out
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}
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/// Blit `src` (width `src_w`, height derived from src.len()) into `dst` at (dx, dy).
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/// Clips against all four edges of `dst`; the destination position may be negative.
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#[allow(dead_code)]
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pub fn blit(dst: &mut [u8], dst_w: usize, dx: i32, dy: i32, src: &[u8], src_w: usize) {
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let dst_w_i = dst_w as i32;
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let dst_h = (dst.len() / dst_w) as i32;
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let src_h = (src.len() / src_w) as i32;
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for row in 0..src_h {
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let y = dy + row;
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if y < 0 || y >= dst_h {
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continue;
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}
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// Clip the horizontal span once per row, then copy it in one shot.
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let x0 = dx.max(0);
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let x1 = (dx + src_w as i32).min(dst_w_i);
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if x0 >= x1 {
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continue;
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}
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let d = dst_w * y as usize + x0 as usize;
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let s = (row * src_w as i32 + (x0 - dx)) as usize;
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let len = (x1 - x0) as usize;
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dst[d..d + len].copy_from_slice(&src[s..s + len]);
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}
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}
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/// Blit an 8×8 tile with transparency: index 0 is skipped.
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/// Clips against all four edges of `dst`; the destination position may be negative.
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pub fn blit_tile(dst: &mut [u8], dst_w: usize, dx: i32, dy: i32, tile: &[u8; 64]) {
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let dst_w_i = dst_w as i32;
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let dst_h = (dst.len() / dst_w) as i32;
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for row in 0..8i32 {
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let y = dy + row;
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if y < 0 || y >= dst_h {
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continue;
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}
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for col in 0..8i32 {
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let x = dx + col;
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if x < 0 || x >= dst_w_i {
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continue;
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}
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let px = tile[(row * 8 + col) as usize];
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if px != 0 {
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dst[dst_w * y as usize + x as usize] = px;
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}
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}
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}
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}
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