Image Splitter — C source

/* Image splitter — tile geometry — C (C11) port of the image-splitter tool. */

#include <stdio.h>

/* One cut of the grid: the source rectangle that becomes a tile. In the
 * browser tool this rect is drawImage'd into its own canvas and encoded
 * to PNG; the geometry here is the deterministic part of that pipeline. */
typedef struct {
    int x, y, w, h;
} TileRect;

/* Split a width x height image into rows x cols tiles, row-major.
 * Mirrors splitToTiles in typescript.ts: tileW = floor(width / cols),
 * tileH = floor(height / rows) — integer division IS Math.floor for
 * positives, so a 1024px width over 3 cols yields 341px tiles and the
 * last 1px column is dropped, exactly like the TS. Writes at most
 * rows * cols rects to out; returns how many were written. */
int split_tiles(int width, int height, int rows, int cols, TileRect *out) {
    int tile_w = width / cols;
    int tile_h = height / rows;
    int n = 0;
    for (int row = 0; row < rows; row++) {
        for (int col = 0; col < cols; col++) {
            out[n].x = col * tile_w;
            out[n].y = row * tile_h;
            out[n].w = tile_w;
            out[n].h = tile_h;
            n++;
        }
    }
    return n;
}

int main(void) {
    /* 1024x768 image, 2 rows x 3 cols -> six 341x384 tiles. */
    TileRect tiles[16];
    int n = split_tiles(1024, 768, 2, 3, tiles);
    for (int i = 0; i < n; i++) {
        printf("tile %d: src=(%d, %d) %dx%d\n",
               i, tiles[i].x, tiles[i].y, tiles[i].w, tiles[i].h);
    }
    return 0;
}