gd_pixelate.c

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#include "gd.h"
 
int gdImagePixelate(gdImagePtr im, int block_size, const unsigned int mode)
{
    int x, y;
 
    if (block_size <= 0) {
        return 0;
    } else if (block_size == 1) {
        return 1;
    }
    switch (mode) {
    case GD_PIXELATE_UPPERLEFT:
        for (y = 0; y < im->sy; y += block_size) {
            for (x = 0; x < im->sx; x += block_size) {
                if (gdImageBoundsSafe(im, x, y)) {
                    int c = gdImageGetPixel(im, x, y);
                    gdImageFilledRectangle(im, x, y, x + block_size - 1, y + block_size - 1, c);
                }
            }
        }
        break;
    case GD_PIXELATE_AVERAGE:
        for (y = 0; y < im->sy; y += block_size) {
            for (x = 0; x < im->sx; x += block_size) {
                int a, r, g, b, c;
                int total;
                int cx, cy;
 
                a = r = g = b = c = total = 0;
                /* sampling */
                for (cy = 0; cy < block_size; cy++) {
                    for (cx = 0; cx < block_size; cx++) {
                        if (!gdImageBoundsSafe(im, x + cx, y + cy)) {
                            continue;
                        }
                        c = gdImageGetPixel(im, x + cx, y + cy);
                        a += gdImageAlpha(im, c);
                        r += gdImageRed(im, c);
                        g += gdImageGreen(im, c);
                        b += gdImageBlue(im, c);
                        total++;
                    }
                }
                /* drawing */
                if (total > 0) {
                    c = gdImageColorResolveAlpha(im, r / total, g / total, b / total, a / total);
                    gdImageFilledRectangle(im, x, y, x + block_size - 1, y + block_size - 1, c);
                }
            }
        }
        break;
    default:
        return 0;
    }
    return 1;
}