root/ext/gd/libgd/gd_pixelate.c

DEFINITIONS

1. gdImagePixelate

#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;
}