Library/loadpng.c at master · WHKnightZ/Library · GitHub

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void Swap_Image(unsigned char *img, unsigned w, unsigned h) {
    unsigned i, j, h2 = h / 2, h3 = h - 1, w2 = w * 4;
    unsigned char *tmp, *tmp2, t;
    for (i = 0; i < h2; ++i) {
        tmp = img + i * w2;
        tmp2 = img + (h3 - i) * w2;
        for (j = 0; j < w; ++j) {
            t = *tmp; *tmp = *tmp2; *tmp2 = t; ++tmp; ++tmp2;
            t = *tmp; *tmp = *tmp2; *tmp2 = t; ++tmp; ++tmp2;
            t = *tmp; *tmp = *tmp2; *tmp2 = t; ++tmp; ++tmp2;
            t = *tmp; *tmp = *tmp2; *tmp2 = t; ++tmp; ++tmp2;
        }
    }
}

// void Swap_Image(unsigned char *img, unsigned w, unsigned h) {
//     int i, j, k, h2 = h / 2, h3 = (h - 1) * 4 * w, l, m;
//     unsigned char tmp;
//     for (i = 0; i < h2; i++) {
//         for (j = 0; j < w; j++) {
//             l = (i * w + j) * 4;
//             m = h3 - (i * w - j) * 4;
//             for (k = 0; k < 4; k++) {
//                 tmp = *(img + l + k);
//                 *(img + l + k) = *(img + m + k);
//                 *(img + m + k) = tmp;
//             }
//         }
//     }
// }

void Load_Png(unsigned char **img, unsigned *w, unsigned *h, const char *filename) {
    lodepng_decode_file(img, w, h, filename, LCT_RGBA, 8);
}

void Load_Png_Swap(unsigned char **img, unsigned *w, unsigned *h, const char *filename) {
    lodepng_decode_file(img, w, h, filename, LCT_RGBA, 8);
    Swap_Image(*img, *w, *h);
}