Function ReadInterleavedImage

win/share/gifread.c:443–493

}

static void
ReadInterleavedImage(FILE *fd, int len, int height)
{
    int v;
    int xpos = 0, ypos = 0, pass = 0;

    while ((v = LWZReadByte(fd, FALSE /*, (int) input_code_size*/ )) >= 0) {
        PPM_ASSIGN(image[ypos][xpos], ColorMap[CM_RED][v],
                   ColorMap[CM_GREEN][v], ColorMap[CM_BLUE][v]);

        ++xpos;
        if (xpos == len) {
            xpos = 0;
            switch (pass) {
            case 0:
            case 1:
                ypos += 8;
                break;
            case 2:
                ypos += 4;
                break;
            case 3:
                ypos += 2;
                break;
            }

            if (ypos >= height) {
                ++pass;
                switch (pass) {
                case 1:
                    ypos = 4;
                    break;
                case 2:
                    ypos = 2;
                    break;
                case 3:
                    ypos = 1;
                    break;
                default:
                    goto fini;
                }
            }
        }
        if (ypos >= height)
            break;
    }

 fini:
    if (LWZReadByte(fd, FALSE /*, (int) input_code_size*/ ) >= 0)
        Fprintf(stderr, "too much input data, ignoring extra...\n");
}

static void
ReadTileStrip(FILE *fd, int len)