我有50张图片的视图。图像可能重叠。我想(例如)选择图像编号33并找到像素颜色。我怎样才能做到这一点 ? PS我使用glReadPixels。
答案 0 :(得分:1)
除非您想要先消除将图像应用为纹理的时间,否则不会使用glReadPixels。您可以直接从UIImage执行此操作:
void pixelExamine( UIImage *image )
{
CGImageRef colorImage = image.CGImage;
int width = CGImageGetWidth(colorImage);
int height = CGImageGetHeight(colorImage);
uint32_t *pixels = (uint32_t *) malloc(width * height * sizeof(uint32_t));
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(pixels, width, height, 8, width * sizeof(uint32_t), colorSpace, kCGBitmapByteOrder32Little | kCGImageAlphaPremultipliedLast);
CGContextDrawImage(context, CGRectMake(0, 0, width, height), colorImage);
int x;
int y;
uint8_t *rgbaPixel;
for( y = 0; y < height; y++)
{
rgbaPixel = (uint8_t *) &pixels[y * width];
for( x = 0; x < width; x++, rgbaPixel+=4)
{
// rgbaPixel[0] = ALPHA 0..255
// rgbaPixel[3] = RED 0..255
// rgbaPixel[2] = GREEN 0..255
// rgbaPixel[1] = BLUE 0..255
}
}
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);
free(pixels);
}