我正在尝试使用 vImage_Buffer 缩放图像,下面的代码对我有用。我的麻烦是我想保持源图像的纵横比,所以我可能需要添加一个xOffset
or yOffset
。以下代码仅适用于yOffset
. 我如何也可以缩放图像xOffset
。我无法进行缩放,CGContext
因为这会影响性能。
CVImageBufferRef imageBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
size_t finalWidth = 1080;
size_t finalHeight = 720;
size_t sourceWidth = CVPixelBufferGetWidth(imageBuffer);
size_t sourceHeight = CVPixelBufferGetHeight(imageBuffer);
CGRect aspectRect = AVMakeRectWithAspectRatioInsideRect(CGSizeMake(sourceWidth, sourceHeight), CGRectMake(0, 0, finalWidth, finalHeight));
size_t bytesPerRow = CVPixelBufferGetBytesPerRow(imageBuffer);
size_t startY = aspectRect.origin.y;
size_t yOffSet = (finalWidth*startY*4);
CVPixelBufferLockBaseAddress(imageBuffer, 0);
void *baseAddress = CVPixelBufferGetBaseAddress(imageBuffer);
void* destData = malloc(finalHeight * finalWidth * 4);
vImage_Buffer srcBuffer = { (void *)baseAddress, sourceHeight, sourceWidth, bytesPerRow};
vImage_Buffer destBuffer = { (void *)destData+yOffSet, aspectRect.size.height, aspectRect.size.width, aspectRect.size.width * 4};
vImage_Error err = vImageScale_ARGB8888(&srcBuffer, &destBuffer, NULL, 0);