OC 常用圖像格式之間轉換

1.CGImageRef to NSImage

CGImageRef cgImage;
NSBitmapImageRep *bitmapRep = [[NSBitmapImageRep alloc] initWithCGImage:cgImage];
// Create an NSImage and add the bitmap rep to it...
NSImage *image = [[NSImage alloc] init];
[image addRepresentation:bitmapRep];

2.NSImage to NSData

NSImage *image;
NSData *imageData = [image TIFFRepresentation];

3.從CGImageRef獲取ARGB數據的幾種方式:

//3.1使用CGDataProviderCopyData 
CGImageRef cgImage;
CFDataRef dataFromCGImageProvider = CGDataProviderCopyData(CGImageGetDataProvider(cgImage));
GLubyte  *imageData = (GLubyte *)CFDataGetBytePtr(dataFromCGImageProvider);


//3.2使用context draw image
CGImageRef cgImage;
size_t width =  CGImageGetWidth(cgImage);
size_t height = CGImageGetHeight(cgImage);
size_t bytesPerRow = CGImageGetBytesPerRow(cgImage);
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
unsigned char *rawData = (unsigned char*) calloc(height * bytesPerRow, sizeof(unsigned char));
NSUInteger bitsPerComponent = 8;
CGContextRef context = CGBitmapContextCreate(rawData, width, height,
                    bitsPerComponent, bytesPerRow, colorSpace,
                    kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
CGColorSpaceRelease(colorSpace);
CGContextDrawImage(context, CGRectMake(0, 0, width, height), cgImage);
uint8_t* rgbaData = (uint8_t*)CGBitmapContextGetData(context);
CGContextRelease(context);


//3.3 先轉NSImage，再轉NSData，再獲取數據
CGImageRef cgImage;
NSBitmapImageRep *bitmapRep = [[NSBitmapImageRep alloc] initWithCGImage:cgImage];
    // Create an NSImage and add the bitmap rep to it...
NSImage *image = [[NSImage alloc] init];
[image addRepresentation:bitmapRep];
NSData *imageData = [image TIFFRepresentation];
uint8_t* rgbaData = (uint8_t*)imageData.bytes;

4.NSData和YUV CVPixelBuffer之間的轉換

//1.YUV CVPixelBuffer轉NSData
- (NSData* ) YUVBufferToData:(CVPixelBufferRef)YUVpixelBuffer
{
    NSMutableData* YUVMutData;
    
    CVPixelBufferLockBaseAddress(YUVpixelBuffer, 0);
    unsigned char* yBaseAddress = (unsigned char*)CVPixelBufferGetBaseAddressOfPlane(YUVpixelBuffer, 0);
    int32_t yBytesPerRow = (int32_t)CVPixelBufferGetBytesPerRowOfPlane(YUVpixelBuffer, 0);
    int32_t width __unused = (int32_t)CVPixelBufferGetWidth(YUVpixelBuffer);
    int32_t height = (int32_t)CVPixelBufferGetHeight(YUVpixelBuffer);
    int32_t yLength = yBytesPerRow*height;
    YUVMutData = [NSMutableData dataWithBytes: yBaseAddress length: yLength];
    
    unsigned char* uvBaseAddress = (unsigned char*)CVPixelBufferGetBaseAddressOfPlane(YUVpixelBuffer, 1);
    int32_t uvBytesPerRow = (int32_t)CVPixelBufferGetBytesPerRowOfPlane(YUVpixelBuffer, 1);
    int32_t uvLength = uvBytesPerRow*height/2;
    NSMutableData* UVData = [NSMutableData dataWithBytes: uvBaseAddress length: uvLength];
    [YUVMutData appendData:UVData];
    NSData* YUVData = [NSData dataWithData:YUVMutData];
    CVPixelBufferUnlockBaseAddress(YUVpixelBuffer, 0);
    return YUVData;
}

//2.NSData轉CVPixelBuffer
- (void) DataToYUVBuffer:(NSData*)YUVData width:(int32_t)YUVWidth height:(int32_t)YUVHeight
{
    unsigned char* srcPtr = (unsigned char*)YUVData.bytes;
    CVPixelBufferLockBaseAddress(_pixelBufferYUV2, 0);
    unsigned char* yBaseAddress = (unsigned char*)CVPixelBufferGetBaseAddressOfPlane(_pixelBufferYUV2, 0);
    unsigned char* uvBaseAddress = (unsigned char*)CVPixelBufferGetBaseAddressOfPlane(_pixelBufferYUV2, 1);
    int32_t yLength = YUVWidth*YUVHeight;
    int32_t uvLength = YUVWidth*YUVHeight/2;
    memcpy(yBaseAddress, srcPtr, yLength);
    memcpy(uvBaseAddress, srcPtr+yLength, uvLength);
    CVPixelBufferUnlockBaseAddress(_pixelBufferYUV2, 0);
    //return _pixelBufferYUV2;
}