Implicit conversion from enumeration type 'enum CGImageAlphaInfo' to different enumeration type 'CGBitmapinfo' (aka) 'enum CGBitmapInfo')

Question

i am converting an old iOS 5 project to iOS6.0 on xCode5 and most of the warnings and errors has been fixed but for this one. any suggestions on how to rewrite the code to avoid the complier warnings.

#define kBitsPerComponent 8
#define kBitmapInfo       kCGImageAlphaPremultipliedLast

 - (UIImage*)scaleToSize:(CGSize)size :(UIImage *)image
{
CGBitmapInfo bitmapInfo = kBitmapInfo;
size_t bytesPerRow = size.width * 4.0;
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(NULL, size.width,
                                             size.height, kBitsPerComponent,
                                             bytesPerRow, colorSpace, bitmapInfo);

CGRect rect = CGRectMake(0.0f, 0.0f, size.width, size.height);
CGContextDrawImage(context, rect, image.CGImage);

CGImageRef scaledImageRef = CGBitmapContextCreateImage(context);
UIImage* scaledImage = [UIImage imageWithCGImage:scaledImageRef];

CGImageRelease(scaledImageRef);
CGContextRelease(context);
CGColorSpaceRelease(colorSpace);

return scaledImage;
}

the code gives a warning Implicit conversion from enumeration type 'enum CGImageAlphaInfo' to different enumeration type 'CGBitmapinfo' (aka) 'enum CGBitmapInfo')

will greatly appreciate if some one can help on how to modify the code.

score 119 · Accepted Answer · answered Sep 20 '13 at 16:45

119

From the docs:

The constants for specifying the alpha channel information are declared with the CGImageAlphaInfo type but can be passed to this parameter safely.

So you can just use a cast to suppress the warning:

CGBitmapInfo bitmapInfo = (CGBitmapInfo) kBitmapInfo;

answered Sep 20 '13 at 16:45

Dietrich Epp

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Good to find this. Lots of answers here on SO use the warning-triggering constants, and it was very puzzling until now, because "Jumping to Definition" in Xcode clearly shows they are completely different `enum`s and it's not clear that they're functionally interchangeable. – Nicolas Miari Jan 28 '15 at 03:47
CGImageAlphaInfo is a part of CGBitmapInfo (first 5 bits) they are not interchangable but one is part of another. – Marcin Mierzejewski Apr 10 '20 at 07:47

Implicit conversion from enumeration type 'enum CGImageAlphaInfo' to different enumeration type 'CGBitmapinfo' (aka) 'enum CGBitmapInfo')

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