Loading retina/normal images using core graphics - iphone

Question

+(UIImage*) createCGImageFromFile:(NSString*)inName
{
if(!inName || [inName length]==0)
return NULL;
// use the data provider to get a CGImage; release the data provider
CGImageRef image= NULL;
CGFloat scale = 1.0f;
CGDataProviderRef dataProvider = NULL;
NSString *fileName = nil;
NSString *path = nil;
if([Utilities isRetinaDevice])
{
NSString *extenstion = [inName pathExtension];
NSString *stringWithoutPath = [inName stringByDeletingPathExtension];
fileName = [NSString stringWithFormat:#"/Images/%##2x.%#",stringWithoutPath,extenstion];
path = [[[NSBundle mainBundle] resourcePath] stringByAppendingString:fileName];
dataProvider = CGDataProviderCreateWithFilename([path UTF8String]);
if(dataProvider)
{
image = CGImageCreateWithPNGDataProvider(dataProvider, NULL, NO,kCGRenderingIntentDefault);
CGDataProviderRelease(dataProvider);
if(image)
{
scale = 2.0f;
}
}
}
if(image == NULL) //Try normal image
{
fileName = [NSString stringWithFormat:#"/Images/%#",inName];
path = [[[NSBundle mainBundle] resourcePath] stringByAppendingString:fileName];
dataProvider = CGDataProviderCreateWithFilename([path UTF8String]);
if(dataProvider)
{
image = CGImageCreateWithPNGDataProvider(dataProvider, NULL, NO,kCGRenderingIntentDefault);
CGDataProviderRelease(dataProvider);
}
}
// make a bitmap context of a suitable size to draw to, forcing decode
size_t width = CGImageGetWidth(image);
size_t height = CGImageGetHeight(image);
unsigned char *imageBuffer = (unsigned char *)malloc(width*height*4);
CGColorSpaceRef colourSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef imageContext =
CGBitmapContextCreate(imageBuffer, width, height, 8, width*4, colourSpace,
kCGImageAlphaPremultipliedFirst | kCGBitmapByteOrder32Little);
CGColorSpaceRelease(colourSpace);
// draw the image to the context, release it
CGContextDrawImage(imageContext, CGRectMake(0, 0, width, height), image);
CGImageRelease(image);
// now get an image ref from the context
CGImageRef cgImageRef = CGBitmapContextCreateImage(imageContext);
CGContextRelease(imageContext);
free(imageBuffer);
UIImage *outImage = nil;
if(cgImageRef)
{
outImage = [[UIImage alloc] initWithCGImage:cgImageRef scale:scale orientation:UIImageOrientationUp];
CGImageRelease(cgImageRef);
}
return outImage;//Need to release by the receiver
}
Earlier the function was not loading retina images since i was not appending #2x to the image path, i thought that apple itself will take care.
Now I modified the code to load #2x images and created UIImage using scale factor, am I missing something in above code? Is it fine?
P.S. Currently I am not facing any problem using this code but I am not 100% sure

Answer 1

I would use UIImage to load it (it will correct the path)
That will greatly simply your code
THEN get a CGImage from it (UIImage is basically just a thin wrapper around CG so thats no real overhead)
then proceed with your code - it looks ok to me