CODEWITHSUNDEEP
iphonememorymemory-leaksuiimagecgbitmapcontextcreate
bbullis21
bbullis21

Reputation: 741

iPhone - CGBitmapContextCreateImage Leak, Anyone else with this problem?

Has anyone else come across this problem? I am resizing images pretty often with an NSTimer. After using Instruments it does not show any memory leaks but my objectalloc just continues to climb. It points directly to CGBitmapContextCreateImage.

Anyone know of a solution? or Even possible ideas?

-(UIImage *) resizedImage:(UIImage *)inImage : (CGRect)thumbRect : (double)interpolationQuality
{
    CGImageRef          imageRef = [inImage CGImage];
    CGImageAlphaInfo    alphaInfo = CGImageGetAlphaInfo(imageRef);

    if (alphaInfo == kCGImageAlphaNone)
        alphaInfo = kCGImageAlphaNoneSkipLast;

    // Build a bitmap context that's the size of the thumbRect
    CGContextRef bitmap = CGBitmapContextCreate(
                    NULL,
                    thumbRect.size.width,
                    thumbRect.size.height,      
                    CGImageGetBitsPerComponent(imageRef),
                    4 * thumbRect.size.width,   
                    CGImageGetColorSpace(imageRef),
                    alphaInfo
                    );

    // Draw into the context, this scales the image
    CGContextSetInterpolationQuality(bitmap, interpolationQuality);
    CGContextDrawImage(bitmap, thumbRect, imageRef);

    // Get an image from the context and a UIImage
    CGImageRef  ref = CGBitmapContextCreateImage(bitmap);
    UIImage*    result = [UIImage imageWithCGImage:ref];

    CGContextRelease(bitmap);   // ok if NULL
    CGImageRelease(ref);

    return [result autorelease];
}

Upvotes: 2

Views: 2403

Answers (5)

rbbtsn0w
rbbtsn0w

Reputation: 75

If you're using garbage collection, use CFMakeCollectable(posterFrame). If you're using traditional memory management, it's very straightforward:

return (CGImageRef)[(id)posterFrame autorelease];

You cast the CFTypeRef (in this case, a CGImageRef) to an Objective-C object pointer, send it the -autorelease message, and then cast the result back to CGImageRef. This pattern works for (almost) any type that's compatible with CFRetain() and CFRelease().

Upvotes: 0

CaseyB
CaseyB

Reputation: 325

Ok, the problem here is that we are defining the return from CGBitmapContextCreateImage as CGImageRef, it should be CGImage. The reason your allocations (im assuming malloc) are perpetually increasing is becuase the CGImage itself is never getting released. Try the below code. Also, there is no need to autorelease the result since it is never 'Alloc'd.

After you make the changes run in insturments with allocation again, this time you will hopefully not see an continual increase in the live bytes.

I typed this on PC so there may be a syntax error if you drop it into XCode; however, this should do the trick.

 // Get an image from the context and a UIImage     
CGImage  cgImage = CGBitmapContextCreateImage(bitmap);     
UIImage*    result = [UIImage imageWithCGImage:cgImage];      
CGContextRelease(bitmap);   // ok if NULL     
CGImageRelease(cgImage);      
return result;

Upvotes: 0

Tony
Tony

Reputation: 19181

Should you be releasing imageRef?

CGImageRelease(imageRef);

Upvotes: 1

rpetrich
rpetrich

Reputation: 32346

Why not use the simpler UIGraphicsBeginImageContext?

@implementation UIImage(ResizeExtension)
- (UIImage *)resizedImageWithSize:(CGSize)newSize interpolationQuality:(CGInterpolationQuality)interpolationQuality;
@end
@implementation UIImage(ResizeExtension)
- (UIImage *)resizedImageWithSize:(CGSize)newSize interpolationQuality:(CGInterpolationQuality)interpolationQuality
{
    UIGraphicsBeginImageContext(newSize);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextSetInterpolationQuality(context, interpolationQuality);
    [image drawInRect:CGRectMake(0, 0, newSize.width, newSize.height)];
    UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return result;
}

@end

Also, this will return an image retained by the current autorelease pool; if you are creating many of these images in a loop, allocate and drain an NSAutoreleasePool manually.

Upvotes: 0

olliej
olliej

Reputation: 36793

Just a sanity check: are you releasing the return UIImage -- normally i would expect a function that allocating a new object (in this case a UIImage) to have create in the name?

Perhaps you want

return [result autorelease]

?

Upvotes: 0

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