CGDataProvider doesn't free up data on callback

Question

Hi,

I am creating a very big buffer (called buffer2 in the code) using CGDataProviderRef with the following code:

-(UIImage *) glToUIImage {
NSInteger myDataLength = 768 * 1024 * 4;
// allocate array and read pixels into it.
GLubyte *buffer = (GLubyte *) malloc(myDataLength);
glReadPixels(0, 0, 768, 1024, GL_RGBA, GL_UNSIGNED_BYTE, buffer);

// gl renders "upside down" so swap top to bottom into new array.
// there's gotta be a better way, but this works.
GLubyte *buffer2 = (GLubyte *) malloc(myDataLength);
for(int y = 0; y <1024; y++)
{
        for(int x = 0; x <768 * 4; x++)
        {
                buffer2[(1023 - y) * 768 * 4 + x] = buffer[y * 4 * 768 + x];
        }
}

 // make data provider with data.
CGDataProviderRef provider = CGDataProviderCreateWithData(NULL, buffer2, myDataLength, &releaseBufferData);

// prep the ingredients
int bitsPerComponent = 8;
int bitsPerPixel = 32;
int bytesPerRow = 4 * 768;
CGColorSpaceRef colorSpaceRef = CGColorSpaceCreateDeviceRGB();
CGBitmapInfo bitmapInfo = kCGBitmapByteOrderDefault;
CGColorRenderingIntent renderingIntent = kCGRenderingIntentDefault;

// make the cgimage
CGImageRef imageRef = CGImageCreate(768, 1024, bitsPerComponent, bitsPerPixel, bytesPerRow, colorSpaceRef, bitmapInfo, provider, NULL, NO, renderingIntent);

// then make the uiimage from that
UIImage *myImage = [UIImage imageWithCGImage:imageRef];

free(buffer);
//[provider autorelease];
CGDataProviderRelease(provider);
CGColorSpaceRelease(colorSpaceRef);
CGImageRelease(imageRef);

return myImage;

}

I expect CGProvider to call back the releaseBufferData method when it is done with buffer2 so that I can free up the memory it's taken. The code for this method is:

static void releaseBufferData (void *info, const void *data, size_t size){  
 free(data);  
}

However, even though my callback method is called, the memory that data (buffer2) takes is never freed and hence it results in massive memory leaks. What am I doing wrong?

Answer 1

Have you ever CGDataProviderRelease your provider? The callback will not be called if you don't release the data provider.

Answer 2

For some peculiar reason this is not an issue anymore.