iPhone: CoreGraphics and memory management
- by carloe
Can someone tell me what I am doing wrong here? I use this method to flip through pages in a PDF. But something in the code seems to not be released properly because every-time I pull a PDF page that contains an image my memory footprint increases. I am fairly new to CoreGraphics, and can't for the life of me figure out where this method would leak memory.
-(UIImage *)pageAtIndex:(NSInteger)pageNumber withWidth:(CGFloat)width andHeight:(CGFloat)height {
if((pageNumber>0) && (pageNumber<=pageCount)) {
CGFloat scaleRatio; // multiplier by which the PDF Page will be scaled
UIGraphicsBeginImageContext(CGSizeMake(width, height));
CGContextRef context = UIGraphicsGetCurrentContext();
CGPDFPageRef page = CGPDFDocumentGetPage(pdf, pageNumber);
CGRect pageRect = CGPDFPageGetBoxRect(page, kCGPDFBleedBox);
//Figure out the orientation of the PDF page and set the scaleRatio accordingly
if(pageRect.size.width/pageRect.size.height < 1.0) {
scaleRatio = height/pageRect.size.height;
}
else {
scaleRatio = width/pageRect.size.width;
}
//Calculate the offset to center the image
CGFloat xOffset = 0.0;
CGFloat yOffset = height;
if(pageRect.size.width*scaleRatio<width) {
xOffset = (width/2)-(pageRect.size.width*scaleRatio/2);
}
else {
yOffset = height-((height/2)-(pageRect.size.height*scaleRatio/2));
}
CGContextTranslateCTM(context, xOffset, yOffset);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextSaveGState(context);
CGAffineTransform pdfTransform = CGPDFPageGetDrawingTransform(page, kCGPDFBleedBox, CGRectMake(0, 0, pageRect.size.width, pageRect.size.height), 0, true);
pdfTransform = CGAffineTransformScale(pdfTransform, scaleRatio, scaleRatio);
CGContextConcatCTM(context, pdfTransform);
CGContextDrawPDFPage(context, page);
UIImage *tempImage = [UIGraphicsGetImageFromCurrentImageContext() retain];
CGContextRestoreGState(context);
UIGraphicsEndPDFContext();
UIGraphicsEndImageContext();
return tempImage;
}
return nil;
}
