I know this question has been asked several times, but I couldn't solve it for my particular case. CGContextDrawPDFPage is indicated as a leak in the leak instrument. Also when this segment of code is run the app crashes which I'm really sure is due to memory issues.
pdfURLDocument = [[NSURL alloc] initFileURLWithPath: [docsDir stringByAppendingPathComponent:documentName]];
pdfDocument = CGPDFDocumentCreateWithURL((CFURLRef)pdfURLDocument);
[pdfURLDocument release];
page = CGPDFDocumentGetPage(pdfDocument, 1);
CGPDFPageRetain(page);
// determine the size of the PDF page
CGRect pageRect = CGPDFPageGetBoxRect(page, kCGPDFMediaBox);
pdfScaleWidth = (1/((CGFloat) gridSizeDocument)) * self.frame.size.width/pageRect.size.width;
pdfScaleHeight = (1/((CGFloat) gridSizeDocument)) * self.frame.size.height/pageRect.size.height;
pageRect.size = CGSizeMake(pageRect.size.width*pdfScaleWidth, pageRect.size.height*pdfScaleHeight);
// Create a low res image representation of the PDF page
UIGraphicsBeginImageContext(pageRect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
// First fill the background with white.
CGContextSetRGBFillColor(context, 1.0,1.0,1.0,1.0);
CGContextFillRect(context,pageRect);
CGContextSaveGState(context);
// Flip the context so that the PDF page is rendered
// right side up.
CGContextTranslateCTM(context, 0.0, pageRect.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
// Scale the context so that the PDF page is rendered
// at the correct size for the zoom level.
CGContextScaleCTM(context, pdfScaleWidth, pdfScaleHeight);
CGContextSetInterpolationQuality(context, kCGInterpolationHigh);
CGContextSetRenderingIntent(context, kCGRenderingIntentDefault);
CGContextDrawPDFPage(context, page);
CGContextRestoreGState(context);
backgroundImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
CGPDFPageRelease(page);
Also, I included CGPDFPageRelease(page); in the dealloc method. Also, it might be helpful to add that it works fine for small documents, but only crashes on large ones. Memory leaks still persist in the smaller ones, however.
I know this is an old question, but two observations:
You need to release your pdfDocument:
CGPDFDocumentRelease(pdfDocument);
You should not release the page with CGPDFPageRelease(page), though, because that is an autoreleased object and you don't own it (unless, of course, you retained it with CGPDFPageRetain).
If you use the static analyzer ("Analyze" on Xcode's "Product" menu), it should point out both of those issues.
The fundamental problem is that CGContextDrawPDFPage leaks in iOS versions prior to 6.0.
The release needs to come after the page has been used, not before. So first, move CGPDFPageRelease(page) to last in this code block and see if that helps. Also, the problem could have something to do with the CGPDFDocumentRef stored in the pdf variable. If the above doesn't help, it would be good if you show how you obtain the reference, and where you retain and release it.
Related
I have a drawing app where I'm using the openGL paint code to draw the strokes, but want to transfer it to another image after the stroke is complete, then clear the OpenGL view. and for that, I'm using CoreGraphics. I'm running into a problem however, where the OpenGL view is being cleared before the image is being transferred via CG (even though I clear it afterwards)
(And I want it the other way, ie the image to be drawn first then the painting image to be erased, to avoid any kind of flickering)
(paintingView is the openGL view)
Here is the code:
// Save the previous line drawn to the "main image"
UIImage *paintingViewImage = [[UIImage alloc] init];
paintingViewImage = [_paintingView snapshot];
UIGraphicsBeginImageContext(self.mainImage.frame.size);
[self.mainImage.image drawInRect:CGRectMake(0, 0, self.mainImage.frame.size.width, self.mainImage.frame.size.height) blendMode:kCGBlendModeNormal alpha:1.0];
// Get the image from the painting view
[paintingViewImage drawInRect:CGRectMake(0, 0, self.mainImage.frame.size.width, self.mainImage.frame.size.height) blendMode:kCGBlendModeNormal alpha:1.0];
self.mainImage.image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
[self.paintingView erase];
So the paintingView is being erased before the mainImage.image variable is being set to the CurrentImage Context.
I'm a only a beginner with these, so any thoughts helpful.
Thanks
You're probably better off using FBOs (OpenGL frame buffer objects). You draw into one FBO, then switch drawing to a new FBO while you save off the previous one. You can ping-pong back-and-forth between the 2 FBOs. Here are the docs for using FBOs on iOS.
I have following method to take a pdf file in documents directory and create a thumbnail out of it. This method is leaking memory in two places as shown in comments. Since I am using ARC I am not sure why is it leaking memory. How can I solve this.
+ (UIImage*)createPdfThumbnail:(NSString*)pdfFilePath {
NSURL *targetURL = [NSURL fileURLWithPath:pdfFilePath];
CGPDFDocumentRef pdf = CGPDFDocumentCreateWithURL((__bridge CFURLRef)targetURL); // 3.0% of memory leak
CGPDFPageRef page = CGPDFDocumentGetPage(pdf, 1);//for the first page
CGRect aRect = CGPDFPageGetBoxRect(page, kCGPDFCropBox);
UIGraphicsBeginImageContext(aRect.size);
CGContextRef context = UIGraphicsGetCurrentContext();
CGContextSaveGState(context);
CGContextTranslateCTM(context, 0.0, aRect.size.height);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextTranslateCTM(context, -(aRect.origin.x), -(aRect.origin.y));
CGContextSetGrayFillColor(context, 1.0, 1.0);
CGContextFillRect(context, aRect);
CGAffineTransform pdfTransform = CGPDFPageGetDrawingTransform(page, kCGPDFCropBox, aRect, 0, false);
CGContextConcatCTM(context, pdfTransform);
CGContextDrawPDFPage(context, page);
UIImage *thumbnail = UIGraphicsGetImageFromCurrentImageContext(); // 97% of memory leak
CGContextRestoreGState(context);
UIGraphicsEndImageContext();
CGPDFDocumentRelease(pdf);
return thumbnail;
}
EDIT:
-(void)fromJSON:(NSDictionary *)JSON{
[super fromJSON:JSON];
self.path = JSON[#"path"];
//Create and save thumbnail
if (self.parentSpecSheet != nil){
#autoreleasepool {
UIImage* thumbnail = [Utilities createPdfThumbnail:self.path];
Photo* thumbnailPhoto = [Photo addObject];
[thumbnailPhoto setDelta:#(0)];
[thumbnailPhoto setImage:thumbnail];
[thumbnailPhoto.file setDelta:#(0)];
self.parentSpecSheet.thumbnail = thumbnailPhoto;
}
}
}
Two thoughts:
I experience a significant leak from CGContextDrawPDFPage when I test your code in iOS5 (and if you search for "CGContextDrawPDFPage leak", you'll see tons of references to permutations of this problem). This appears to be a known problem.
I see no appreciable leak in iOS 6 from the above code, though.
If you're still seeing this leak in iOS 6, then I suspect the problem does not rest in the above code. Do you have any other leaks reported? I'd also suggest you confirm that the object that owns this thumbnail is successfully getting deallocated itself (e.g. log/breakpoint in its dealloc method).
Unfortunately, when you look at the leaks tool, it's reporting where the leaked object was instantiated, not where the leak took place. You might want to confirm that the owner of this thumbnail is not, somehow, maintaining a strong reference to it (e.g., the owner, itself, has a retain cycle, or something like that).
Or this code can be executed in a background thread safely?
CGImageRef cgImage;
CGContextRef context;
CGColorSpaceRef colorSpace;
// Sets the CoreGraphic Image to work on it.
cgImage = [uiImage CGImage];
// Sets the image's size.
_width = CGImageGetWidth(cgImage);
_height = CGImageGetHeight(cgImage);
// Extracts the pixel informations and place it into the data.
colorSpace = CGColorSpaceCreateDeviceRGB();
_data = malloc(_width * _height * 4);
context = CGBitmapContextCreate(_data, _width, _height, 8, 4 * _width, colorSpace,
kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
CGColorSpaceRelease(colorSpace);
// Adjusts position and invert the image.
// The OpenGL uses the image data upside-down compared commom image files.
CGContextTranslateCTM(context, 0, _height);
CGContextScaleCTM(context, 1.0, -1.0);
// Clears and ReDraw the image into the context.
CGContextClearRect(context, CGRectMake(0, 0, _width, _height));
CGContextDrawImage(context, CGRectMake(0, 0, _width, _height), cgImage);
// Releases the context.
CGContextRelease(context);
How to acheive the same result, if not?
(My problem is that I can't see my OpenGL textures based on the output buffer of this method, if it runs in the background)
I think you might have trouble with running this code on a separate thread from GL's like this. Even if it would work you might encounter half drawn images/textures. You could avoid this by creating a double buffer:
Your "_data" should be allocated only once and should hold 2 raw image data buffers. Then just create 2 pointers defined as foreground and background buffer (void *fg = _data[0], void *bg = _data[1] to begin with). Now when your method collects data from CGImage to bg just swap the pointers (then void *fg = _data[1], void *bg = _data[0] or the other way around)
Now your GL thread should fill your texture with data on fg (same thread as drawing).
Also you might need some locking mechanisms:
Before you push data to texture you should lock "buffer swap" and
unlock it after the push.
You will probably want to know if the
buffer has been swapped and only push fg data to texture in such
case.
Also note that if you call GL methods on more then 1 thread you will have trouble in most cases.
That looks OK to me, assuming that uiImage, _width, _height and _data aren't being manipulated from another thread at the same time. (Assuming you're using iOS 4 and above.)
Are you uploading the texture to OpenGL on the background thread? If so, that's probably the problem (since a given OpenGL context should only be accessed from a single thread at a time).
As long as you don't access UIKit (or similar frameworks) (directly or indirectly) and as long as you don't access the variables in your code from multiple threads, it's OK.
I've found some code which gives me a UIImage out of a PDF-File. It works, but I have two questions:
Is there a possibility to achieve a better quality of the UIImage? (See Screenshot)
I only see the first page in my UIImageView. Do I have to embed the file in a UIScrollView to be complete?
Or is it better to render just one page and use buttons to navigate through the pages?
P.S. I know that UIWebView can display PDF-Pages with some functionalities but I need it as a UIImage or at least in a UIView.
Bad quality Image:
Code:
-(UIImage *)image {
UIGraphicsBeginImageContext(CGSizeMake(280, 320));
CGContextRef context = UIGraphicsGetCurrentContext();
CFURLRef pdfURL = CFBundleCopyResourceURL(CFBundleGetMainBundle(), CFSTR("ls.pdf"), NULL, NULL);
CGPDFDocumentRef pdf = CGPDFDocumentCreateWithURL((CFURLRef)pdfURL);
CGContextTranslateCTM(context, 0.0, 320);
CGContextScaleCTM(context, 1.0, -1.0);
CGPDFPageRef page = CGPDFDocumentGetPage(pdf, 4);
CGContextSaveGState(context);
CGAffineTransform pdfTransform = CGPDFPageGetDrawingTransform(page, kCGPDFCropBox, CGRectMake(0, 0, 280, 320), 0, true);
CGContextConcatCTM(context, pdfTransform);
CGContextDrawPDFPage(context, page);
CGContextRestoreGState(context);
UIImage *resultingImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return resultingImage;
}
I know i'm a little late here, but i hope i can help someone else looking for an answer.
As to the questions asked:
I'm afraid the only way to achieve a better image quality is to render a bigger image, and letting the UIImageView resize it for you. I don't think you can set the resolution, but using a bigger image may be a good choice. It won't take too long for the page to render, and the image will have a better quality. PDF files are rendered on demand depending on the zoom level, that's why they seem to have "better quality".
As to rendering all the pages, you can get the number of pages in the document calling CGPDFDocumentGetNumberOfPages( pdf ) and using a simple for loop you can concat all the images generated in one single image. For displaying it, use the UIScrollVIew.
In my opinion, this approach is better than the above, but you should try to optimize it, for example rendering always the current, the previous and the next page. For nice scrolling transition effects, why not use a horizontal UIScrollView.
For more generic rendering code, i always do the rotation like this:
int rotation = CGPDFPageGetRotationAngle(page);
CGContextTranslateCTM(context, 0, imageSize.height);//moves up Height
CGContextScaleCTM(context, 1.0, -1.0);//flips horizontally down
CGContextRotateCTM(context, -rotation*M_PI/180);//rotates the pdf
CGRect placement = CGContextGetClipBoundingBox(context);//get the flip's placement
CGContextTranslateCTM(context, placement.origin.x, placement.origin.y);//moves the the correct place
//do all your drawings
CGContextDrawPDFPage(context, page);
//undo the rotations/scaling/translations
CGContextTranslateCTM(context, -placement.origin.x, -placement.origin.y);
CGContextRotateCTM(context, rotation*M_PI/180);
CGContextScaleCTM(context, 1.0, -1.0);
CGContextTranslateCTM(context, 0, -imageSize.height);
Steipete already mentioned setting the white background:
CGContextSetRGBFillColor(context, 1, 1, 1, 1);
CGContextFillRect(context, CGRectMake(0, 0, imageSize.width, imageSize.height));
So the last thing to keep in mind is when exporting an image, set the quality to the maximum. For example:
UIImageJPEGRepresentation(image, 1);
What are you doing with the CGContextTranslateCTM(context, 0.0, 320); call?
You should extract the proper metrics form the pdf, with code like this:
cropBox = CGPDFPageGetBoxRect(page, kCGPDFCropBox);
rotate = CGPDFPageGetRotationAngle(page);
Also, as you see, the pdf might has rotation info, so you need to use the CGContextTranslateCTM/CGContextRotateCTM/CGContextScaleCTM depending on the angle.
You also might wanna clip any content that is outside of the CropBox area, as pdf has various viewPorts that you usually don't wanna display (e.g. for printers so that seamless printing is possible) -> use CGContextClip.
Next, you're forgetting that the pdf reference defines a white background color. There are a lot of documents out there that don't define any background color at all - you'll get weird results if you don't draw a white background on your own --> CGContextSetRGBFillColor & CGContextFillRect.
I have a problem. When I use the "renderInContext" in the iPad, the used memory is never released and accumulates until the application closes with "Memory Warning" Level=1 and Level=2
My code:
CGRect mediaBox = CGRectMake(0, 0, 16.54 * 72.0, 24.02 * 72.0);
CGContextRef ctx = CGPDFContextCreateWithURL((CFURLRef)[NSURL fileURLWithPath:posterPath isDirectory:NO], &mediaBox, NULL);
CGPDFContextBeginPage(ctx, NULL);
CGContextScaleCTM(ctx, 0.516, -0.516);
CGContextTranslateCTM(ctx, 0, -mediaBox.size.height - 1500);
[[self returnBigView].layer renderInContext:ctx];
CGPDFContextEndPage(ctx);
CGPDFContextClose(ctx);
CGContextRelease(ctx);
I have tried several ways, but no free memory. Any ideas?
** Sorry for my bad English
I had the same issue too, inside a loop - setting the layer contents to nil worked for me:
Releasing renderInContext result within a loop
I had the same issue. After a long investigation, it seems the memory was not released because the code did not run on the main thread. So don't execute renderInContext when you're not working on the main thread!