图像上下文生成巨大的内存分配而未释放

时间:2012-07-29 18:49:37

标签: iphone objective-c ios ipad core-text

我正在继承一个UILabel而不是使用drawRect我在背景中将文本呈现给UIImage ..这是代码:

- (UIImage *)imageForText
{
    UIGraphicsBeginImageContextWithOptions(self.frameSize, NO, 0);

            CGContextRef ctx = UIGraphicsGetCurrentContext();
            CGContextSaveGState(ctx);

            CGAffineTransform transform = [self _transformForCoreText];
            CGContextConcatCTM(ctx, transform);

            if (nil == self.textFrame) {
                CFAttributedStringRef attributedString = (__bridge CFAttributedStringRef)attributedStringWithLinks;
                CTFramesetterRef framesetter = CTFramesetterCreateWithAttributedString(attributedString);

                CGMutablePathRef path = CGPathCreateMutable();
                // We must tranform the path rectangle in order to draw the text correctly for bottom/middle
                // vertical alignment modes.
                CGPathAddRect(path, &transform, rect);
                if (nil != self.shadowColor) {
                    CGContextSetShadowWithColor(ctx, self.shadowOffset, self.shadowBlur, self.shadowColor.CGColor);
                }
                self.textFrame = CTFramesetterCreateFrame(framesetter, CFRangeMake(0, 0), path, NULL);
                CGPathRelease(path);
                CFRelease(framesetter);
            }

            // Draw the tapped link's highlight.
            if ((nil != self.touchedLink || nil != self.actionSheetLink) && nil != self.highlightedLinkBackgroundColor) {
                [self.highlightedLinkBackgroundColor setFill];

                NSRange linkRange = nil != self.touchedLink ? self.touchedLink.range : self.actionSheetLink.range;

                CFArrayRef lines = CTFrameGetLines(self.textFrame);
                CFIndex count = CFArrayGetCount(lines);
                CGPoint lineOrigins[count];
                CTFrameGetLineOrigins(self.textFrame, CFRangeMake(0, 0), lineOrigins);

                for (CFIndex i = 0; i < count; i++) {
                    CTLineRef line = CFArrayGetValueAtIndex(lines, i);

                    CFRange stringRange = CTLineGetStringRange(line);
                    NSRange lineRange = NSMakeRange(stringRange.location, stringRange.length);
                    NSRange intersectedRange = NSIntersectionRange(lineRange, linkRange);
                    if (intersectedRange.length == 0) {
                        continue;
                    }

                    CGRect highlightRect = [self _rectForRange:linkRange inLine:line lineOrigin:lineOrigins[i]];

                    if (!CGRectIsEmpty(highlightRect)) {
                        CGFloat pi = (CGFloat)M_PI;

                        CGFloat radius = 5.0f;
                        CGContextMoveToPoint(ctx, highlightRect.origin.x, highlightRect.origin.y + radius);
                        CGContextAddLineToPoint(ctx, highlightRect.origin.x, highlightRect.origin.y + highlightRect.size.height - radius);
                        CGContextAddArc(ctx, highlightRect.origin.x + radius, highlightRect.origin.y + highlightRect.size.height - radius,
                                        radius, pi, pi / 2.0f, 1.0f);
                        CGContextAddLineToPoint(ctx, highlightRect.origin.x + highlightRect.size.width - radius,
                                                highlightRect.origin.y + highlightRect.size.height);
                        CGContextAddArc(ctx, highlightRect.origin.x + highlightRect.size.width - radius,
                                        highlightRect.origin.y + highlightRect.size.height - radius, radius, pi / 2, 0.0f, 1.0f);
                        CGContextAddLineToPoint(ctx, highlightRect.origin.x + highlightRect.size.width, highlightRect.origin.y + radius);
                        CGContextAddArc(ctx, highlightRect.origin.x + highlightRect.size.width - radius, highlightRect.origin.y + radius,
                                        radius, 0.0f, -pi / 2.0f, 1.0f);
                        CGContextAddLineToPoint(ctx, highlightRect.origin.x + radius, highlightRect.origin.y);
                        CGContextAddArc(ctx, highlightRect.origin.x + radius, highlightRect.origin.y + radius, radius, 
                                        -pi / 2, pi, 1);
                        CGContextFillPath(ctx);
                    }
                }


            CTFrameDraw(self.textFrame, ctx);
            CGContextRestoreGState(ctx);
            self.renderedImage = UIGraphicsGetImageFromCurrentImageContext();
            UIGraphicsEndImageContext();
                return self.renderedImage;
}

现在,这是我在仪器上的分配工具上获得的快照。

enter image description here

我不确定如何更深入地了解这一点,但似乎图像没有被释放并保存在内存中并且随着我滚动UIScrollView而增加,并且越来越多地调用此方法。有任何想法吗?上面的代码有问题吗?我确实使用泄漏进行了剖析,没有发现漏水迹象......

修改

我添加了关于我如何调用imageForText的代码:

dispatch_async(dispatch_get_global_queue(DISPATCH_QUEUE_PRIORITY_HIGH, 0), ^{
             NSAutoreleasePool * pool = [[NSAutoreleasePool alloc] init];
            [self parseTagsInComment];
            [self.commentsText_ setLinkColor:self.textColor_];
              [weakSelf.commentsText_ imageForText];


            UIImage *renderedImage = [weakSelf.commentsText_ imageForText];
            dispatch_async(dispatch_get_main_queue(), ^{
                [weakSelf.commentTextImageView_ setImage:renderedImage];
                [weakSelf.commentTextImageView_ setAlpha:0.0];
                [UIView animateWithDuration:0.3 animations:^{
                    [weakSelf.commentTextImageView_ setAlpha:1.0];
                }];
            });

             [pool release];
         });

我甚至尝试过这样做:

[self.commentsText_ imageForText];

然而记忆仍然飙升

2 个答案:

答案 0 :(得分:0)

我们需要看看你是如何打电话给imageForText告诉你的,但是你可能会认为你是双重保留来自UIGraphicsGetImageFromCurrentImageContext()的图像。您将self.renderedImage设置为UIImage UIGraphicsGetImageFromCurrentImageContext(),并返回图像。我假设renderedImagestrong属性,因此它会保留一次。返回的图像可能设置在局部变量中或以其他方式保留在其他位置。 imageForText更典型的模式不具有保留图像的副作用,如果您需要将图像保留在属性中,则将其调用如下:

self.renderedImage = [self imageForText];
// Do whatever you want with self.renderedImage ...

另一个潜在的问题是,当你说你“在背景中将文本呈现给UIImage”时,希望你不要在后台线程中表示。像UIGraphicsBeginImageContextWithOptions()这样的UIKit函数只能从应用程序的主线程中调用。

答案 1 :(得分:0)

您应该在辅助线程中显式创建位图上下文。从后台线程使用CoreGraphics没有问题,但是不要从辅助线程调用UIKit方法,这将导致很难调试问题。苹果文档(如UIFont)中明确提到了一些例外,但一般规则是不使用UIKit函数,因为它们除了主线程外不能正常工作。另外,不要调用self.frameSize等访问方法,因为这会调用UIKit。

因为您正在使用CoreText,所以您可能也会因此内存泄漏而感到沮丧memory-usage-grows-with-ctfontcreatewithname-and-ctframesetterref