这是 ipad 杂志应用程序。我们需要读取 PDF 并将其转换为 PNG 图像作为缩略图。在转换之前读取 PDF(调用 CGContextDrawPDFPage)后,内存会快速增加,并且永远不会释放,直到崩溃。我尝试了很多方法但都不起作用。如果有人能提供帮助,我真的很感激。
CGContextDrawPDFPage(上下文,aPage);//这是内存 killer
完整代码如下:
-(UIImage *)图像:(CGPDFPageRef)aPage 矩形:(CGRect)aRect { CGRect pdfcropBox = CGRectIntegral(CGPDFPageGetBoxRect(aPage, kCGPDFCropBox));
if ((float)pdfcropBox.size.width/(float)pdfcropBox.size.height >
(float)aRect.size.width/(float)aRect.size.height) //pdf width too big
{
aRect.size.height = aRect.size.width * pdfcropBox.size.height / pdfcropBox.size.width;
}
//CGRect pdfcropBox = aRect;
CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef context = CGBitmapContextCreate(NULL,aRect.size.width,
aRect.size.height,
8,
(int)aRect.size.width * 4,
colorSpace,
kCGImageAlphaPremultipliedLast | kCGBitmapByteOrder32Big);
CGColorSpaceRelease(colorSpace);
colorSpace = nil;
CGPDFPageRetain(aPage);
CGAffineTransform pdfTransform = CGPDFPageGetDrawingTransform(aPage,
kCGPDFCropBox,
CGRectMake(0, 0, aRect.size.width,aRect.size.height),
0, true);
CGContextSaveGState(context);
CGContextConcatCTM(context, pdfTransform);
CGContextDrawPDFPage(context, aPage);
CGPDFPageRelease (aPage);
aPage = nil;
CGContextRestoreGState(context);
CGImageRef image = CGBitmapContextCreateImage(context);
UIImage *resultingImage = [UIImage imageWithCGImage:image];
CGContextClearRect(context, aRect);
CGContextClearRect(context, pdfcropBox);
CGContextRelease(context);
CGImageRelease(image);
context = nil;
NSLog(@"colorSpace :%d,aPage :%d,context :%d",[colorSpace retainCount],[aPage retainCount],[context retainCount]);
return resultingImage;
}
最佳答案
您需要按照此处的说明释放并重新打开 CGPDFDocument Fast and Lean PDF Viewer for iPhone / iPad / iOs - tips and hints?
关于iphone - 如何释放 CGContextDrawPDFPage 创建的内存,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/4623086/