1

我正在尝试将整个 UIWebView（甚至是屏幕外的内容）捕获到 PNG。以下代码在大多数设备上运行良好，但在某些 iPad 1st gens 上它在此行上崩溃：

[self.webview.layer renderInContext:resizedContext]; /// crash

如何通过停止 renderInContext 进程来防止崩溃？

有关问题的上下文，请参见下面的代码示例：

//Create original tmp bounds
CGRect tmpFrame = self.webview.frame;
CGRect tmpBounds = self.webview.bounds;
CGRect aFrame = self.webview.bounds;
aFrame.size.width = self.webview.frame.size.width;
aFrame.size.height = self.webview.frame.size.height;
self.webview.frame = aFrame;
aFrame.size.height = [self.webview sizeThatFits:[[UIScreen mainScreen] bounds].size].height;

NSLog(@"webpage size %f",self.webview.frame.size.height);

self.webview.frame = aFrame;
UIGraphicsBeginImageContext([self.webview sizeThatFits:[[UIScreen mainScreen] bounds].size]);
CGContextRef resizedContext = UIGraphicsGetCurrentContext();

// crash
[self.webview.layer renderInContext:resizedContext]; // crash
// crash

UIImage *image = UIGraphicsGetImageFromCurrentImageContext();

UIGraphicsEndImageContext();
self.webview.frame = tmpFrame;
NSArray *paths = NSSearchPathForDirectoriesInDomains(NSCachesDirectory, NSUserDomainMask, YES);
    NSString *documentsDirectory = [paths objectAtIndex:0];
    NSString *pngPath = [documentsDirectory stringByAppendingPathComponent:[NSString stringWithFormat:@"%@.png",@"TestImage"]];
NSError *error;
[UIImagePNGRepresentation(image) writeToFile:pngPath options:NSDataWritingAtomic error:&error];

NSURL *url = [NSURL fileURLWithPath:pngPath];

//reset webview
self.webview.bounds = tmpBounds;
self.webview.frame = tmpFrame;

模拟器不会崩溃，以下是在设备上运行时来自控制台的日志记录错误：

May 16 12:33:41 unknown SpringBoard[29] <Warning>: Application 'AppName' exited abnormally     with signal 11: Segmentation fault: 11
May 16 12:33:41 unknown DTMobileIS[652] <Warning>: _memoryNotification : {
    OSMemoryNotificationLevel = 0;
    timestamp = "2012-05-16 19:33:41 +0000";
}
May 16 12:33:41 unknown DTMobileIS[652] <Warning>: _memoryNotification : <NSThread: 0x1d5286d0>{name = (null), num = 1}
May 16 12:33:41 unknown DTMobileIS[652] <Warning>: _memoryNotification : {
    OSMemoryNotificationLevel = 0;
    timestamp = "2012-05-16 19:33:41 +0000";
}
4

1 回答 1

1

我在做类似的事情时遇到了同样的问题，并通过首先计算图像的高度是否超过大约 8,000 像素来解决它。

如果是这样，我就失败了，并警告用户页面对于这个过程来说太大了，只要它是 iPad 1 硬件版本。

我从来没有找到任何真正解决这个问题的方法。

于 2013-09-03T19:38:58.407 回答