以高品质的iOS

我带着我的iPad 3的屏幕截图以这种方式截图：以高品质的iOS

UIGraphicsBeginImageContext(self.view.frame.size); 
[self.view.layer renderInContext:UIGraphicsGetCurrentContext()]; 
UIImage *viewImage = UIGraphicsGetImageFromCurrentImageContext(); 
UIGraphicsEndImageContext(); 

NSArray *paths = NSSearchPathForDirectoriesInDomains(NSDocumentDirectory, 
                NSUserDomainMask, YES); 
NSString *documentsDirectory = [paths objectAtIndex:0]; 

int num = arc4random() % 100000000000000; 

NSString* path = [documentsDirectory stringByAppendingPathComponent: [NSString stringWithFormat:@"%dtest.png", num]]; 
NSData* data = UIImagePNGRepresentation(viewImage); 
[data writeToFile:path atomically:YES];

的问题是，我有质量的重大损失。我可以看到像素，但是它的iPad 3，它怎么可能？

来源

2013-02-10 user2014474

我忘了说，但请记住，我没有采取整个屏幕的屏幕截图，但在屏幕的特定部分 – user2014474 2013-02-10 11:26:10

你知道如果你的随机数发生器输出任何数字超过2147483647'num '会有垃圾价值。 – 2013-02-10 14:08:15

- (UIImage*)screenshot 
{ 
    // Create a graphics context with the target size 
    // On iOS 4 and later, use UIGraphicsBeginImageContextWithOptions to take the scale into consideration 
    // On iOS prior to 4, fall back to use UIGraphicsBeginImageContext 
    CGSize imageSize = [[UIScreen mainScreen] bounds].size; 
    if (NULL != UIGraphicsBeginImageContextWithOptions) 
     UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0); 
    else 
     UIGraphicsBeginImageContext(imageSize); 

    CGContextRef context = UIGraphicsGetCurrentContext(); 

    // Iterate over every window from back to front 
    for (UIWindow *window in [[UIApplication sharedApplication] windows]) 
    { 
     if (![window respondsToSelector:@selector(screen)] || [window screen] == [UIScreen mainScreen]) 
     { 
      // -renderInContext: renders in the coordinate space of the layer, 
      // so we must first apply the layer's geometry to the graphics context 
      CGContextSaveGState(context); 
      // Center the context around the window's anchor point 
      CGContextTranslateCTM(context, [window center].x, [window center].y); 
      // Apply the window's transform about the anchor point 
      CGContextConcatCTM(context, [window transform]); 
      // Offset by the portion of the bounds left of and above the anchor point 
      CGContextTranslateCTM(context, 
            -[window bounds].size.width * [[window layer] anchorPoint].x, 
            -[window bounds].size.height * [[window layer] anchorPoint].y); 

      // Render the layer hierarchy to the current context 
      [[window layer] renderInContext:context]; 

      // Restore the context 
      CGContextRestoreGState(context); 
     } 
    } 

    // Retrieve the screenshot image 
    UIImage *image = UIGraphicsGetImageFromCurrentImageContext(); 

    UIGraphicsEndImageContext(); 

    return image; 
}

更多信息，请阅读一本技术报告： Technical Q&A QA1703 Screen Capture in UIKit Applications

来源

2013-02-10 11:22:36

如何拍摄特定位置而不是整个屏幕？ – user2014474 2013-02-10 15:06:05

嗨bitmapdata.com，我正在寻找上述问题的答案，关于如何屏幕上的特定点的任何想法？ – Karthik 2014-04-08 01:31:44

你的尺寸不对，使用此：

CGRect screenBounds = [[UIScreen mainScreen] bounds]; 
CGFloat screenScale = [[UIScreen mainScreen] scale]; 
CGSize screenSize = CGSizeMake(screenBounds.size.width * screenScale, screenBounds.size.height * screenScale); 
UIGraphicsBeginImageContext(screenSize); 
//screenshot code..

来源

2013-02-10 11:19:33

从DOC：

UIGraphicsBeginImageContextWithOptions 
Creates a bitmap-based graphics context with the specified options. 

void UIGraphicsBeginImageContextWithOptions(
    CGSize size, 
    BOOL opaque, 
    CGFloat scale 
);

然后：

UIGraphicsBeginImageContextWithOptions(self.view.frame.size,NO,2.0);

来源

2013-02-10 11:22:00

以高品质的iOS

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