ios - 部分屏幕截图

Question

如果按下 UIButton，如何截取屏幕的一部分？我已经搜索了很多，但我找不到有效的答案。Xcode 一直在抱怨，谁能给我一个适用于 iOS 6 的代码？

Answer 1

我以前在小班下面写过这个。你可以利用它。后一个函数获取整个屏幕的截图（并且它是从苹果的指南中获得的，所以它绝对是安全的）。我添加的第一部分处理不同的比例（视网膜或常规）。愿它有所帮助。

#import "ScreenshotTaker.h"
#import <QuartzCore/QuartzCore.h>

@implementation ScreenshotTaker


+(UIImage *) captureRectOfScreen:(CGRect) rect
{
    UIImage *wholeScreen = [ScreenshotTaker screenshot];

    //Add status bar height
    rect.origin.y += UIInterfaceOrientationIsLandscape([UIApplication sharedApplication].statusBarOrientation) ? [[UIApplication sharedApplication] statusBarFrame].size.width : [[UIApplication sharedApplication] statusBarFrame].size.height;

    //NSLog(@"%@",NSStringFromCGSize([wholeScreen size]));

    CGFloat scale = wholeScreen.scale;

    rect.origin.x *= scale;
    rect.origin.y *= scale;
    rect.size.width *= scale;
    rect.size.height *= scale;

    UIImage *cropped = [UIImage imageWithCGImage:CGImageCreateWithImageInRect([wholeScreen CGImage], rect) scale:wholeScreen.scale orientation:wholeScreen.imageOrientation];

    //NSLog(@"Whole Screen Capt :%@ Scale: %f",NSStringFromCGSize([wholeScreen size]), wholeScreen.scale);
    //NSLog(@"Rect to Crop :%@ Cropped :%@",NSStringFromCGRect(rect), NSStringFromCGSize([cropped size]));

    return cropped;
}

+(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;
}

@end

Answer 2

要捕获一个特定视图：

UIView *theView = self.view;
CGSize imageSize = [theView bounds].size
UIGraphicsBeginImageContextWithOptions(imageSize, NO, 0);
CGContextRef context = UIGraphicsGetCurrentContext();
[[theView layer] renderInContext:context];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

您现在可以保存生成的图像或对它做任何您想做的事情。

Answer 3

您可以使用此代码（未经测试）：

UIGraphicsBeginImageContext(USE UR SCREEN PART);
[self.window.layer renderInContext:UIGraphicsGetCurrentContext()];
UIImage *image = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
NSData * data = UIImagePNGRepresentation(image);
[data writeToFile:@"yourscreenshot.png" atomically:YES];

只需在 UIGraphicsBeginImageContext 括号中设置您的屏幕部件信息。