如何在当前屏幕的ios获得特定区域的UIImage

Question

下面的代码获得UIImage的当前屏幕：

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

如果我有一个的CGRect正确，而且我只想得到当前屏幕的UIImage在那里，我该怎么办？

Answer 1

对于获取矩形（裁剪）图片：

UIImage *croppedImg = nil; 
CGRect cropRect = CGRectMake(AS You Need); 
croppedImg = [self croppIngimageByImageName:self.imageView.image toRect:cropRect]; 

使用下面的方法（只要你想图像的大小）返回UIImage

- (UIImage *)croppIngimageByImageName:(UIImage *)imageToCrop toRect:(CGRect)rect 
    { 
     //CGRect CropRect = CGRectMake(rect.origin.x, rect.origin.y, rect.size.width, rect.size.height+15); 

     CGImageRef imageRef = CGImageCreateWithImageInRect([imageToCrop CGImage], rect); 
     UIImage *cropped = [UIImage imageWithCGImage:imageRef]; 
     CGImageRelease(imageRef); 

     return cropped; 
    } 

Answer 2

传递其所需的图像按照您的要求修剪并更改image.size.width和image.size.height

-(UIImage *)cropSquareImage:(UIImage *)image 
{ 
    CGRect cropRect; 

    if (image.size.width < image.size.height) 
    { 
     float x = 0; 
     float y = (image.size.height/2) - (image.size.width/2); 

     cropRect = CGRectMake(x, y, image.size.width, image.size.width); 
    } 
    else 
    { 
     float x = (image.size.width/2) - (image.size.height/2); 
     float y = 0; 

     cropRect = CGRectMake(x, y, image.size.height, image.size.height); 
    } 


    CGImageRef imageRef = CGImageCreateWithImageInRect([image CGImage], cropRect); 
    return [UIImage imageWithCGImage:imageRef]; 


}