图像修剪问题

Question

我要裁剪的UIImage用下面的代码：

- (UIImage*)imageByCropping:(UIImage *)imageToCrop toRect:(CGRect)rect 
{ 
    CGImageRef imageRef = CGImageCreateWithImageInRect([imageToCrop CGImage], rect); 
    // or use the UIImage wherever you like 
    UIImage * img = [UIImage imageWithCGImage:imageRef]; 
    CGImageRelease(imageRef); 
    return img; 
} 

此代码工作在模拟器不错，但给人的设备不寻常的结果。

Answer 1

创建一个UIImage的类别，然后尝试在此。

@implementation UIImage的（作物）

- (UIImage *)crop:(CGRect)cropRect { 

    cropRect = CGRectMake(cropRect.origin.x*self.scale, 
         cropRect.origin.y*self.scale, 
         cropRect.size.width*self.scale, 
         cropRect.size.height*self.scale);  

    CGImageRef imageRef = CGImageCreateWithImageInRect([self CGImage], cropRect); 
    UIImage *result = [UIImage imageWithCGImage:imageRef 
              scale:self.scale 
            orientation:self.imageOrientation]; 
    CGImageRelease(imageRef); 
    return result; 
} 

Answer 2

试试这个：

- (UIImage *)cropImage:(UIImage *)oldImage { 
      CGSize imageSize = oldImage.size; 
      UIGraphicsBeginImageContextWithOptions(CGSizeMake(imageSize.width,imageSize.height - 150),NO,0.); 
      [oldImage drawAtPoint:CGPointMake(0, -80) blendMode:kCGBlendModeCopy alpha:1.]; 
      UIImage *croppedImage = UIGraphicsGetImageFromCurrentImageContext(); 
      UIGraphicsEndImageContext(); 
      return croppedImage; 
    }