iOS 图片处理-图片旋转和裁剪

╰+哭是因爲堅強的太久メ 2022-06-11 09:57 393阅读 0赞

项目中要求处理图片, 简单记录一下图片旋转和裁剪过程

/\*\* 将图片旋转弧度radians \*/  
\- (UIImage \*)imageRotatedByRadians:(CGFloat)radians  
\{  
    // calculate the size of the rotated view's containing box for our drawing space  
    UIView \*rotatedViewBox = \[\[UIView alloc\] initWithFrame:CGRectMake(0,0,self.size.width, self.size.height)\];  
    CGAffineTransform t = CGAffineTransformMakeRotation(radians);  
    rotatedViewBox.transform = t;  
    CGSize rotatedSize = rotatedViewBox.frame.size;  
      
    // Create the bitmap context  
    UIGraphicsBeginImageContext(rotatedSize);  
    CGContextRef bitmap = UIGraphicsGetCurrentContext();  
      
    // Move the origin to the middle of the image so we will rotate and scale around the center.  
    CGContextTranslateCTM(bitmap, rotatedSize.width/2, rotatedSize.height/2);  
      
    //   // Rotate the image context  
    CGContextRotateCTM(bitmap, radians);  
      
    // Now, draw the rotated/scaled image into the context  
    CGContextScaleCTM(bitmap, 1.0, -1.0);  
    CGContextDrawImage(bitmap, CGRectMake(-self.size.width / 2, -self.size.height / 2, self.size.width, self.size.height), \[self CGImage\]);  
      
    UIImage \*newImage = UIGraphicsGetImageFromCurrentImageContext();  
    UIGraphicsEndImageContext();  
      
    return newImage;  
\}

\#pragma mark - 截取当前image对象rect区域内的图像  
\- (UIImage \*)subImageWithRect:(CGRect)rect  
\{  
    CGImageRef newImageRef = CGImageCreateWithImageInRect(self.CGImage, rect);  
      
    UIImage \*newImage = \[UIImage imageWithCGImage:newImageRef\];  
      
    CGImageRelease(newImageRef);  
      
    return newImage;  
\}  
  
\#pragma mark - 压缩图片至指定尺寸  
\- (UIImage \*)rescaleImageToSize:(CGSize)size  
\{  
    CGRect rect = (CGRect)\{CGPointZero, size\};  
      
    UIGraphicsBeginImageContext(rect.size);  
      
    \[self drawInRect:rect\];  
      
    UIImage \*resImage = UIGraphicsGetImageFromCurrentImageContext();  
      
    UIGraphicsEndImageContext();  
      
    return resImage;  
\}  
  
\#pragma mark - 压缩图片至指定像素  
\- (UIImage \*)rescaleImageToPX:(CGFloat )toPX  
\{  
    CGSize size = self.size;  
      
    if(size.width <= toPX && size.height <= toPX)  
    \{  
        return self;  
    \}  
      
    CGFloat scale = size.width / size.height;  
      
    if(size.width > size.height)  
    \{  
        size.width = toPX;  
        size.height = size.width / scale;  
    \}  
    else  
    \{  
        size.height = toPX;  
        size.width = size.height \* scale;  
    \}  
      
    return \[self rescaleImageToSize:size\];  
\}

一些处理UIImage相关的category: [https://github.com/wyon0313/UIImageCategory][https_github.com_wyon0313_UIImageCategory]

[https_github.com_wyon0313_UIImageCategory]: https://github.com/wyon0313/UIImageCategories