最近項目中用到了自定義圖片裁剪區域的圖片裁剪功能，自己寫了一個，可能有諸多不完善的地方，請大家指正。

支持任意區域裁剪，9:16裁剪、16:9裁剪、1:1裁剪、圓形裁剪等等，總之裁剪框的大小，裁剪框的區域都自定義；

如下截圖：

裁剪器.gif

整體思路：

1.利用scrollview的zoom縮放功能，縮放對象是所需裁剪圖片的imageView；
2.利用scrollView的contentInset參數，保證裁剪圖片在裁剪框內，并且可以裁剪圖片任意位置；
3.坐標轉換找出裁剪區域對應的在圖片中的位置，進行圖片的渲染裁剪。

使用方法

    LZImageCropping *imageBrowser = [[LZImageCropping alloc]init];
    //設置代理
    imageBrowser.delegate = self;
    //設置自定義裁剪區域大小
    imageBrowser.cropSize = CGSizeMake(self.view.frame.size.width - 60, (self.view.frame.size.width-60));
    //設置圖片
    NSString *path = [[NSBundle mainBundle] pathForResource:@"IMG_1121"  ofType:@"jpg"];
    UIImage *image = [UIImage imageWithContentsOfFile:path];
    cropper.image = image;
    //是否需要圓形
    imageBrowser.isRound = YES;
    [self presentViewController:imageBrowser animated:YES completion:nil];

以下為關鍵代碼

二、自定義矩形遮罩 圓形遮罩 處理

透明區域是用了兩條貝塞爾曲線，第一條是整個灰色區域，然后第二條是需要透明的區域。將第二條附加的第一條上，并且設置填充規則為：

shapeLayer.fillRule = kCAFillRuleEvenOdd;

矩形遮罩

//矩形裁剪區域
- (void)transparentCutSquareArea{
    //圓形透明區域
    UIBezierPath *alphaPath = [UIBezierPath bezierPathWithRect:CGRectMake(0, 0, _selfWidth, _selfHeight)];
    UIBezierPath *squarePath = [UIBezierPath bezierPathWithRect:_cropFrame];
    [alphaPath appendPath:squarePath];
    CAShapeLayer *shapeLayer = [CAShapeLayer layer];
    shapeLayer.path = alphaPath.CGPath;
    shapeLayer.fillRule = kCAFillRuleEvenOdd;
    self.overLayView.layer.mask = shapeLayer;
    
    //裁剪框
    UIBezierPath *cropPath = [UIBezierPath bezierPathWithRect:CGRectMake(_cropFrame.origin.x-1, _cropFrame.origin.y-1, _cropFrame.size.width+2, _cropFrame.size.height+2)];
    CAShapeLayer *cropLayer = [CAShapeLayer layer];
    cropLayer.path = cropPath.CGPath;
    cropLayer.fillColor = [UIColor whiteColor].CGColor;
    cropLayer.strokeColor = [UIColor whiteColor].CGColor;
    [self.overLayView.layer addSublayer:cropLayer];
}

圓形裁剪遮罩

//圓形裁剪區域
-(void)transparentCutRoundArea{
    CGFloat arcX = _cropFrame.origin.x + _cropFrame.size.width/2;
    CGFloat arcY = _cropFrame.origin.y + _cropFrame.size.height/2;
    CGFloat arcRadius;
    if (_cropSize.height > _cropSize.width) {
        arcRadius = _cropSize.width/2;
    }else{
        arcRadius  = _cropSize.height/2;
    }
    
    //圓形透明區域
    UIBezierPath *alphaPath = [UIBezierPath bezierPathWithRect:CGRectMake(0, 0, _selfWidth, _selfHeight)];
    UIBezierPath *arcPath = [UIBezierPath bezierPathWithArcCenter:CGPointMake(arcX, arcY) radius:arcRadius startAngle:0 endAngle:2*M_PI clockwise:NO];
    [alphaPath appendPath:arcPath];
    CAShapeLayer  *layer = [CAShapeLayer layer];
    layer.path = alphaPath.CGPath;
    layer.fillRule = kCAFillRuleEvenOdd;
    self.overLayView.layer.mask = layer;
    
    //裁剪框
    UIBezierPath *cropPath = [UIBezierPath bezierPathWithArcCenter:CGPointMake(arcX, arcY) radius:arcRadius+1 startAngle:0 endAngle:2*M_PI clockwise:NO];
    CAShapeLayer *cropLayer = [CAShapeLayer layer];
    cropLayer.path = cropPath.CGPath;
    cropLayer.strokeColor = [UIColor whiteColor].CGColor;
    cropLayer.fillColor = [UIColor whiteColor].CGColor;
    [self.overLayView.layer addSublayer:cropLayer];
}

三、裁剪圖片

裁剪矩形圖片

-(UIImage *)getSubImage{
    //裁剪區域在原始圖片上的位置
    CGRect myImageRect = CGRectMake(leftTopPoint.x * scaleRatio, leftTopPoint.y*scaleRatio, width, height);
    
    //裁剪圖片
    CGImageRef imageRef = self.image.CGImage;
    CGImageRef subImageRef = CGImageCreateWithImageInRect(imageRef, myImageRect);
    UIGraphicsBeginImageContext(myImageRect.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextDrawImage(context, myImageRect, subImageRef);
    UIImage* smallImage = [UIImage imageWithCGImage:subImageRef];
    CGImageRelease(subImageRef);
    UIGraphicsEndImageContext();
    
    //是否需要圓形圖片
    if (self.isRound) {
        //將圖片裁剪成圓形
        smallImage = [self clipCircularImage:smallImage];
    }
    return smallImage;
}

裁剪圓形圖片

//將圖片裁剪成圓形
-(UIImage *)clipCircularImage:(UIImage *)image{
    CGFloat arcCenterX = image.size.width/ 2;
    CGFloat arcCenterY = image.size.height / 2;
    UIGraphicsBeginImageContext(image.size);
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextBeginPath(context);
    CGContextAddArc(context, arcCenterX, arcCenterY, image.size.width/2, 0.0, 2*M_PI, NO);
    CGContextClip(context);
    CGRect myRect = CGRectMake(0 , 0, image.size.width ,  image.size.height);
    [image drawInRect:myRect];
    
    UIImage *newImage = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    
    return  newImage;
}

最后

代碼很簡單，大家自己的需求可以直接在demo里面修改，具體代碼詳見github，幫助到你的話，可以隨手給個星星哦！
代碼： https://github.com/FirstStepzz/LZImageCropping.git