撮影部分を切り取る処理

specify-ranged-camera.swift

func cropImage(image:UIImage) -> UIImage {
        
        
        var srcImage:UIImage = image;
        
        // 画像の回転禁止
        UIGraphicsBeginImageContext(srcImage.size)
        srcImage.drawInRect(CGRectMake(0, 0, srcImage.size.width, srcImage.size.height))
        srcImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        
        //self.viewの縦横比を算出
        let widthToHeightRatio:CGFloat = self.view.bounds.size.width/self.view.bounds.size.height
        
        var cropRect:CGRect = CGRectMake(0, 0, 0, 0)
        
        //self.viewの比率にimageサイズを合わせる
        cropRect.size.width = srcImage.size.width
        cropRect.size.height = srcImage.size.width / widthToHeightRatio
        
        //y軸のずれを算出
        cropRect.origin.x = 0
        cropRect.origin.y = (srcImage.size.height - cropRect.size.height) / 2.0
        
        //srcImage上のpreviewviewに当たる部分を算出
        var point:CGPoint = CGPointZero
        point.x = cameraView.frame.origin.x * srcImage.size.width / self.view.bounds.size.width;
        point.y = (cameraView.frame.origin.y * cropRect.size.height / self.view.bounds.size.height) + cropRect.origin.y;
        
        let srcWidth:CGFloat = cameraView.frame.size.width*srcImage.size.width/self.view.bounds.size.width
        let srcHeight:CGFloat = cameraView.frame.size.height*srcImage.size.height/self.view.bounds.size.height
        
        let trimArea = CGRectMake(point.x, point.y ,srcWidth, srcHeight)
        
        let srcImageRef:CGImageRef = srcImage.CGImage!
        let trimmedImageRef:CGImageRef = CGImageCreateWithImageInRect(srcImageRef, trimArea)!
        let trimmmedImage:UIImage = UIImage(CGImage: trimmedImageRef)
        
        return trimmmedImage;
    }