從中心向外裁剪UIImage？

我正在製作包含數碼變焦的相機應用程序。我有一個滑塊（zoomSlider），其最小值爲1，最大值爲4.當用戶點擊相機按鈕時，它會拍攝一張照片，然後裁剪出來進行縮放。我有兩個問題：從中心向外裁剪UIImage？

如何剪切圖像的中間部分？（例如2倍變焦，Rect將以尺寸爲600x800（適用於iPhone 2G/3G）爲中心）

當我這樣做時，它會旋轉圖像。我通過旋轉UIImageView來彌補它的不足，但這會導致人像照片變成風景，反之亦然。

這裏是我的代碼：

- (void)imagePickerController:(UIImagePickerController *)picker didFinishPickingMediaWithInfo:(NSDictionary *)info { 

    if ([mediaType isEqualToString:@"public.image"]){ 

UIImage *image = [info objectForKey:@"UIImagePickerControllerOriginalImage"]; 

      CGRect clippedRect = CGRectMake(600, 450, image.size.width/zoomSlider.value, image.size.height/zoomSlider.value); 

      UIImage *cropped = [self imageByCropping:image toRect:clippedRect]; 

      CGRect croppedImageSize = CGRectMake(0, 0, image.size.width/zoomSlider.value, image.size.height/zoomSlider.value); 

      [cropped drawInRect:croppedImageSize]; 

      zoomPhoto.frame = croppedImageSize; 

      zoomPhoto.image = cropped; 

CGAffineTransform rotateTransform = CGAffineTransformRotate(CGAffineTransformIdentity, 

                        RADIANS(90.0)); 

      zoomPhoto.transform = rotateTransform; 
} 

- (UIImage *)imageByCropping:(UIImage *)imageToCrop toRect:(CGRect)rect 

{ 

    CGImageRef imageRef = CGImageCreateWithImageInRect([imageToCrop CGImage], rect); 



    UIImage *cropped = [UIImage imageWithCGImage:imageRef]; 

CGImageRelease(imageRef); 




return cropped;

}

來源

2009-12-13 iSkythe

CGFloat newWidth = image.size.width/zoomSlider.value; 
CGFloat newHeight = image.size.height/zoomSlider.value; 

CGRect clippedRect = CGRectMake((image.size.width-newWidth)/2, (image.size.height-newHeight)/2, newWidth, newHeight);

這個刪除不旋轉圖像：

CGAffineTransform rotateTransform = CGAffineTransformRotate(CGAffineTransformIdentity,RADIANS(90.0)); 

zoomPhoto.transform = rotateTransform;

來源

2010-01-21 04:25:27

從中心向外裁剪UIImage？

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