如何裁剪UIImage？ [英] How to crop the UIImage?

问题描述

我开发了一个应用程序，其中我使用其像素处理图像，但在该图像处理中需要花费大量时间。因此我想裁剪UIImage（仅图像的中间部分，即删除/裁剪图像的边界部分）。我有开发代码，

I develop an application in which i process the image using its pixels but in that image processing it takes a lot of time. Therefore i want to crop UIImage (Only middle part of image i.e. removing/croping bordered part of image).I have the develop code are,

- (NSInteger) processImage1: (UIImage*) image
{

 CGFloat width = image.size.width;
 CGFloat height = image.size.height;
 struct pixel* pixels = (struct pixel*) calloc(1, image.size.width * image.size.height * sizeof(struct pixel));
 if (pixels != nil)
 {
  // Create a new bitmap
  CGContextRef context = CGBitmapContextCreate(
              (void*) pixels,
              image.size.width,
              image.size.height,
              8,
              image.size.width * 4,
              CGImageGetColorSpace(image.CGImage),
              kCGImageAlphaPremultipliedLast
              );
  if (context != NULL)
  {
   // Draw the image in the bitmap
   CGContextDrawImage(context, CGRectMake(0.0f, 0.0f, image.size.width, image.size.height), image.CGImage);
   NSUInteger numberOfPixels = image.size.width * image.size.height;

   NSMutableArray *numberOfPixelsArray = [[[NSMutableArray alloc] initWithCapacity:numberOfPixelsArray] autorelease];
}

我如何拍摄（在边界外裁剪）UIImage的中间部分??? ??????

How i take(croping outside bordered) the middle part of UIImage?????????

推荐答案

尝试这样的事情：

CGImageRef imageRef = CGImageCreateWithImageInRect([largeImage CGImage], cropRect);
image = [UIImage imageWithCGImage:imageRef]; 
CGImageRelease(imageRef);

注意：cropRect是较小的矩形，图像的中间部分...

Note: cropRect is smaller rectangle with middle part of the image...

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