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图像裁剪

程序员文章站 2022-03-24 19:59:28
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因为这里的背景的黑色,所以使用不透明。裁剪图片的代码:

- (UIImage *)clipImage:(UIImage *)image toSize:(CGSize)size {
  UIGraphicsBeginImageContextWithOptions(size, YES, [UIScreen mainScreen].scale);
  
  CGSize imgSize = image.size;
  CGFloat x = MAX(size.width / imgSize.width, size.height / imgSize.height);
  CGSize resultSize = CGSizeMake(x * imgSize.width, x * imgSize.height);
  
  [image drawInRect:CGRectMake(0, 0, resultSize.width, resultSize.height)];
  
  UIImage *finalImage = UIGraphicsGetImageFromCurrentImageContext();
  UIGraphicsEndImageContext();
  
  return finalImage;
}

异步去剪裁图片,在剪裁完成后再更新:

dispatch_async(dispatch_get_global_queue(0, 0), ^{
  UIImage *image = [UIImage imageNamed:model.imageName];
  image = [self clipImage:image toSize:self.imageView.frame.size];
  dispatch_async(dispatch_get_main_queue(), ^{
    model.clipedImage = image;
    self.imageView.layer.contents = (__bridge id _Nullable)(model.clipedImage.CGImage);
  });
});