问题描述
我需要复制 UIButton 在点击时对图像的效果，即突出显示.见:
I need to replicate the effect that the UIButton does on an image when tapped, the highlighting. See:
原始 PNG 是一个带有 alpha 背景的正方形.当我将它设置为 UIButton 的图像时，它会自动对图像的非 alpha 像素应用效果.
The original PNG is a square with alpha background. When I set it as UIButton's image it automatically apply an effect on the non-alpha pixels of the image.
这个效果怎么做?
推荐答案
您可以通过 UIImage 上的简单类别来实现:
You could achieve this with a simple category on UIImage:
@interface UIImage (Tint)
- (UIImage *)tintedImageUsingColor:(UIColor *)tintColor;
@end
@implementation UIImage (Tint)
- (UIImage *)tintedImageUsingColor:(UIColor *)tintColor {
UIGraphicsBeginImageContextWithOptions(self.size, NO, self.scale);
CGRect drawRect = CGRectMake(0, 0, self.size.width, self.size.height);
[self drawInRect:drawRect];
[tintColor set];
UIRectFillUsingBlendMode(drawRect, kCGBlendModeSourceAtop);
UIImage *tintedImage = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();
return tintedImage;
}
@end
对于上面显示的效果，您需要传递类似 [UIColor colorWithWhite:0.0 alpha:0.3] 作为 tintColor 参数(使用 alpha 值进行实验).
For the effect shown above, you'd pass something like [UIColor colorWithWhite:0.0 alpha:0.3] as the tintColor parameter (experiment with the alpha value).
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