[英]iOS SDK - Image masking
How to mask an image with another image by non transparent pixels? 如何用非透明像素用另一个图像遮盖一个图像? Eg 例如
When the mask image is black&white, I use this function: 当蒙版图像为黑白时,我使用以下功能:
- (UIImage *)maskImage:(UIImage *)image withMask:(UIImage *)maskImage {
CGImageRef maskRef = maskImage.CGImage;
CGImageRef mask = CGImageMaskCreate(CGImageGetWidth(maskRef),
CGImageGetHeight(maskRef),
CGImageGetBitsPerComponent(maskRef),
CGImageGetBitsPerPixel(maskRef),
CGImageGetBytesPerRow(maskRef),
CGImageGetDataProvider(maskRef), NULL, false);
CGImageRef masked = CGImageCreateWithMask([image CGImage], mask);
return [UIImage imageWithCGImage:masked];
}
But how to do this in my case? 但是在我的情况下该如何做呢?
Here are the steps, to achieve the result 这是实现结果的步骤
1) Create an image view, and calculate the optimal size for it (+ set aspectFit option) 1)创建一个图像视图,并为其计算最佳尺寸(+设置AspectFit选项)
2) Get the image view frame, and create a mask with that options (ie scale your predefined mask image) 2)获取图像视图框架,并使用该选项创建遮罩(即缩放您的预定义遮罩图像)
3) Mask image view, with your created mask 3)使用创建的蒙版蒙版图像视图
UIImageView *maskView = [[UIImageView alloc] initWithImage:[UIImage imageNamed:@"star_mask_alpha.png"]]; self.needsMaskImageView.layer.mask = maskView.layer; [self.needsMaskImageView setNeedsDisplay];
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