用另一个UIImage掩盖UIImage

Question

我在屏蔽两个UIImage的逻辑之间挣扎。我想在面具UIImage上掩饰婴儿脸UIImage。最大的问题是尺寸。如果2 UIImages大小相同，那么我可以很容易地做到，但是当尺寸不同时，它就不起作用了！

以下是尝试过的解决方案，但没有一个按预期工作。

  

解决方案1 ​​

- (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 maskedImageRef = CGImageCreateWithMask([image CGImage], mask);
    UIImage *maskedImage = [UIImage imageWithCGImage:maskedImageRef];

    CGImageRelease(mask);
    CGImageRelease(maskedImageRef);

    // returns new image with mask applied
    return maskedImage;
}

  

解决方案2

- (UIImage*) maskImage:(UIImage *)image withMask:(UIImage *)maskImage {
    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();

    CGImageRef maskImageRef = [maskImage CGImage];

    // create a bitmap graphics context the size of the image
    CGContextRef mainViewContentContext = CGBitmapContextCreate (NULL, maskImage.size.width, maskImage.size.height, 8, 0, colorSpace, kCGImageAlphaPremultipliedLast);
    CGColorSpaceRelease(colorSpace);

    if (mainViewContentContext==NULL)
        return NULL;

    CGFloat ratio = 0;

    ratio = maskImage.size.width/ image.size.width;

    if(ratio * image.size.height < maskImage.size.height) {
        ratio = maskImage.size.height/ image.size.height;
    }

    CGRect rect1  = {{0, 0}, {maskImage.size.width, maskImage.size.height}};
    CGRect rect2  = {{-((image.size.width*ratio)-maskImage.size.width)/2 , -((image.size.height*ratio)-maskImage.size.height)/2}, {image.size.width*ratio, image.size.height*ratio}};

    CGContextClipToMask(mainViewContentContext, rect1, maskImageRef);
    CGContextDrawImage(mainViewContentContext, rect2, image.CGImage);


    // Create CGImageRef of the main view bitmap content, and then
    // release that bitmap context
    CGImageRef newImage = CGBitmapContextCreateImage(mainViewContentContext);
    CGContextRelease(mainViewContentContext);

    UIImage *theImage = [UIImage imageWithCGImage:newImage];

    CGImageRelease(newImage);

    // return the image
    return theImage;
}

  

更新

婴儿脸部图像尺寸小于蒙版图像。所以我想屏蔽特定rect上的图像。