如何在 iOS 中更改部分透明图像的颜色？

发布于 2024-10-26 11:06:21 字数 1173 浏览 8 评论 0原文

我有一个具有部分透明度的单色图像。我有正常版本和@2X 版本的图像。我希望能够用代码将图像着色为不同的颜色。下面的代码适用于普通图像，但 @2X 最终会出现伪影。正常图像可能有类似的问题如果是这样，由于分辨率的原因我无法检测到它。

+(UIImage *) newImageFromMaskImage:(UIImage *)mask inColor:(UIColor *) color {
    CGImageRef maskImage = mask.CGImage;
    CGFloat width = mask.size.width;
    CGFloat height = mask.size.height;
    CGRect bounds = CGRectMake(0,0,width,height);

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGContextRef bitmapContext = CGBitmapContextCreate(NULL, width, height, 8, 0, colorSpace, kCGImageAlphaPremultipliedLast);
    CGContextClipToMask(bitmapContext, bounds, maskImage);
    CGContextSetFillColorWithColor(bitmapContext, color.CGColor);    
    CGContextFillRect(bitmapContext, bounds);

    CGImageRef mainViewContentBitmapContext = CGBitmapContextCreateImage(bitmapContext);
    CGContextRelease(bitmapContext);

    UIImage *result = [UIImage imageWithCGImage:mainViewContentBitmapContext];
    return result;
}

如果重要的话，可以使用 UIImage imageNamed: 加载遮罩图像。另外，我确认在视网膜模拟器上运行时正在加载 @2X 图像。

更新：上面的代码有效。我看到的伪像是由图像使用者进行的额外转换造成的。这个问题可以被删除，因为它不再是一个真正的问题，或者留给后代了。

原文

I have a single-color image that has partial transparency. I have both normal and @2X versions of the image. I would like to be able to tint the image a different color, in code. The code below works fine for the normal image, but the @2X ends up with artifacts. The normal image might have a similar issue If so, I can't detect it on account of resolution.

+(UIImage *) newImageFromMaskImage:(UIImage *)mask inColor:(UIColor *) color {
    CGImageRef maskImage = mask.CGImage;
    CGFloat width = mask.size.width;
    CGFloat height = mask.size.height;
    CGRect bounds = CGRectMake(0,0,width,height);

    CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
    CGContextRef bitmapContext = CGBitmapContextCreate(NULL, width, height, 8, 0, colorSpace, kCGImageAlphaPremultipliedLast);
    CGContextClipToMask(bitmapContext, bounds, maskImage);
    CGContextSetFillColorWithColor(bitmapContext, color.CGColor);    
    CGContextFillRect(bitmapContext, bounds);

    CGImageRef mainViewContentBitmapContext = CGBitmapContextCreateImage(bitmapContext);
    CGContextRelease(bitmapContext);

    UIImage *result = [UIImage imageWithCGImage:mainViewContentBitmapContext];
    return result;
}

If it matters, the mask image is loaded using UIImage imageNamed:. Also, I confirmed that the @2X image is loading when run on the retina simulator.

Update: The above code works. The artifacts I was seeing were caused by additional transforms done by the consumer of the images. This question could be deleted since it's not really a question anymore or left for posterity.

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浸婚纱 2024-11-02 11:06:21

我已经更新了上面的代码以考虑视网膜分辨率图像：

- (UIImage *) changeColorForImage:(UIImage *)mask toColor:(UIColor*)color {

CGImageRef maskImage = mask.CGImage;
CGFloat width = mask.scale * mask.size.width;
CGFloat height = mask.scale * mask.size.height;
CGRect bounds = CGRectMake(0,0,width,height);

CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef bitmapContext = CGBitmapContextCreate(NULL, width, height, 8, 0, colorSpace, (CGBitmapInfo)kCGImageAlphaPremultipliedLast);
CGContextClipToMask(bitmapContext, bounds, maskImage);
CGContextSetFillColorWithColor(bitmapContext, color.CGColor);    
CGContextFillRect(bitmapContext, bounds);

CGImageRef mainViewContentBitmapContext = CGBitmapContextCreateImage(bitmapContext);
CGContextRelease(bitmapContext);

return [UIImage imageWithCGImage:mainViewContentBitmapContext scale:mask.scale orientation:UIImageOrientationUp];
}

I have updated the code above to account for retina resolution images:

- (UIImage *) changeColorForImage:(UIImage *)mask toColor:(UIColor*)color {

CGImageRef maskImage = mask.CGImage;
CGFloat width = mask.scale * mask.size.width;
CGFloat height = mask.scale * mask.size.height;
CGRect bounds = CGRectMake(0,0,width,height);

CGColorSpaceRef colorSpace = CGColorSpaceCreateDeviceRGB();
CGContextRef bitmapContext = CGBitmapContextCreate(NULL, width, height, 8, 0, colorSpace, (CGBitmapInfo)kCGImageAlphaPremultipliedLast);
CGContextClipToMask(bitmapContext, bounds, maskImage);
CGContextSetFillColorWithColor(bitmapContext, color.CGColor);    
CGContextFillRect(bitmapContext, bounds);

CGImageRef mainViewContentBitmapContext = CGBitmapContextCreateImage(bitmapContext);
CGContextRelease(bitmapContext);

return [UIImage imageWithCGImage:mainViewContentBitmapContext scale:mask.scale orientation:UIImageOrientationUp];
}

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