objective-c - 如何使用灰色模板图像创建类似 Xcode 的彩色按钮

Question

如果我有一个使用模板图像的 NSButton，我如何像 Apple 在 Xcode 中那样为它着色？

Answer 1

没有 API 可以为按钮中的模板图像着色。在我最新的应用程序之一中，我刚刚编写了一个小工厂，它可以从灰色图像中动态创建彩色图像。我正在使用核心图像过滤器，它处理图像的速度令人难以置信。

这是工厂进行着色的主要方法:

- (NSImage *)imageNamed:(NSString *)name withOptions:(HcToolbarImageOptions)options
{
    NSString *key = [self keyForName:name withOptions:options];
    NSImage *image = _cache[key];
    if (!image) {
        NSImage *sourceImage = [NSImage imageNamed:name];
        NSAssert1(sourceImage != nil, @"Could not find any image named %@", name);
        if (options == 0) {
            image = sourceImage;
        } else {
            image = [NSImage imageWithSize:sourceImage.size flipped:NO drawingHandler:^BOOL(NSRect dstRect) {
                CIContext *context = [[NSGraphicsContext currentContext] CIContext];
                CGContextRef cgContext = [[NSGraphicsContext currentContext] graphicsPort];
                NSRect proposedRect = dstRect;
                CGImageRef cgImage = [sourceImage CGImageForProposedRect:&proposedRect context:[NSGraphicsContext currentContext] hints:nil];
                CIImage *result = [CIImage imageWithCGImage:cgImage];
                if (options & HcToolbarImage_Enabled) {
                    CIFilter *filter1 = [CIFilter filterWithName:@"CIGammaAdjust"];
                    [filter1 setDefaults];
                    [filter1 setValue:result forKey:kCIInputImageKey];
                    [filter1 setValue:@0.6 forKey:@"inputPower"];
                    result = [filter1 valueForKey:kCIOutputImageKey];
                    CIFilter *filter2 = [CIFilter filterWithName:@"CIColorMonochrome"];
                    [filter2 setDefaults];
                    [filter2 setValue:result forKey:kCIInputImageKey];
                    [filter2 setValue:@1.0f forKey:kCIInputIntensityKey];
                    [filter2 setValue:[CIColor colorWithRed:0.2 green:0.5 blue:1.0] forKey:kCIInputColorKey];
                    result = [filter2 valueForKey:kCIOutputImageKey];
                }
                CGRect extent = [result extent];
                CGImageRef finalImage = [context createCGImage:result fromRect:extent];
                if (options & HcToolbarImage_NotKeyWindow) {
                    CGContextSetAlpha(cgContext, 0.5);
                }
                CGContextDrawImage(cgContext, dstRect, finalImage);
                return YES;
            }];
        }
        [_cache setObject:image forKey:key];
    }
    return image;
}

最终图像缓存在 NSMutableDictionary 中。