17

我试图在一些当前的 UIImage（它们是白色的）上添加一个黑色叠加层。我一直在尝试使用以下代码：

[[UIColor blackColor] set];
[image drawAtPoint:CGPointMake(0, 0) blendMode:kCGBlendModeOverlay alpha:1.0];

但它不起作用，我很确定 set 不应该在那里。

4

9 回答 9

54

因此，将所有答案总结为一个，这里的插入式方法可以完美地适用于iOS 6各种iOS 11图像和图标：

+ (UIImage *)filledImageFrom:(UIImage *)source withColor:(UIColor *)color{

    // begin a new image context, to draw our colored image onto with the right scale
    UIGraphicsBeginImageContextWithOptions(source.size, NO, [UIScreen mainScreen].scale);

    // get a reference to that context we created
    CGContextRef context = UIGraphicsGetCurrentContext();

    // set the fill color
    [color setFill];

    // translate/flip the graphics context (for transforming from CG* coords to UI* coords
    CGContextTranslateCTM(context, 0, source.size.height);
    CGContextScaleCTM(context, 1.0, -1.0);

    CGContextSetBlendMode(context, kCGBlendModeColorBurn);
    CGRect rect = CGRectMake(0, 0, source.size.width, source.size.height);
    CGContextDrawImage(context, rect, source.CGImage);

    CGContextSetBlendMode(context, kCGBlendModeSourceIn);
    CGContextAddRect(context, rect);
    CGContextDrawPath(context,kCGPathFill);

    // generate a new UIImage from the graphics context we drew onto
    UIImage *coloredImg = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();

    //return the color-burned image
    return coloredImg;
}

更新： Swift 3 版本

func filledImage(source: UIImage, fillColor: UIColor) -> UIImage {

    UIGraphicsBeginImageContextWithOptions(source.size, false, UIScreen.main.scale)

    let context = UIGraphicsGetCurrentContext()
    fillColor.setFill()

    context!.translateBy(x: 0, y: source.size.height)
    context!.scaleBy(x: 1.0, y: -1.0)

    context!.setBlendMode(CGBlendMode.colorBurn)
    let rect = CGRect(x: 0, y: 0, width: source.size.width, height: source.size.height)
    context!.draw(source.cgImage!, in: rect)

    context!.setBlendMode(CGBlendMode.sourceIn)
    context!.addRect(rect)
    context!.drawPath(using: CGPathDrawingMode.fill)

    let coloredImg : UIImage = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()

    return coloredImg
}
于 2014-05-08T12:00:05.820 回答
31

您需要将上下文剪辑到图像蒙版，然后用纯色填充：

- (void)drawRect:(CGRect)rect
{
    CGRect bounds = [self bounds];
    [[UIColor blackColor] set];
    CGContextRef context = UIGraphicsGetCurrentContext();
    CGContextClipToMask(context, bounds, [myImage CGImage]);
    CGContextFillRect(context, bounds);
}

注意：myImage应该是一个包含UIImage. 我不确定它是从 alpha 通道中获取蒙版还是从强度中获取蒙版，所以两者都试试。

于 2009-05-11T03:37:33.933 回答
11

我刚刚写了一个教程来帮助解决这个问题。我的方法为您提供了 UIImage 的副本，其中包含您想要的颜色更改。rpetrich 的方法很棒，但要求您创建一个子类。我的方法只是几行代码，可以在任何你需要的地方放置。http://coffeeshopped.com/2010/09/iphone-how-to-dynamically-color-a-uiimage

NSString *name = @"badge.png";
UIImage *img = [UIImage imageNamed:name];

// begin a new image context, to draw our colored image onto
UIGraphicsBeginImageContext(img.size);

// get a reference to that context we created
CGContextRef context = UIGraphicsGetCurrentContext();

// set the fill color
[color setFill];

// translate/flip the graphics context (for transforming from CG* coords to UI* coords
CGContextTranslateCTM(context, 0, img.size.height);
CGContextScaleCTM(context, 1.0, -1.0);

// set the blend mode to color burn, and the original image
CGContextSetBlendMode(context, kCGBlendModeColorBurn);
CGRect rect = CGRectMake(0, 0, img.size.width, img.size.height);
CGContextDrawImage(context, rect, img.CGImage);

// set a mask that matches the shape of the image, then draw (color burn) a colored rectangle
CGContextClipToMask(context, rect, img.CGImage);
CGContextAddRect(context, rect);
CGContextDrawPath(context,kCGPathFill);

// generate a new UIImage from the graphics context we drew onto
UIImage *coloredImg = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

//return the color-burned image
return coloredImg;
于 2010-09-27T17:40:28.850 回答
9

看看这个方法 

 + (UIImage *)imageWithColor:(UIColor *)color andSize:(CGSize)size;
    {
      UIImage *img = nil;

      CGRect rect = CGRectMake(0, 0, size.width, size.height);
      UIGraphicsBeginImageContext(rect.size);
      CGContextRef context = UIGraphicsGetCurrentContext();
      CGContextSetFillColorWithColor(context,
                                     color.CGColor);
      CGContextFillRect(context, rect);
      img = UIGraphicsGetImageFromCurrentImageContext();

      UIGraphicsEndImageContext();

      return img;
    }
于 2012-05-16T13:57:06.713 回答
9

从 iOS 7 开始，有一个更简单的解决方案：

UIImage* im = [UIImage imageNamed:@"blah"];
im = [im imageWithRenderingMode:UIImageRenderingModeAlwaysTemplate];
[[UIColor blackColor] setFill];
[im drawInRect:rect];
于 2014-07-05T20:42:40.250 回答
3

除了 rpetrich 的解决方案（顺便说一句很棒 - 帮助我极好），您还可以将 CGContextClipToMask 行替换为：

    CGContextSetBlendMode(context, kCGBlendModeSourceIn); //this is the main bit!

正是 SourceIn blendmode 完成了通过 GetCurrentContext 中的任何内容来掩盖颜色的工作。

于 2009-07-21T23:26:34.673 回答
1

以下是使用Swift 3.0和使用 UIImage 扩展的方法。超级简单。

public extension UIImage {
    func filledImage(fillColor: UIColor) -> UIImage {
        UIGraphicsBeginImageContextWithOptions(self.size, false, UIScreen.main.scale)

        let context = UIGraphicsGetCurrentContext()!
        fillColor.setFill()

        context.translateBy(x: 0, y: self.size.height)
        context.scaleBy(x: 1.0, y: -1.0)

        context.setBlendMode(CGBlendMode.colorBurn)

        let rect = CGRect(x: 0, y: 0, width: self.size.width, height: self.size.height)
        context.draw(self.cgImage!, in: rect)

        context.setBlendMode(CGBlendMode.sourceIn)
        context.addRect(rect)
        context.drawPath(using: CGPathDrawingMode.fill)

        let coloredImg : UIImage = UIGraphicsGetImageFromCurrentImageContext()!
        UIGraphicsEndImageContext()

        return coloredImg
    }
}

然后运行它只需执行以下操作：

let image = UIImage(named: "image_name").filledImage(fillColor: UIColor.red)
于 2016-12-05T02:55:36.810 回答
0

您可以通过以下方式在Swift 4.x中以编程方式执行此操作：

imageView.image = UIImage(named: "imageName")?.withRenderingMode(.alwaysTemplate)
imageView.tintColor = .purple
于 2019-03-22T22:41:04.743 回答
-1

-set用于设置不包括 blits 的后续绘图操作的颜色。我建议作为第一个电话，UIView在您的上方显示另一个（空）UIImageView并设置其背景颜色：

myView.backgroundColor = [UIColor colorWithWhite:0.0 alpha:0.5];

显然你应该使用你想要的白色和阿尔法值。

于 2009-05-10T13:21:57.703 回答