swift 编程如何在 UIimage 中设置背景颜色

Question

我用drawInRect()方法画了一张图。

我的矩形是 120*120，我的图片是 100*100。

如何在 swift 中为我的图像设置背景颜色？

Answer 1

最好使用 UIImageView 的 backgroundColor 属性。您可以按如下方式执行此操作 -

self.imageView.backgroundColor = UIColor.redColor()

存在以下预设颜色：

blackColor
darkGrayColor
lightGrayColor
whiteColor
grayColor
redColor
greenColor
blueColor
cyanColor
yellowColor
magentaColor
orangeColor
purpleColor
brownColor
clearColor

如果您想以编程方式创建具有给定颜色的 UIImage，您可以按如下方式执行此操作：

var rect = CGRectMake(0, 0, size.width, size.height)
UIGraphicsBeginImageContextWithOptions(size, false, 0)
color.setFill()
UIRectFill(rect)
var image: UIImage = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()

其中 var 'image' 是您的彩色 UIImage。

Answer 2

您也可以使用此扩展程序：

    extension UIImage {
        func imageWithColor(tintColor: UIColor) -> UIImage {
            UIGraphicsBeginImageContextWithOptions(self.size, false, self.scale)

            let context = UIGraphicsGetCurrentContext()!
            context.translateBy(x: 0, y: self.size.height)
            context.scaleBy(x: 1.0, y: -1.0);
            context.setBlendMode(.normal)

            let rect = CGRect(x: 0, y: 0, width: self.size.width, height: self.size.height) as CGRect
            context.clip(to: rect, mask: self.cgImage!)
            tintColor.setFill()
            context.fill(rect)

            let newImage = UIGraphicsGetImageFromCurrentImageContext()!
            UIGraphicsEndImageContext()

            return newImage
        }
    }

然后

image.imageWithColor("#1A6BAE".UIColor)

编辑：2019-11：由@Yuto

更新为Swift 5

Answer 3

更新了@Egghead 对 Swift 3

的解决方案

extension UIImage {
   static func imageWithColor(tintColor: UIColor) -> UIImage {
        let rect = CGRect(x: 0, y: 0, width: 1, height: 1)
        UIGraphicsBeginImageContextWithOptions(rect.size, false, 0)
        tintColor.setFill()
        UIRectFill(rect)
        let image: UIImage = UIGraphicsGetImageFromCurrentImageContext()!
        UIGraphicsEndImageContext()
        return image
    }
}

用法：

UIImage.imageWithColor(tintColor: <Custom color>)

Answer 4

另一种获取带有扩展名的背景色图像的方法是：(Swift 3)

extension UIImage {

    /**
        Returns an UIImage with a specified background color.
        - parameter color: The color of the background
     */
    convenience init(withBackground color: UIColor) {

        let rect: CGRect = CGRect(x: 0, y: 0, width: 1, height: 1)
        UIGraphicsBeginImageContext(rect.size);
        let context:CGContext = UIGraphicsGetCurrentContext()!;
        context.setFillColor(color.cgColor);
        context.fill(rect)

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

        self.init(ciImage: CIImage(image: image)!)

    }
}

然后：

// change UIColor.white with your color
let image = UIImage(withBackground: UIColor.white)

Answer 5

swift 4 的解决方案基于已接受的答案：

func imageWithColor(tintColor: UIColor) -> UIImage {
    UIGraphicsBeginImageContextWithOptions(self.size, false, self.scale)

    let context = UIGraphicsGetCurrentContext() as! CGContext
    context.translateBy(x: 0, y: size.height)
    context.scaleBy(x: 1, y: -1)
    context.setBlendMode(.normal)

    let rect = CGRect(x: 0, y: 0, width: self.size.width, height: self.size.height) as CGRect
    context.clip(to: rect, mask: self.cgImage!)
    tintColor.setFill()
    context.fill(rect)
    let newImage = UIGraphicsGetImageFromCurrentImageContext() as! UIImage
    UIGraphicsEndImageContext()

    return newImage
}

用法：

image.imageWithColor("#1A6BAE".UIColor)

Answer 6

Swift 5, 4

如果需要绘制图片的背景，为了优化和装饰的目的，可以按照特定的方式绘制图片：

UIImage(named: "someImage")?.withBackground(color: .white)

扩展

extension UIImage {
  func withBackground(color: UIColor, opaque: Bool = true) -> UIImage {
    UIGraphicsBeginImageContextWithOptions(size, opaque, scale)
        
    guard let ctx = UIGraphicsGetCurrentContext(), let image = cgImage else { return self }
    defer { UIGraphicsEndImageContext() }
        
    let rect = CGRect(origin: .zero, size: size)
    ctx.setFillColor(color.cgColor)
    ctx.fill(rect)
    ctx.concatenate(CGAffineTransform(a: 1, b: 0, c: 0, d: -1, tx: 0, ty: size.height))
    ctx.draw(image, in: rect)
        
    return UIGraphicsGetImageFromCurrentImageContext() ?? self
  }
}

swift 编程如何在 UIimage 中设置背景颜色

how to set a background color in UIimage in swift programming

ios

swift

uiimage

Swift 5, 4

扩展