MacOS：在 Swift 中向图像添加文本叠加层

Question

我为 UIImage 编写了一个小扩展，它可以向图像添加文本：

extension UIImage {

    func addTextToImage(textToAdd: String) -> UIImage {
        let textColor = UIColor.white
        let textFont = UIFont(name: "Snell Roundhand", size: 40)!
        let scale = UIScreen.main.scale
        UIGraphicsBeginImageContextWithOptions(self.size, false, scale)

        let paragraphStyle = NSMutableParagraphStyle()
        paragraphStyle.alignment = NSTextAlignment.center

        var textFontAttributes = [
            NSAttributedString.Key.font: textFont,
            NSAttributedString.Key.foregroundColor: textColor,
            NSAttributedString.Key.paragraphStyle: paragraphStyle
            ] as [NSAttributedString.Key : Any]


        self.draw(in: CGRect(origin: CGPoint.zero, size: self.size))
        let textFrame = CGPoint(x: self.size.width/4, y: self.size.height/4)
        let rect = CGRect(origin: textFrame, size: CGSize(width: self.size.width/2, height: self.size.height/2) )
        text.draw(in: rect, withAttributes: textFontAttributes)

        let newImage = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()

        return newImage!
    }
}

结果应该是这样的：

现在我想在 MacOS 上对 NSImage 执行与运行相同的操作。

知道怎么做吗？

Whosebug 上的所有类似问题都非常陈旧，没有答案，或者在 Objective C

Answer 1

找到解决方案：

extension NSImage {

    func addTextToImage(drawText text: String) -> NSImage {

        let targetImage = NSImage(size: self.size, flipped: false) { (dstRect: CGRect) -> Bool in

            self.draw(in: dstRect)
            let textColor = NSColor.white
            let textFont = NSFont(name: "Snell Roundhand", size: 36)! //Helvetica Bold
            let paragraphStyle = NSMutableParagraphStyle()
            paragraphStyle.alignment = NSTextAlignment.center

            var textFontAttributes = [
                NSAttributedString.Key.font: textFont,
                NSAttributedString.Key.foregroundColor: textColor,
                ] as [NSAttributedString.Key : Any]

            let textOrigin = CGPoint(x: self.size.height/3, y: -self.size.width/4)
            let rect = CGRect(origin: textOrigin, size: self.size)
            text.draw(in: rect, withAttributes: textFontAttributes)
            return true
        }
        return targetImage
    }
}

MacOS：在 Swift 中向图像添加文本叠加层

MacOS: Add a text overlay to an image in Swift

macos

core-graphics

uikit

swift