Swift: 旋转 UIImage 并填充它

Question

我目前正在旋转图像并用 swift 填充它。如果我使用下面的代码（我从互联网上获得），我可以旋转图像，保持大小。代码下方说明了一个示例。而且，问题是，旋转后我在每个角落都有一个灰色间隙。我想用白色填充它，这样图像看起来不错。

在swift轮换后有什么方法可以填补空缺吗？

谢谢！

extension UIImage {

    func rotatedBy(degree: CGFloat) -> UIImage {
        let radian = -degree * CGFloat.pi / 180
        UIGraphicsBeginImageContext(self.size)
        let context = UIGraphicsGetCurrentContext()!
        context.translateBy(x: self.size.width / 2, y: self.size.height / 2)
        context.scaleBy(x: 1.0, y: -1.0)

        context.rotate(by: radian)
        context.draw(self.cgImage!, in: CGRect(x: -(self.size.width / 2), y: -(self.size.height / 2), width: self.size.width, height: self.size.height))

        let rotatedImage = UIGraphicsGetImageFromCurrentImageContext()!
        UIGraphicsEndImageContext()
        return rotatedImage
    }

}

Answer 1

您只需要在旋转图像之前设置填充颜色并填充上下文即可：

extension UIImage {
    func rotatedBy(degree: CGFloat) -> UIImage? {
        guard let cgImage = cgImage else { return nil }
        UIGraphicsBeginImageContextWithOptions(size, false, 0)
        guard let context = UIGraphicsGetCurrentContext() else { return nil }
        defer { UIGraphicsEndImageContext() }
        UIColor.white.setFill()
        context.fill(.init(origin: .zero, size: size))
        context.translateBy(x: size.width/2, y: size.height/2)
        context.scaleBy(x: 1, y: -1)
        context.rotate(by: -degree * .pi / 180)
        context.draw(cgImage, in: CGRect(origin: .init(x: -size.width/2, y: -size.height/2), size: size))
        return UIGraphicsGetImageFromCurrentImageContext()
    }
}

Swift: 旋转 UIImage 并填充它

Swift: Rotating UIImage and filling it

ios

swift

xcode

image-processing

uiimage