Swift:如何将图像添加到另一个图像？

Question

请问我如何选择另一张透明图片并将其添加到另一张图片上？
透明图片如:小丑鼻子,帽子,帽子,耳环,小胡子,眼镜等.
它存在于几个应用程序但我无法找到任何关于此的Swift样本.

谢谢你的帮助.

Answer 1

我在UIImage扩展上有一个很好的功能:

extension UIImage {

    static func imageByMergingImages(topImage: UIImage, bottomImage: UIImage, scaleForTop: CGFloat = 1.0) -> UIImage {
        let size = bottomImage.size
        let container = CGRect(x: 0, y: 0, width: size.width, height: size.height)
        UIGraphicsBeginImageContextWithOptions(size, false, 2.0)
        UIGraphicsGetCurrentContext()!.interpolationQuality = .high
        bottomImage.draw(in: container)

        let topWidth = size.width / scaleForTop
        let topHeight = size.height / scaleForTop
        let topX = (size.width / 2.0) - (topWidth / 2.0)
        let topY = (size.height / 2.0) - (topHeight / 2.0)

        topImage.draw(in: CGRect(x: topX, y: topY, width: topWidth, height: topHeight), blendMode: .normal, alpha: 1.0)

        return UIGraphicsGetImageFromCurrentImageContext()!
    }

}

所以你可以这样打电话:

let image = UIImage.imageByMergingImages(topImage: top, bottomImage: bottom)

对于您的特定情况,考虑到要在图像上添加许多叠加层,您应该具有如下函数:

extension UIImage {

    func imageOverlayingImages(_ images: [UIImage], scalingBy factors: [CGFloat]? = nil) -> UIImage {
        let size = self.size
        let container = CGRect(x: 0, y: 0, width: size.width, height: size.height)
        UIGraphicsBeginImageContextWithOptions(size, false, 2.0)
        UIGraphicsGetCurrentContext()!.interpolationQuality = .high

        self.draw(in: container)

        let scaleFactors = factors ?? [CGFloat](repeating: 1.0, count: images.count)

        for (image, scaleFactor) in zip(images, scaleFactors) {
            let topWidth = size.width / scaleFactor
            let topHeight = size.height / scaleFactor
            let topX = (size.width / 2.0) - (topWidth / 2.0)
            let topY = (size.height / 2.0) - (topHeight / 2.0)

            image.draw(in: CGRect(x: topX, y: topY, width: topWidth, height: topHeight), blendMode: .normal, alpha: 1.0)
        }
        return UIGraphicsGetImageFromCurrentImageContext()!
    }

}

然后你可以用这种方式组合你的最终图像:

var imageClownFace = UIImage(named: "clown_face")!
imageClownFace = imageClownFace.imageOverlayingImages([imageNose, imageHat, imageCap])