如何使用此代码向图像添加水印？

Question

我知道还有其他几种方法可以做到这一点；我不想导入任何我不需要的东西。如果有人可以帮助我修改他的代码，那就太好了。

目前只保存原图，不带水印图片。

extension UIImage {

    class func imageWithWatermark(image1: UIImageView, image2: UIImageView) -> UIImage {
        UIGraphicsBeginImageContextWithOptions(image1.bounds.size, false, 0.0)
        image2.layer.renderInContext(UIGraphicsGetCurrentContext()!)
        image1.layer.renderInContext(UIGraphicsGetCurrentContext()!)
        let img = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return img
    }
}

func addWatermark() {
    let newImage = UIImage.imageWithWatermark(imageView, image2: watermarkImageView)
    UIImageWriteToSavedPhotosAlbum(newImage, nil, nil, nil)
}

编辑：我保存的图像上出现了水印。

我必须切换图层的顺序：

 image1.layer.renderInContext(UIGraphicsGetCurrentContext()!)
 image2.layer.renderInContext(UIGraphicsGetCurrentContext()!)

但是，它没有出现在正确的位置。它似乎总是出现在图像的中心。

Answer 1

如果你抓取 UIImageViews 的图像，你可以使用以下概念：

if let img = UIImage(named: "image.png"), img2 = UIImage(named: "watermark.png") {

    let rect = CGRect(x: 0, y: 0, width: img.size.width, height: img.size.height)

    UIGraphicsBeginImageContextWithOptions(img.size, true, 0)
    let context = UIGraphicsGetCurrentContext()

    CGContextSetFillColorWithColor(context, UIColor.whiteColor().CGColor)
    CGContextFillRect(context, rect)

    img.drawInRect(rect, blendMode: .Normal, alpha: 1)
    img2.drawInRect(CGRectMake(x,y,width,height), blendMode: .Normal, alpha: 1)

    let result = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    UIImageWriteToSavedPhotosAlbum(result, nil, nil, nil)

}

Answer 2

SWIFT 4 用这个

let backgroundImage = imageData!
let watermarkImage = #imageLiteral(resourceName: "jodi_url_icon")

let size = backgroundImage.size
let scale = backgroundImage.scale

UIGraphicsBeginImageContextWithOptions(size, false, scale)
backgroundImage.draw(in: CGRect(x: 0.0, y: 0.0, width: size.width, height: size.height))
watermarkImage.draw(in: CGRect(x: 10, y: 10, width: size.width, height: size.height - 40))

let result = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()

使用结果到UIImageView，经过测试。

Answer 3

@mrkbxt 的回答

斯威夫特5：

func addWatermartToImage (image: UIImage?) {
    if let img = image, let watermarkImg = UIImage(named: "watermark.png") {

        let rect = CGRect(x: 0, y: 0, width: img.size.width, height: img.size.height)

        UIGraphicsBeginImageContextWithOptions(img.size, true, 0)
        let context = UIGraphicsGetCurrentContext()

        context!.setFillColor(UIColor.white.cgColor)
        context!.fill(rect)

        img.draw(in: rect, blendMode: .normal, alpha: 1)
        watermarkImg.draw(in: CGRect(x: x, y: y, width: width, height: height), blendMode: .normal, alpha: 0.6)

        let result = UIGraphicsGetImageFromCurrentImageContext()!
        UIGraphicsEndImageContext()

        UIImageWriteToSavedPhotosAlbum(result, nil, nil, nil)

    }
}