iPhone，如何将一张图像叠加到另一张图像上以创建要保存的新图像？ （水印）

Question

基本上，我想拍摄用户从照片库中选择的图像，然后应用水印，即右下角的三角形，上面有应用程序名称。我已经在 Photoshop 中用透明层制作了第二张图像。

我尝试了一个函数，我不记得它的确切名称，但它涉及 CGIImages 和蒙版。这将两个图像结合在一起，但作为遮罩，这使得透明层所在的图像变暗，并且图像本身并未合并，只是被遮罩了。

如何将水印图像与另一个图像合并以制作 UIImage，而不在屏幕上显示图像？

谢谢。

Answer 1

这很简单：

UIImage *backgroundImage = [UIImage imageNamed:@"image.png"];
UIImage *watermarkImage = [UIImage imageNamed:@"watermark.png"];

UIGraphicsBeginImageContext(backgroundImage.size);
[backgroundImage drawInRect:CGRectMake(0, 0, backgroundImage.size.width, backgroundImage.size.height)];
[watermarkImage drawInRect:CGRectMake(backgroundImage.size.width - watermarkImage.size.width, backgroundImage.size.height - watermarkImage.size.height, watermarkImage.size.width, watermarkImage.size.height)];
UIImage *result = UIGraphicsGetImageFromCurrentImageContext();
UIGraphicsEndImageContext();

如果您希望背景和水印具有相同的大小，则使用此代码

...
[backgroundImage drawInRect:CGRectMake(0, 0, backgroundImage.size.width, backgroundImage.size.height)];
[watermarkImage drawInRect:CGRectMake(0, 0, backgroundImage.size.width, backgroundImage.size.height)];
...

Answer 2

omz 提供的解决方案也适用于 Swift，如下所示：

let backgroundImage = UIImage(named: "image.png")!
let watermarkImage = UIImage(named: "watermark.png")!

UIGraphicsBeginImageContextWithOptions(backgroundImage.size, false, 0.0)
backgroundImage.draw(in: CGRect(x: 0.0, y: 0.0, width: backgroundImage.size.width, height: backgroundImage.size.height))
watermarkImage.draw(in: CGRect(x: backgroundImage.size.width - watermarkImage.size.width, y: backgroundImage.size.height - watermarkImage.size.height, width: watermarkImage.size.width, height: watermarkImage.size.height))
let result = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()

Answer 3

SWIFT 4

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

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

let result = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()
self.imgaeView.image = result

使用 UIImageView 的结果进行测试。

Answer 4

您可以使用这种方法，它非常动态，您可以指定第二个图像的起始位置和图像的总大小。

-(UIImage *) addImageToImage:(UIImage *)img withImage2:(UIImage *)img2 andRect:(CGRect)cropRect withImageWidth:(int) width{

    CGSize size = CGSizeMake(width,40);
    UIGraphicsBeginImageContext(size);

    CGPoint pointImg1 = CGPointMake(0,0);
    [img drawAtPoint:pointImg1];

    CGPoint pointImg2 = cropRect.origin;
    [img2 drawAtPoint: pointImg2];

    UIImage* result = UIGraphicsGetImageFromCurrentImageContext();
    UIGraphicsEndImageContext();
    return result;

}

Answer 5

SWIFT 5 功能：

func addWaterMark(image: UIImage) -> UIImage {
        let backgroundImage = image//UIImage(named: "image.png")
        let watermarkImage = UIImage(named: "waterMark.png")

        UIGraphicsBeginImageContextWithOptions(backgroundImage.size, false, 0.0)
        backgroundImage.draw(in: CGRect(x: 0.0, y: 0.0, width: backgroundImage.size.width, height: backgroundImage.size.height))
        watermarkImage!.draw(in: CGRect(x: backgroundImage.size.width - watermarkImage!.size.width, y: backgroundImage.size.height - watermarkImage!.size.height, width: watermarkImage!.size.width, height: watermarkImage!.size.height))
        let result = UIGraphicsGetImageFromCurrentImageContext()
        UIGraphicsEndImageContext()
        return result!
    }