iPhone，如何将一个图像叠加到另一个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，右下角有一个应用程序名称的三角形。我已经在photoshop中使用透明层制作了第二张图像。

我尝试了一个功能，我不记得确切的名字，但它涉及CGIImages和蒙版。这组合了两个图像，但作为一个遮罩，使得图像在透明层所在的位置更暗，图像本身没有合并，只是掩盖了。

如何在不在屏幕上显示图像的情况下，将水印图像与其他图像合并，制作UII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的大小相同，请使用此代码

...
[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.drawInRect(CGRect(0.0, 0.0, backgroundImage.size.width, backgroundImage.size.height))
watermarkImage.drawInRect(CGRect(backgroundImage.size.width - watermarkImage.size.width, backgroundImage.size.height - watermarkImage.size.height, watermarkImage.size.width, watermarkImage.size.height))
let result = UIGraphicsGetImageFromCurrentImageContext()
UIGraphicsEndImageContext()

Answer 3

您可以使用此方法，这是非常动态的，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 4

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

将结果用于UIImageView，经过测试。

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!
    }