iPhone, how does one overlay one image onto anothe

2019-01-30 01:11发布

Basically I want to take an image that the user chooses from their photo library and then apply a watermark, a triangle in the lower right that has the app name on it. I have the second image already made with a transparent layer in photoshop.

I tried a function, which I can't remember the exact name, but it involved CGIImages and masks. This combines the two images, but as a mask, which made the image darker where the transparent layer was and the images were not merged per se, just masked.

How would I get the watermark image to merge with another image, to make a UIImage, without displaying the images on the screen?

Thank you.

4条回答
劫难
2楼-- · 2019-01-30 01:25

You can use this method, which is very dynamic and you can specify the starting position of the second image and total size of the image.

-(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;

}
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放荡不羁爱自由
3楼-- · 2019-01-30 01:31

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

Use result to UIImageView, tested.

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Evening l夕情丶
4楼-- · 2019-01-30 01:37

It's pretty easy:

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();

If you want the background and watermark to be of the same size then use this code

...
[backgroundImage drawInRect:CGRectMake(0, 0, backgroundImage.size.width, backgroundImage.size.height)];
[watermarkImage drawInRect:CGRectMake(0, 0, backgroundImage.size.width, backgroundImage.size.height)];
...
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Anthone
5楼-- · 2019-01-30 01:40

The solution provided by omz also works in Swift, like so:

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()
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