Question

代码已添加到Github，以便您了解真正的问题。

这是层次结构：

-- ViewController.View P [width: 375, height: 667]
---- UIImageView A       [width: 375, height: 667] Name: imgBackground
                         [A is holding an image of size(1287,1662)]
---- UIImageView B       [width: 100, height: 100] Name: imgForeground
                         [B is holding an image of size(2400,982)]

我正在尝试将A与B合并，但结果已拉长。

这是合并代码：

func mixImagesWith(frontImage:UIImage?, backgroundImage: UIImage?, atPoint point:CGPoint, ofSize signatureSize:CGSize) -> UIImage {
    let size = self.imgBackground.frame.size
    UIGraphicsBeginImageContextWithOptions(size, false, UIScreen.main.scale)
    backgroundImage?.draw(in: CGRect.init(x: 0, y: 0, width: size.width, height: size.height))
    frontImage?.draw(in: CGRect.init(x: point.x, y: point.y, width: signatureSize.width, height: signatureSize.height))
    let newImage:UIImage = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()
    return newImage
}

注意：

.contentMode = .scaleAspectFit
代码有效，但结果已拉长。
在代码let size = self.imgBackground.frame.size中查看此行 - 我需要更改此内容以解决问题。 Find the origin of subview with respect to UIImage size

以下是了解问题的屏幕截图：

我该怎么做才能获得合适功能的正确输出？

Answer 1

尝试下面对我有用的代码，希望它也适合你，

func addWaterMarkToImage(img:UIImage, sizeWaterMark:CGRect, waterMarkImage:UIImage, completion : ((UIImage)->())?){
     handler = completion
    let img2:UIImage = waterMarkImage
    let rect = CGRect(x: 0, y: 0, width: img.size.width, height: img.size.height)
    UIGraphicsBeginImageContext(img.size)
    img.draw(in: rect)
    let frameAspect:CGRect = getAspectFitFrame(sizeImgView: sizeWaterMark.size, sizeImage: waterMarkImage.size)
    let frameOrig:CGRect = CGRect(x: sizeWaterMark.origin.x+frameAspect.origin.x, y: sizeWaterMark.origin.y+frameAspect.origin.y, width: frameAspect.size.width, height: frameAspect.size.height)
    img2.draw(in: frameOrig, blendMode: .normal, alpha: 1)

    let result = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

    if handler != nil {
        handler!(result!)
    }
}
//MARK - Get Aspect Fit frame of UIImage
func getAspectFitFrame(sizeImgView:CGSize, sizeImage:CGSize) -> CGRect{

    let imageSize:CGSize  = sizeImage
    let viewSize:CGSize = sizeImgView

    let hfactor : CGFloat = imageSize.width/viewSize.width
    let vfactor : CGFloat = imageSize.height/viewSize.height

    let factor : CGFloat = max(hfactor, vfactor)

    // Divide the size by the greater of the vertical or horizontal shrinkage factor
    let newWidth : CGFloat = imageSize.width / factor
    let newHeight : CGFloat = imageSize.height / factor

    var x:CGFloat = 0.0
    var y:CGFloat = 0.0
    if newWidth > newHeight{
        y = (sizeImgView.height - newHeight)/2
    }
    if newHeight > newWidth{
        x = (sizeImgView.width - newWidth)/2
    }
    let newRect:CGRect = CGRect(x: x, y: y, width: newWidth, height: newHeight)

    return newRect

}

Answer 2

您的代码中有两个错误：

您还应计算文档图像的宽高比以使其适合UIImageView。在mergeImages()替换：

img.draw(in: CGRect(x: 0, y: 0, width: size.width, height: size.height))

使用：

img.draw(in: getAspectFitFrame(sizeImgView: size, sizeImage: img.size))

计算宽高比时，如果宽度/高度小于UIImageView宽度/高度，则水平/垂直居中。但是，不应该比较newWidth和newHeight，而应该比较因素：
```
if hfactor > vfactor {
    y = (sizeImgView.height - newHeight) / 2
} else {
    x = (sizeImgView.width - newWidth) / 2
}
```

如何在保持宽高比和大小的同时合并两个UIImages？

2 个答案: