如何在保持宽高比和尺寸的同时合并两个UIImage? [英] How to merge two UIImages while keeping the aspect ratio and size?

问题描述

代码已添加到 Github 中，以使您了解真正的问题.

The code is added to Github to let you understand the real problem.

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，但结果却很复杂.

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，但结果得到了扩展.
• 请参见代码let size = self.imgBackground.frame.size中的此行–我需要更改此行以解决问题. 找到关于UIImage大小的子视图的来源

• .contentMode = .scaleAspectFit
• Code works but the result is stretched.
• See this line in code, let size = self.imgBackground.frame.size – I need to change this to fix the problem. Find the origin of subview with respect to UIImage size

以下是了解问题的屏幕截图:

Here's the screenshot to understand the problem:

我应该怎么做才能获得正确的合并功能输出?

What should I do to get the proper output of merge function?

推荐答案

您的代码中有两个错误:

You have two bugs in your code:

1. 您还应该计算文档图像的长宽比以适合UIImageView.在mergeImages()中替换:

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

具有:

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

在计算宽高比时，如果宽度/高度小于UIImageView宽度/高度，则可以水平/垂直居中放置图像.但是，除了比较newWidth和newHeight之外，您还应该比较因素:

When calculating aspect you center image horizontally/vertically if its width/height less then UIImageView width/height. But instead of comparing newWidth and newHeight you should compare factors:

if hfactor > vfactor {
    y = (sizeImgView.height - newHeight) / 2
} else {
    x = (sizeImgView.width - newWidth) / 2
}

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