How can I use CGRect() dynamically?-CodePudding

I have the following scene example where I can crop an image based on the selection (red square).

That square has dynamic Height and Width - base on this fact I want to use the selected Height and Width to crop what is inside of the Red square.

The function that I am using for cropping is from Apple developer and looks like this:

func cropImage(_ inputImage: UIImage, toRect cropRect: CGRect, viewWidth: CGFloat, viewHeight: CGFloat) -> UIImage? 
{    
    let imageViewScale = max(inputImage.size.width / viewWidth,
                             inputImage.size.height / viewHeight)

    // Scale cropRect to handle images larger than shown-on-screen size
    let cropZone = CGRect(x:cropRect.origin.x * imageViewScale,
                          y:cropRect.origin.y * imageViewScale,
                          width:cropRect.size.width * imageViewScale,
                          height:cropRect.size.height * imageViewScale)

    // Perform cropping in Core Graphics
    guard let cutImageRef: CGImage = inputImage.cgImage?.cropping(to:cropZone)
    else {
        return nil
    }

    // Return image to UIImage
    let croppedImage: UIImage = UIImage(cgImage: cutImageRef)
    return croppedImage
}

Now. I want to use the given Height and Width to crop that selection.

 let croppedImage =  cropImage(image!, toRect: CGRect(x:?? , y:?? , width: ??, height: ??), viewWidth: ??, viewHeight: ??)

What should I fill in these parameters in order to crop the image based on the above dynamic selection?

CodePudding user response：

Ok, since you just have info of width and height of the cropping shape. You'll need to calculate the x and y by yourself.

First, let's consider these information:

// let's pretend this is a sample of size that your crop tool provides to you
let cropSize = CGSize(width: 120, height: 260)

Next, you'll need to obtain the display size (width and height) of your image. Display size here is the frame's size of your image, not the size of the image itself.

// again, lets pretend it's just a frame size of your image
let imageSize = CGSize(width: 320, height: 480)

With this info, you can obtain the x and y necessary to compose a CGRect and then, provide to a cropping function you desire.

let x = (imageSize.width - cropSize.width) / 2
let y = (imageSize.height - cropSize.height) / 2

So now, you can create a rectangle to crop your image like this:

let cropRect = CGRect(x: x, y: y, width: cropSize.width, height: cropSize.height)

With cropRect you can use on both cropping or cropImage functions mentioned in your question.

CodePudding user response：

Ok, let's assume that your image is in imageView, wich is located somewhere in your screen. The rect is a variable where your selected frame (related to the imageView.frame) is stored. So the result is:

let croppedImage =  cropImage(image!, toRect: rect, viewWidth: imageView.width, viewHeight: imageView.height)