Makalele February 2016

Saving edited image after zooming, rotating and panning

I've created Swift version of this class: https://github.com/bennythemink/ZoomRotatePanImageView/blob/master/ZoomRotatePanImageView.m Works nice. Now I want to save modified image to file. The thing is I want to save it in full resolution and also I want to save area which is only visible to user.

Let me show you simple example:

enter image description here

This is how it looks in my app. Image is one a few samples in iOS simulator. Most of it is out of screen. I want only visible part.

After saving without cropping it looks like this:

enter image description here

So far so good after clipping it'd be nice.

But now let's make some changes:

enter image description here

After saving:

enter image description here

Looks like it's transformed by wrong pivot. How can I fix it?

Here's my code for saving:

    UIGraphicsBeginImageContextWithOptions(image.size, false, 0)
    let context = UIGraphicsGetCurrentContext()
    let transform = imageView.transform
    let imageRect = CGRectMake(0, 0, image.size.width, image.size.height)

    CGContextSetFillColorWithColor(context, UIColor.blueColor().CGColor) //for debugging
    CGContextFillRect(context, imageRect)

    CGContextConcatCTM(context, transform)

    image.drawInRect(imageRect)
    let newImage = UIGraphicsGetImageFromCurrentImageContext()!
    UIGraphicsEndImageContext()

There's a

Answers


Arun Ammannaya February 2016

Updated code to work with image of any size :

     let boundsScale = imageView.bounds.size.width / imageView.bounds.size.height
    let imageScale = image!.size.width / image!.size.height

    let size = (image?.size)!

    var canvasSize = size

    if boundsScale > imageScale {
        canvasSize.width =  canvasSize.height * boundsScale
    }else{
        canvasSize.height =  canvasSize.width / boundsScale
    }

    let xScale = canvasSize.width / imageView.bounds.width
    let yScale = canvasSize.height / imageView.bounds.height

    let center = CGPointApplyAffineTransform(imageView.center, CGAffineTransformScale(CGAffineTransformIdentity, xScale, yScale))

    let xCenter = center.x
    let yCenter = center.y

    UIGraphicsBeginImageContextWithOptions(canvasSize, false, 0);
    let context = UIGraphicsGetCurrentContext()!

    //Apply transformation
    CGContextTranslateCTM(context, xCenter, yCenter)

    CGContextConcatCTM(context, imageView.transform)

    CGContextTranslateCTM(context, -xCenter, -yCenter)

    var drawingRect : CGRect = CGRectZero
    drawingRect.size = canvasSize

    //Transaltion
    drawingRect.origin.x = (xCenter - size.width*0.5)
    drawingRect.origin.y = (yCenter - size.height*0.5)

    //Aspectfit calculation
    if boundsScale > imageScale {
        drawingRect.size.width =  drawingRect.size.height * imageScale
    }else{
        drawingRect.size.height = drawingRect.size.width / imageScale
    }

    image!.drawInRect(drawingRect)

    let newImage = UIGraphicsGetImageFromCurrentImageContext()
    UIGraphicsEndImageContext()

Simulator screen shot Simulator

Saved image Saved

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Asked in February 2016
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