Positioning on changing of the screen orientation

[oxodpavel]

Hi!

There is a minor drawback, that when screen orientation changes, the vertical scale loses its position and goes to some range around original (previous).

Conditions:

• occurs only when some scaling has been performed
• occurs only on positions which are not aligned to the horizontal and vertical axes (to thier zero values)
• changing screen orientation back restores graph position to the original state (seems like, horiz and vert orientations have independent positioning parameters, am I write)
  
  

[leoMehlig]

I had the same problem and solved it by overriding this method in my Chart-Class:

public override func observeValueForKeyPath(
keyPath: String?,
ofObject object: AnyObject?, 
change: [String : AnyObject]?, 
context: UnsafeMutablePointer<Void>) {     

        var oldPoint: CGPoint?
        if keyPath == "frame" || keyPath == "bounds" {
            oldPoint = viewPortHandler.contentRect.origin
            getTransformer(.Left).pixelToValue(&oldPoint!)
        }
        super.observeValueForKeyPath(keyPath, ofObject: object, change: change, context: context)
        if var p = oldPoint {
            getTransformer(.Left).pointValueToPixel(&p)
            viewPortHandler.centerViewPort(pt: p, chart: self)
        }
} 

[liuxuan30]

I fixed the md in your comment @leoMehlig, nice solution btw
@oxodpavel will it solve your issue, or you can override to get what you want?

[oxodpavel]

Yes, thank you! This patch works fine

[leoMehlig]

@liuxuan30 is this a feature that should be implemented internally?

[liuxuan30]

@leoMehlig I'm not sure if everyone has such requirements, some may want keep centered, while some want nothing changed :) If you think it's useful, than add a switch to turn it on and a PR :)