chart is scrolling to top when reach maxScaleY and try zoom in again

[liuxuan30]

Steps to reproduce, using ChartsDemo:
for normal bar chart:

[_chartView.viewPortHandler setMaximumScaleY:3.0];

for horizontal bar chart:

// which is a little confusing, it means the x axis for horizontal bar chart
[_chartView.viewPortHandler setMaximumScaleY:3.0]; 

First reach the max scale level, scroll the chart to the middle, and try zoom in again, it actually starts a scrolling to top, which at first seems zooming.

@noais I guess it's introduced in #388?

[noais]

@liuxuan30 yes you right this happens on all charts.
I put this gift http://imgur.com/chYcHLV to explain the issue.

It's hard to fix this issue and the worst part is to not have time to fix him 😓

[iangmaia]

Isn't that the same as #437?
I've sent a pull request that seems to have fixed the issue but it hasn't been reviewed yet.

[liuxuan30]

@iangmaia I don't see it on maxScaleX, only scaleY. Your PR #438 seems only to fix the x axis, while I don't have this problem on x axis. Could you clarify?

[iangmaia]

@liuxuan30 Yes, you're right. I've added now scaleY handling as well.
I think I took the assumption that they were also always gonna be changed together (which is my case and it seemed to fix the issue).

[iangmaia]

@liuxuan30 Actually, I've played around with it a bit more and I realized it fixes only when pinchZoom is enabled. When it is disabled, unfortunately it is still there.

[liuxuan30]

@iangmaia thanks, but why can't it be applied when pinchZoom disabled?

[danielgindi]

I have merge that PR, and made some fixes. Now it works properly