Add more versatile zoom to ChartView

We have a PinchArea in ChartView and we would like to be able to zoom the chart in and out dynamically with a pinch. The problem is that most of the zooming functions in ChartView zoom on the center of the chart. Only with zoomIn(rect) you can use custom center point. Thus zooming interactively anywhere in the chart with a pinch is not easily available even if it is the most intuitive for the end user.