JavaFX LineChart zooming is not precise - javafx

Question

I'm trying to implement a zoom rectange for LineChart. Here is my code :
private void doZoom(Rectangle zoomRect, LineChart<Number, Number> chart) {
Point2D zoomTopLeft = new Point2D(zoomRect.getX(), zoomRect.getY());
Point2D zoomBottomRight = new Point2D(zoomRect.getX() + zoomRect.getWidth(), zoomRect.getY() + zoomRect.getHeight());
NumberAxis yAxis = (NumberAxis) chart.getYAxis();
NumberAxis xAxis = (NumberAxis) chart.getXAxis();
xAxis.setAutoRanging(false);
yAxis.setAutoRanging(false);
var xAxisMaxBoundValuePoint = xAxis.sceneToLocal(zoomBottomRight);
var xAxisMinBoundValuePoint = xAxis.sceneToLocal(zoomTopLeft);
var xAxisScaleFactor = xAxis.getScale();
xAxis.setLowerBound(xAxisMinBoundValuePoint.getX()/xAxisScaleFactor);
xAxis.setUpperBound(xAxisMaxBoundValuePoint.getX()/xAxisScaleFactor);
var yAxisMinBoundValuePoint = yAxis.sceneToLocal(zoomBottomRight);
var yAxisMaxBoundValuePoint = yAxis.sceneToLocal(zoomTopLeft);
var yAxisScaleFactor = yAxis.getScale();
yAxis.setLowerBound(yAxisMinBoundValuePoint.getY()/yAxisScaleFactor);
yAxis.setUpperBound(yAxisMaxBoundValuePoint.getY()/yAxisScaleFactor);
zoomRect.setWidth(0);
zoomRect.setHeight(0);
}
I see that xAxis limits are fine - the match zoom Rectange but yAxis are not precise. Upper bound is a little bit less and Lower bound is a little bit lower than expected. What is so special about it?
PS
I tried this https://gist.github.com/james-d/7252698 as an example but there seems to be a bug in case axis are not always positive...

Answer 1

Thanks to James_d, I've developed the following solution :
private void doZoom(Rectangle zoomRect, LineChart<Number, Number> chart) {
Point2D zoomTopLeft = new Point2D(zoomRect.getX(), zoomRect.getY());
Point2D zoomBottomRight = new Point2D(zoomRect.getX() + zoomRect.getWidth(),
zoomRect.getY() + zoomRect.getHeight());
var zoomTopLeftScene = zoomRect.localToScene(zoomTopLeft.getX(),zoomTopLeft.getY());
var zoomBottomRightScene = zoomRect.localToScene(zoomBottomRight.getX(), zoomBottomRight.getY());
NumberAxis yAxis = (NumberAxis) chart.getYAxis();
NumberAxis xAxis = (NumberAxis) chart.getXAxis();
xAxis.setAutoRanging(false);
yAxis.setAutoRanging(false);
var minXDisplay = xAxis.sceneToLocal(zoomTopLeftScene);
var maxXDisplay = xAxis.sceneToLocal(zoomBottomRightScene);
var xLowerBound = xAxis.getValueForDisplay(minXDisplay.getX());
var xUpperBound = xAxis.getValueForDisplay(maxXDisplay.getX());
xAxis.setLowerBound( xLowerBound.doubleValue() );
xAxis.setUpperBound( xUpperBound.doubleValue() );
var maxYDisplay = yAxis.sceneToLocal(zoomTopLeftScene);
var minYDisplay = yAxis.sceneToLocal(zoomBottomRightScene);
var yLowerBound = yAxis.getValueForDisplay(minYDisplay.getY());
var yUpperBound = yAxis.getValueForDisplay(maxYDisplay.getY());
yAxis.setLowerBound( yLowerBound.doubleValue() );
yAxis.setUpperBound( yUpperBound.doubleValue() );
zoomRect.setWidth(0);
zoomRect.setHeight(0);
}