JavaFX：如何在XY线图的Y轴上正确实现`getValueForDisplay（）`？ [英] JavaFX: How to correctly implement `getValueForDisplay()` on Y Axis of a XY line Graph?

问题描述

我正在尝试在折线图上实现工具提示以显示X和Y轴的值，我正确地获得X轴的值，但是没有正确计算Y轴值。我试着做数学，但是当我们调整窗口大小时，到目前为止没有任何帮助。是否有任何逻辑可以帮助我们正确计算Y轴上的值？

I am trying to implement tooltip on a line graph to show values of X and Y Axis, i am getting values at X axis correctly, but Y axis values are not getting calculated properly. I tried to do the Math, but nothing helped so far values get incorrect when we resize the window. Is there any logic which help us to calculate value on Y axis correctly?

       // lineChart is an object of AreaChart Or XYChart
       lineChart.setOnMouseMoved(new EventHandler<MouseEvent>() {

        @Override
        public void handle(MouseEvent event) {

            Tooltip t= new Tooltip("X:"+lineChart.getXAxis().getValueForDisplay(event.getX()-lineChart.getXAxis().getLayoutX())+", Y:"+
            lineChart.getYAxis().getValueForDisplay(event.getY()));
            t.show(stage);
        }
    });

推荐答案

这应该可以满足您的需求：

This should do what you need:

public void handle(MouseEvent event) {
    Point2D pointInScene = new Point2D(event.getSceneX(), event.getSceneY());
    Axis<Number> xAxis = lineChart.getXAxis();
    Axis<Number> yAxis = lineChart.getYAxis();
    double xPosInAxis = xAxis.sceneToLocal(new Point2D(pointInScene.getX(), 0)).getX();
    double yPosInAxis = yAxis.sceneToLocal(new Point2D(0, pointInScene.getY())).getY();
    double x = xAxis.getValueForDisplay(xPosInAxis).doubleValue();
    double y = yAxis.getValueForDisplay(yPosInAxis).doubleValue();

    Tooltip t = new Tooltip("X: "+x+", Y:"+y);
    t.show(stage);
}

这篇关于JavaFX：如何在XY线图的Y轴上正确实现`getValueForDisplay（）`？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！