MPAndroidChart set center vertical line

Question

I want to set a vertical line in center of LineChart like this:

When scrolling to each point, it can notify to change the date below (

Answer 1

Have you tried using getEntryByTouchPoint on your chart supplying the x and y coordinates of the center of the chart?

public Entry getEntryByTouchPoint(float x, float y)

returns the Entry object displayed at the touched position of the chart

Answer 2

Maybe it's too late but here is my answer. It's encoded in Swift using Charts (MPAndroidCharts port for iOS) but API is 99% the same ;)

let verticalPointEntry = ChartDataEntry(x: xValue, y: yValue)

let dataSet = LineChartDataSet(values: [verticalPointEntry], label: "")
dataSet.drawCirclesEnabled = false
dataSet.drawValuesEnabled = false
dataSet.setDrawHighlightIndicators(true)
dataSet.drawHorizontalHighlightIndicatorEnabled = false
dataSet.highlightColor = UIColor.white
dataSet.highlightLineWidth = 1   

let highlightPoint = Highlight(x: xValue, y: yValue, dataSetIndex: datasetIndex)
self.highlightValues([highlightPoint])

// "yourNormalDataSet" is your regular dataSet in which you want to display vertical line over it
let chartData = LineChartData(dataSets: [yourNormalDataSet, dataSet])
self.data = chartData
self.data?.notifiyDataChanged()
self.notifyDataSetChanged

This will display a vercital line over the point defined by your xValue variable.

Hope it helps!

Answer 3

Take a look at the method

protected void drawGridBackground(Canvas c) {

in the BarLineChartBase class (parent for a LineChart). In that method you have all data to draw your line right in the middle. Something like this

RectF rectF = mViewPortHandler.getContentRect();
float xMiddle = (rectF.right - rectF.left)/2;
Paint p = new Paint();
p.setColor(Color.BLACK);
c.drawLine(xMiddle, rectF.bottom, xMiddle, rectF.top, p);