Currently I use the MPAndroidChart from GITHUB and draw the piechart to display the two line text, each line has different color and different font size,I check the source codes
You can accomplish this without modifying MPAndroidChart source by nesting your com.github.mikephil.charting.charts.PieChart component and your center text within a RelativeLayout in your activity layout. You can use a LinearLayout component to format your center text rows.
Be careful to place your LinearLayout containing your center text below your PieChart component. Here is the end result.