Android Paint. How is the character width calculated?

Question

I need to know how the width of text changes when I increase paint.getTextSize() n times. I thought that is proportional, but first test indicates that it is not. I got result like below, where

• 1st number - size of text set by Paint.setTextSize(float)

• 2nd number - width of text measured with Paint.measureText(String)
  

       1;1.0
       2;1.0
       3;2.0
       4;2.0
       5;3.0
       6;3.0
       7;4.0
       8;4.0
       9;5.0
       10;5.0
       11;6.0
       12;7.0
       13;7.0
       14;8.0
       15;8.0
       16;9.0
       17;9.0
       18;10.0
       19;10.0
       20;11.0
       21;11.0
       22;12.0
       23;13.0
       24;13.0
       25;14.0
       26;14.0
       27;15.0
       28;15.0
       29;16.0
       30;16.0
       31;17.0
       32;17.0
       33;18.0
       34;19.0
       35;19.0
       36;20.0
       37;20.0
       38;21.0
       39;21.0
       40;22.0
       41;22.0
       42;23.0
       43;23.0
       44;24.0
       45;24.0
       46;25.0
       47;26.0
       48;26.0
       49;27.0
       50;27.0
       51;28.0
       52;28.0
       53;29.0
  

Is it possible to calculate how the text width would change after changing text size n times?
I don't want to use Paint.measureText(String) method ever time i change size, because it's bad for performance.
Thanks in advance!

Answer 1

See Getting height of text view before rendering to layout. Maybe it will measure text faster. An example for height is below.

public static int getHeight(TextView t) {
    int widthMeasureSpec = View.MeasureSpec.makeMeasureSpec(screenWidth(t.getContext()), View.MeasureSpec.AT_MOST);
    int heightMeasureSpec = View.MeasureSpec.makeMeasureSpec(0, View.MeasureSpec.UNSPECIFIED);
    t.measure(widthMeasureSpec, heightMeasureSpec);
    return t.getMeasuredHeight();
}

public static int screenWidth(Context context)
{
    WindowManager wm = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
    Display display = wm.getDefaultDisplay();
    return display.getWidth();
}

Also you can try to estimate a formula of changing.