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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!

Jan Rozenbajgier
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  • What if you have a long text? When you will resize it, it will wrap to the 2nd line. It also depends on font, style. Maybe depends on screen density. – CoolMind May 06 '22 at 19:37
  • @CoolMind thanks for answer, I have a single line, so line wraping does not take place here, but screen density seems to be possible factor. – Jan Rozenbajgier May 06 '22 at 19:43

1 Answers1

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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.

CoolMind
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  • Thanks, I don't use TextView, but draw text on Canvas. I've developed my own line wrapping algorithm which is faster than StaticLayout. I want also to modify it to resize text automitcally to fit the box. I need to know how the line width would change if I change size `n` times. – Jan Rozenbajgier May 06 '22 at 19:57
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    I tried to find the formula for ex. `width = Math.ceil(0.5441613 * textSize)` (this weird number is an average change factor I've calculated), but there are always exceptions. – Jan Rozenbajgier May 06 '22 at 20:00
  • also tried with round and floor – Jan Rozenbajgier May 06 '22 at 20:01