Android -- How to scale/resize text to fit a TextView?

Question

Hello all,

I'm trying to create a method for resizing multi-line text in a TextView such that it fits within the bounds (both the X and Y dimensions) of the TextView. At present, I have something, but all it does is resize the text such that just the first letter/character of the text fills the dimensions of the TextView (i.e. only the first letter is viewable, and it's huge). I need it to fit all the lines of the text within the bounds of the TextView.

Here is what I have so far:

public static void autoScaleTextViewTextToHeight(TextView tv)
{
    final float initSize = tv.getTextSize();
    //get the width of the view's back image (unscaled).... 
    float minViewHeight;
    if(tv.getBackground()!=null)
    {
      minViewHeight = tv.getBackground().getIntrinsicHeight();
    }
    else
    {
      minViewHeight = 10f;//some min.
    }
    final float maxViewHeight = tv.getHeight() - (tv.getPaddingBottom()+tv.getPaddingTop())-12;// -12 just to be sure
    final String s = tv.getText().toString();

    //System.out.println(""+tv.getPaddingTop()+"/"+tv.getPaddingBottom());

    if(minViewHeight >0 && maxViewHeight >2)
    {
      Rect currentBounds = new Rect();
      tv.getPaint().getTextBounds(s, 0, s.length(), currentBounds);
      //System.out.println(""+initSize);
      //System.out.println(""+maxViewHeight);
      //System.out.println(""+(currentBounds.height()));

      float resultingSize = 1;
      while(currentBounds.height() < maxViewHeight)
      {
        resultingSize ++;
        tv.setTextSize(resultingSize);

        tv.getPaint().getTextBounds(s, 0, s.length(), currentBounds);
        //System.out.println(""+(currentBounds.height()+tv.getPaddingBottom()+tv.getPaddingTop()));
        //System.out.println("Resulting: "+resultingSize);
      }
      if(currentBounds.height()>=maxViewHeight)
      {
        //just to be sure, reduce the value
        tv.setTextSize(resultingSize-1);
      }
    }
}

I think the problem is in the use of tv.getPaint().getTextBounds(...). It always returns small numbers for the text bounds... small relative to the tv.getWidth() and tv.getHeight() values... even if the text size is far larger than the width or height of the TextView.

Please help. Thanks.

Answer 1

maybe try setting setHoriztonallyScrolling() to true before taking text measurements so that the textView doesn't try to layout your text on multiple lines

Answer 2

Hi @borg17of20, this is not really an answer, but I don't have enough reputation to comment yet. Did you ever make this work? I am also trying to do the same thing, mind if we share ideas? :)

Answer 3

I was able to answer my own question using the following code (see below), but my solution was very specific to the application. For instance, this will probably only look good and/or work for a TextView sized to approx. 1/2 the screen (with also a 40px top margin and 20px side margins... no bottom margin).

The using this approach though, you can create your own similar implementation. The static method basically just looks at the number of characters and determines a scaling factor to apply to the TextView's text size, and then incrementally increases the text size until the overall height (an estimated height -- using the width of the text, the text height, and the width of the TextView) is just below that of the TextView. The parameters necessary to determine the scaling factor (i.e. the if/else if statements) were set by guess-and-check. You'll likely have to play around with the numbers to make it work for your particular application.

This isn't the most elegant solution, though it was easy to code and it works for me. Does anyone have a better approach?

public static void autoScaleTextViewTextToHeight(final TextView tv, String s)
    {       
        float currentWidth=tv.getPaint().measureText(s);
        int scalingFactor = 0;
        final int characters = s.length();
        //scale based on # of characters in the string
        if(characters<5)
        {
            scalingFactor = 1;
        }
        else if(characters>=5 && characters<10)
        {
            scalingFactor = 2;
        }
        else if(characters>=10 && characters<15)
        {
            scalingFactor = 3;
        }
        else if(characters>=15 && characters<20)
        {
            scalingFactor = 3;
        }
        else if(characters>=20 && characters<25)
        {
            scalingFactor = 3;
        }
        else if(characters>=25 && characters<30)
        {
            scalingFactor = 3;
        }
        else if(characters>=30 && characters<35)
        {
            scalingFactor = 3;
        }
        else if(characters>=35 && characters<40)
        {
            scalingFactor = 3;
        }
        else if(characters>=40 && characters<45)
        {
            scalingFactor = 3;
        }
        else if(characters>=45 && characters<50)
        {
            scalingFactor = 3;
        }
        else if(characters>=50 && characters<55)
        {
            scalingFactor = 3;
        }
        else if(characters>=55 && characters<60)
        {
            scalingFactor = 3;
        }
        else if(characters>=60 && characters<65)
        {
            scalingFactor = 3;
        }
        else if(characters>=65 && characters<70)
        {
            scalingFactor = 3;
        }
        else if(characters>=70 && characters<75)
        {
            scalingFactor = 3;
        }
        else if(characters>=75)
        {
            scalingFactor = 5;
        }

        //System.out.println(((int)Math.ceil(currentWidth)/tv.getWidth()+scalingFactor));
        //the +scalingFactor is important... increase this if nec. later
        while((((int)Math.ceil(currentWidth)/tv.getWidth()+scalingFactor)*tv.getTextSize())<tv.getHeight())
        {
            tv.setTextSize(TypedValue.COMPLEX_UNIT_SP, tv.getTextSize()+0.25f);
            currentWidth=tv.getPaint().measureText(s);
            //System.out.println(((int)Math.ceil(currentWidth)/tv.getWidth()+scalingFactor));
        }

        tv.setText(s);
    }

Thanks.

Answer 4

If your only requirement is to have the text automatically split and continue in the next line and the height is not important then just have it like this.

<TextView
    android:layout_height="wrap_content"
    android:layout_width="wrap_content"
    android:maxEms="integer"
    android:width="integer"/>

This will have your TextView wrap to it's content vertically depending on your maxEms value.