Android Open Source - AutoFitTextView Auto Resize Text View

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Back to project page AutoFitTextView.

License

The source code is released under:

Apache License

Java Source Code

package com.lb.auto_fit_textview;
import android.annotation.TargetApi;
import android.content.Context;
import android.content.res.Resources;
import android.graphics.RectF;
import android.graphics.Typeface;
import android.os.Build;
import android.text.Layout.Alignment;
import android.text.StaticLayout;
import android.text.TextPaint;
import android.util.AttributeSet;
import android.util.SparseIntArray;
import android.util.TypedValue;
import android.widget.TextView;
//from  w  ww.jav  a 2  s.c  om
/**
 * a textView that is able to self-adjust its font size depending on the min and max size of the font, and its own size.<br/>
 * code is heavily based on this StackOverflow thread:
 * http://stackoverflow.com/questions/16017165/auto-fit-textview-for-android/21851239#21851239 <br/>
 * It should work fine with most Android versions, but might have some issues on Android 3.1 - 4.04, as setTextSize will only work for the first time. <br/>
 * More info here: https://code.google.com/p/android/issues/detail?id=22493 and here in case you wish to fix it: http://stackoverflow.com/a/21851239/878126
 */
public class AutoResizeTextView extends TextView{
  private static final int NO_LINE_LIMIT=-1;
  private final RectF _availableSpaceRect=new RectF();
  private final SparseIntArray _textCachedSizes=new SparseIntArray();
  private final SizeTester _sizeTester;
  private float _maxTextSize;
  private float _spacingMult=1.0f;
  private float _spacingAdd=0.0f;
  private float _minTextSize;
  private int _widthLimit;
  private int _maxLines;
  private boolean _enableSizeCache=true;
  private boolean _initiallized=false;
  private TextPaint paint;

  private interface SizeTester{
    /**
     * @param suggestedSize  Size of text to be tested
     * @param availableSpace available space in which text must fit
     * @return an integer < 0 if after applying {@code suggestedSize} to
     * text, it takes less space than {@code availableSpace}, > 0
     * otherwise
     */
    public int onTestSize(int suggestedSize,RectF availableSpace);
  }

  public AutoResizeTextView(final Context context){
    this(context,null,0);
  }

  public AutoResizeTextView(final Context context,final AttributeSet attrs){
    this(context,attrs,0);
  }

  public AutoResizeTextView(final Context context,final AttributeSet attrs,final int defStyle){
    super(context,attrs,defStyle);
    // using the minimal recommended font size
    _minTextSize=TypedValue.applyDimension(TypedValue.COMPLEX_UNIT_SP,12,getResources().getDisplayMetrics());
    _maxTextSize=getTextSize();
    if(_maxLines==0)
      // no value was assigned during construction
      _maxLines=NO_LINE_LIMIT;
    // prepare size tester:
    _sizeTester=new SizeTester(){
      final RectF textRect=new RectF();

      @TargetApi(Build.VERSION_CODES.JELLY_BEAN)
      @Override
      public int onTestSize(final int suggestedSize,final RectF availableSPace){
        paint.setTextSize(suggestedSize);
        final String text=getText().toString();
        final boolean singleline=getMaxLines()==1;
        if(singleline){
          textRect.bottom=paint.getFontSpacing();
          textRect.right=paint.measureText(text);
        }else{
          final StaticLayout layout=new StaticLayout(text,paint,_widthLimit,Alignment.ALIGN_NORMAL,_spacingMult,_spacingAdd,true);
          // return early if we have more lines
          if(getMaxLines()!=NO_LINE_LIMIT&&layout.getLineCount()>getMaxLines())
            return 1;
          textRect.bottom=layout.getHeight();
          int maxWidth=-1;
          for(int i=0;i<layout.getLineCount();i++)
            if(maxWidth<layout.getLineRight(i)-layout.getLineLeft(i))
              maxWidth=(int)layout.getLineRight(i)-(int)layout.getLineLeft(i);
          textRect.right=maxWidth;
        }
        textRect.offsetTo(0,0);
        if(availableSPace.contains(textRect))
          // may be too small, don't worry we will find the best match
          return -1;
        // else, too big
        return 1;
      }
    };
    _initiallized=true;
  }

  @Override
  public void setTypeface(final Typeface tf){
    if(paint==null)
      paint=new TextPaint(getPaint());
    paint.setTypeface(tf);
    super.setTypeface(tf);
  }

  @Override
  public void setTextSize(final float size){
    _maxTextSize=size;
    _textCachedSizes.clear();
    adjustTextSize();
  }

  @Override
  public void setMaxLines(final int maxlines){
    super.setMaxLines(maxlines);
    _maxLines=maxlines;
    reAdjust();
  }

  @Override
  public int getMaxLines(){
    return _maxLines;
  }

  @Override
  public void setSingleLine(){
    super.setSingleLine();
    _maxLines=1;
    reAdjust();
  }

  @Override
  public void setSingleLine(final boolean singleLine){
    super.setSingleLine(singleLine);
    if(singleLine)
      _maxLines=1;
    else _maxLines=NO_LINE_LIMIT;
    reAdjust();
  }

  @Override
  public void setLines(final int lines){
    super.setLines(lines);
    _maxLines=lines;
    reAdjust();
  }

  @Override
  public void setTextSize(final int unit,final float size){
    final Context c=getContext();
    Resources r;
    if(c==null)
      r=Resources.getSystem();
    else r=c.getResources();
    _maxTextSize=TypedValue.applyDimension(unit,size,r.getDisplayMetrics());
    _textCachedSizes.clear();
    adjustTextSize();
  }

  @Override
  public void setLineSpacing(final float add,final float mult){
    super.setLineSpacing(add,mult);
    _spacingMult=mult;
    _spacingAdd=add;
  }

  /**
   * Set the lower text size limit and invalidate the view
   *
   * @param minTextSize
   */
  public void setMinTextSize(final float minTextSize){
    _minTextSize=minTextSize;
    reAdjust();
  }

  private void reAdjust(){
    adjustTextSize();
  }

  private void adjustTextSize(){
    // This is a workaround for truncated text issue on ListView, as shown here: https://github.com/AndroidDeveloperLB/AutoFitTextView/pull/14
    // TODO think of a nicer, elegant solution.
    post(new Runnable(){
      @Override
      public void run(){
        if(!_initiallized)
          return;
        final int startSize=(int)_minTextSize;
        final int heightLimit=getMeasuredHeight()-getCompoundPaddingBottom()-getCompoundPaddingTop();
        _widthLimit=getMeasuredWidth()-getCompoundPaddingLeft()-getCompoundPaddingRight();
        if(_widthLimit<=0)
          return;
        _availableSpaceRect.right=_widthLimit;
        _availableSpaceRect.bottom=heightLimit;
        superSetTextSize(startSize);
      }
    });
  }

  private void superSetTextSize(int startSize){
    super.setTextSize(TypedValue.COMPLEX_UNIT_PX,efficientTextSizeSearch(startSize,(int)_maxTextSize,_sizeTester,_availableSpaceRect));
  }

  /**
   * Enables or disables size caching, enabling it will improve performance
   * where you are animating a value inside TextView. This stores the font
   * size against getText().length() Be careful though while enabling it as 0
   * takes more space than 1 on some fonts and so on.
   *
   * @param enable enable font size caching
   */
  public void setEnableSizeCache(final boolean enable){
    _enableSizeCache=enable;
    _textCachedSizes.clear();
    adjustTextSize();
  }

  private int efficientTextSizeSearch(final int start,final int end,final SizeTester sizeTester,final RectF availableSpace){
    if(!_enableSizeCache)
      return binarySearch(start,end,sizeTester,availableSpace);
    final String text=getText().toString();
    final int key=text==null?0:text.length();
    int size=_textCachedSizes.get(key);
    if(size!=0)
      return size;
    size=binarySearch(start,end,sizeTester,availableSpace);
    _textCachedSizes.put(key,size);
    return size;
  }

  private int binarySearch(final int start,final int end,final SizeTester sizeTester,final RectF availableSpace){
    int lastBest=start;
    int lo=start;
    int hi=end-1;
    int mid=0;
    while(lo<=hi){
      mid=lo+hi>>>1;
      final int midValCmp=sizeTester.onTestSize(mid,availableSpace);
      if(midValCmp<0){
        lastBest=lo;
        lo=mid+1;
      }else if(midValCmp>0){
        hi=mid-1;
        lastBest=hi;
      }else return mid;
    }
    // make sure to return last best
    // this is what should always be returned
    return lastBest;
  }

  @Override
  protected void onTextChanged(final CharSequence text,final int start,final int before,final int after){
    super.onTextChanged(text,start,before,after);
    reAdjust();
  }

  @Override
  protected void onSizeChanged(final int width,final int height,final int oldwidth,final int oldheight){
    _textCachedSizes.clear();
    super.onSizeChanged(width,height,oldwidth,oldheight);
    if(width!=oldwidth||height!=oldheight)
      reAdjust();
  }
}

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