Android Open Source - PICwidget Text Clipper

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License

The source code is released under:

Apache License

Java Source Code

/*
 * Copyright 2014 Jason J.//ww w .  java  2 s .  c om
 * 
 * Licensed under the Apache License, Version 2.0 (the "License"); you may not
 * use this file except in compliance with the License. You may obtain a copy of
 * the License at
 * 
 * http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations under
 * the License.
 */
package com.ovrhere.android.picwidget.utils;

import java.util.ArrayList;
import java.util.List;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

import android.graphics.Paint;
import android.util.Log;


/** 
 * Breaks text into lines.
 * @author Jason J.
 * @version 0.1.0-20140813
 */
public class TextClipper {
  /** Class name for debugging purposes. */
  final static private String CLASS_NAME = TextClipper.class.getSimpleName();
  /** Whether or not to debug. */
  final static private boolean DEBUG = false;
  /** The pattern for character breaks in lines. */
  final static private Pattern CHARACTER_BREAKS = Pattern.compile("\\W\\w+?$");
  
  
  /** Shows the index to clip text at for a given line width.
   * @param text The text to test.
   * @param textSize The text size given in px 
   * @param targetWidth The targetWidth to end at given in px
   * @return The number of characters that will fit on a given line.
   */
  static public int clipTextCount(String text, float textSize, float targetWidth){
    Paint paintHandle = new Paint();
    paintHandle.setTextSize(textSize);
    // http://stackoverflow.com/questions/14280046/understanding-paint-measuretext
    paintHandle.setSubpixelText(true); //required for i, w, l
    return _breakText(text, targetWidth, paintHandle); 
  }

  
  
  /** Takes a string and clips the text into chunks based on the 
   * given width and line count.
   * @param text The text to clip. 
   * @param textSize The text size given in px
   * @param targetWidth The target width given in px
   * @param lineCount The number of lines (per block).
   * @return The text blocks that <code>text</code> has been clipped into.
   */
  static public List<String> clipText(String text, float textSize, 
      float targetWidth, int lineCount){
    List<String > list = new ArrayList<String>();
    Paint paint = new Paint();
    paint.setTextSize(textSize);
    paint.setSubpixelText(true); //required for i, w, l
    
    while (text.length() > 0){
      String textBlock = ""; //the text to concat.
      if (DEBUG){
        Log.d(CLASS_NAME, "block index: "+list.size());
        Log.d(CLASS_NAME, "text: [["+text+"]]");
      }
      for(int count = 0; count < lineCount && !text.isEmpty(); count++){
        int clipIndex = _breakText(text, targetWidth, paint);
        String line = text.substring(0, clipIndex);
        int breakIndex = checkForBreakChars(line)+1;
        if (DEBUG){
          Log.d(CLASS_NAME, "count: "+count);
          Log.d(CLASS_NAME, "breakIndex: "+breakIndex);
        }
        if (breakIndex > 0){
          clipIndex = breakIndex;
        }
        textBlock += text.substring(0, clipIndex);
        text = text.substring(clipIndex);
        if (DEBUG){
          Log.d(CLASS_NAME, "text-block: "+textBlock);
          Log.d(CLASS_NAME, "text: [["+text+"]]");
        }
      }
      list.add(textBlock.trim());
    }
    return list;
  }

  

  /** Checks for the last character that could break the line in a readable way.
   * @param line The line to test for breaking characters.
   * @return The new index or -1 if none are found.
   */
  private static int checkForBreakChars(String line) {
    Matcher matcher = CHARACTER_BREAKS.matcher(line);
    int index = line.indexOf("\n");
    if (index >= 0){
      if (DEBUG){
        Log.d(CLASS_NAME, "newline found at: "+index);
      }
      return index;
    } else if (matcher.find()){
      index = matcher.start();
    }
    return index;    
  }
  
  /////////////////////////////////////////////////////////////////////////////////////////////////
  /// Private Utility methods 
  ////////////////////////////////////////////////////////////////////////////////////////////////
  /**
   * Break text based upon given paint object.
   * @param text The text to break.
   * @param targetWidth The target width
   * @param paint The preset paint handle (with text size + font set).
   * @return The number of characters that will fit.
   */
  private static int _breakText(String text, float targetWidth,
      Paint paint) {
    // See: https://android-review.googlesource.com/#/c/48690/
    return paint.breakText(text, true, targetWidth, null);
  }
}

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