| /* TextMeasurer.java |
| Copyright (C) 2006 Free Software Foundation, Inc. |
| |
| This file is part of GNU Classpath. |
| |
| GNU Classpath is free software; you can redistribute it and/or modify |
| it under the terms of the GNU General Public License as published by |
| the Free Software Foundation; either version 2, or (at your option) |
| any later version. |
| |
| GNU Classpath is distributed in the hope that it will be useful, but |
| WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| General Public License for more details. |
| |
| You should have received a copy of the GNU General Public License |
| along with GNU Classpath; see the file COPYING. If not, write to the |
| Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA |
| 02110-1301 USA. |
| |
| Linking this library statically or dynamically with other modules is |
| making a combined work based on this library. Thus, the terms and |
| conditions of the GNU General Public License cover the whole |
| combination. |
| |
| As a special exception, the copyright holders of this library give you |
| permission to link this library with independent modules to produce an |
| executable, regardless of the license terms of these independent |
| modules, and to copy and distribute the resulting executable under |
| terms of your choice, provided that you also meet, for each linked |
| independent module, the terms and conditions of the license of that |
| module. An independent module is a module which is not derived from |
| or based on this library. If you modify this library, you may extend |
| this exception to your version of the library, but you are not |
| obligated to do so. If you do not wish to do so, delete this |
| exception statement from your version. */ |
| |
| |
| package java.awt.font; |
| |
| import java.text.AttributedCharacterIterator; |
| import java.text.AttributedString; |
| import java.awt.Shape; |
| |
| /** |
| * TextMeasurer is a small utility class for measuring the length of laid-out |
| * text objects. |
| * |
| * @author Sven de Marothy |
| * @since 1.3 |
| */ |
| public final class TextMeasurer implements Cloneable |
| { |
| private AttributedCharacterIterator text; |
| private FontRenderContext frc; |
| private TextLayout totalLayout; |
| private int numChars; |
| |
| /** |
| * Creates a TextMeasurer from a given text in the form of an |
| * <code>AttributedCharacterIterator</code> and a |
| * <code>FontRenderContext</code>. |
| */ |
| public TextMeasurer (AttributedCharacterIterator text, FontRenderContext frc) |
| { |
| this.text = text; |
| this.frc = frc; |
| totalLayout = new TextLayout( text, frc ); |
| numChars = totalLayout.getCharacterCount(); |
| } |
| |
| /** |
| * Clones the TextMeasurer object |
| */ |
| protected Object clone () |
| { |
| return new TextMeasurer( text, frc ); |
| } |
| |
| /** |
| * Update the text if a character is deleted at the position deletePos |
| * @param newParagraph - the updated paragraph. |
| * @param deletePos - the deletion position |
| */ |
| public void deleteChar (AttributedCharacterIterator newParagraph, |
| int deletePos) |
| { |
| totalLayout = new TextLayout(newParagraph, frc); |
| if( deletePos < 0 || deletePos > totalLayout.getCharacterCount() ) |
| throw new NullPointerException("Invalid deletePos:"+deletePos); |
| numChars = totalLayout.getCharacterCount(); |
| text = newParagraph; |
| } |
| |
| /** |
| * Update the text if a character is inserted at the position insertPos |
| * @param newParagraph - the updated paragraph. |
| * @param insertPos - the insertion position |
| */ |
| public void insertChar (AttributedCharacterIterator newParagraph, |
| int insertPos) |
| { |
| totalLayout = new TextLayout(newParagraph, frc); |
| if( insertPos < 0 || insertPos > totalLayout.getCharacterCount() ) |
| throw new NullPointerException("Invalid insertPos:"+insertPos); |
| numChars = totalLayout.getCharacterCount(); |
| text = newParagraph; |
| } |
| |
| /*** |
| * Returns the total advance between two positions in the paragraph. |
| * Characters from start to limit-1 (inclusive) are included in this count. |
| * |
| * @param start - the starting character index. |
| * @param limit - the limiting index. |
| */ |
| public float getAdvanceBetween (int start, int limit) |
| { |
| Shape s = totalLayout.getLogicalHighlightShape( start, limit ); |
| return (float)s.getBounds2D().getWidth(); |
| } |
| |
| /** |
| * Returns a <code>TextLayout</code> object corresponding to the characters |
| * from text to limit. |
| * @param start - the starting character index. |
| * @param limit - the limiting index. |
| */ |
| public TextLayout getLayout (int start, int limit) |
| { |
| if( start >= limit ) |
| throw new IllegalArgumentException("Start position must be < limit."); |
| return new TextLayout( totalLayout, start, limit ); |
| } |
| |
| /** |
| * Returns the line-break index from a given starting index and a maximum |
| * advance. The index returned is the first character outside the given |
| * advance (or the limit of the string, if all remaining characters fit.) |
| * |
| * @param start - the starting index. |
| * @param maxAdvance - the maximum advance allowed. |
| * @return the index of the first character beyond maxAdvance, or the |
| * index of the last character + 1. |
| */ |
| public int getLineBreakIndex (int start, float maxAdvance) |
| { |
| if( start < 0 ) |
| throw new IllegalArgumentException("Start parameter must be > 0."); |
| |
| double remainingLength = getAdvanceBetween( start, numChars ); |
| |
| int guessOffset = (int)( ( (double)maxAdvance / (double)remainingLength) |
| * ( (double)numChars - (double)start ) ); |
| guessOffset += start; |
| if( guessOffset > numChars ) |
| guessOffset = numChars; |
| |
| double guessLength = getAdvanceBetween( start, guessOffset ); |
| boolean makeSmaller = ( guessLength > maxAdvance ); |
| int inc = makeSmaller ? -1 : 1; |
| boolean keepGoing = true; |
| |
| do |
| { |
| guessOffset = guessOffset + inc; |
| if( guessOffset <= start || guessOffset > numChars ) |
| { |
| keepGoing = false; |
| } |
| else |
| { |
| guessLength = getAdvanceBetween( start, guessOffset ); |
| if( makeSmaller && ( guessLength <= maxAdvance) ) |
| keepGoing = false; |
| if( !makeSmaller && ( guessLength >= maxAdvance) ) |
| keepGoing = false; |
| } |
| } |
| while( keepGoing ); |
| |
| // Return first index that doesn't fit. |
| if( !makeSmaller ) |
| guessOffset--; |
| |
| if( guessOffset > numChars ) |
| return numChars; |
| |
| return guessOffset; |
| } |
| } |