net.sourceforge.phpeclipse/src/net/sourceforge/phpdt/internal/ui/text/LineBreakingReader.java

   1 package net.sourceforge.phpdt.internal.ui.text;
   2
   3 /*
   4  * (c) Copyright IBM Corp. 2000, 2001.
   5  * All Rights Reserved.
   6  */
   7
   8 import java.io.BufferedReader;
   9 import java.io.IOException;
  10 import java.io.Reader;
  11
  12 import java.text.BreakIterator;
  13 import org.eclipse.swt.graphics.GC;
  14
  15 /*
  16  * Not a real reader. Could change if requested
  17  */
  18 public class LineBreakingReader {
  19
  20         private BufferedReader fReader;
  21         private GC fGC;
  22         private int fMaxWidth;
  23
  24         private String fLine;
  25         private int fOffset;
  26
  27         private BreakIterator fLineBreakIterator;
  28
  29         /**
  30          * Creates a reader that breaks an input text to fit in a given width.
  31          * @param reader Reader of the input text
  32          * @param gc The graphic context that defines the currently used font sizes
  33          * @param maxLineWidth The max width (pixes) where the text has to fit in
  34          */
  35         public LineBreakingReader(Reader reader, GC gc, int maxLineWidth) {
  36                 fReader= new BufferedReader(reader);
  37                 fGC= gc;
  38                 fMaxWidth= maxLineWidth;
  39                 fOffset= 0;
  40                 fLine= null;
  41                 fLineBreakIterator= BreakIterator.getLineInstance();
  42         }
  43
  44         public boolean isFormattedLine() {
  45                 return fLine != null;
  46         }
  47
  48         /**
  49          * Reads the next line. The lengths of the line will not exceed the gived maximum
  50          * width.
  51          */
  52         public String readLine() throws IOException {
  53                 if (fLine == null) {
  54                         String line= fReader.readLine();
  55                         if (line == null)
  56                                 return null;
  57
  58                         int lineLen= fGC.textExtent(line).x;
  59                         if (lineLen < fMaxWidth) {
  60                                 return line;
  61                         }
  62                         fLine= line;
  63                         fLineBreakIterator.setText(line);
  64                         fOffset= 0;
  65                 }
  66                 int breakOffset= findNextBreakOffset(fOffset);
  67                 String res;
  68                 if (breakOffset != BreakIterator.DONE) {
  69                         res= fLine.substring(fOffset, breakOffset);
  70                         fOffset= findWordBegin(breakOffset);
  71                         if (fOffset == fLine.length()) {
  72                                 fLine= null;
  73                         }
  74                 } else {
  75                         res= fLine.substring(fOffset);
  76                         fLine= null;
  77                 }
  78                 return res;
  79         }
  80
  81         private int findNextBreakOffset(int currOffset) {
  82                 int currWidth= 0;
  83                 int nextOffset= fLineBreakIterator.following(currOffset);
  84                 while (nextOffset != BreakIterator.DONE) {
  85                         String word= fLine.substring(currOffset, nextOffset);
  86                         int wordWidth= fGC.textExtent(word).x;
  87                         int nextWidth= wordWidth + currWidth;
  88                         if (nextWidth > fMaxWidth) {
  89                                 if (currWidth > 0) {
  90                                         return currOffset;
  91                                 } else {
  92                                         return nextOffset;
  93                                 }
  94                         }
  95                         currWidth= nextWidth;
  96                         currOffset= nextOffset;
  97                         nextOffset= fLineBreakIterator.next();
  98                 }
  99                 return nextOffset;
 100         }
 101
 102         private int findWordBegin(int idx) {
 103                 while (idx < fLine.length() && Character.isWhitespace(fLine.charAt(idx))) {
 104                         idx++;
 105                 }
 106                 return idx;
 107         }
 108 }