net.sourceforge.phpeclipse.ui/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 import java.text.BreakIterator;
  12
  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
  22         private GC fGC;
  23
  24         private int fMaxWidth;
  25
  26         private String fLine;
  27
  28         private int fOffset;
  29
  30         private BreakIterator fLineBreakIterator;
  31
  32         /**
  33          * Creates a reader that breaks an input text to fit in a given width.
  34          *
  35          * @param reader
  36          *            Reader of the input text
  37          * @param gc
  38          *            The graphic context that defines the currently used font sizes
  39          * @param maxLineWidth
  40          *            The max width (pixes) where the text has to fit in
  41          */
  42         public LineBreakingReader(Reader reader, GC gc, int maxLineWidth) {
  43                 fReader = new BufferedReader(reader);
  44                 fGC = gc;
  45                 fMaxWidth = maxLineWidth;
  46                 fOffset = 0;
  47                 fLine = null;
  48                 fLineBreakIterator = BreakIterator.getLineInstance();
  49         }
  50
  51         public boolean isFormattedLine() {
  52                 return fLine != null;
  53         }
  54
  55         /**
  56          * Reads the next line. The lengths of the line will not exceed the gived
  57          * maximum width.
  58          */
  59         public String readLine() throws IOException {
  60                 if (fLine == null) {
  61                         String line = fReader.readLine();
  62                         if (line == null)
  63                                 return null;
  64
  65                         int lineLen = fGC.textExtent(line).x;
  66                         if (lineLen < fMaxWidth) {
  67                                 return line;
  68                         }
  69                         fLine = line;
  70                         fLineBreakIterator.setText(line);
  71                         fOffset = 0;
  72                 }
  73                 int breakOffset = findNextBreakOffset(fOffset);
  74                 String res;
  75                 if (breakOffset != BreakIterator.DONE) {
  76                         res = fLine.substring(fOffset, breakOffset);
  77                         fOffset = findWordBegin(breakOffset);
  78                         if (fOffset == fLine.length()) {
  79                                 fLine = null;
  80                         }
  81                 } else {
  82                         res = fLine.substring(fOffset);
  83                         fLine = null;
  84                 }
  85                 return res;
  86         }
  87
  88         private int findNextBreakOffset(int currOffset) {
  89                 int currWidth = 0;
  90                 int nextOffset = fLineBreakIterator.following(currOffset);
  91                 while (nextOffset != BreakIterator.DONE) {
  92                         String word = fLine.substring(currOffset, nextOffset);
  93                         int wordWidth = fGC.textExtent(word).x;
  94                         int nextWidth = wordWidth + currWidth;
  95                         if (nextWidth > fMaxWidth) {
  96                                 if (currWidth > 0) {
  97                                         return currOffset;
  98                                 } else {
  99                                         return nextOffset;
 100                                 }
 101                         }
 102                         currWidth = nextWidth;
 103                         currOffset = nextOffset;
 104                         nextOffset = fLineBreakIterator.next();
 105                 }
 106                 return nextOffset;
 107         }
 108
 109         private int findWordBegin(int idx) {
 110                 while (idx < fLine.length()
 111                                 && Character.isWhitespace(fLine.charAt(idx))) {
 112                         idx++;
 113                 }
 114                 return idx;
 115         }
 116 }