View source for FAQ How do I change the selection on a double-click in my editor?

By default, double-clicking in a text editor will cause the complete
word under the mouse to be selected.  When creating your own
text-based editor, you can change this behavior from your 
<tt>SourceConfiguration</tt> by overriding the method
<tt>getDoubleClickStrategy</tt>.  The method must return an
instance of <tt>ITextDoubleClickStrategy</tt>, a simple interface
that gets called whenever the user double-clicks within the editor area.


When double-clicking in a text-based editor,
the selection will typically change to incorporate the nearest enclosing syntactic
unit.  For example, clicking next to a brace in the Java editor will expand
the selection to include everything in the matched set of braces.  
Double-clicking in the sample HTML editor will cause the word under 
the mouse to be selected or, if no word is under the mouse, the entire HTML element. 
This involves scanning the document forwards
and backwards from the current cursor position and then setting the
selection accordingly.  The following example is a bit contrived
and is English-specific, but it 
illustrates the usual steps by selecting the text range up to the next
vowel.  If no vowel is found, nothing is selected:
<pre>
   public void doubleClicked(ITextViewer part) {
      final int offset = part.getSelectedRange().x;
      int length = 0;
      IDocument doc = part.getDocument();
      while (true) {
         char c = doc.getChar(offset + length);
         if (c=='a'||c=='e'||c=='i'||c=='o'||c=='u')
            break;
         if (offset + ++length >= doc.getLength())
            return;
      }
      part.setSelectedRange(offset, length);
   }
</pre>


Of course, double-clicking doesn&#146;t have to change the selection.  You
can perform any manipulation you want on the editor or its document
from within a double-click strategy implementation.  For example,
double-clicking could trigger Content Assist or present possible
refactorings.  The only real restriction is that you can&#146;t use
double-click to perform a manipulation on an existing text selection
as the first click of the double-click will have eliminated any
previous selection.

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