Building a fully functional code editor based on the JFace Text framework: Part 3rd

Double Click and Triple click

Double click (double click) and Triple click (Triple click) are accessibility features that make it easy for users to select text (which, of course, does not necessarily have to be selected). This article describes how to customize the double-click behavior in JTF and how to add three-click Support for JTF.

Double Click

In Eclipse's Java editor, when the user double-clicks the editing area with the mouse, you can see that the word that is double-clicked is selected, which is the JTF double click (double click) feature. The actions that are triggered when you double-click are customizable, and you do not have to select a piece of text.

The interface associated with double-clicking is Itextdoubleclickstrategy, it has only one method called doubleclicked, as long as the interface is implemented, in the example, I added the Exprdoubleclickstrategy class:

Listing 1. Exprdoubleclickstrategy implements the Itextdoubleclickstrategy interface

public　class　ExprDoubleClickStrategy　implements　ITextDoubleClickStrategy　{
public　void　doubleClicked(ITextViewer　viewer)　{
　 //　get　doc
　 IDocument　doc　=　viewer.getDocument();

　 //　get　token　list
　 TokenList　tokenList　=　TokenManager.getTokenList(doc);

　 //　get　double　click　position　
　 int　offset　=　viewer.getSelectedRange().x;

　 //　get　token　in　that　offset
　 CommonToken　token　=　tokenList.getToken(offset);

　 //　select　whole　token　if　token　is　not　null
　 if(token　!=　null　&&　token.getType()　!=　Token.EOF)
　 {
　　 //　select　double　clicked　token　
　 viewer.setSelectedRange(
　 token.getStartIndex(),　token.getStopIndex()　-　token.getStartIndex()　+　1);
　 }
　 }
}

This process is very straightforward, gets the location that is clicked, gets the corresponding symbol through the position, and then selects the entire symbol. We again took advantage of the symbol Tokenlist came to the specified character offset.

As with the second part of the series, with the implementation you have to let JTF know your implementation, we then modify the exprconfiguation, overwriting a Getdoubleclickstrategy method:

Listing 2. Let JTF know your Double Click implementation

public　ITextDoubleClickStrategy　getDoubleClickStrategy(
　　　　　 ISourceViewer　sourceViewer,　String　contentType)
{
　　 return　new　ExprDoubleClickStrategy();
}

Simply return to our implementation of the Itextdoubleclickstrategy only, so that JTF know our double-click Behavior, and note that the double-click Behavior is also bound to the text type, but we have only one type, so did not use this information.

The reader can try the example in this article, double-click a variable to see if the variable is all selected.