JHotDraw Pattern Language

Using ConnectionTool

The most common way to create ConnectionFigures on a drawing is to create a tool in the application. JHotDraw uses a class called ConnectionTool to create tools that can be used to instantiate any kind of ConnectionFigure.

ConnectionTool is an implementation of the Prototype design pattern. ConnectionTool can be parameterised to create any kind of ConnectionFigure. To create the tool call the ConnectionTool constructor and pass into it an instance (the Prototype) of the type of ConnectionFigure you want to create.

   protected void createTools(Panel palette){
            ... define other tools here
        ConnectionTool connectionTool = new connectionTool(new LineConnection());
        //add a button to the toolbar that represents the tool

Tools are represented in the applications GUI as a button.

The ConnectionTool automatically provides the behaviour for setting the end points of a connection (i.e. when the tool is selected, using the mouse click on a figure to start the connection then drag the mouse to another figure to end the connection).


Copyright Douglas Kirk