Re: Problem extending MouseHelper class for customized mousehandling

• To: Steve Potts <spotts@xxxxxxxxxxxx>
• Subject: Re: Problem extending MouseHelper class for customized mousehandling
• From: "From: Bill Hibbard <hibbard@xxxxxxxxxxxxxxxxx>" <billh@xxxxxxxxxxxxx>
• Date: Tue, 28 Aug 2001 17:46:03 -0500 (CDT)

> I am writing customized mouse handling by extending the MouseHelper class.
> Depending on a display button selectable by the user, I need the application
> to toggle between different MouseHelper classes (the old one and my new
> one(s) ).  I've created an extended MouseHelper class called
> MouseGateHelper, and when the user clicks the appropriate display button,
> the program creates a new DefaultDisplayRendererJ2D that uses this
> MouseHelper subclass.  But I can't find a method for telling display to use
> this new display renderer (DisplayImpl only has a getRenderer(), not a
> setRenderer() methods).  

Once a DisplayImpl is constructed, don't try to changes its
DisplayRenderer, MouseBehavior or MouseHelper. Rather, do
as I describe below.

> When a user selects the alternative mousehandling, the application
> constructs MouseGateHelper, but then continues to handle mouse events using
> the old MouseHelper.  I may be overlooking something obvious--here's the
> code:
> 
> //MouseGateHelper extends MouseHelper for customized mouse events
> 
> DisplayImpl display = ...
> 
>  DefaultDisplayRendererJ2D dr = new
> DefaultDisplayRendererJ2D(MouseGateHelper.class);
>   try{
>     dr.setDisplay(display);
>   } catch (VisADException e) {}
>   
> MouseBehaviorJ2D mb = new
> MouseBehaviorJ2D(dr,surrogate2.MouseGateHelper.class);
>        
> display.setMouseBehavior(mb);

Don't call setMouseBehavior(). Instead define your
MouseGateHelper class, and an extension of
MouseBehaviorJ2D, perhaps named surrogate2.MouseGateBehaviorJ2D,
that is nothing more than the constructor:

  public MouseGateBehaviorJ2D(DisplayRendererJ2D displayRenderer) {
    super(displayRenderer, surrogate2.MouseGateHelper.class);
  }

Then in your application, construct your DisplayRenderer
and DisplayImpl as:

  DisplayRendererJ2D displayRenderer
    new DefaultDisplayRendererJ2D(surrogate2.MouseGateBehaviorJ2D.class);
  DisplayImplJ2D display = new DisplayImplJ2D("display", displayRenderer);

Now display will be constructed with your MouseGateBehaviorJ2D.
It should make any dynamic changes internally, rather than having
your application try to replace it.

Cheers,
Bill

• References:
  • Problem extending MouseHelper class for customized mousehandling
    • From: Steve Potts