> I have created a widget that overrides handle(int). Inside
> handle, I want to
> process various events depending on whether a callback for
> the widget has
> been set.
>
> For example,
>
> int Fl_MyWidget::handle(int e)
> {
> switch(e)
> {
> case FL_PUSH:
> if(callback())
> {
> fl_cursor(FL_CURSOR_HAND);
Just a thought, but isn't FL_PUSH too late to change the cursor to a
hand, is it not more normal to change it on FL_ENTER or something?
> return 1;
> }
> break;
>
> // other cases ...
> }
> }
>
> Then the app, assigns or removes the callback I defined as needed.
>
> My problem is that when I create Fl_MyWidget, its callback is
> automagically
> set to Fl::default_callback(). My questions are:
What widget are you deriving your widget from? I wonder if that makes a
difference to what is assigned by default? E.g. does Fl_Box get a
default callback or not? I do not know... Might be worth a try though. I
suspect that the deafult callback IS set for everything, however...
> 1. What is the purpose of this callback?
It puts a pointer to your widget into the fltk queue - it kind of makes
a list of widgets that may have been modified and require processing, I
think.
> 2. Is it safe to set the callback for Fl_MyWidget (in the
> ctor) to NULL?
Erm, possibly... Certainly worth a try, I'd say. What's the worst that
can happen... :-)
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