Steve Lidie <sol0@xxxxxxxxxx> writes:
>Here's how to do it (in Populate):
>
> $self->{'real_can'} = $self->{'can'}->Subwidget('scrolled');
>######## more on this later
> my( @bindtags ) = $self->{'real_can'}->bindtags;
> $self->{'real_can'}->bindtags( [ @bindtags, 'CanvasDirTree-B1' ] );
> $self->{'real_can'}->CanvasBind( 'CanvasDirTree-B1', '<Button-1>'
>=> [\&pick_one, $self] );
All that is fine. But bindtags includes the name of the class already.
This is so that one can assoicate class bindings with it.
So what I intended for one to do was:
$self->{'real_can'}->CanvasBind( ref($self), '<Button-1>' ...);
But that is I hope unnecessarily complicated - see below.
>>
>> sub ClassInit
>> {
>> my ($class, $mw) = @_;
>> $class->SUPER::ClassInit($mw);
What that will do by the way is call Canvas::ClassInit.
This isn't quite a no-op - it calls XYscrollBind
Which binds mouse wheel and <Up>, <Down> etc. so that
scrolls happen (if widget has the focus for keystroke cases).
Once that has happened - and of course if you don't want
that you don't have to call it!
We can now add bindings to the class name.
Which would look like:
$mw->bind( $class, '<Button-1>', 'pick_one' );
>> }
At this point $mw is _a_ widget (the MainWindow) which is all we need
to talk to core Tk. It isn't a Canvas so no spurious binds are in scope.
And it is called as a "static" method so 1st arg is the class name.
As 'pick_one' is a sub in our class we treat it as a method just use its
name in the binding.
When a particular _instance_ of the class gets a Button-1 the class binding
is called and the sub is called (as a method) passing the instance
widget as 1st arg. This achieves the same as original
... '<Button-1>' => [\&pick_one, $self] );
But with the additional advantage that if someone derives from _your_
class they can override the pick_one method if your pick_one isn't
quite what they want.
-++**==--++**==--++**==--++**==--++**==--++**==--++**==
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