[ruby-fltk-devel] Problem with draw

[Kevin S. <kev...@ya...>]

Right now, child widgets inside a window do not get drawn.
I think I understand the problem, and the solution. I'll
fix it, but I wanted to let you know what I'm doing.

The problem is that right now, when FLTK calls draw, it
goes to the virtual method in our RBFL class. That calls
the Ruby draw method, which (by default) calls the Ruby
call_parent_draw method. That casts the C++ pointer to
RBFLWidget, and calls call_parent_draw.

Now, inside there, it can't just call draw, because that
would cause infinite recursion. It needs to call the FLTK
class's draw instead. Right now, it is calling
Fl_Widget::draw. But if the widget is actually an
Fl_Window, we still call Fl_Widget::draw because we specify
that class. All subclasses end up calling Fl_Widget::draw.

I think the chain instead should be: FLTK calls draw, which
is our RBFL virtual method. It should call the Ruby draw
method. But by default, the Ruby draw method should simply
call its own RBFL call_parent_draw method, which will call
the correct FTLK draw.

To do this, I will create a macro FN_CALL_RENAME, which
will allow us to map a Ruby method ("draw") to a different
RBFL method ("call_parent_draw"). Since every Ruby draw
method has to call its own RBFL call_parent_draw, every
class will have to have:

static FN_CALL_RENAME(Window, draw, call_parent_draw);

and

  DEF_METHOD(Window, draw, 0);

We can then get rid of the rb_flwidget_draw and
rb_flwidget_call_parent_draw methods in flwidget.cc.

I should be able to do this right now, and check it in
within an hour or so.

Kevin

__________________________________________________
Do You Yahoo!?
Get email alerts & NEW webcam video instant messaging with Yahoo! Messenger
http://im.yahoo.com