Re: Implementing a LED-like widget

[Antonio Coralles <noche suapie reflex at>]

Marcus Lundblad wrote:

> I'm trying to implement a widget simulating a LED.
> What I have is a widget derived from Gtk::Frame (with style SHADOW_IN).
> This frame holds a Gtk::DrawingArea (display in the follwing code..)
>
> I have the following code intended to turn the inside of the widget 
> yellow
> (as an example).
>
> --------------------------------
>
> Constructor contains this:
>
>    set_shadow_type(Gtk::SHADOW_IN);
>    set_size_request(10,10);
>    display = new Gtk::DrawingArea;
>    display->set_size_request(8,8);
>    add(*display);

As far as I can tell your constructor should be ok ...

> The method setting the LED in on-state:

From the nature of the code, I think you are calling this in 
on_realize() ...

>      int width, height;
>      Glib::RefPtr<Gdk::Window> win = display->get_window();
>      win->get_size(width, height);
>      Glib::RefPtr<Gdk::GC> gc = Gdk::GC::create(win);
>      gc->set_foreground(Gdk::Color("Yellow"));
>      win->draw_rectangle(gc, true, 0, 0, width, height);

But as far as I know, you should only do

//////////////////////////////////////////////////////////////////////////////////////////////////
Glib::RefPtr<Gdk::Window> win = display->get_window();
Glib::RefPtr<Gdk::GC> gc = Gdk::GC::create(win);
gc->set_foreground(Gdk::Color("Yellow"));
//////////////////////////////////////////////////////////////////////////////////////////////////

in your overiden version of Gtk::DrawingArea::on_realize().
Assuming that gc is a member variable, calling

//////////////////////////////////////////////////////////////////////////////////////////////////
int width, height;
Glib::RefPtr<Gdk::Window> win = display->get_window();
win->get_size(width, height);
win->draw_rectangle(gc, true, 0, 0, width, height);
/////////////////////////////////////////////////////////////////////////////////////////////////
from your version of Gtk::DrawingArea::on_expose_event(GdkEventExpose*)
should have the desired effect.

Antonio

> ----------------------------------
>
> but nothing happens when calling the code to turn it on.
> And by the way, I've set the minimum size of the frame and the drawing
> area using set_size_request.
>
> Isn't this the correct way of using a Gtk::DrawingArea?
> It seems to me not too far from the example code "example_drawingarea.cc".
>
> //Marcus
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