Re: Implementing a LED-like widget

[Rob Benton <rob benton conwaycorp net>]

Marcus Lundblad wrote:
> -----------------------------------------------------------
>
> desk_indicator.hh:
>
> #include <gtkmm.h>
> #include <gdkmm.h>
>
> #ifndef DESK_INDICATOR
> #define DESK_INDICATOR
>
> class desk_indicator : public Gtk::Frame {
> public:
>   desk_indicator();
>   ~desk_indicator();
>
>   void set_active(bool active = true);
>   bool active() const { return is_active; }
>
> private:
>
>   class led_area : public Gtk::DrawingArea {
>   public:
>     led_area();
>     void set_active(bool active = true) { this->is_active = active; }
>     bool active() const { return is_active; }
>
>     void on_realize();
>     bool on_expose_event(GdkEventExpose* ev);
>
>   private:
>     bool is_active;
>     Glib::RefPtr<Gdk::GC> gc;
>
>   };
>
>   bool is_active;
>
>   led_area led;
> };
>
> #endif //DESK_INDICATOR
>
> ------------------------------------------------------------------
> desk_indicator.cc:
>
> #include "desk_indicator.hh"
>
> #include <gdkmm.h>
> #include <iostream>
>
> desk_indicator::desk_indicator()
> {
>   std::cerr << "desk_indicator::desk_indicator" << std::endl;
>   set_shadow_type(Gtk::SHADOW_IN);
>   set_size_request(10,10);
>   add(led);
>   is_active = false;
> }
>
> desk_indicator::~desk_indicator()
> {
> }
>
> void
> desk_indicator::set_active(bool active)
> {
>   this->is_active = active;
>   led.set_active(active);
> }
>
> desk_indicator::led_area::led_area()
> {
>   is_active = false;
>   set_size_request(10, 10);
> }
>
> void
> desk_indicator::led_area::on_realize()
> {
>   Glib::RefPtr<Gdk::Window> win = get_window();
>   gc = Gdk::GC::create(win);
>   gc->set_foreground(Gdk::Color("Yellow"));
> }
>
> bool
> desk_indicator::led_area::on_expose_event(GdkEventExpose* event)
> {
>   std::cerr << "desk_indicator::on_expose_event" << std::endl;
>   if(active()) {
>     int width, height;
>     Glib::RefPtr<Gdk::Window> win = get_window();
>     win->get_size(width, height);
>     win->draw_rectangle(gc, true, 0, 0, width, height);
>   }
>   return true;
> }
>
> ---------------------------------------------------------------------

Marcus, I've been working a lot with Gtk::DrawingArea widgets lately and 
I have been looking at your code.  I noticed in this example here you 
never explicitly show() the led object.  Did I miss where that is happening?

Also I've never tried to use a temporary Gdk::Color object in the 
set_foreground() call.  I've always used alloc_color() from the colormap 
object (my method of getting the colormap is for an old 2.4 bug):

	_colormap = Gdk::Screen::get_default()->get_default_colormap();
	_bgcolor.set_rgb(43690, 43690, 43690);
	_colormap->alloc_color(_bgcolor);

and then called free_colors() when I am done:

	_colormap->free_colors(_bgcolor, 1);

When you step through your code with GDB, how much of your widgets get 
shown?