Re: GDK bug

[Carlos Pereira <carlos pehoe civil ist utl pt>]

> I have tried to connect the "expose-event" signal of my window to the
> callback in charge of the resizing and it seems the signal isn't
> emitted until the window is obscured and "unobscured" by another one.

> Using "configure-event", it works perfectly. This is logical, since
> the configure-event is emitted when the window is configured by the
> window manager (isn't it?) and expose-event is emitted when an aera of
> the widget has to be repainted after being covered by another window.

Generally speaking, you should connect:

1) the expose-event, to a function that is responsible 
for drawing a drawing area or gl_area; This signal will
be triggered automatically by X, everytime a situation
occurs where it is obvious that the image needs to be
redrawn, in particular a configure event always triggers
the expose-event, in the end. This function
has nothing to do with resizing, so no commands to handle
resizing should go here. You can always force a redrawing
yourself, calling for example gtk_widget_queue_draw.

2) the configure event, to a function that handles
aspects related with resizing, a typical example
is to define the new size of a OpenGL viewport. You
must realize that this function has actually nothing
to do with redrawing: no draw commands at all should
be in this callback, because the expose_event callback 
is always executed after the configure_event callback.
configure_event and expose_event should be totally
independent, they handle two totally different things.

See this example below, when the window is resized,
app_mesa_configure_gl_area() informs OpenGL of the new size, 
and then app_mesa_configure_gl_area() redraws the picture, 
already using the new size. app_mesa_configure_gl_area()
doesn't know nothing about drawing, and app_mesa_expose_gl_area()
doesn't know nothing about resizing, they are totally
independent.

Carlos

gtk_signal_connect (GTK_OBJECT (gl_area), "expose_event",
                    GTK_SIGNAL_FUNC (app_mesa_expose_gl_area), data);

gtk_signal_connect (GTK_OBJECT (gl_area), "configure_event",
                    GTK_SIGNAL_FUNC (app_mesa_configure_gl_area), data);

gint app_mesa_configure_gl_area (GtkWidget *widget, GdkEventConfigure *event, gpointer data)
{
if (gtk_gl_area_make_current (GTK_GL_AREA (widget)))
  glViewport (0, 0, widget->allocation.width, widget->allocation.height);

return TRUE;
}

gint app_mesa_expose_gl_area (GtkWidget *widget, GdkEventExpose *event, gpointer data)
{
GtkGLArea *gl_area = GTK_GL_AREA (widget);
app_window *window = APP_CAST_WINDOW data;

/* Draw only last expose. */
if (event->count > 0) return TRUE;

glClear (GL_COLOR_BUFFER_BIT);

if (gtk_gl_area_make_current(gl_area))
  {
  /* actual drawing function */
  app_mesa_draw_window (window);
  gtk_gl_area_swapbuffers (gl_area);
  }
return TRUE;
}