ArcGIS Engine Developer Guide

C++ APPLICATION PROGRAMMING INTERFACE
Step 6: Begin the event handling loop
The next step for this application is to idle until a user generates an event.
gtk_widget_show_all(window);
gtk_main();
Step 7: Shut down the application
As mentioned above, this application will run indefinitely unless it receives an
event that tells it to do otherwise. To allow proper shutdown of the application,
you will handle the signals that tell you the window is going to be closed.
After the widgets are shown and before the event loop is started by gtk_main,
you will listen for those signals:
gtk_widget_show_all(window);
g_signal_connect(G_OBJECT(window), "delete_event", G_CALLBACK(delete_event),
NULL);
g_signal_connect(G_OBJECT(window), "destroy", G_CALLBACK(destroy_event), NULL);
You will also provide the callbacks DeleteEvent and DestroyEvent that have the
application close when the signals are recieved. As for the other callback, make
sure you place a forward declaration before main.
static void destroy_event(GtkWidget *widget, gpointer data)
{
gtk_main_quit();
}
For ArcGIS Engine C++ programming, you must
call AoExit before returning. You must call
AoUninitialize before shutting down the
application with AoExit.
static gboolean delete_event(GtkWidget *widget, GdkEvent *event,
gpointer data)
{
return FALSE; // must return false to trigger destroy event for window
}
Trying it out
To compile your GTK program, you will need to link against libraries for GTK,
Xt, and X11, in that order. If you are programming on Solaris, you will compile
with the Sun Workshop (Forte), and if you are programming on Linux you will
use GCC.
Solaris:
CC pbExample.cpp -o pbExample ‘pkg-config gtk+-2.0 —cflags —libs‘
Linux:
g++ pbExample.cpp -o pbExample ‘pkg-config gtk+-2.0 —cflags —libs‘
Run the program:
./pbExample
As you click the button, you will see the number of the button you pressed
appear in your terminal window.
Now that you have a feeling for GTK programming, look at the C++ samples for
GTK, and see these steps applied there.
244 • ArcGIS Engine Developer Guide