ArcGIS Engine Developer Guide

C++ APPLICATION PROGRAMMING INTERFACE
int main(int argc, char* argv[])
{
...
GtkWidget* mapWidget;
IMapControl3Ptr ipMapControl;
mapWidget = gtk_axctl_new(AoPROGID_MapControl);
gtk_axctl_get_interface(mapWidget, (IUnknown **)&ipMapControl);
gtk_widget_set_size_request(mapWidget, -1, -1);
gtk_container_add(GTK_CONTAINER(window), mapWidget);
...
}
EVENT HANDLING ON ARCGIS CONTROLS
Events occur any time there is interaction with an application during its runtime.
When a new map is loaded, when the mouse moves inside the control window, or
when a keyboard button is pressed are examples of when events occur, and at
such times the information regarding the event is reported. If the application is
listening for events, it will execute code associated with the event that has occurred.
Although there are also Motif and GTK events,
interacting with ArcObjects (such as popup
menus) through those events is not recommended.
Instead, you should interact through the
ArcObjects event interfaces.
To make an application that responds to events on the controls without having a
tool or command selected, you will not only need to tell the application what to
do when such events are received, but will also have to tell the computer to be
listening for and reacting to such events. This document details how to listen for
the events, but does not go into detail on how to write your event class. For help
on writing an event class, see ‘Writing a MapControl Event class’ and ‘Writing a
Transform Event class’ in the developer help system under Development Environments
> C++ > Walkthroughs.
If, however, you want to use a tool or a command, you will not need to listen for
events. Custom tools and commands interact with the controls through their own
functions, which are called upon similar events. See ‘Creating a custom command
using AoBaseCommand’ or ‘Creating a custom tool using AoBaseTool’ in the
developer help system under Development Environments > C++ >
Walkthroughs.
Events on the controls
To handle control events you will need to write a class that inherits from the
events with which you want to interact. For the main events on a control, which
implement IDispatch, your C++ API event classes will inherit from a helper
interface. Listening for these events is then simplified. The events this applies to
are listed in the table below. For all other event types, you will implement a class
that inherits from the ArcObjects interface with the events you want to listen
for. Then you will listen for the events as outlined under ‘Other ArcObjects
events—Implemented with custom interfaces’ below.
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Once you have implemented your class, you will need to have your application
listen for the events. To do so, you will use IEventHelper, which passes information
between your application and the events, handling reference counting for
you.