xapplication is a base class which implements the main
thread of control in an application: initialization, event loop and
termination.
Each application must derive a subclass from xapplication and
define exactly one static object of this class.
An application does not need a main() function.
AXE has its own main which calls the member functions of the
xapplication object.
The baseclass constructor registers its this pointer in a
global area: xapplication *XApp.
The main thread of control for an application is implemented in virtual
functions of xapplication.
The class derived from xapplication may override these
functions to implement application-specific behavior.
The functionality performed in xapplication is :
xapplication object maintains a list of all
window objects that are used
by the application.
The list of windows is maintained by the contructor and destructor
of the window class.
A window object handles events through virtual functions.
Classes derived from window, like buttons, menu items,
slider and scrollbars implement their specific behavior by overriding
these event-handling functions.
The event dispatcher in the xapplication object passes
an appropriate XEvent structure as a parameter to the event-handling
function of the window.
The event-handling function returns TRUE if the application can
continue, or FALSE if the application should terminate.
Some windows may send commands back to the xapplication object.
A menu item, for instance sends a command to the application when it is
clicked.
To send a command to the application, an object (usually a window)
calls the function XApp->DoCommand(code).
This function dispatches the command to a handler function.
| Member functions | |
|---|---|
| add_window | Add a window to the application's list of windows |
| remove_window | Remove a window from the application's list of windows |
| Pgrab | Set the window that grabs the pointer |
| DispatchEvent | Find the window object and call its event-handling function |
| Overridable member functions | |
| Initialize | Initialize the application |
| ParseArguments | Parse the command-line arguments |
| SetupResources | Create all visible objects |
| UserInit | Perform user-specific initialization |
| DoCommand | Handle a command form another object |
| Cleanup | Cleanup the application when it exits |