Window Procedures Every window has an associated window procedure — a function that processes all messages sent or posted to all windows of the class. All aspects of a window's appearance and behavior depend on the window procedure's response to these messages.

Overviews

About Window Procedures

Each window is a member of a particular window class. The window class determines the default window procedure that an individual window uses to process its messages.

Using Window Procedures

This section explains how to perform the following tasks associated with window procedures.

Functions

CallWindowProc

The CallWindowProc function passes message information to the specified window procedure.

DefWindowProc

The DefWindowProc function calls the default window procedure to provide default processing for any window messages that an application does not process. This function ensures that every message is processed. DefWindowProc is called with the same parameters received by the window procedure.

WindowProc

The WindowProc function is an application-defined function that processes messages sent to a window. The WNDPROC type defines a pointer to this callback function. WindowProc is a placeholder for the application-defined function name.