Window Class Library with Command Table Dispatching

Window Class Library with Command Table Dispatching

       The invention is a software library designed to enhance
the productivity of application developers in windowing, event-driven
environments such as OS/2* Presentation Manager*, DOS Windows, or
X-Windows.  An enhanced method for the dispatching of event messages
is described.  The library is currently implemented in the C++
programming language for the OS/2 PM environment.

      The prototype graphical user interface application consists of
one or more loosely coupled visible windows, commonly called dialogs,
created in a supporting environment such as OS/2 Presentation Manager
(PM).  We will use the latter, PM, and its specific implementation to
exemplify application of the invention. The PM component of the
underlying operating system sends event messages to the application,
indicating user action such as keystrokes or mouse input.  Typically,
event messages are dispatched for handling to coded procedures that
are associated with each dialog of the application.  Messages are
categorized by a type code such as WM_KEYCHAR which indicates that a
user keystroke is being directed to the window. Using the C
programming language, it is typical to write a single window
procedure for every dialog.  The address of the window procedure is
passed to PM when the dialog is loaded or created.  As events occur
that pertain to the dialog, PM calls the dialog's window procedure
with arguments that give the message ID code of the event and related
information.  The developer will typically use a switch statement to
break out the handling of the messages.
     //
     // typical C code window procedure
     //
     void far *far pascal mywindproc(HWND hwnd, USHORT msgid,
           MPARAM mp1, MPARAM mp2) {
         switch(msgid) {
             case WM_INITDLG
             ...call some code
                 break;
             case WM_COMMAND
                 switch(SHORT1FROMMP(mp1)){
                     ... case handling of menu items and/or
                     ... dialog pushbutton commands
                     }
             ...call some code
                 break;
             case WM_DESTROY
             ...call some code
                 break;
             default
                 return WinDefWindowProc(hwnd, msgid, mp1, mp2);
             }
         return WinDefWindowProc(hwnd, msgid, mp1, mp2);
         }

      With the disclosed C++ library, the dispatching of events has
been streamlined so that the developer writes individual handler
member functions only for each specific event which is customized.
Events that handlers are not written for are handled in the library.
The developer do...