WINDOWS PROGRAMMING MODEL
Message processing:
When writing MS – DOS program the only required function is main.
When windows operating system launches a program, it calls WinMain function.
Its task is to create the application’s main window which has its own code to process messages that windows sends to it.
Windows based program processes user input via messages from the operating system.
For example
WM_CREATE message is sent when a window is being created.
WM_LBUTTONDOWN message is sent when the user presses the left mouse button.
WM_CHAR message is sent when the user types a character.
WM_CLOSE message is sent when the user closes the window.
Windows Graphics Device Interface:
Windows provides a layer of abstraction called graphics device interface.
Instead of addressing the hardware, program calls the GDI functions that reference a data structure called a device context.
Windows maps the device context structure to a physical device and issues appropriate input / output instructions.
Resource Based Programming:
In windows the data is stored in a resource file using a number of established format.
The linker combines the binary resource file with the C++ compiler’s output to generate an executable program.
Resource files can include bitmaps, icons, menu definitions, dialog based layouts and strings.
Dynamic Link Libraries:
Windows allows dynamic linking, means that specially constructed libraries can be loaded and linked at runtime.
Multiple applications can share dynamic link libraries which saves memory and disk space.
DLL increases program modularity – since it can be compiled and tested separately.
AppWizard:
Is a code generator that creates a workspace frame of a windows application with features, class names and source code file names.
ClassWizard:
Is a program that’s accessible from visual C++ view menu.
Application Framework:
Is an integrated collection of object oriented software components that offers all that needed for a generic application.
It defines the structure of the program.
By convention, MFC library class names begin with the letter C.
View:
A view is an ordinary window that the user can size, move and close in the same way as any other windows – based application window.
From the programmer’s angle, a view is a C++ object of a class derived from the MFC library CView class.
Single Document Interface (SDI):
An SDI application has only one window, only one document can be loaded at a time. Notepad is an example for single document interface.
Multiple Document Interface (MDI):
An MDI application has multiple child windows, each corresponds to an individual document. Microsoft word is an example for MDI.
