windows gui programming with win32 and mfc

Win32 & MFC 1

Windows GUI ProgrammingWindows GUI Programming

with Win32 and MFCwith Win32 and MFC

DEPARTMENT OF COMPUTER SCIENCE AND SOFTWARE ENGINEERING CONCORDIA UNIVERSITY

Feb 6, 2008

by Emil Vassevby Emil Vassev

Win32 & MFC 2

Windows Programming Model

Windows application? Examples?

Win32 API ? Application Programming Interface - the Windows

programming interface; Includes hundreds (over 2000) of functions that an

application can call to perform various tasks such as creating a window, drawing a line, and performing file input and output.

MFC ? Microsoft Foundation Classes – a class library to work

with Win32 API.

:: Win32 API & MFC

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Windows Programming Model

Windows programming is event-driven. Windows and its device drivers capture hardware events generated by user interaction and translates these events into messages that Windows programs can understand - Windows messages.

Windows stores these messages in data structures called message queues.

In a multitasking environment, messages are stored for each process in separate queues called application queues. Applications wait for messages related to user input.

:: Introduction

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•Win apps respond to events by processing messages sent by the OS.

•Event - a keystroke, a mouse click, or a command for a window to repaint itself, etc.

•The entry point for a Windows program is a function named WinMain() (not main()).

• WndProc - the most important function (known as window procedure). Processes messages for the

main window. WndProc

Win32 API Model

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Win32

A function that receives and processes all messages sent to the main window.

Every window object in Windows has a window procedure to respond to messages.

The system sends a message to a window procedure by passing the message data as arguments to the procedure.

WndProc() is the window procedure function we write to receive all input directed to our window.

Messages that we do not handle in WndProc() should be handled in a default way, i.e. we must call DefWindowProc() for them.

:: Window Procedure

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Win32

CALLBACK function can be called by the OS.

Proc params:hWnd - unique handle of the window; message – unique ID; wParam – data carried by the message;lParam – more data;

Windows messages:•WM_COMMAND. •WM_PAINT.•WM_KEYDOWN.•WM_DESTROY

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Win32

Over 140 predefined messages.WM_DESTROY - sent if the user has closed the window. You should post a message telling windows to destroy the window as it is shown.WM_COMMAND - sent when a menu item or an accelerator key is pressed.WM_PAINT – sent when the window needs redrawing – i.e. when it’s created, maximized, brought to front etc.WM_KEYDOWN – sent when a key is pressed. There is also a WM_KEYUP message. The wParam contains a virtual key code.

:: Windows Messages - I

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Win32

WM_MOUSEMOVESent to the window when the mouse is moved over its surface area. wParam indicates if a specific key or mouse button is held down. The low word of lParam is the x position of the mouse and the high word is the y position. So to retrieve the position and button states:

:: Windows Messages - II

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Win32

Like main() in C/C++.In this function: we set up our application; enter a loop that will continue until the application is closed.

Signatures:

:: WinMain – The Application Entry Point

•hInstance - the instance handle that uniquely identifies the application running in Windows;

•hPrevInstance - always NULL, so we can ignore it. •lpCmdLine – the command-line arguments. •nCmdShow – how the window should be shown to start with. For example, SW_SHOWMAXIMIZED and SW_SHOWMINIMIZED.

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Win32

WinMain() calls the InitInstance() function to create the main window:

:: WinMain – Creating the Window

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Win32

Use the Win32 App wizard:

:: Create your First WIn32 Application

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Win32

http://www.tenouk.com/cplusplusnmfc.htmltheForger’s Win32 API Programming Tutorial

http://www.winprog.org/tutorial/

:: Additional Reading Material and Code Samples

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MFC – Microsoft Foundation Classes :: Visual C++ Application Build Process

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MFC – Microsoft Foundation Classes

The Microsoft Foundation Classes (MFC) Library is: A Hierarchy of C++ classes designed to facilitate Windows

programming. An alternative to using Win32 API functions. A Visual C++ Windows application can use either Win32 API,

MFC, or both:

:: Introduction

VC++ Windows Application

MFC Library

Win32 API

Computer Hardware

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MFC Library: Comprises about 200 MFC classes (versus more than 2000 API

functions). MFC Hierarchy Chart. Provides a framework upon which to build Windows applications. Is object oriented (arguably) - encapsulates most of the Win32

API in a set of logically organized classes. Has the convenience of code reuse:

Many tasks common to all Windows apps are provided by MFC.

Our programs can inherit and modify this functionality as needed.

We don't need to recreate these tasks. MFC handles many clerical details in Windows programs.

:: Characteristics

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The first task to be done in any MFC application is to create a window and the MFC application running that window.

MFC provides two important classes - CWinApp and CFrameWnd, which can be used to create a window & the application.

CWinApp provides the application level functionalities. CFrameWnd provides the functionalities related to GUI. Both classes have their own message handling mechanisms,

screen-drawing functions etc., Both classes are derived from CCmdTarget which in turn is

derived from CObject. CCmdTarget is created with the capability to handle windows

messages, which is referred as Message Maps.

:: Creating an MFC Application

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To create a useful frame window we create a class that derives the MFC class CFrameWnd.

We create the window by using the CFrameWnd::Create() function.

:: The Window

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A MFC Windows application starts at the WinMain() function. This function is hidden by MFC, i.e. it is implemented by MFC

for you. The MFC program entry point is the member function

CWinApp::InitInstance() – compare to Win32 InitInstance().

:: The Application

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Message Maps are the way by which MFC handles the application messages.

Any class which is derived from CCmdTarget is a candidate for handling messages.

A Message Map is a table that associates messages with functions. When an application receives a message, MFC will go through its

Message Map and search for a corresponding message handler. MFC has many predefined macros, which associate messages with

your member function.

Example:Example: The ON_WM_CLOSE macro associates the WM_CLOSE message

with the OnClose() member function.

:: Message Maps

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MFC – Microsoft Foundation Classes :: Sample - The Modified Window Class

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We use only 5 additional macros for defining the Message Map.

DECLARE_MESSAGE_MAPDECLARE_MESSAGE_MAP()()

This tells the application that the class in which this is called is going to have a message map and handle messages.

A class can have only one message map. A class will be eligible to execute a message map if it is derived

from CCmdTarget or a class which is derived from CCmdTarget.

:: Implementing the Message Map - I

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BEGIN_MESSAGE_MAP & END_MESSAGE_MAPBEGIN_MESSAGE_MAP & END_MESSAGE_MAP

The first macro takes two parameters - the class name which implements the message map and the base class for it.

It then is followed by the macros which represent messages - ON_WM_LBUTTONDOWN and ON_WM_LBUTTONDOWN.

It is closed by END_MESSAGE_MAP.

:: Implementing the Message Map - II

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ON_WM_LBUTTONDOWNON_WM_LBUTTONDOWN & & ON_WM_ON_WM_RRBUTTONDOWNBUTTONDOWN

These are the macros which declares that the MFCTutorialWindow is going to handle left and right button clicks messages.

The functions that will handle those messages are OnLButtonDown() and OnRButtonDown().

When there is any related click, the mentioned functions will be called automatically with the specific parameters.

:: Implementing the Message Map - III

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Usually, the MFC applications are far more complex. They contain application and frame classes plus two other classes

that represent the document (CDocument) and the view (CView). The document-view architecture is the core of the MFC

application framework and is based on the Model-View-Controller design pattern.

:: Documents and Views

The relationship between a document and its view

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Single Document Interface (SDI) applications support just one open document at a time.

Multiple Document Interface (MDI) applications permit two or more documents to be open concurrently and also support multiple views of a given document.

Dialog-Based MFC applications.

:: SDI and MDI

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MFC – Microsoft Foundation Classes :: MFC Paint Brush Application - I

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When the left mouse button is pressed down, the application stores the mouse pointer’s coordinates in the variable called m_StartPoint of type CPoint.

When the mouse button is released the mouse pointer’s coordinates are stored in the variable m_EndPoint of the same CPoint type.

The function CClientDC::MoveTo() is used for moving to a particular co-ordinate and CClientDC::LineTo() is used for drawing the line.

CClientDC is the device context that directs the outputs to the screen. There is a concept in windows programming, called Device Context in windows. This is used in conjunction with the outputs.

:: MFC Paint Brush Application - II

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Next Lecture

Creating MFC Applications; Dialogs; Drawing - a sample application how to draw hexagons.

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• C++ & MFC, http://www.tenouk.com/cplusplusnmfc.html

• CoderSource.net, “MFC Tutorial”, http://www.codersource.net/codersource_mfc_prog.html

References

windows gui programming with win32 and mfc

Documents

main window

window procedure function

window object

processes messages

processing messages

datawindows messages

predefined messages

windows programming