chapter 1: hello, mfc your first mfc application department of digital contents sang il park

Chapter 1: Hello, MFCYour first MFC Application

Department of Digital Contents

Sang Il Park

API Windows Programming(or SDK-Style)

Win32 ? ( = Windows API)

• API (Application Programming Interface)– A library contains functions for controlling and

using operating system. – Mostly C functions.

• Win32– Name of the Windows API– Collection of C functions for making windows

programming (library)– Ex.) Functions for “creating new windows”,

“adding a button”, “adding a new menu” and so on.

Code looks complex, but…#include <windows.h>LONG WINAPI WndProc (HWND, UINT, WPARAM, LPARAM);

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpszCmdLine, int nCmdShow){ WNDCLASS wc; HWND hwnd; MSG msg;

wc.style = 0; wc.lpfnWndProc = (WNDPROC) WndProc; wc.cbClsExtra = 0; wc.cbWndExtra = 0; wc.hInstance = hInstance; wc.hIcon = LoadIcon (NULL, IDI_WINLOGO); wc.hCursor = LoadCursor (NULL, IDC_ARROW); wc.hbrBackground = (HBRUSH) (COLOR_WINDOW + 1); wc.lpszMenuName = NULL; wc.lpszClassName = "MyWndClass";

RegisterClass (&wc);

hwnd = CreateWindow ( "MyWndClass", // WNDCLASS name "SDK Application", // Window title WS_OVERLAPPEDWINDOW, // Window style CW_USEDEFAULT, // Horizontal position CW_USEDEFAULT, // Vertical position CW_USEDEFAULT, // Initial width CW_USEDEFAULT, // Initial height HWND_DESKTOP, // Handle of parent window NULL, // Menu handle hInstance, // Application's instance handle NULL // Window-creation data );

ShowWindow (hwnd, nCmdShow); UpdateWindow (hwnd);

while (GetMessage (&msg, NULL, 0, 0)) { TranslateMessage (&msg); DispatchMessage (&msg); } return msg.wParam;}

#include <windows.h>LONG WINAPI WndProc (HWND, UINT, WPARAM, LPARAM);

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpszCmdLine, int nCmdShow){ WNDCLASS wc; HWND hwnd; MSG msg;

wc.style = 0; wc.lpfnWndProc = (WNDPROC) WndProc; wc.cbClsExtra = 0; wc.cbWndExtra = 0; wc.hInstance = hInstance; wc.hIcon = LoadIcon (NULL, IDI_WINLOGO); wc.hCursor = LoadCursor (NULL, IDC_ARROW); wc.hbrBackground = (HBRUSH) (COLOR_WINDOW + 1); wc.lpszMenuName = NULL; wc.lpszClassName = "MyWndClass";

RegisterClass (&wc);

hwnd = CreateWindow ( "MyWndClass", // WNDCLASS name "SDK Application", // Window title WS_OVERLAPPEDWINDOW, // Window style CW_USEDEFAULT, // Horizontal position CW_USEDEFAULT, // Vertical position CW_USEDEFAULT, // Initial width CW_USEDEFAULT, // Initial height HWND_DESKTOP, // Handle of parent window NULL, // Menu handle hInstance, // Application's instance handle NULL // Window-creation data );

ShowWindow (hwnd, nCmdShow); UpdateWindow (hwnd);

while (GetMessage (&msg, NULL, 0, 0)) { TranslateMessage (&msg); DispatchMessage (&msg); } return msg.wParam;}

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam){ PAINTSTRUCT ps; HDC hdc;

switch (message) { case WM_PAINT: hdc = BeginPaint (hwnd, &ps); Ellipse (hdc, 0, 0, 200, 100); EndPaint (hwnd, &ps);

return 0;

case WM_DESTROY: PostQuitMessage (0); return 0; } return DefWindowProc (hwnd, message, wParam, lParam);}

LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam){ PAINTSTRUCT ps; HDC hdc;

switch (message) { case WM_PAINT: hdc = BeginPaint (hwnd, &ps); Ellipse (hdc, 0, 0, 200, 100); EndPaint (hwnd, &ps);

return 0;

case WM_DESTROY: PostQuitMessage (0); return 0; } return DefWindowProc (hwnd, message, wParam, lParam);}

Event-DrivenProgramming ModelEvent-DrivenProgramming Model

Compile and Run it!

Summary:

WinMain(…) main function{

WNDCLASS … Registration of the programCreateWindows (…) Define and show a window

while( GetMessage (…)) Get Message{

DispatchMessage(…) Going to Message Handler} (Calls WindProc fucntion)

}

WindProc(…){

switch(message){case …: Message(Event) Handler}

}

Win32 Program Structure

Initialization

Message Loop

Introducing MFC

Microsoft Foundation Classes

• C++ Library– an object-oriented wrapper around the windows

API– More than 200 classes

• Application Framework– Defines a structure of an application for ready-to-

use– Encapsulates virtually every aspect of a

program’s operation: (hide or access)– Provides a well-designed way of making

application: ex) Document/View architecture

Benefits of using c++ and MFC

• Inheritance is the key for reusability– A provided class as a good start point– By adding details or more functions, you can

customize what you want easily

– Ex) Making a button having a movie on it

1. Inherit a regular button class

2. Customize it to have a movie

Your first MFC Application

download hello.h and hello.cpp in our homepage and add it into your projectand run it! http://dasan.sejong.ac.kr/~sipark/class2012/wp/code_0313.zip

For set up the project: In TextbookChapter 1-3: Your First MFC Application - Building the Application

Look into the codesclasses

Code Structure

myApp(CMyApp : CWinApp)

m_pMainFrame(CMainWindow : CFrameWnd)

Program itselfRunning message loop

“Look” of the applicationTaking care of the user interactions

Application Object

• CMyApp class is our program itself• It is inherited (derived) from the CWinApp

class– CWinApp has necessary data but they are hidden– CWinApp class has a message loop but it is

hidden– Customization can be done by overriding

virtual functions ! Ex) InitInstance(), ExitInstance()class CMyApp : public CWinApp { public:

virtual BOOL InitInstance (); };

class CMyApp : public CWinApp { public:

virtual BOOL InitInstance (); };

CMyApp myApp;CMyApp myApp;

Hello.h

Hello.cpp

Frame Window Object• CWnd class

– The most basic class for all windows– Object-oriented interface which contains basic functions

and data for windows– Getting messages,

• CFrameWnd is derived from CWnd class– Interface of the application to the user

• Ready for Mouse input, keyboard input, menu, toolbar and so on

• CMainWindow is our window derived from CFrameWnd– Having Customized constructor– Having Customized OnPaint function

CWndCWnd

CFrameWndCFrameWnd

CMainWindowCMainWindow

Code Structure

myApp(CMyApp : CWinApp)

m_pMainFrame(CMainWindow : CFrameWnd)

Program itselfRunning message loop

“Look” of the applicationTaking care of the user interactions

Message Map

• Where is the switch statement for WM_PAINT ?– Massage map is a trick by microsoft– Massage map is a macro for hiding repeating codings– All CWnd derived classes have all possible windows

message handlers. – You can override any message handler when

necessary

• How to use it:1.Declare that there is a message map by saying

“DECLARE_MASSAGE_MAP” in the class declaration2.Implement the message map by saying

“ON_WM_...” such as “ON_WM_PAINT” between “BEGIN_MESSAGE_MAP” and “END_..”

3.Overriding your message handler. The name of the function is already given such as “OnPaint”

Adding a New Message handler

• Add a member function into your CMainWindow

• Modify your message map

void OnLButtonDown(UINT nFlags, CPoint point);void OnLButtonDown(UINT nFlags, CPoint point);Hello.h

void CMainWindow::OnLButtonDown(UINT nFlags, CPoint point){

AfxMessageBox("Haha");}

void CMainWindow::OnLButtonDown(UINT nFlags, CPoint point){

AfxMessageBox("Haha");}

Hello.cpp

BEGIN_MESSAGE_MAP (CMainWindow, CFrameWnd) ON_WM_PAINT ()

ON_WM_LBUTTONDOWN()END_MESSAGE_MAP ()

BEGIN_MESSAGE_MAP (CMainWindow, CFrameWnd) ON_WM_PAINT ()

ON_WM_LBUTTONDOWN()END_MESSAGE_MAP ()

Hello.cpp

In summary: The big picture

• The Main function is hidden in MFC.

• CMyApp is the program which initializes the windows and runs the message loop.

• CMinWindow is included in CMyApp which is the “look” of the window and processes the messages regarding to Input/Output.

• MFC simplifies the coding work.

Chapter 2: Drawing a Window

Before Windows…

• In 1980s, before the birth of the “windows 95”– MS-DOS (Disk Operating System)

– Graphics Card: CGA(4colors)/EGA(16colors)/VGA(256colors)

A game using CGA graphics cardCGA graphics card

DOS did not take care of graphicsDOS did not take care of graphics

A game company took care of the graphics driversA game company took care of the graphics drivers

Before Windows…

• In 1980s, before the birth of the “windows 95”– MS-DOS (Disk Operating System)

– Graphics Card:

DOS does not take care of graphicsDOS does not take care of graphics

A game company took care of the graphics driversA game company took care of the graphics drivers

Too complicated, so people started to think about

“Device-Independent”

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Two big things of WindowsTM

• Changes after windows– Multi-tasking

• We can run Multiple applications at the same time• Windows controls and distributes its resources to the

application.

– Device-independent• Windows controls the input and outputs.• Applications only communicate with Windows and do

not directly access to the actual hardwares.

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Issues when drawing

• Because of the multi-tasking– An application takes just a part of the window:

the position and the size of the window can change

– Multiple applications can run at the same time:There will be overlapping. One is hiding the other

Chapter 2: Drawing a Window

The Windows GDI

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The Windows GDI

• GDI(Graphics Device Interface)– A part of the Operating System. – Translate the applications’ signals into the

hardwares’ signal.– Determine whether it is shown or not.

Applications GDIOutput Hardwares(Monitor or printer)

Devide-Independent

Device-Dependent

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GDI and Device Context

• Device Context (DC)– Data structure for information about displaying– It determines how to display in Multi-tasking GUI

environment.

CDC: MFC Device Context Class

A package for displaying:(physical hardware information,Many functions for drawing)

CDC: MFC Device Context Class

A package for displaying:(physical hardware information,Many functions for drawing)

≒ A canvas and tools ready to draw

≒ A canvas and tools ready to draw

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How to draw in Windows

• Procedure (step-by-Step)1. Application: Requires Device Context

Windows(GDI): Creates a DC and returns its handle

2. Application: Draws on the DCWindows(GDI): Checks the availability and displays the drawing if possibleCDC* pDC = GetDC (); // require DC // Do some drawing ReleaseDC (pDC); // release D

C

CDC* pDC = GetDC (); // require DC // Do some drawing ReleaseDC (pDC); // release D

C

CDC DC(this); // require DC // Do some drawing CDC DC(this); // require DC // Do some drawing

or

Using pointer

Using class

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Various kinds of Device Context

Class Name Description

CPaintDC For drawing in a window's client area (OnPaint handlers only)

CClientDC For drawing in a window's client area (anywhere but OnPaint)

CWindowDC For drawing anywhere in a window, including the nonclient area

CMetaFileDC For drawing to a GDI metafileClass Hierarchy

Drawing test using PaintDC

• Where you should put your drawing code?– In the WM_PAINT message handler ==

OnPaint()void CMainWindow::OnPaint() {

CPaintDC dc(this); dc.Rectangle(50,50,250,250);dc.Ellipse(100,100,200,200);

}

void CMainWindow::OnPaint() {

CPaintDC dc(this); dc.Rectangle(50,50,250,250);dc.Ellipse(100,100,200,200);

}

WM_PAINT??

• WM: Windows Message – A set of the basic messages predefined by MFC– Usually regarding to the creation/changing of the

windows, mouse controlling, and keyboard typing

• WM_PAINT– A signal from windows that it is time to update

the screen: an “invalid region” happens– When:

• A windows is popping up (when creating or maximizing)• Another window which blocked the window is moving

out.• The user (or application) demands it

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WM_PAINT – Invalid Region

• When it is no longer valid:

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WM_PAINT from yourself

• You may need to update the screen when the contents change

• You can make Windows to send WM_PAINT message to your application

– Make the screen invalid == Invalidate

void CWnd::Invalidate (BOOL bErase = TRUE);void CWnd::Invalidate (BOOL bErase = TRUE);

Code Practice

1. Draw a small rectangle

2. Enlarge the size of the rectangle when the left mouse button is clicked

3. Reduce the size of the rectangle when the right mouse button is clicked