windows程序设计读书笔记1——创建窗口

第一个win32程序,简单的创建窗口:

#include <windows.h>

LRESULT CALLBACK WndProc (HWND, UINT, WPARAM, LPARAM) ;

int WINAPI WinMain (HINSTANCE hInstance, HINSTANCE hPrevInstance,
PSTR szCmdLine, int iCmdShow)
{
static TCHAR szAppName[] = TEXT ("HelloWin") ;
HWND hwnd ;
MSG msg ;
WNDCLASS wndclass ; wndclass.style = CS_HREDRAW | CS_VREDRAW ;
wndclass.lpfnWndProc = WndProc ;
wndclass.cbClsExtra = ;
wndclass.cbWndExtra = ;
wndclass.hInstance = hInstance ;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION) ;
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW) ;
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
wndclass.lpszMenuName = NULL ;
wndclass.lpszClassName = szAppName ; if (!RegisterClass (&wndclass))
{
MessageBox (NULL, TEXT ("This program requires Windows NT!"),
szAppName, MB_ICONERROR) ;
return ;
} hwnd = CreateWindow (szAppName, // window class name
TEXT ("The Hello Program"), // window caption
WS_OVERLAPPEDWINDOW, // window style
CW_USEDEFAULT, // initial x position
CW_USEDEFAULT, // initial y position
CW_USEDEFAULT, // initial x size
CW_USEDEFAULT, // initial y size
NULL, // parent window handle
NULL, // window menu handle
hInstance, // program instance handle
NULL) ; // creation parameters ShowWindow (hwnd, iCmdShow) ;
UpdateWindow (hwnd) ; while (GetMessage (&msg, NULL, , ))
{
TranslateMessage (&msg) ;
DispatchMessage (&msg) ;
}
return msg.wParam ;
} LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{
HDC hdc ;
PAINTSTRUCT ps ;
RECT rect ; switch (message)
{
case WM_CREATE:return ; case WM_PAINT:
hdc = BeginPaint (hwnd, &ps) ; GetClientRect (hwnd, &rect) ; DrawText (hdc, TEXT ("Hello, Windows Program!"), -, &rect,
DT_SINGLELINE | DT_CENTER | DT_VCENTER) ; EndPaint (hwnd, &ps) ;
return ; case WM_DESTROY:
PostQuitMessage () ;
return ;
}
return DefWindowProc (hwnd, message, wParam, lParam) ;
}

窗口是由窗口类创建的即WNDCLASS,窗口类确定了处理窗口消息的窗口过程。

MSDN中是这样定义的:

typedef struct {
UINT style;
WNDPROC lpfnWndProc;
int cbClsExtra;
int cbWndExtra;
HINSTANCE hInstance;
HICON hIcon;
HCURSOR hCursor;
HBRUSH hbrBackground;
LPCTSTR lpszMenuName;
LPCTSTR lpszClassName;
} WNDCLASS, *PWNDCLASS;

在程序中,我们一般这样定义和初始化

  WNDCLASS     wndclass ;

     wndclass.style         = CS_HREDRAW | CS_VREDRAW ;
wndclass.lpfnWndProc = WndProc ;
wndclass.cbClsExtra = ;
wndclass.cbWndExtra = ;
wndclass.hInstance = hInstance ;
wndclass.hIcon = LoadIcon (NULL, IDI_APPLICATION) ;
wndclass.hCursor = LoadCursor (NULL, IDC_ARROW) ;
wndclass.hbrBackground = (HBRUSH) GetStockObject (WHITE_BRUSH) ;
wndclass.lpszMenuName = NULL ;
wndclass.lpszClassName = szAppName ;

wndclass.style字段表示类的风格,具体参加MSDN:

Style Action
CS_BYTEALIGNCLIENT

Aligns the window's client area on a byte boundary (in the x direction).

This style affects the width of the window and its horizontal placement on the display.

CS_BYTEALIGNWINDOW

Aligns the window on a byte boundary (in the x direction).

This style affects the width of the window and its horizontal placement on the display.

CS_CLASSDC Allocates one device context to be shared by all windows in the class. 
CS_DBLCLKS

Sends a double-click message to the window procedure when the user double-clicks the mouse

while the cursor is within a window belonging to the class.

CS_DROPSHADOW

Windows XP: Enables the drop shadow effect on a window.

The effect is turned on and off through SPI_SETDROPSHADOW.

CS_GLOBALCLASS

Specifies that the window class is an application global class.

For more information, see Application Global Classes.

CS_HREDRAW Redraws the entire window if a movement or size adjustment changes the width of the client area.
CS_NOCLOSE Disables Close on the window menu.
CS_OWNDC Allocates a unique device context for each window in the class.
CS_PARENTDC

Sets the clipping rectangle of the child window to that of the parent window so that the child can draw on the parent.

A window with the CS_PARENTDC style bit receives a regular device context from the system's cache of device contexts.

CS_SAVEBITS Saves, as a bitmap, the portion of the screen image obscured by a window of this class. 
CS_VREDRAW Redraws the entire window if a movement or size adjustment changes the height of the client area.

我们这里选择的是CS_HREDRAW | CS_VREDRAW,表示无论垂直还是水平尺寸的改变,窗口都将重绘。

wndclass.lpfnWndProc表示窗口过程设置,指向一个函数WndProc。

wndclass.cbClsExtra和cbWndExtra用于维护内部窗口结构中一些预留的空间,可以根据需要来使用这些预留的空间。

wndclass.hInstance表示应用程序的实例句柄即WinMain第一个参数。

wndclass.hIcon为该窗口类设定图标。若要使用本地的图标,第一个参数必须为hInstance实例句柄,第二个参数为图标标示,对于预定义的图标以IDI开头。

wndclass.hCursor与上面类似,载入鼠标指针。

wndclass.hbrBackground指定背景色,这里我们用白色画刷。

wndclass.lpszMenuName即窗口菜单。

wndclass.lpszClassName为窗口类指定名字。

这样窗口类的初始化完成,使用RegisterClass注册类,下面就是窗口的创建了,

使用createWindow函数,MSDN定义如下:

HWND CreateWindow(
__in LPCTSTR lpClassName,   //窗口名称
__in LPCTSTR lpWindowName,  //窗口标题
__in DWORD dwStyle,      //窗口风格
__in int x,           //x坐标
__in int y,          //y坐标
__in int nWidth,       //长度
__in int nHeight,       //高度 
__in HWND hWndParent,     //父窗口句柄
__in HMENU hMenu, //窗口菜单句柄
__in HINSTANCE hInstance, //程序实例句柄
__in LPVOID lpParam //创建参数
);

CreateWindow只是在内部创建窗口,即windows分配了一片内存,要想显示窗口还要使用ShowWindow函数。

第一个参数是CreateWindow创建的窗口句柄,第二个是WinMain接受的iCmdShow值,该参数决定窗口初始显示格式。

UpdateWindow是重绘窗口,这是通过发送一条WM_PAINT消息完成的。

最后则是消息的循环,即不断接受消息,当有消息时调用WndProc函数进行处理。

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