Windows学习笔记――HELLOWIN和SYSMETS

第一个窗口程序(HELLOWIN.cpp)，和第一个系统度量程序(SYSMETS1.cpp).

代码注释，如下：

//HELLOWIN.cpp
#include <windows.h>

/* #define CALLBACK _stdcall
   typedef LONG     LRESULT;
   */

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

int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,
                   LPSTR lpCmdLine,int nShowCmd)
{
    HWND hWnd;
    MSG msg;
    WNDCLASS wndclass;

    static TCHAR szAppName[]=TEXT("HelloWin"); //static?

    //初始化窗口类的属性
    wndclass.cbClsExtra=0;
    wndclass.cbWndExtra=0;

    wndclass.hbrBackground=(HBRUSH)GetStockObject(WHITE_BRUSH); //wndclass结构体的成员hbrBackground,类型是HBRUSH
    wndclass.hCursor=LoadCursor(NULL,IDC_ARROW);
    wndclass.hIcon=LoadIcon(NULL,IDI_APPLICATION); //第一个参数为什么为NULL?表示第二个参数加载的是系统默认图标ID.

    wndclass.hInstance=hInstance;
    wndclass.lpfnWndProc=WndProc;

    wndclass.lpszClassName=szAppName;
    wndclass.lpszMenuName=NULL;
    wndclass.style=CS_HREDRAW | CS_VREDRAW;

    //注册窗口类
    if(!RegisterClass(&wndclass))
    {
        MessageBox(NULL,TEXT("This pragram requiers Windows NT."),
                   szAppName,MB_ICONERROR);
        return 0;
    }

    //创建窗口
    hWnd=CreateWindow(szAppName,TEXT("The Hello Pragram"),WS_OVERLAPPEDWINDOW,
                      CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,
                      NULL,NULL,hInstance,NULL);

    ShowWindow(hWnd,nShowCmd); //第二个参数：nShowCmd与iCmdShow？除了名字，一样的.
    UpdateWindow(hWnd);

    //循环获取消息
    while(GetMessage(&msg,NULL,0,0))
    {
        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:
        PlaySound(TEXT("hellowin.wav"),NULL,SND_FILENAME | SND_ASYNC);
        return 0;
    case WM_PAINT:
        hdc=BeginPaint(hWnd,&ps);

        GetClientRect(hWnd,&rect);
        DrawText(hdc,TEXT("Hello,Windows 98!"),-1,&rect,DT_SINGLELINE | DT_CENTER | DT_VCENTER);

        EndPaint(hWnd,&ps);
        return 0;
    case WM_DESTROY:
        PostQuitMessage(0); //参数为什么为0?把0传给msg.wParam.
        return 0;
    }

    return DefWindowProc(hWnd,message,wParam,lParam);
}

//SYSMETS1.cpp
#include <windows.h>
#include "SYSMETS.H"

/* #define CALLBACK _stdcall
   typedef LONG     LRESULT;
   */

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

int WINAPI WinMain(HINSTANCE hInstance,HINSTANCE hPrevInstance,
                   LPSTR lpCmdLine,int nShowCmd)
{
    HWND hWnd;
    MSG msg;
    WNDCLASS wndclass;

    static TCHAR szAppName[]=TEXT("SysMets1"); //static?

    //初始化窗口类的属性
    wndclass.cbClsExtra=0;
    wndclass.cbWndExtra=0;

    wndclass.hbrBackground=(HBRUSH)GetStockObject(WHITE_BRUSH); //wndclass结构体的成员hbrBackground,类型是HBRUSH
    wndclass.hCursor=LoadCursor(NULL,IDC_ARROW);
    wndclass.hIcon=LoadIcon(NULL,IDI_APPLICATION); //第一个参数为什么为NULL?表示第二个参数加载的是系统默认图标ID.

    wndclass.hInstance=hInstance;
    wndclass.lpfnWndProc=WndProc;

    wndclass.lpszClassName=szAppName;
    wndclass.lpszMenuName=NULL;
    wndclass.style=CS_HREDRAW | CS_VREDRAW;

    //注册窗口类
    if(!RegisterClass(&wndclass))
    {
        MessageBox(NULL,TEXT("This pragram requiers Windows NT."),
                   szAppName,MB_ICONERROR);
        return 0;
    }

    //创建窗口
    hWnd=CreateWindow(szAppName,TEXT("Get System Metrics No.1"),WS_OVERLAPPEDWINDOW,
                      CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,CW_USEDEFAULT,
                      NULL,NULL,hInstance,NULL);

    ShowWindow(hWnd,nShowCmd); //第二个参数：nShowCmd与iCmdShow？除了名字，一样的.
    UpdateWindow(hWnd);

    //循环获取消息
    while(GetMessage(&msg,NULL,0,0))
    {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }

    return msg.wParam;
}

LRESULT CALLBACK WndProc(HWND hWnd,UINT message,WPARAM wParam,LPARAM lParam)
{
    //定义变量
    static int cxChar,cyChar,cxCaps; //static?
    TCHAR  szBuffer[10];
    int i;

    HDC hdc;
    PAINTSTRUCT ps;
    //RECT rect;

    TEXTMETRIC tm;

    //处理消息
    switch(message)
    {
    case WM_CREATE:
        hdc=GetDC(hWnd);

        GetTextMetrics(hdc,&tm);
        cxChar=tm.tmAveCharWidth;
        cyChar=tm.tmHeight+tm.tmExternalLeading;
        cxCaps=((tm.tmPitchAndFamily&1)? 3:2)*cxChar / 2;

        ReleaseDC(hWnd,hdc);
        return 0;
    case WM_PAINT:
        hdc=BeginPaint(hWnd,&ps);

        for(i=0;i<NUMLINES;i++)
        {
            TextOut(hdc,0,cyChar * i,
                    sysmetrics[i].szLabel,
                    lstrlen(sysmetrics[i].szLabel));

            TextOut(hdc,22 * cxCaps,cyChar * i,
                    sysmetrics[i].szDesc,
                    lstrlen(sysmetrics[i].szDesc));

            SetTextAlign(hdc,TA_RIGHT | TA_TOP);
            TextOut(hdc,22*cxCaps + 40*cxChar,cyChar * i,
                    szBuffer,
                    wsprintf(szBuffer,TEXT("%5d"),GetSystemMetrics(sysmetrics[i].iIndex)));
            SetTextAlign(hdc,TA_LEFT | TA_TOP);
        }

        EndPaint(hWnd,&ps);
        return 0;
    case WM_DESTROY:
        PostQuitMessage(0); //参数为什么为0?把0传给msg.wParam.
        return 0;
    }

    return DefWindowProc(hWnd,message,wParam,lParam);
}

函数原型：