C++Builder6 for SDK窗口编程

SDK窗口编程，在C++Builder6上编译通过.
打开C++Builder6 IDE,新建一个Application应用程序，删除默认的窗口文件：即Unit1.cpp,Unit1.h,Unit1.dfm三个文件。打开和工程同名的.cpp文件，删除全部内容，输入如下内容：

//---------------------------------------------------------------------------#include <windows.h>#include <stdio.h>#pragma hdrstop//---------------------------------------------------------------------------#pragma argsused//---------------------------------------------------------------------------long __stdcall WndProc(HWND hwnd,UINT msg,WPARAM WParam,LPARAM LParam){    switch(msg)    {        case WM_CLOSE:            PostQuitMessage(0);            break;        case WM_LBUTTONDOWN:            MessageBoxA(0,"ok","提示",0);            PostQuitMessage(0);            break;        case WM_PAINT:        {            HDC hdc;            hdc = GetDC(hwnd);            RECT rect;            GetClientRect(hwnd,&rect);                        rect.left   = rect.right/2;            rect.top    = rect.bottom/2;            rect.right  = rect.left+50;            rect.bottom = rect.top+30;            DrawText(hdc,"hello",5,&rect,0);            ReleaseDC(NULL,hdc);        }        default:            return DefWindowProc(hwnd,msg,WParam,LParam);    }    return 0;}WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPreHinstance, LPSTR, int){     WNDCLASS theClass ={0};     char * lpszClassName = "hello";     char * lpszTitle     ="测试窗口";     HWND hwnd;     MSG  msg;     theClass.style       = 0;//缺省窗口风格     theClass.lpfnWndProc = WndProc;     theClass.cbClsExtra  = 0;//窗口类无扩展     theClass.cbWndExtra  = 0;//窗口实例无扩展     theClass.hInstance =  hInstance;     //窗口的最小化图标为缺省图标,即窗口左上角图标     //VC中资源ID为IDI_APPLICATION     //在BCB中资源名为MAINICON     theClass.hIcon=LoadIcon(hInstance,"MAINICON");     //theClass.hIcon=LoadIcon(NULL,IDI_APPLICATION);//VC中窗口的最小化图标为缺省图标     theClass.hCursor=LoadCursor(NULL,IDC_ARROW); // 窗口采用箭头光标     theClass.hbrBackground=(HBRUSH)(GetStockObject(WHITE_BRUSH)); //窗口背景为白色     theClass.lpszMenuName=NULL; //窗口无菜单     theClass.lpszClassName=  lpszClassName; //窗口类名为"窗口"     if(!RegisterClass(&theClass)) //如果注册失败 发出警告     {          MessageBeep(0);          return FALSE;     }     hwnd=CreateWindow( lpszClassName, //窗口类名      lpszTitle, //窗口标题名      WS_OVERLAPPEDWINDOW, //窗口的风格      CW_USEDEFAULT,      CW_USEDEFAULT, //窗口左上角坐标值为缺省值      CW_USEDEFAULT, CW_USEDEFAULT, //窗口的高和宽为缺省值      NULL, //此窗口无父窗口      NULL, //此窗口无子菜单      hInstance, //创建此窗口的应用程序的当前句柄      NULL //不使用该值      );     ShowWindow(hwnd,SW_SHOW);     UpdateWindow(hwnd);     while(true)     {         if(PeekMessage(&msg,NULL,0,0,PM_REMOVE))         {           if (msg.message == WM_QUIT)               break;           TranslateMessage(&msg);           DispatchMessage(&msg);         }//         if (GetMessage (&msg, NULL, 0, 0))//         {//               TranslateMessage (&msg) ;//               DispatchMessage (&msg) ;//         }//         else//           break;     }          return msg.wParam; //消息循环结束 即程序结束时 将信息返回系统}

PeekMessage与GetMessage函数处理不相同，两种方式都可以.PeekMessage是不阻塞的，GetMessage是线程阻塞的，内部处理退出消息，所以不用判断退出消息，关闭时，就跳到break结束循环。运行效果如下图：

这个简单的窗口有什么用呢？是有用的：第一，了解窗口运行机制；第二，在嵌入式开中，特别是WINCE的开发，就是从这样一个简单的窗口开始，逐渐实现复杂的功能。
在WM_PAINT消息中绘图如下:

    PAINTSTRUCT ps ={0};    HDC hdc = BeginPaint(hwnd,&ps);    //HPEN hPen = GetStockObject(WHITE_PEN);    HPEN hPen = CreatePen(PS_DASHDOTDOT,1,RGB(255 , 0 , 0 ));    HGDIOBJ oldPen = (HGDIOBJ)SelectObject(hdc,hPen);    if(!oldPen)    {        int err = GetLastError();        char buff[20]={0};        itoa(err,buff,10);        OutputDebugStringA(buff);    }    //画矩形    Rectangle(hdc,20,30,80,120);    //画线    MoveToEx ( hdc , 20 , 10 , NULL );    LineTo( hdc , 200 ,100);    SelectObject(hdc, oldPen);    DeleteObject(hPen);    EndPaint(hwnd,&ps);