VC++窗口创建过程，图形绘制，时钟程序

创建窗口步骤：

（1）注册窗口类（RegisterClassEx）

（2）创建窗口（CreateWindowEx）

（3）在桌面显示窗口（ShowWindow）

（4）更新窗口客户区（UpdateWindow）

（5）进入无限的消息获取和处理的循环：获取消息（GetMessage）;分派消息至窗口函数处理（DisPatchMessage）;

如果是WM_QUIT,函数（GetMessage）返回False,消息循环结束，程序退出。

注册窗口类需要初始化一个窗口类结构，将其写成一个函数如下：

ATOM MyRegisterClass(HINSTANCE hInstance)
{
    WNDCLASSEXW wcex;  //窗口类结构
    wcex.cbSize = sizeof(WNDCLASSEX); //结构大小
    wcex.style          = CS_HREDRAW | CS_VREDRAW|CS_OWNDC;//CS:class style此窗口类派生的窗口具有的风格
    //CS_OWNDC使得windows将每次对DC的设置保存下来，CS_HREDRAW | CS_VREDRAW窗口大小变化就刷新
    wcex.lpfnWndProc    = WndProc;    //窗口函数指针
    wcex.cbClsExtra     = ;  //紧跟在窗口类结构后的附加字节数
    wcex.cbWndExtra     = ;  //紧跟在窗口事例后的附加字节数
    wcex.hInstance      = hInstance;//本模块的实例句柄
    wcex.hIcon          = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_CLOCKWINDOW));//窗口左上角图标句柄
    wcex.hCursor        = LoadCursor(nullptr, IDC_ARROW);//光标句柄
    wcex.hbrBackground  = (HBRUSH)(COLOR_WINDOW); //背景画刷句柄
    wcex.lpszMenuName   = MAKEINTRESOURCEW(IDC_CLOCKWINDOW);//菜单名
    //wcex.lpszMenuName   =NULL;  //无菜单
    wcex.lpszClassName  = szWindowClass;  //此窗口类名
    wcex.hIconSm        = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));//小图标句柄
    return RegisterClassExW(&wcex);  //注册此窗口类
}

创建窗口、显示窗口、刷新客户区写成一个函数如下：

BOOL InitInstance(HINSTANCE hInstance, int nCmdShow)
{
    hInst = hInstance; // 将实例句柄存储在全局变量中
   HWND hWnd = CreateWindowW(szWindowClass,       //窗口类名
                             szTitle,             //窗口标题
                             WS_OVERLAPPEDWINDOW, //窗口风格 WS:window style
                             CW_USEDEFAULT,       //初始位置X坐标
                             CW_USEDEFAULT,       //初始位置Y坐标
                             ,                 //宽度
                             ,                 //高度
                             nullptr,             //父窗口句柄
                             nullptr,             //菜单句柄
                             hInstance,           //程序实例句柄
                             nullptr);            //用户数据
   if (!hWnd)
   {
      return FALSE;
   }
   ShowWindow(hWnd, nCmdShow);  //显示窗口
   UpdateWindow(hWnd);          //刷新客户区
   return TRUE;
}

因此主函数可以写为：

int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
                     _In_opt_ HINSTANCE hPrevInstance,
                     _In_ LPWSTR    lpCmdLine,
                     _In_ int       nCmdShow)
{
    UNREFERENCED_PARAMETER(hPrevInstance);
    UNREFERENCED_PARAMETER(lpCmdLine);
    // 初始化全局字符串
    LoadStringW(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
    LoadStringW(hInstance, IDC_CLOCKWINDOW, szWindowClass, MAX_LOADSTRING);

    MyRegisterClass(hInstance);
    // 执行应用程序初始化:
    if (!InitInstance (hInstance, nCmdShow))
    {
        return FALSE;
    }

    HACCEL hAccelTable = LoadAccelerators(hInstance, MAKEINTRESOURCE(IDC_CLOCKWINDOW));

    MSG msg;
    // 主消息循环:
    while (GetMessage(&msg, nullptr, , ))//GetMessage返回False程序结束
    {
        if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
    }
    return (int) msg.wParam;  //程序结束时返回最后一个MSG的wParam。
}

在窗口作图

测试一：先打开notepad，之后运行此代码

    HWND hWnd;
    HDC hDC;
    hWnd = ::FindWindow(_TEXT("Notepad"), NULL);
    hDC = ::GetDC(hWnd);
    while (::IsWindow(hWnd))
    {
        ::SetTextColor(hDC, RGB(, , ));
        ::SetBkColor(hDC, RGB(, , ));
        ::TextOut(hDC, , , _T("this is a test."), sizeof("this is a test.") - );

        HPEN hPen = CreatePen(NULL,,RGB(,,));
        ::SelectObject(hDC, hPen);
        ::SelectObject(hDC, ::GetStockObject(BLACK_BRUSH));
        Ellipse(hDC, , , , );
        Sleep();
        ::SelectObject(hDC, ::GetStockObject(WHITE_BRUSH));
        Ellipse(hDC, , , , );
        Sleep();
        ::SelectObject(hDC, ::GetStockObject(LTGRAY_BRUSH));
        Ellipse(hDC, , , , );
        Sleep();
        ::SelectObject(hDC, ::GetStockObject(GRAY_BRUSH));
        Ellipse(hDC, , , , );
        Sleep();
        ::SelectObject(hDC, ::GetStockObject(DKGRAY_BRUSH));
        Ellipse(hDC, , , , );
        Sleep();
        ::SelectObject(hDC, ::GetStockObject(DKGRAY_BRUSH));
        Ellipse(hDC, , , , );
        Sleep();
    }
    ReleaseDC(hWnd, hDC);

绘图首先要取得设备环境句柄

            PAINTSTRUCT ps;
            HDC hdc = BeginPaint(hWnd, &ps);  //取得（窗口客户区无效区域）设备环境句柄
            //绘图代码
            //EndPaint(hWnd, &ps);
            HDC hdcW = ::GetWindowDC(hWnd);   //取得整个窗口设备环境句柄
            HDC hdcD = ::GetDC(hWnd);         //取得窗口客户区设备环境句柄(函数可用在任何地方)        

接着有时为了作图方便需要修改默认坐标系

void SetIsotropic(HWND hWnd,HDC hdc)
{
    RECT rect;
    GetClientRect(hWnd, &rect);       //取得客户区大小
    ::SetMapMode(hdc, MM_ANISOTROPIC);  //自定义坐标系MM_ANISOTROPIC：X!=Y,MM_ISOTROPIC:X=Y
    ::SetWindowExtEx(hdc, , , NULL);   //逻辑刻度，第四个参数可用于返回原来的大小
    ::SetViewportExtEx(hdc, rect.right, -rect.bottom, NULL); //像素刻度(坐标方向)，第四个参数可用于返回原来的大小
    ::SetViewportOrgEx(hdc, rect.right / , rect.bottom / , NULL);
    //修改坐标系(参照之前坐标系的位置坐标)，第四个参数可用于返回原来的原点
}

修改完坐标系后开始绘制时钟表面

void paintClock(HWND hWnd,HDC hdc)
{
    HPEN hPenTri, hPenTime, hPenCent;
    HBRUSH hBrushTr, hBrushTime, hBrushCent;
    int colorUseR = (rand() % ( -  + )) + ;   //(rand() % (b-a+1))+ a; a~b随机数
    int colorUseG = (rand() % ( -  + )) + ;
    int colorUseB = (rand() % ( -  + )) + ;
    hPenTri = CreatePen(NULL, , RGB(, colorUseG, ));
    hBrushTr = ::CreateSolidBrush(RGB(, colorUseG, ));
    bankColor = RGB(, colorUseG, );
    hPenTime = CreatePen(NULL, , RGB(colorUseR, , ));
    hBrushTime = ::CreateSolidBrush(RGB(colorUseR, , ));
    hPenCent = ::CreatePen(NULL, , RGB(, , colorUseB));
    hBrushCent = ::CreateSolidBrush(RGB(, , colorUseB));

    SetIsotropic(hWnd,hdc);
///三角形////////////////////////////////////////////////////////////////////////////////////
    //SetDCBrushColor(hdc, RGB(255, 255, 255));//（无效）
    ::SelectObject(hdc, hPenTri);
    ::SelectObject(hdc, hBrushTr);
  //POINT Mypoint[12] = { (250,10),(375,33.5),(466.5,125),(490,250),(466.5,375),(375,466.5),(250,490),(125,466.5),(33.5,375),(10,250),(33.5,125),(125,33.5) };//写法错误
    POINT Mypoint[] = { ,,,207.84,207.84,,,,207.84,-,,-207.84,,-,-,-207.84,-207.84,-,-,,-207.84,,-,207.84 };
 //::ClientToScreen(hWnd, point);   //投射到屏幕坐标,返回至point
    POINT Mypoint1[] = { Mypoint[],Mypoint[],Mypoint[] };
    POINT Mypoint2[] = { Mypoint[],Mypoint[],Mypoint[] };
    POINT Mypoint3[] = { Mypoint[],Mypoint[],Mypoint[] };
    POINT Mypoint4[] = { Mypoint[],Mypoint[],Mypoint[] };
    //POINT Mypoint5[4]={ Mypoint1 ,Mypoint2,Mypoint3,Mypoint4}//不好用for循环简化操作，二维数组用不了？？
    Polygon(hdc, Mypoint1, );
    Polygon(hdc, Mypoint2, );
    Polygon(hdc, Mypoint3, );
    Polygon(hdc, Mypoint4, );
//圆形===============================================================

    ::SelectObject(hdc, hPenTime);
    ::SelectObject(hdc, hBrushTime);//图形填充色
    for (int i = ; i < ; i++)
    {
        Ellipse(hdc, Mypoint[i].x - , Mypoint[i].y - , Mypoint[i].x + , Mypoint[i].y + );
    }
//中心点加文本=======================================================
    ::SelectObject(hdc, hPenCent);
    ::SelectObject(hdc, hBrushCent);
    ::Ellipse(hdc, -, , , -);
    ::SetTextColor(hdc, RGB(, , ));  //文字颜色
  //::SetBkColor(hdc, TRANSPARENT);  //文字背景色，设置为透明无效
    ::SetBkMode(hdc, TRANSPARENT);  //文字背景透明

    CString strText = _T("时钟");
    TextOut(hdc, -, , (LPCWSTR)strText, sizeof(strText) - );
}

绘制时钟的指针函数

void DrawHand(HDC hdc, int nLength, int nWidth, int nDegrees, COLORREF clrColor)
{
    double nRadians = (double)nDegrees *  * 3.1415926 / ;
    POINT pt[];
    pt[].x = (int)(nLength*sin(nRadians));
    pt[].y = (int)(nLength*cos(nRadians));
    pt[].x = pt[].x /-;
    pt[].y = pt[].y /-;
    HPEN hPen = ::CreatePen(PS_SOLID, nWidth, clrColor);
    HPEN oldPen = (HPEN)::SelectObject(hdc, hPen);
    ::MoveToEx(hdc, pt[].x, pt[].y, NULL);
    LineTo(hdc, pt[].x, pt[].y);

    ::SelectObject(hdc, oldPen);
    ::DeleteObject(hPen);
}

在窗口函数WM_CREATE下设置定时器

    case WM_CREATE:
//当一个应用程序通过CreateWindowEx函数或者CreateWindow函数请求创建窗口时发送此消息，(此消息在函数返回之前发送)。
        SYSTEMTIME time;
        ::GetLocalTime(&time);
        s_PreHour = time.wHour%;//取余
        s_PreMinute = time.wMinute;
        s_PreSecond = time.wSecond;
        SetTimer(hWnd,   //窗口句柄
                IDT_CLOCK,//TimerID
                ,     //间隔
                NULL);     //计时器函数指针
        return ;
        //它应当返回0以使得窗口的创建过程得以继续。如果对于这个消息程序返回-1，窗口将会被销毁。
        //并且CreateWindowEx或者CreateWindow函数将会返回一个值为NULL的句柄。

在WM_TIMER下控制指针的变化与重画

    case WM_TIMER:
        paintClock(hWnd, hDC);
        //paintClock(hWnd, hDC);重画了时钟面板，使得覆盖了旧的时钟指针
        if (::IsIconic(hWnd))   //如果窗口是最小化
        {
            return ;
        }
        ::GetLocalTime(&time);
        //HDC hDC = ::GetDC(hWnd);//(无法写在这里)
        SetIsotropic(hWnd, hDC);//建立坐标系
        if (time.wMinute != s_PreMinute)
        {
            //DrawHand(hDC, 140, 8, s_PreHour * 30 + s_PreMinute / 2, bankColor);//使用时钟面板颜色覆盖原指针
            //DrawHand(hDC, 170, 6, s_PreMinute * 6, bankColor);
            //覆盖失败（不能使得指针颜色完全消失，如同在相同的两点好几条画好几条线，看起来线条变粗并不像一条直线）

            s_PreHour = time.wHour;
            s_PreMinute = time.wMinute;
        }
        if (time.wSecond != s_PreSecond)
        {
            //DrawHand(hDC, 170, 1, s_PreSecond * 6, bankColor);//使用时钟面板颜色覆盖原指针
            DrawHand(hDC, , , s_PreHour *  + s_PreMinute / , RGB(,,));
            DrawHand(hDC, , , s_PreMinute * , RGB(, , ));
            DrawHand(hDC, , , s_PreSecond * , RGB(, , ));
            s_PreSecond = time.wSecond;
        }
        //::MessageBeep(MB_ICONASTERISK);//发出“嘟嘟”声
        break;

效果图