一个时钟程序(c语言)

这几天看完了windows程序设计的GDI部分,贴上一段代码,演示的是一个时钟程序.

/**/ ///////////////////////////////////////////////////////////////
//  by tianzhihen 

#include  < windows.h >
#include  " resource.h "
#include  < math.h >

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

int  __stdcall WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine,  int  nShowCmd)
... {
    char szWindowClass[] = "MyClock";
    
    // 注册窗口类
    WNDCLASSEX wcex;
    
    wcex.cbSize        = sizeof(WNDCLASSEX); 
    wcex.style        = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc    = (WNDPROC)WndProc;
    wcex.cbClsExtra        = 0;
    wcex.cbWndExtra        = 0;
    wcex.hInstance        = hInstance;
    wcex.hIcon        = LoadIcon(hInstance, (LPCTSTR)IDI_MAIN);
    wcex.hCursor        = LoadCursor(NULL, IDC_ARROW);
    wcex.hbrBackground    = (HBRUSH)(COLOR_3DFACE+1);
    wcex.lpszMenuName    = NULL;
    wcex.lpszClassName    = szWindowClass;
    wcex.hIconSm        = NULL;
    
    ::RegisterClassEx(&wcex);
    
    
    // 创建并线程主窗口
    HWND hWnd = ::CreateWindowEx( 
        WS_EX_CLIENTEDGE,    // 扩展样式
        szWindowClass,        // 类名
        "时钟",    // 标题
        WS_POPUP|WS_SYSMENU|WS_SIZEBOX,    // 窗口样式
        100,    // 初始 X 坐标
        100,    // 初始 X 坐标
        300,    // 宽度
        300,    // 高度
        NULL,        // 父窗口句柄
        NULL,            // 菜单句柄
        hInstance,    // 程序实例句柄
        NULL);     
    
    ::ShowWindow(hWnd, nShowCmd);
    ::UpdateWindow(hWnd);
    
    // 进入消息循环
    MSG msg;
    while(::GetMessage(&msg, NULL, 0, 0))
    ...{
        ::TranslateMessage(&msg);
        ::DispatchMessage(&msg); 
    }
    
    return 1;
}


//  消息处理代码

#define  IDT_CLOCK 1
const   int  IDM_HELP  =   100 ;
const   int  IDM_TOPMOST  =   101 ;

//  实现函数
void  SetIsotropic(HDC hdc,   int  cxClient,  int  cyClient);
void  DrawClockFace(HDC hdc);
void  DrawHand(HDC hdc,  int  nLength,  int  nWidth,  int  nDegrees, COLORREF clrColor);

//  上一次Windows通知时的时间
static   int  s_nPreHour;         //  小时    
static   int  s_nPreMinute;     //  分钟
static   int  s_nPreSecond;     //  秒
//  窗口客户区的大小
static   int  s_cxClient;        
static   int  s_cyClient;
//  是否位于最顶层
static  BOOL s_bTopMost;

//  消息处理函数
LRESULT __stdcall WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
... {
    
    switch(message)
    ...{
        
    case WM_CREATE:        //CreateWindowEx()时调用
        ...{    
            
            HMENU hSysMenu;
            hSysMenu=::GetSystemMenu(hWnd,FALSE);
            ::AppendMenu(hSysMenu,MF_SEPARATOR,0,NULL);
            ::AppendMenu(hSysMenu,MF_STRING,IDM_TOPMOST,"总在最前");
            ::AppendMenu(hSysMenu,MF_STRING,IDM_HELP,"帮助");
            // 设置时间
            SYSTEMTIME time;
            ::GetLocalTime(&time);
            s_nPreHour = time.wHour%12;
            s_nPreMinute = time.wMinute;
            s_nPreSecond = time.wSecond;
            
            // 创建定时器
            ::SetTimer(hWnd, IDT_CLOCK, 1000, NULL);
            return 0;
        }
        
    case WM_SIZE:    //ShowWindow()时调用
        ...{
            s_cxClient = LOWORD(lParam);
            s_cyClient = HIWORD(lParam);
            return 0;
        }
    case WM_PAINT:    //客户区无效时调用
        ...{
            PAINTSTRUCT ps;
            HDC hdc = ::BeginPaint(hWnd, &ps);
            
            // 设置坐标系
            SetIsotropic(hdc, s_cxClient, s_cyClient);
            
            // 绘制时钟外观
            DrawClockFace(hdc);
            
            // 绘制指针
            
            // 经过1个小时时针走30度（360/12），经过1分钟时针走0.5度（30/60）
            DrawHand(hdc, 200, 8, s_nPreHour*30 + s_nPreMinute/2, RGB(0, 0, 0));
            // 经过1分钟分针走6度（360/60）
            DrawHand(hdc, 400, 6, s_nPreMinute*6, RGB(0, 0, 0));
            // 经过1秒钟秒针走6度（360/60）
            DrawHand(hdc, 400, 1, s_nPreSecond*6, RGB(0, 0, 0));
            
            ::EndPaint(hWnd, &ps);
            return 0;
        }
        
    case WM_TIMER:
        ...{
            // 如果窗口处于最小化状态就什么也不做
            if(::IsIconic(hWnd))    // IsIconic函数用来判断窗口是否处于最小化状态
                return 0;
            
            // 取得系统时间
            SYSTEMTIME time; 
            ::GetLocalTime(&time);
            
            // 建立坐标系
            HDC hdc = ::GetDC(hWnd);
            SetIsotropic(hdc, s_cxClient, s_cyClient);
            
            // 以COLOR_3DFACE为背景色就可以擦除指针了（因为窗口的背景色也是COLOR_3DFACE）
            COLORREF crfColor = ::GetSysColor(COLOR_3DFACE); 
            
            // 如果分钟改变的话就擦除时针和分针
            if(time.wMinute != s_nPreMinute)
            ...{
                // 擦除时针和分针
                DrawHand(hdc, 200, 8, s_nPreHour*30 + s_nPreMinute/2, crfColor);
                DrawHand(hdc, 400, 6, s_nPreMinute*6, crfColor);
                s_nPreHour = time.wHour;
                s_nPreMinute = time.wMinute;
            }
            
            // 如果秒改变的话就擦除秒针，然后重画所有指针
            if(time.wSecond != s_nPreSecond)
            ...{
                // 擦除秒针
                DrawHand(hdc, 400, 1, s_nPreSecond*6, crfColor);
            }
            
            // 重画所有指针
            DrawHand(hdc, 400, 1, time.wSecond*6, RGB(0, 0, 0));
            DrawHand(hdc, 200, 8, time.wHour*30 + time.wMinute/2, RGB(0, 0, 0));
            DrawHand(hdc, 400, 6, time.wMinute*6, RGB(0, 0, 0));
            s_nPreSecond = time.wSecond;
            
            return 0;
        }
        
    case WM_NCHITTEST:
        
        ...{
            UINT nHitTest;
            nHitTest=::DefWindowProc(hWnd,WM_NCHITTEST,wParam,lParam);
            // 如果鼠标左键按下，GetAsyncKeyState函数的返回值小于0
            if(nHitTest==HTCLIENT&&::GetAsyncKeyState(MK_LBUTTON)<0) 
                nHitTest=HTCAPTION;
            
            return nHitTest;
        }
        
    case WM_CONTEXTMENU:    //点击鼠标右键
        
        ...{
            POINT pt;
            pt.x=LOWORD(lParam);
            pt.y=HIWORD(lParam);
            HMENU hSysMenu=::GetSystemMenu(hWnd,FALSE);
            
            int nID=::TrackPopupMenu(hSysMenu,TPM_LEFTALIGN|TPM_RETURNCMD,
                pt.x,pt.y,0,hWnd,NULL);
            if(nID>0)
                ::SendMessage(hWnd,WM_SYSCOMMAND,nID,0);
            return 0;
        }
        
    case WM_SYSCOMMAND:
        ...{
            int nID = wParam;
            ...{
                if(nID == IDM_HELP)
                ...{
                    ::MessageBox(hWnd, "一个时钟的例子", "时钟", 0);
                }
                else if(nID == IDM_TOPMOST)
                ...{
                    HMENU hSysMenu = ::GetSystemMenu(hWnd, FALSE);
                    if(s_bTopMost)
                    ...{
                        ::CheckMenuItem(hSysMenu, IDM_TOPMOST, MF_UNCHECKED);
                        ::SetWindowPos(hWnd, HWND_NOTOPMOST, 0, 0, 0, 0, 
                            SWP_NOMOVE | SWP_NOREDRAW | SWP_NOSIZE);
                        s_bTopMost = FALSE;
                    }
                    else
                    ...{
                        ::CheckMenuItem(hSysMenu, IDM_TOPMOST, MF_CHECKED);
                        ::SetWindowPos(hWnd, HWND_TOPMOST, 0, 0, 0, 0,
                            SWP_NOMOVE | SWP_NOREDRAW | SWP_NOSIZE);
                        s_bTopMost = TRUE;
                    }
                }

                  break;
                
            }
        }
        
        
        
        
    case WM_CLOSE:
        ...{
            ::KillTimer(hWnd, IDT_CLOCK);
            ::DestroyWindow(hWnd);
            return 0;
        }    
        
    case WM_DESTROY:    // 窗口正在被销毁
        ...{        
            ::PostQuitMessage(0);
            return 0;
        }
        
    }
    
    
    return ::DefWindowProc(hWnd, message, wParam, lParam);
}



// 绘制坐标系
void  SetIsotropic(HDC hdc,  int  cx,  int  cy)
... {
    ::SetMapMode(hdc, MM_ISOTROPIC);
    ::SetWindowExtEx(hdc, 1000, 1000, NULL);
    ::SetViewportExtEx(hdc, cx, -cy, NULL);
    ::SetViewportOrgEx(hdc, cx/2, cy/2, NULL);
}

//  绘制时钟的外观
void  DrawClockFace(HDC hdc)
... {
    const int SQUARESIZE = 20;
    static POINT pt[] =
    ...{
        0, 450,        // 12点
            225, 390,    // 1点
            390, 225,    // 2点
            450, 0,        // 3点
            390, -225,    //... 下面的坐标是上面的点的对称点（以X轴、Y轴或原点对称）
            225, -390,
            0, -450,
            -225, -390,
            -390, -225,
            -450, 0,
            -390, 225,
            -225, 390
    };
    
    // 选择一个黑色的画刷
    ::SelectObject(hdc, ::GetStockObject(NULL_BRUSH));
    
    // 画12个圆
    for(int i=0; i<12; i++)
    ...{
        ::Ellipse(hdc, pt[i].x - SQUARESIZE, pt[i].y + SQUARESIZE,
            pt[i].x + SQUARESIZE, pt[i].y - SQUARESIZE);
    }
}



//  指针的长度、宽度、相对于0点偏移的角度、颜色分别由参数nLength、nWidth、nDegrees、clrColor指定
void  DrawHand(HDC hdc,  int  nLength,  int  nWidth,  int  nDegrees, COLORREF clrColor)
... {
    // 将角度nDegrees转化成弧度 .    2*3.1415926/360 == 0.0174533
    double nRadians = (double)nDegrees*0.0174533;
    
    // 计算坐标
    POINT pt[2];
    pt[0].x = (int)(nLength*sin(nRadians));
    pt[0].y = (int)(nLength*cos(nRadians));
    pt[1].x = -pt[0].x/5;
    pt[1].y = -pt[0].y/5;
    
    // 创建画笔，并选如DC结构中
    HPEN hPen = ::CreatePen(PS_SOLID, nWidth, clrColor);
    HPEN hOldPen = (HPEN)::SelectObject(hdc, hPen);
    
    // 画线
    ::MoveToEx(hdc, pt[0].x, pt[0].y, NULL);
    ::LineTo(hdc, pt[1].x, pt[1].y);
    
    ::SelectObject(hdc, hOldPen);
    ::DeleteObject(hPen);
}

总的来说程序不是很难,可能有时候对windows内部一些机制还存在疑惑,不过没办法,谁让它不开源呢？

还存在一点疑惑,记录下来:

在这段代码中:

     case  WM_SYSCOMMAND:
         ... {
            int nID = wParam;
            ...{
                if(nID == IDM_HELP)
                ...{
                    ::MessageBox(hWnd, "一个时钟的例子", "时钟", 0);
                }
                else if(nID == IDM_TOPMOST)
                ...{
                    HMENU hSysMenu = ::GetSystemMenu(hWnd, FALSE);
                    if(s_bTopMost)
                    ...{
                        ::CheckMenuItem(hSysMenu, IDM_TOPMOST, MF_UNCHECKED);
                        ::SetWindowPos(hWnd, HWND_NOTOPMOST, 0, 0, 0, 0, 
                            SWP_NOMOVE | SWP_NOREDRAW | SWP_NOSIZE);
                        s_bTopMost = FALSE;
                    }
                    else
                    ...{
                        ::CheckMenuItem(hSysMenu, IDM_TOPMOST, MF_CHECKED);
                        ::SetWindowPos(hWnd, HWND_TOPMOST, 0, 0, 0, 0,
                            SWP_NOMOVE | SWP_NOREDRAW | SWP_NOSIZE);
                        s_bTopMost = TRUE;
                    }
                }

                  break;
                
            }
        }

返回值不能是0,一定要是DefWindowProc函数,因此用break弹出switch语句,再去执行DefWindowProc函数,否则该始终程序不能移动,不知缘何？若有哪位朋友知道的还望告诉我一下,不盛感激.