windows编程之路一：画钟表

画表首先要注意的地方是有以下几点：

1:把钟表上面的12个点依次画出来

　　在这里我们选择用小圆点, 此时我们需要确定他们的坐标, 也就是  x = 屏幕水平宽度的一半+圆半径*sin(指针和水平方向的夹角), y = 屏幕的高度/2 - 圆半径*cos(指针和水平方向的夹角),接着用for循环,依次画出12个点,在下面的代码中有.

2: 把时分秒针动画出来

　　这里实现的原理和上面实现的逻辑是一样的,就是再画一个小圆,可以这样理解.

3: 把时针分针动起来

　　我们可以获取系统当前的事件,并设置一个定时器,1s刷新一次界面,这样就可以实现他们的移动.

// 画表.cpp : 定义应用程序的入口点。
//

#include "stdafx.h"
#include "画表.h"
#include <math.h>
#include <time.h>
#pragma warning(disable:4996)

#define MAX_LOADSTRING 100
#define _CRT_SECURE_NO_WARNINGS
// 全局变量: 
HINSTANCE hInst;                                // 当前实例
WCHAR szTitle[MAX_LOADSTRING];                  // 标题栏文本
WCHAR szWindowClass[MAX_LOADSTRING];            // 主窗口类名


//====================================================
//自己定义的函数

void drawClockDial(HDC hdc,HWND hwnd);
void drawHand(HDC hdc, HWND hWnd);//====================================================
//自己定义的变量

const int WINDOWWIDTH  = 400;//窗口的宽度
const int WINDOWHEIGHT = 400;//窗口的高度


const int SCALERADIOUS = 5; //刻度画圆的半径
const double PI = 3.1415926;
const int BORDER = 20;


//====================================================



// 此代码模块中包含的函数的前向声明: 
ATOM                MyRegisterClass(HINSTANCE hInstance);
BOOL                InitInstance(HINSTANCE, int);
LRESULT CALLBACK    WndProc(HWND, UINT, WPARAM, LPARAM);
INT_PTR CALLBACK    About(HWND, UINT, WPARAM, LPARAM);

int APIENTRY wWinMain(_In_ HINSTANCE hInstance,
                     _In_opt_ HINSTANCE hPrevInstance,
                     _In_ LPWSTR    lpCmdLine,
                     _In_ int       nCmdShow)
{
    UNREFERENCED_PARAMETER(hPrevInstance);
    UNREFERENCED_PARAMETER(lpCmdLine);

    // TODO: 在此放置代码。

    // 初始化全局字符串
    LoadStringW(hInstance, IDS_APP_TITLE, szTitle, MAX_LOADSTRING);
    LoadStringW(hInstance, IDC_MY, 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_MY));

    MSG msg;

    // 主消息循环: 
    while (GetMessage(&msg, nullptr, 0, 0))
    {
        if (!TranslateAccelerator(msg.hwnd, hAccelTable, &msg))
        {
            TranslateMessage(&msg);
            DispatchMessage(&msg);
        }
    }

    return (int) msg.wParam;
}



//
//  函数: MyRegisterClass()
//
//  目的: 注册窗口类。
//
ATOM MyRegisterClass(HINSTANCE hInstance)
{
    WNDCLASSEXW wcex;

    wcex.cbSize = sizeof(WNDCLASSEX);

    wcex.style          = CS_HREDRAW | CS_VREDRAW;
    wcex.lpfnWndProc    = WndProc;
    wcex.cbClsExtra     = 0;
    wcex.cbWndExtra     = 0;
    wcex.hInstance      = hInstance;
    wcex.hIcon          = LoadIcon(hInstance, MAKEINTRESOURCE(IDI_MY));
    wcex.hCursor        = LoadCursor(nullptr, IDC_ARROW);
    wcex.hbrBackground = (HBRUSH)(COLOR_GRAYTEXT);//(HBRUSH)(COLOR_WINDOW+1);
    wcex.lpszMenuName    = 0;//MAKEINTRESOURCEW(IDC_MY);//不显示工具栏;
    wcex.lpszClassName  = szWindowClass;
    wcex.hIconSm        = LoadIcon(wcex.hInstance, MAKEINTRESOURCE(IDI_SMALL));

    return RegisterClassExW(&wcex);
}

//
//   函数: InitInstance(HINSTANCE, int)
//
//   目的: 保存实例句柄并创建主窗口
//
//   注释: 
//
//        在此函数中，我们在全局变量中保存实例句柄并
//        创建和显示主程序窗口。
//
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, szTitle, WS_OVERLAPPEDWINDOW,
      CW_USEDEFAULT, 0, WINDOWWIDTH, WINDOWHEIGHT, nullptr, nullptr, hInstance, nullptr);
   //SetTimer(ID_CLOCK_TIMER, 1000, NULL);
   
   if (!hWnd)
   {
      return FALSE;
   }

   ShowWindow(hWnd, nCmdShow);
   UpdateWindow(hWnd);

   return TRUE;
}

//
//  函数: WndProc(HWND, UINT, WPARAM, LPARAM)
//
//  目的:    处理主窗口的消息。
//
//  WM_COMMAND  - 处理应用程序菜单
//  WM_PAINT    - 绘制主窗口
//  WM_DESTROY  - 发送退出消息并返回
//
//
LRESULT CALLBACK WndProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam)
{
    switch (message)
    {
    case WM_COMMAND:
        {
            int wmId = LOWORD(wParam);
            // 分析菜单选择: 
            switch (wmId)
            {
            case IDM_ABOUT:
                DialogBox(hInst, MAKEINTRESOURCE(IDD_ABOUTBOX), hWnd, About);
                break;
            case IDM_EXIT:
                DestroyWindow(hWnd);
                break;
            default:
                return DefWindowProc(hWnd, message, wParam, lParam);
            }
        }
        break;
    case WM_CREATE:
        SetTimer(hWnd, 1, 1000, NULL);//设置定时器,在窗口创建的的时候
        break;
    case WM_TIMER:
        
        InvalidateRect(hWnd, NULL, TRUE);//没一秒自动触发WM_TIMER,然后调用这个函数窗体重新绘制。
    break;

    case WM_PAINT:
        {
            PAINTSTRUCT ps;
            HDC hdc = BeginPaint(hWnd, &ps);
            // TODO: 在此处添加使用 hdc 的任何绘图代码...
            drawClockDial(hdc,hWnd);
            drawHand(hdc, hWnd);
            EndPaint(hWnd, &ps);
        }
        break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, message, wParam, lParam);
    }
    return 0;
}

// “关于”框的消息处理程序。
INT_PTR CALLBACK About(HWND hDlg, UINT message, WPARAM wParam, LPARAM lParam)
{
    UNREFERENCED_PARAMETER(lParam);
    switch (message)
    {
    case WM_INITDIALOG:
        return (INT_PTR)TRUE;

    case WM_COMMAND:
        if (LOWORD(wParam) == IDOK || LOWORD(wParam) == IDCANCEL)
        {
            EndDialog(hDlg, LOWORD(wParam));
            return (INT_PTR)TRUE;
        }
        break;
    }
    return (INT_PTR)FALSE;
}
void drawClockDial(HDC hdc,HWND hWnd) 
{
    RECT rectClient;
    GetClientRect(hWnd, &rectClient);
    POINT point;
    point.x = (rectClient.right - rectClient.left) / 2;
    point.y = (rectClient.bottom - rectClient.top) / 2;
    SelectObject(hdc, CreateSolidBrush(RGB(255, 0, 0)));
    Ellipse(hdc,
        point.x + SCALERADIOUS ,
        point.y + SCALERADIOUS,
        point.x ,
        point.y 
    );
    for (int i = 0; i < 12; i++)
    {
        DWORD radious = (rectClient.right - rectClient.left) / 2 - BORDER;
        double a = sin(PI / 6 * i)*radious;
        double b = cos(PI / 6 * i)*radious;
        Ellipse(hdc,
            point.x + a - SCALERADIOUS,
            point.y - b - SCALERADIOUS,
            point.x + a,
            point.y - b
        );
    }
}
void drawHand(HDC hdc, HWND hWnd) 
{
    time_t timep;
    struct tm *p;
    time(&timep); /*获得time_t结构的时间，UTC时间*/
    p = localtime(&timep); /*转换为struct tm结构的当地时间*/
    RECT rectClient;
    GetClientRect(hWnd, &rectClient);
    POINT point;
    point.x = (rectClient.right - rectClient.left) / 2;
    point.y = (rectClient.bottom - rectClient.top) / 2;
    float Radious = (point.x - BORDER) ;
    SelectObject(hdc, CreatePen(0, 10, RGB(0, 255, 255)));
    //时针
    MoveToEx(hdc, point.x + SCALERADIOUS / 2, point.y + SCALERADIOUS / 2, NULL);
    LineTo(hdc, point.x + Radious/2*sin(PI / 6*p->tm_hour), point.y - Radious/2*cos(PI / 6*p->tm_hour));
    
    //分针
    SelectObject(hdc, CreatePen(0, 7, RGB(0, 255, 0)));
    MoveToEx(hdc, point.x + SCALERADIOUS / 2, point.y + SCALERADIOUS / 2, NULL);
    LineTo(hdc, point.x + Radious/1.5*sin(PI / 30*p->tm_min), point.y - Radious/1.5*cos(PI / 30*p->tm_min));

    //秒针
    SelectObject(hdc, CreatePen(0, 5, RGB(0, 0, 255)));
    MoveToEx(hdc, point.x + SCALERADIOUS / 2, point.y + SCALERADIOUS / 2, NULL);
    LineTo(hdc, point.x + Radious / 1.2*sin(PI / 180 * p->tm_sec), point.y - Radious / 1.2*cos(PI / 180 * p->tm_sec));
}
}