//短的函数最好定义为宏

#define BUFFER(x,y) *(y*cxBuffer+x+pBuffer)//取出一个字符

//字符消息

//WM_CHAR,WM_DEADCHAR,WM_SYSCHAR,WM_SYSDEADCHAR

//前两个是由WM_KEYDOWN/UP消息产生，后两个是由WM_SYSKEYDOWN/UP消息产生

//DEADCHAR是某些国家字母有符号，多种表现形式。有DEADCHAR会组合更多，但是我们有不到这个

//消息参数

//wParam：指定该按键的虚拟键代码

//在下面两种消息中的含义

//----WM_KEYDOWN:虚拟键代码                            key

//----WM_CHAR:ANSI或Unicode字符码（看宏定义区别）    char

//lParam

//扩展键标记（手册）

//消息排序 假设按下A键并释放，大写状态关闭

//1.WM_KEYDOWN    'A'的虚拟按键代码0x41    无论大小写都是大写的按键代码，区别在WM_CHAR处

//2.WM_CHAR        'a'的虚拟按键代码0x61

//3.WM_KEYUP    'A'的虚拟按键代码0x41

//若是持续按下‘A'键

//会循环1、2步骤，在抬起时走3

//插入符号    一个程序共享一个插入符号 获得焦点(活动窗口)    响应WM_SETFOCUS WM_KILLFOCUS

//createcaret,setcaretpos,showcaret,hidecaret.destroycaret

LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)

{

    HDC hdc;

    RECT rect; PAINTSTRUCT ps;

    TEXTMETRIC tm;

    static int cxClient, cyClient;    //客户区大小

    static int cxChar, cyChar;        //字体大小

    static int cxCaret, cyCaret;    //插入符位置

    static int cxBuffer, cyBuffer;    //列数行数

    static TCHAR * pBuffer = NULL;

    int x, y, i;//用于循环使用

    switch (message)

    {

    case WM_CREATE:

        //获取字体大小

        hdc = GetDC(hwnd);

        //系统默认等宽字体

        SelectObject(hdc, GetStockObject(SYSTEM_FIXED_FONT));

        GetTextMetrics(hdc, &tm);

        cxChar = tm.tmAveCharWidth;

        cyChar = tm.tmHeight + tm.tmExternalLeading;

        ReleaseDC(hwnd, hdc);

        break;

    case WM_SIZE:

        //获取屏幕大小

        cxClient = LOWORD(lParam);

        cyClient = HIWORD(lParam);

        //获取行数和列数

        cxBuffer = (int)cxClient / cxChar;

        cyBuffer = (int)cyClient / cyChar;

        cxBuffer = max(, cxBuffer);

        cyBuffer = max(, cyBuffer);

        //设置字符集指针的大小

        if (pBuffer!=NULL)

        {

            free(pBuffer);

        }

        pBuffer = (TCHAR *)malloc(cxBuffer*cyBuffer*sizeof(TCHAR));

        //初始化这个空间

        for (y = ; y < cyBuffer; y++)

        {

            for (x = ; x < cxBuffer; x++)

            {

                BUFFER(x,y) = ' ';

            }

        }

        //设置光标位置,左上角

        cxCaret = ;

        cyCaret = ;

        if (hwnd==GetFocus())

        {

            SetCaretPos(cxCaret*cxChar, cyCaret*cyChar);

            //设为0,0处，先不需要显示

        }

        InvalidateRect(hwnd, NULL, TRUE);

        break;

    case WM_SETFOCUS:

        CreateCaret(hwnd, NULL, cxChar, cyChar);

        SetCaretPos(cxCaret*cxChar, cyCaret*cyChar);//左上角

        ShowCaret(hwnd);

        break;

    case WM_KILLFOCUS:

        HideCaret(hwnd);

        DestroyCaret();

        break;

    case WM_KEYDOWN:

        switch (wParam)

        {

        case VK_DOWN:

            cyCaret += ;

            break;

        case VK_UP:

            cyCaret -= ;

            break;

        case VK_LEFT:

            cxCaret -= ;

            break;

        case VK_RIGHT:

            cxCaret += ;

            break;

        case VK_DELETE:

            for (x = cxCaret; x < cxBuffer - ;x++)

            {

                BUFFER(x, cyCaret) = BUFFER(x + , cyCaret);

            }

            BUFFER(cxBuffer - , cyCaret) = ' ';

            HideCaret(hwnd);

            hdc = GetDC(hwnd);

            TextOut(hdc, , cyCaret*cyChar, &BUFFER(, cyCaret), cxBuffer);//重绘这一行

            ReleaseDC(hwnd, hdc);

            ShowCaret(hwnd);

        default:

            break;

        }

        cxCaret = max(, cxCaret);

        cyCaret = max(, cyCaret);

        cxCaret = min(cxCaret, cxBuffer - );

        cyCaret = min(cyCaret, cyBuffer - );

        SetCaretPos(cxCaret*cxChar, cyCaret*cyChar);

        break;

    case WM_CHAR:

        for (i = ; i < (int)LOWORD(lParam);i++)//用户按键过快时

        {

            switch (wParam)

            {

            case '\b':

                if (cxCaret>)

                {

                    cxCaret--;

                    SendMessage(hwnd, WM_KEYDOWN, VK_DELETE, );

                }

                break;

            default:

                BUFFER(cxCaret, cyCaret) = (TCHAR)wParam;

                hdc = GetDC(hwnd);

                //先隐藏光标

                HideCaret(hwnd);

                TextOut(hdc, cxCaret*cxChar, cyCaret*cyChar, &BUFFER(cxCaret, cyCaret), );

                if (++cxCaret == cxBuffer)

                {

                    cxCaret = ;

                    if (++cyCaret == cyBuffer)

                    {

                        cyCaret = ;

                    }

                }

                //显示光标

                ShowCaret(hwnd);

                ReleaseDC(hwnd, hdc);

            }

        }

        break;

    case WM_PAINT:

        hdc = BeginPaint(hwnd, &ps);

        GetClientRect(hwnd, &rect);

        for (y = ; y < cyBuffer;y++)

        {

            TextOut(hdc, , y*cyChar, &pBuffer[y*cxBuffer], cxBuffer);

        }

        EndPaint(hwnd, &ps);

        break;

    case WM_DESTROY:

        PostQuitMessage();

        return ;

    }

    return DefWindowProc(hwnd, message, wParam, lParam);

}