初探GDI——基本框架（文字输出）

　　由之前彩色随机矩形线条获得启发，今日学习文字输出时，使用随机色定义字体颜色，获得彩色变换文字输出。

    //随机字体颜色    SetTextColor(g_hdc, RGB(rand() % 256, rand() % 256, rand() % 256));

　　由于WM_PAINT消息目前仅在窗口大小发生改变时触发，故获得炫彩效果需拖动窗口边框。

　　在定位字体位置时，观察到TextOut（）函数输出位置定位在字符串左上角。同时发现通过MoveWindow（）函数设置窗口位置、大小时，设置的大小为窗口区大小，并非之前以为的客户区大小。之后会检索窗口区大小的设置问题。

　　为求基本框架熟记，以及提高代码书写水平，每次新建项目书写基本框架均使用手打方式，不采用复制之前框架的做法。

源代码：

/*学习使用GDI文字输出2017/08/19*///头文件#include <Windows.h>#include <time.h>   //生成随机数//全局函数声明LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam,                        LPARAM lParam);bool Game_Init(HWND hwnd);void Game_Paint(HWND hwnd);bool Game_Cleanup(HWND hwnd);//全局变量HDC g_hdc = 0;//入口函数int WINAPI WinMain(HINSTANCE hInstance,    HINSTANCE hPrevInstance,    LPSTR lpCmdLine,    int nCmdShow) {    //创建窗口类    WNDCLASSEX wndClass = { 0 };    wndClass.cbClsExtra = 0;    wndClass.cbWndExtra = 0;    wndClass.cbSize = sizeof(WNDCLASSEX);    wndClass.hbrBackground = (HBRUSH)GetStockObject(GRAY_BRUSH);    wndClass.hCursor = LoadCursor(nullptr, IDC_ARROW);    wndClass.hIcon = LoadIcon(nullptr, IDI_APPLICATION);    wndClass.hInstance = hInstance;    wndClass.lpfnWndProc = WndProc;    wndClass.lpszClassName = L"GDI_Text";    wndClass.lpszMenuName = nullptr;    wndClass.style = CS_HREDRAW | CS_VREDRAW;    //注册窗口类    if ( !RegisterClassEx(&wndClass) )    {        MessageBox(nullptr, L"窗口类创建失败！", L"", MB_OK);        return -1;    }    //创建窗口    HWND hwnd = CreateWindow(L"GDI_Text", L"文字输出演示", WS_OVERLAPPEDWINDOW,        CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, nullptr, nullptr, hInstance,        nullptr);    //显示刷新窗口    ShowWindow(hwnd, nCmdShow);    MoveWindow(hwnd, 0, 0, 800, 600, true);    UpdateWindow(hwnd);    Game_Init(hwnd);    //消息循环    MSG msg = { 0 };    while (msg.message!=WM_QUIT)    {        if (PeekMessage(&msg,0,0,0,PM_REMOVE))        {            TranslateMessage(&msg);            DispatchMessage(&msg);        }    }    //注销窗口类    UnregisterClass(L"GDI_Text", hInstance);    return 0;}//全局函数定义LRESULT CALLBACK WndProc(HWND hwnd, UINT message, WPARAM wParam,    LPARAM lParam){    PAINTSTRUCT paintstruct;    switch (message)    {    //如果窗口刷新，调用Game_Paint重绘画面    case WM_PAINT:        g_hdc = BeginPaint(hwnd, &paintstruct);        Game_Paint(hwnd);        EndPaint(hwnd, &paintstruct);        ValidateRect(hwnd, nullptr);        break;    case WM_CLOSE:        if (IDYES == MessageBox(hwnd, L"是否退出程序?", L" ", MB_YESNO))            DestroyWindow(hwnd);        break;    case WM_DESTROY:        Game_Cleanup(hwnd);        PostQuitMessage(0);        break;    default:        return DefWindowProc(hwnd, message, wParam, lParam);    }}bool Game_Init(HWND hwnd){    //设置随机数种子    srand((unsigned)time(nullptr));    Game_Paint(hwnd);    return true;}void Game_Paint(HWND hwnd){    g_hdc = GetDC(hwnd);    wchar_t text1[] = L"我就试试";    //设置字体    HFONT hFont = CreateFont(80, 0, 0, 0, 0, 0, 0, 0, GB2312_CHARSET, 0, 0, 0, 0,        L"幼圆");    SelectObject(g_hdc, hFont);    //设置字体透明背景    SetBkMode(g_hdc, TRANSPARENT);    //随机字体颜色    SetTextColor(g_hdc, RGB(rand() % 256, rand() % 256, rand() % 256));    TextOut(g_hdc, 0, 50, text1, wcslen(text1));    ReleaseDC(hwnd, g_hdc);}bool Game_Cleanup(HWND hwnd){    return true;}