SDK Hello world

/// @file exam_1.cpp
/// @brief 查阅本地MSDN, 手工写SDK程序

#include <windows.h>
#include <tchar.h>
#include <stdlib.h>
#include <stdio.h>

void ShowErrMsg();
LRESULT CALLBACK WindowProc(
                            HWND hwnd,      // handle to window
                            UINT uMsg,      // message identifier
                            WPARAM wParam,  // first message parameter
                            LPARAM lParam   // second message parameter
                            );

int WINAPI WinMain(
                   HINSTANCE hInstance,  // handle to current instance
                   HINSTANCE hPrevInstance,  // handle to previous instance
                   LPSTR lpCmdLine,      // pointer to command line
                   int nCmdShow          // show state of window
                   ) {
    
    /// 设计，注册窗口类
    ATOM _atom;
    WNDCLASS WndClass = {0};
    
    WndClass.style = CS_HREDRAW | CS_VREDRAW;
    WndClass.lpfnWndProc = &WindowProc;
    WndClass.cbClsExtra = 0;
    WndClass.cbWndExtra = 0;
    WndClass.hInstance = hInstance;
    WndClass.hIcon = NULL;
    WndClass.hCursor = NULL /*LoadCursor(NULL, IDC_ARROW)*/;
    WndClass.hbrBackground = (HBRUSH)COLOR_WINDOW;
    WndClass.lpszMenuName = NULL;
    WndClass.lpszClassName = _T("test class");///< 不能为空
    
    _atom = RegisterClass(&WndClass);
    if (0 == _atom) {
        ShowErrMsg();
        goto WINMAIN_END;
    }
    
    /// 创建, 显示窗口
    HWND hWnd;
    hWnd = CreateWindow(
        _T("test class"),  // pointer to registered class name
        _T("test class window"), // pointer to window name
        WS_OVERLAPPEDWINDOW,        // window style
        100,                // horizontal position of window
        100,                // vertical position of window
        800,           // window width
        600,          // window height
        NULL,      // handle to parent or owner window
        NULL,          // handle to menu or child-window identifier
        hInstance,     // handle to application instance
        NULL        // pointer to window-creation data
        );
    if (NULL == hWnd) {
        ShowErrMsg();
        goto WINMAIN_END;
    }
    
    ShowWindow(hWnd, SW_SHOWNORMAL);
    UpdateWindow(hWnd);
    
    /// 消息循环
    MSG msg;
    while (GetMessage(
        &msg,         // address of structure with message
        hWnd,           // handle of window
        0,  // first message
        0   // last message
        )) {
        TranslateMessage(&msg);
        DispatchMessage(&msg);
    }
    
WINMAIN_END:
    return 0;
}

/**
WM_XXX 
键盘，鼠标，绘制消息

  WM_COMMAND
  菜单，快捷键消息
  快捷键消息和键盘消息不同。
  键盘消息是一个一个的按键
  快捷键消息是组合键.
  
    WM_NOTIFY
    子窗口的消息
*/
LRESULT CALLBACK WindowProc(
                            HWND hwnd,      // handle to window
                            UINT uMsg,      // message identifier
                            WPARAM wParam,  // first message parameter
                            LPARAM lParam   // second message parameter
                            ) {
    switch (uMsg) {
    case WM_CLOSE:
        if (IDYES == MessageBox(hwnd, _T("是否退出?"), _T("提示"), MB_YESNO)) {
            // WM_QUIT使GetMessage为FALSE, 跳出消息循环的处理
            PostMessage(hwnd, WM_QUIT, 0, 0);
        }
        break;
        
    default:
        /// The DefWindowProc function calls the default window procedure 
        /// to provide default processing for any window messages 
        /// that an application does not process. 
        return DefWindowProc(hwnd, uMsg, wParam, lParam);
        break;
    }
    
    /// 除了 DefWindowProc的处理, 其它都应该返回 FALSE
    /// 否则UI上点击按钮无反应, 鼠标拖动时, UI也移动不了
    return FALSE;
}

void ShowErrMsg() {
    LPVOID lpMsgBuf = NULL;
    
    FormatMessage( 
        FORMAT_MESSAGE_ALLOCATE_BUFFER 
        | FORMAT_MESSAGE_FROM_SYSTEM
        | FORMAT_MESSAGE_IGNORE_INSERTS,
        NULL,
        GetLastError(),
        MAKELANGID(LANG_NEUTRAL, SUBLANG_DEFAULT), // Default language
        (LPTSTR)&lpMsgBuf,
        0,
        NULL);
    
    MessageBox(NULL, (LPCTSTR)lpMsgBuf, _T("Error"), MB_OK | MB_ICONINFORMATION);
    LocalFree(lpMsgBuf);
}
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</p>

WM_QUIT执行的时机

LRESULT CALLBACK WindowProc(
  HWND hwnd,      // handle to window
  UINT uMsg,      // message identifier
  WPARAM wParam,  // first message parameter
  LPARAM lParam   // second message parameter
  ) {
    BOOL bCallDefault = FALSE;
    switch (uMsg) {
    case WM_CLOSE:
        /// 只能在WM_CLOSE处发WM_QUIT消息
        /// WM_DESTROY处发WM_QUIT消息晚了
        /// 发出了WM_QUIT后, 不能再调用DefWindowProc
        PostMessage(hwnd, WM_QUIT, 0, 0);
        break;

    default:
        bCallDefault = TRUE;
        break;
    };

    return bCallDefault ? DefWindowProc(hwnd, uMsg, wParam, lParam) : 0;
}