VC++深入详解（孙鑫）（第一章 Windows 程序内部运行机制）学习笔记

 1.API（Application Programming Interface，应用程序编程接口）；

 2.SDK（Software Development Kit，软件开发包）；

 3.窗口：窗口是屏幕上的一块矩形区域，是Windows应用程序与用户进行交互的接口。

 4.句柄（HANDLE）：句柄是Windows程序资源的标识号。

　　常见的句柄：HWND（窗口句柄）、HICON（图标句柄）、HCURSOR（光标句柄）、HBRUSH（画刷句柄）；

 5.消息与消息队列

　　在Windows程序中，消息是由MSG结构体来表示的。MSG结构体的定义如下（参考MSDN）:

typedef struct tagMSG {
  HWND   hwnd;
  UINT   message;
  WPARAM wParam;
  LPARAM lParam;
  DWORD  time;
  POINT  pt;
} MSG, *PMSG, *LPMSG;

　　消息队列是在消息的传输过程中保存消息的容器。

　　Windows将产生的消息依次放到消息队列中，而应用程序则通过一个消息循环不断地从消息队列中取出消息，并进行响应。这种消息机制，就是Windows程序运行的机制。

6.WinMain函数

　　WinMain函数的原型声明如下： 

int WINAPI wWinMain(
  HINSTANCE hInstance,      // handle to an instance
  HINSTANCE hPrevInstance,  // has no meaning. It was used in 16-bit Windows, but is now always zero.
  PWSTR pCmdLine,           // contains the command-line arguments as a Unicode string.
  int nCmdShow              // a flag that says whether the main application window will be minimized, maximized, or shown normally.
);

7.窗口的创建过程

1. 设计窗口类
2. 注册窗口类
3. 创建窗口
4. 显示及更新窗口

　　窗口的特征是由WNDCLASS结构体定义的，定义如下：

typedef struct tagWNDCLASS {
  UINT      style;          // The class style(s). 
  WNDPROC   lpfnWndProc;    // A pointer to the window procedure. 
  int       cbClsExtra;     // The number of extra bytes to allocate following the window-class structure.
  int       cbWndExtra;     // The number of extra bytes to allocate following the window instance. 
  HINSTANCE hInstance;      // A handle to the instance that contains the window procedure for the class.
  HICON     hIcon;          // A handle to the class icon.If this member is NULL, the system provides a default icon. 
  HCURSOR   hCursor;        // A handle to the class cursor. 
  HBRUSH    hbrBackground;  // A handle to the class background brush.
  LPCTSTR   lpszMenuName;   // The resource name of the class menu, as the name appears in the resource file. 
  LPCTSTR   lpszClassName;  // A pointer to a null-terminated string or is an atom. 
} WNDCLASS, *PWNDCLASS;

　　窗口过程函数的定义如下：

LRESULT CALLBACK WindowProc(
  __in  HWND hwnd,      // A handle to the window. 
  __in  UINT uMsg,      // The message.
  __in  WPARAM wParam,  // Additional message information.
  __in  LPARAM lParam   // Additional message information. 
);

　　注册窗口类的函数定义如下：

ATOM WINAPI RegisterClass(
  __in  const WNDCLASS *lpWndClass  // A pointer to a WNDCLASS structure.
);

　　创建窗口的函数定义如下：

HWND WINAPI CreateWindow(
  __in_opt  LPCTSTR lpClassName,   // The registered class name.
  __in_opt  LPCTSTR lpWindowName,  // The window name.
  __in      DWORD dwStyle,         // The style of the window being created. 
  __in      int x,                 // The initial horizontal position of the window. 
  __in      int y,                 // The initial vertical position of the window.
  __in      int nWidth,            // The width, in device units, of the window.
  __in      int nHeight,           // The height, in device units, of the window. 
  __in_opt  HWND hWndParent,       // A handle to the parent or owner window of the window being created.
  __in_opt  HMENU hMenu,           // A handle to a menu, or specifies a child-window identifier depending on the window style.
  __in_opt  HINSTANCE hInstance,   // A handle to the instance of the module to be associated with the window.
  __in_opt  LPVOID lpParam         // Pointer to window-creation data.
);

　　显示窗口的函数定义如下：

BOOL WINAPI ShowWindow(
  __in  HWND hWnd,    // A handle to the window. 
  __in  int nCmdShow  // Controls how the window is to be shown.
);

　　更新窗口的函数定义如下：

BOOL UpdateWindow(
  __in  HWND hWnd  // Handle to the window to be updated.
);

　　从消息队列中获取消息示例：

BOOL bRet;
MSG msg;
while( (bRet = GetMessage( &msg, hWnd, 0, 0 )) != 0)
{ 
    if (bRet == -1)
    {
        // handle the error and possibly exit
    }
    else
    {
        TranslateMessage(&msg); 
        DispatchMessage(&msg); 
    }
}

8.Windows程序示例

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

LRESULT CALLBACK MyWndProc(
    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,          // command line
    int nCmdShow              // show state
)
{
    // 设计窗口类
    WNDCLASS wndcls;
    wndcls.style = CS_HREDRAW | CS_VREDRAW;
    wndcls.lpfnWndProc = MyWndProc;
    wndcls.cbClsExtra = 0;
    wndcls.cbWndExtra = 0;
    wndcls.hInstance = hInstance;
    wndcls.hIcon = LoadIcon(NULL, IDI_ERROR); // LoadIcon(hInstance, MAKEINTRESOURCE(IDI_SAMPLE1));
    wndcls.hCursor = LoadCursor(NULL, IDC_CROSS);
    wndcls.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH); // (HBRUSH)(COLOR_WINDOW+1);
    wndcls.lpszMenuName = NULL; // MAKEINTRESOURCE(IDC_SAMPLE1);
    wndcls.lpszClassName = "MyClassName";

    // 注册窗口类
    RegisterClass(&wndcls);

    // 创建窗口类
    HWND hWnd;
    hWnd = CreateWindow("MyClassName", "MyWindowName", WS_OVERLAPPEDWINDOW, 
        0, 0, 600, 400, NULL, NULL, hInstance, NULL);

    // 显示和更新窗口
    ShowWindow(hWnd, SW_SHOWNORMAL);
    UpdateWindow(hWnd);

    // 消息循环
    BOOL bRet;
    MSG msg;
    while( (bRet = GetMessage( &msg, hWnd, 0, 0 )) != 0)
    {
        if (bRet == -1)
        {
            // handle the error and possibly exit
            return -1;
        }
        else
        {
            TranslateMessage(&msg); 
            DispatchMessage(&msg); 
        }
    }

    return 0;
}

LRESULT CALLBACK MyWndProc(
    HWND hWnd,      // handle to window
    UINT uMsg,      // message identifier
    WPARAM wParam,  // first message parameter
    LPARAM lParam   // second message parameter
)
{
    switch(uMsg)
    {
    case WM_CHAR:
        {
            char szChar[20];
            sprintf(szChar, "char is %c", char(wParam));
            MessageBox(hWnd, szChar, "WM_CHAR", 0);
        }
        break;
    case WM_LBUTTONDOWN:
        {
            MessageBox(hWnd, "mouse clicked", "WM_LBUTTONDOWN", 0);
            HDC hDC;
            hDC = GetDC(hWnd);
            TextOut(hDC, 0, 50, "WM_LBUTTONDOWN", strlen("WM_LBUTTONDOWN"));
            ReleaseDC(hWnd, hDC);
        }
        break;
    case WM_PAINT:
        {
            PAINTSTRUCT ps;
            HDC hDC;
            hDC=BeginPaint(hWnd, &ps);
            TextOut(hDC, 0, 0, "WM_PAINT", strlen("WM_PAINT"));
            EndPaint(hWnd, &ps);
        }
        break;
    case WM_CLOSE:
        {
            if(IDYES == MessageBox(hWnd, "是否真的结束？", "WM_CLOSE", MB_YESNO))
                DestroyWindow(hWnd);
        }
    break;
    case WM_DESTROY:
        PostQuitMessage(0);
        break;
    default:
        return DefWindowProc(hWnd, uMsg, wParam, lParam);
    }
    return 0;
}