//WinMain.cpp
#include <windows.h>
#include <stdio.h>

LRESULT CALLBACK WinAzeProc(
   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
          )
{
  //設(shè)計(jì)一個(gè)窗口類
  WNDCLASS wndcls;
  wndcls.cbClsExtra = 0;
  wndcls.cbWndExtra = 0;
  wndcls.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH);
  wndcls.hCursor = LoadCursor(NULL, IDC_CROSS);
  wndcls.hIcon = LoadIcon(NULL, IDI_ERROR);
  wndcls.hInstance = hInstance;  //應(yīng)用程序?qū)嵗浔蒞inMain函數(shù)傳進(jìn)來(lái)
  wndcls.lpfnWndProc = WinAzeProc;
  wndcls.lpszClassName = "aze_003";
  wndcls.lpszMenuName = NULL;
  wndcls.style = CS_HREDRAW | CS_VREDRAW;

  RegisterClass(&wndcls);  //注冊(cè)窗口類
  
  //創(chuàng)建窗口，定義一個(gè)變量用來(lái)保存成功創(chuàng)建后返回的句柄
  HWND hwnd;  
  hwnd = CreateWindow("aze_003", "first Application", WS_OVERLAPPEDWINDOW, 0, 0, 600, 500, NULL, NULL,hInstance, NULL);

  ShowWindow(hwnd, SW_SHOWNORMAL);  //顯示窗口
  UpdateWindow(hwnd);    //刷新窗口

  //定義消息結(jié)構(gòu)體，開(kāi)始消息循環(huán)
  MSG msg;
  while( GetMessage(&msg, NULL, 0, 0) )
  {
    TranslateMessage(&msg);
    DispatchMessage(&msg);
  }
  return msg.wParam;
}

//編寫(xiě)窗口過(guò)程函數(shù)
LRESULT CALLBACK WinAzeProc(
   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 code is %d", wParam);
    MessageBox(hwnd, szChar, "char", 0);
    break;
  case WM_LBUTTONDOWN:
    MessageBox(hwnd, "mouse clicked", "message", 0);
    HDC hdc;
    hdc = GetDC(hwnd);    //不能在響應(yīng)WM_PAINT消息時(shí)調(diào)用
    TextOut( hdc, 0, 50, "程序員之家!",strlen("程序員之家！") );
    ReleaseDC(hwnd, hdc);
    break;
  case WM_PAINT:
    HDC hDC;
    PAINTSTRUCT ps;
    hDC = BeginPaint(hwnd, &ps);  //BeginPaint只能在響應(yīng)WM_PAINT消息是調(diào)用
    TextOut(hDC, 0, 0, "http://www.sunxin.org", strlen("http://www.sunxin.org"));
    EndPaint(hwnd, &ps);
    break;
  case WM_CLOSE:
    if( IDYES == MessageBox(hwnd, "是否真的退出？", "message", MB_YESNO) )
    {
      DestroyWindow(hwnd);
    }
    break;
  case WM_DESTROY:
    PostQuitMessage(0);
    break;
  default:
    return DefWindowProc(hwnd, uMsg, wParam, lParam);
  }
  return 0;
}

//The MSG structure contains message information from a thread's message queue. 

typedef struct tagMSG {
 HWND  hwnd;     //消息所屬的窗口，消息都是與窗口相關(guān)聯(lián)的
 UINT  message;   //the message identifier
 WPARAM wParam;    //指定消息的附加消息
 LPARAM lParam;    //指定消息的附加消息
 DWORD time;     //消息投遞到隊(duì)列中的時(shí)間
 POINT pt;      //鼠標(biāo)的當(dāng)前位置
} MSG, *PMSG;

//The WinMain function is called by the system as the initial entry point for a Windows-based application. 

int WINAPI WinMain(
 HINSTANCE hInstance,   // handle to current instance當(dāng)前窗口句柄
 HINSTANCE hPrevInstance, // handle to previous instance前一個(gè)打開(kāi)的窗口句柄
 LPSTR lpCmdLine,     // command line 指定傳遞給應(yīng)用程序的*命令行*參數(shù)
 int nCmdShow       // show state 指定窗口應(yīng)該如何顯示，如：最大（小）化、隱藏等
);

typedef struct _WNDCLASS { 
  UINT    style;    //指定*這一類型*窗口的樣式，如：CS_HREDRAW、CS_VREDRAW、CS_NOCLOSE、CS_DBLCLKS
  WNDPROC  lpfnWndProc;   //函數(shù)指針，指向窗口過(guò)程函數(shù)（窗口過(guò)程函數(shù)是一回調(diào)函數(shù)）
  int    cbClsExtra;   //一般為0
  int    cbWndExtra;   //同上
  HINSTANCE hInstance;   //指定包含窗口過(guò)程的程序的實(shí)例句柄
  HICON   hIcon;     //指定窗口類的圖標(biāo)句柄
  HCURSOR  hCursor;   //指定窗口類的光標(biāo)句柄
  HBRUSH   hbrBackground;   //指定窗口類的背景畫(huà)刷句柄；當(dāng)窗口發(fā)生重繪值，系統(tǒng)使用這里指定的畫(huà)刷來(lái)查處窗口的背景
  LPCTSTR  lpszMenuName;   //指定菜單資源的名字 **菜單并不是一個(gè)窗口**
  LPCTSTR  lpszClassName;   //指定窗口類的名字
} WNDCLASS, *PWNDCLASS;

typedef LRESULT (CALLBACK* WNDPROC)(HWND, UINT, WPARAM, LPARAM); //LRESULT=long, CALLBACK=_stdcall WNDPROC是函數(shù)指針類型。

//The GetStockObject function retrieves a handle to one of the stock pens, brushes, fonts, or palettes. 

HGDIOBJ GetStockObject(
 int fnObject  // stock object type
);

wndcls.hbrBackground = (HBRUSH)GetStockObject(BLACK_BRUSH); 

ATOM RegisterClass(
 CONST WNDCLASS *lpWndClass // class data, 窗口類對(duì)象的指針
               // Pointer to a WNDCLASS structure. You must fill the structure with the appropriate class attributes before passing it to the function. 
);

HWND CreateWindow(
 LPCTSTR lpClassName, // registered class name 即：窗口類WNDCLASS的lpszClassName成員指定的名稱（必須先注冊(cè)）
 LPCTSTR lpWindowName, // window name  指定窗口的名字
 DWORD dwStyle,    // window style 指定創(chuàng)建窗口的樣式 如：WS_OVERLAPPEDWINDOW
 int x,        // horizontal position of window
 int y,        // vertical position of window
 int nWidth,      // window width
 int nHeight,     // window height
 HWND hWndParent,   // handle to parent or owner window 指定被創(chuàng)建窗口的父窗口句柄
 HMENU hMenu,     // menu handle or child identifier
 HINSTANCE hInstance, // handle to application instance
 LPVOID lpParam    // window-creation data 作為WM_CREATE消息的附加參數(shù)lParam傳入的數(shù)據(jù)指針（一般為：NULL）
);

BOOL ShowWindow(
 HWND hWnd,   // handle to window 該參數(shù)為成功創(chuàng)建窗口后返回的那個(gè)窗口句柄
 int nCmdShow  // show state 如：SW_HIDE、SW_SHOW、SW_SHOWNORMAL、SW_SHOWMINIMIZED、SW_SHOWMAXIMIZED··
);

BOOL UpdateWindow(
 HWND hWnd  // handle to window 創(chuàng)建成功后的窗口句柄
);

BOOL GetMessage(
 LPMSG lpMsg,     // message information 指向一個(gè)消息（MSG）結(jié)構(gòu)體，GetMessage從線程的消息隊(duì)列中取出的消息信息將保存在該結(jié)構(gòu)體對(duì)象中
 HWND hWnd,      // handle to window 指定接收屬于哪一個(gè)窗口的消息；NULL：用于接收屬于調(diào)用線程的所有窗口的窗口消息
 UINT wMsgFilterMin, // first message 指定獲取打的消息的最小值
 UINT wMsgFilterMax  // last message 如果wMsgFilterMin=0和wMsgFilterMax=0，則接收所有消息
);

//消息循環(huán)代碼，一般形式
  MSG msg;
  while( GetMessage(&msg, NULL, 0, 0) )
  {
    TranslateMessage(&msg); //TranslateMessage函數(shù)將虛擬鍵消息*轉(zhuǎn)換*為字符消息，被投遞到調(diào)用線程的消息隊(duì)列中，當(dāng)下一次調(diào)用GetMessage函數(shù)時(shí)被取出
    DispatchMessage(&msg);  //DispatchMessage函數(shù)分派一個(gè)消息到窗口過(guò)程，有窗口過(guò)程函數(shù)對(duì)消息進(jìn)行處理
//DispatchMessage實(shí)際上是將消息會(huì)傳給操作系統(tǒng)，有操作系統(tǒng)調(diào)用窗口過(guò)程函數(shù)對(duì)消息進(jìn)行處理（響應(yīng)）
  }

BOOL PeekMessage(
 LPMSG lpMsg,     // message information
 HWND hWnd,      // handle to window
 UINT wMsgFilterMin, // first message
 UINT wMsgFilterMax, // last message
 UINT wRemoveMsg   // removal options
);

LRESULT CALLBACK WindowProc(  //窗口過(guò)程函數(shù)的名字可以隨便取，如：WinAzeProc，但函數(shù)聲明與定義要一致；
 HWND hwnd,   // handle to window
 UINT uMsg,   // message identifier 消息代碼
 WPARAM wParam, // first message parameter 消息代碼的兩個(gè)附加值
 LPARAM lParam  // second message parameter
);

//編寫(xiě)窗口過(guò)程函數(shù)
LRESULT CALLBACK WinAzeProc(
              HWND hwnd,   // handle to window
              UINT uMsg,   // message identifier
              WPARAM wParam, // first message parameter
              LPARAM lParam  // second message parameter
              )
{
  switch(uMsg)
  {
  case WM_CHAR:  //通過(guò)調(diào)用TranslateMessage函數(shù)轉(zhuǎn)換得到
    char szChar[20];
    sprintf(szChar, "char code is %d", wParam);
    MessageBox(hwnd, szChar, "char", 0);
    break;
  case WM_LBUTTONDOWN:
    MessageBox(hwnd, "mouse clicked!", "message", 0);
    HDC hdc;
    hdc = GetDC(hwnd);    //用hdc保存GetDC函數(shù)返回的與特定窗口相關(guān)聯(lián)的DC的句柄。
                //GetDC()不能在響應(yīng)WM_PAINT消息時(shí)調(diào)用
    TextOut( hdc, 0, 50, "程序員之家!",strlen("程序員之家！") );  //TextOut利用得到的DC句柄在指定的位置（0，50）出輸出一行文字
    ReleaseDC(hwnd, hdc);  //釋放hdc
    break;
  case WM_PAINT:  //當(dāng)窗口客服區(qū)的一部分或者全部變?yōu)椤盁o(wú)效”時(shí)，系統(tǒng)會(huì)發(fā)送WM_PAINT消息，通知應(yīng)用程序重新繪制窗口
          //窗口剛創(chuàng)建時(shí)，客戶區(qū)是無(wú)效狀態(tài)，當(dāng)調(diào)用UpdateWindow函數(shù)時(shí)，會(huì)發(fā)送WM_PAINT消息給窗口過(guò)程，對(duì)窗口進(jìn)行刷新
          //當(dāng)窗口從無(wú)到有、改變尺寸、最小化在恢復(fù)、被其他窗口遮蓋后在顯示時(shí)，窗口的客戶區(qū)都將變?yōu)闊o(wú)效，此時(shí)系統(tǒng)會(huì)給應(yīng)用程序發(fā)送WM_PAINT消息，通知應(yīng)用程序重新繪制
          //提示：窗口大小發(fā)生變化時(shí)，是否發(fā)生重繪，取決于WNDCLASS結(jié)構(gòu)體中style成員是否設(shè)置了CS_HREDRAW和CS_VREDRAW標(biāo)志
    HDC hDC;
    PAINTSTRUCT ps;    //ps用于接收繪制的信息
    hDC = BeginPaint(hwnd, &ps);  //BeginPaint只能在響應(yīng)WM_PAINT消息是調(diào)用
    TextOut(hDC, 0, 0, "http://www.sunxin.org", strlen("http://www.sunxin.org")); 
    EndPaint(hwnd, &ps);
    break;
  case WM_CLOSE:
    if( IDYES == MessageBox(hwnd, "是否真的退出？", "message", MB_YESNO) )
    {
      DestroyWindow(hwnd);
    }
    break;
  case WM_DESTROY:
    PostQuitMessage(0);
    break;
  default:
    return DefWindowProc(hwnd, uMsg, wParam, lParam); //DefWindowProc調(diào)用默認(rèn)的窗口過(guò)程，對(duì)應(yīng)用程序沒(méi)有處理的其他消息提供默認(rèn)處理。
//對(duì)于大多數(shù)的消息，應(yīng)用程序可以直接調(diào)用DefWindowProc函數(shù)進(jìn)行處理。
//在編寫(xiě)窗口過(guò)程時(shí)，應(yīng)將DefWindowProc函數(shù)的調(diào)用放到default語(yǔ)句中，并將該函數(shù)的返回值作為窗口過(guò)程函數(shù)的返回值。
  }
  return 0;
}