在DLL中產生對話方塊的方法1

什麼是Dll?

     Stands for "Dynamic Link Library." A DLL (.dll) file contains a library of functions and other information that can be accessed by a Windows program. When a program is launched, links to the necessary .dll files are created. If a static link is created, the .dll files will be in use as long as the program is active. If a dynamic link is created, the .dll files will only be used when needed. Dynamic links help programs use resources, such as memory and hard drive space, more efficiently.

對話方塊：
      對話方塊可以分為modal和modeless兩種。
 
在Win32 Dll中建立modal對話方塊。
       在一個Win32Dll中建立modal對話方塊非常簡單，我們都知道，Win32函數DialogBox能夠建立一個modal對話方塊，並且modal對話方塊的訊息是獨立於主程式訊息迴圈的，所以可以直接在Dll內部建立對話方塊自己的視窗過程。下面就是一個在Win32 Dll中建立modal對話方塊的樣本：
//name: Modal_Dialog.cpp
#include<windows.h>
#include"resource.h"
BOOL CALLBACK DlgProc(HWND hwnd,UINT Msg,WPARAM wParam,LPARAM lParam)
 {
     switch(Msg)
     {
     case WM_INITDIALOG:
         return TRUE;
 
     case WM_COMMAND:
         switch(wParam)
         {
         case IDOK:
              MessageBox(NULL,"這是一個modal對話方塊的例子","提示",MB_OK);       
              EndDialog(hwnd, 0);
              return TRUE;
         }
         break;
     }
 
     return FALSE;
 }
 
extern"C" __declspec(dllexport) void ShowDialog()
{
     HINSTANCE hinst;
     hinst=LoadLibrary("Modal_Dialog.dll");     //擷取庫所在的執行個體控制代碼
     DialogBox(hinst,MAKEINTRESOURCE(IDD_DIALOG1),NULL,DlgProc);
     FreeLibrary(hinst);
}
//name: Test.cpp
……
     typedef void (*fp)();
     HINSTANCE hDll;
     fp Show;
     hDll = LoadLibrary("Modal_Dialog.dll");
     Show = (fp)GetProcAddress(hDll,"ShowDialog");
     (*Show)();
     FreeLibrary(hDll);
……
在Win32 Dll 中建立modeless對話方塊。
       與modal對話方塊不同，modeless對話方塊的訊息是要經過主程式訊息迴圈的，這樣一來，就必須在調用該Dll的主程式中處理對話方塊的訊息迴圈，這就無法達到利用Dll來完成組件化開發的要求。其實我們可以人為的Modeless對話方塊建立一個視窗類別，我們知道視窗過程是屬於視窗類別的，這樣一來就有了主視窗的訊息迴圈。
//name: Modeless_Dialog.cpp
#include <windows.h>
#include"resource.h"
LRESULT CALLBACK WndProc     (HWND, UINT, WPARAM, LPARAM) ;
BOOL    CALLBACK DlgProc (HWND, UINT, WPARAM, LPARAM) ;
 
extern"C" int __declspec(dllexport) ShowDialog()
{
     static TCHAR szAppName[] = TEXT ("Modeless_Dialog") ;
     HWND         hwnd ;
     MSG          msg ;
     WNDCLASS     wndclass ;
      HINSTANCE hInstance;
      HWND hDialog;
 
    hInstance = LoadLibrary("Modeless_Dialog.dll");
    
 
      wndclass.style         = CS_HREDRAW | CS_VREDRAW;
     wndclass.lpfnWndProc   = WndProc ;
     wndclass.cbClsExtra    = 0 ;
     wndclass.cbWndExtra    = DLGWINDOWEXTRA ;    // Note!
     wndclass.hInstance     = hInstance ;
     wndclass.hIcon         = LoadIcon (hInstance, szAppName) ;
     wndclass.hCursor       = LoadCursor (NULL, IDC_ARROW) ;
     wndclass.hbrBackground = (HBRUSH) (COLOR_BTNFACE + 1) ;
     wndclass.lpszMenuName = NULL ;
     wndclass.lpszClassName = szAppName ;
     hwnd = CreateWindow (szAppName, TEXT ("Modeless_Dialog"),
                          WS_OVERLAPPEDWINDOW | WS_CLIPCHILDREN,
                          CW_USEDEFAULT, CW_USEDEFAULT,
                          CW_USEDEFAULT, CW_USEDEFAULT,
                          NULL, NULL, hInstance, NULL) ;
    
    // ShowWindow (hwnd, iCmdShow) ;       //並不在這裡顯示主視窗
    // UpdateWindow (hwnd) ; 
hDialog = CreateDialog (hInstance, MAKEINTRESOURCE(IDD_DIALOG1), hwnd, DlgProc) ;
    
     while (GetMessage (&msg, NULL, 0, 0))
     {
          if(hDialog==0||!IsDialogMessage(hDialog,&msg))
          {
          TranslateMessage (&msg) ;
          DispatchMessage (&msg) ;
          }
     }
     return msg.wParam ;
 
}
BOOL CALLBACK DlgProc (HWND hDlg, UINT message,
                           WPARAM wParam, LPARAM lParam)
{
     switch(message)
     {
         case WM_INITDIALOG :
              return true;
         case WM_COMMAND:
              switch(wParam)
              {
              case(IDOK):
                   MessageBox(NULL,"這是一個modeless對話方塊的例子","提示",MB_OK);
                   DestroyWindow(hDlg);
                   PostQuitMessage (0) ;
                   return TRUE;
              }
     }
     return FALSE;
}
LRESULT CALLBACK WndProc (HWND hwnd, UINT message, WPARAM wParam, LPARAM lParam)
{   
     switch (message)
     {
     case WM_DESTROY:
          PostQuitMessage (0) ;
          return 0 ;
     }
     return DefWindowProc (hwnd, message, wParam, lParam) ;
}
      CreateDialog用來建立視窗,並且對話方塊模板要指定visible屬性為True,只有這樣才能顯示對話方塊.
       if(hDialog==0||!IsDialogMessage(hDialog,&msg))這一句是起訊息分流作用的,對於屬於對話方塊的訊息一律交給對話方塊過程DlgProc來處理。
        處理對話方塊的退出一定要使用DetroyWindow函數,並且要發送一個退出訊息,使那個沒有顯示的主視窗也能夠退出訊息迴圈,不至於造成記憶體泄露。

本文來自CSDN部落格，轉載請標明出處：http://blog.csdn.net/hailongchang/archive/2006/12/19/1448782.aspx