在DLL中产生对话框的方法1

什么是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.

对话框：
对话框可以分为modal和modeless两种。

在Win32 Dll中创建modal对话框。
在一个Win32Dll中创建modal对话框非常简单，我们都知道，Win32函数DialogBox能够创建一个modal对话框，并且modal对话框的消息是独立于主程序消息循环的，所以可以直接在Dll内部建立对话框自己的窗口过程。下面就是一个在Win32 Dll中创建modal对话框的示例：
//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,"这是一个modal对话框的例子","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"); //获取库所在的实例句柄
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 中创建modeless对话框。
与modal对话框不同，modeless对话框的消息是要经过主程序消息循环的，这样一来，就必须在调用该Dll的主程序中处理对话框的消息循环，这就无法达到利用Dll来完成组件化开发的要求。其实我们可以人为的Modeless对话框创建一个窗口类，我们知道窗口过程是属于窗口类的，这样一来就有了主窗口的消息循环。
//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) ; //并不在这里显示主窗口
// 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,"这是一个modeless对话框的例子","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用来创建窗口,并且对话框模板要指定visible属性为True,只有这样才能显示对话框.
if(hDialog==0||!IsDialogMessage(hDialog,&msg))这一句是起消息分流作用的,对于属于对话框的消息一律交给对话框过程DlgProc来处理。
处理对话框的退出一定要使用DetroyWindow函数,并且要发送一个退出消息,使那个没有显示的主窗口也能够退出消息循环,不至于造成内存泄露。

本文来自CSDN博客，转载请标明出处：http://blog.csdn.net/hailongchang/archive/2006/12/19/1448782.aspx