Category : C Source Code
Archive   : TERMWAIT.ZIP
Filename : CALLBACK.C

//****************************************************************************
// File: callback.c
//
// Purpose: callback funtions including notification call back
//
// Functions:
// MainWndProc - message handler for Main window
// NotifyRegisterCallback - callback for NotifyRegister
// AfterChildHasTerminated - code to be executed after child has terminated
// AboutDlg - dialog function for about box
//
// Development Team:
// Vinoo Cherian
//
// Written by Microsoft Product Support Services, Windows Developer Support
// Copyright (c) 1992 Microsoft Corporation. All rights reserved.
//****************************************************************************
#include
#include
#include
#include "termwait.h"

// Globals
HTASK ghtaskParent;
BOOL bChildIsExecuting = FALSE;
HINSTANCE ghInstChild;

// Local function prototypes
BOOL FAR PASCAL NotifyRegisterCallback (WORD, DWORD);
BOOL CALLBACK AboutDlg (HWND , UINT, WPARAM, LPARAM);
void AfterChildHasTerminated(HWND);

//****************************************************************************
// Function: MainWndProc
//
// Purpose: Message handler for main overlapped window.
//
// Parameters:
// hwnd == Handle to _this_ window.
// msg == Message to process.
// wParam == WORD parameter -- depends on message
// lParam == LONG parameter -- depends on message
//
// Returns: Depends on message.
//
// Comments:
//
// History: Date Author Reason
// 4/17/92 Vinoo Cherian Created
//****************************************************************************
LRESULT CALLBACK MainWndProc (HWND hwnd, UINT msg, WPARAM wParam, LPARAM lParam)
{
static LPFNNOTIFYCALLBACK lpfnCallback;

switch (msg)
{
case WM_CREATE:
ghtaskParent = GetCurrentTask();
return 0;

case WM_COMMAND:
switch (wParam)
{
case IDM_WINEXECNOTEPAD:

{
// Install notification callback
lpfnCallback = (LPFNNOTIFYCALLBACK)MakeProcInstance((FARPROC)NotifyRegisterCallback, ghInst);
if (!NotifyRegister(NULL, lpfnCallback, NF_NORMAL))
{
MessageBox(hwnd, "NotifyRegister Failed", "Error", MB_OK);
FreeProcInstance(lpfnCallback);
break;
}

// Winexec child
// bChildIsExecuting can used to determine if the child is executing.
// Any code that should not be executed while the child is executing
// can check the value of bChildIsExecuting.
bChildIsExecuting = TRUE;
if ((ghInstChild = (HINSTANCE)WinExec("notepad.exe", SW_SHOW)) < 32 )
{
char achMes[30];

bChildIsExecuting = FALSE;
NotifyUnRegister(NULL);
FreeProcInstance(lpfnCallback);
wsprintf((LPSTR)achMes, "WinExec failed. Error code : %d", (int)ghInstChild);
MessageBox(hwnd, achMes,"Error", MB_OK);
break;
}
break;
}

case IDM_ABOUT:
{
DLGPROC lpDlgProc;
char szAboutBoxName[STR_LEN];

LoadString(ghInst, IDS_ABOUTBOXNAME, szAboutBoxName, STR_LEN);
lpDlgProc = MakeProcInstance(AboutDlg, ghInst);

DialogBox(ghInst, szAboutBoxName, hwnd, lpDlgProc);
FreeProcInstance(lpDlgProc);
break;
}
}
return 0;


case PM_TASKEND:
// Child has terminated
bChildIsExecuting = FALSE;
NotifyUnRegister(NULL);
FreeProcInstance(lpfnCallback);
// Do the processing that MUST be done after the child terminates
AfterChildHasTerminated(hwnd);
break;

case WM_INITMENU:
// Gray any menuitems that may cause reentrancy problems, while
// waiting for the child to terminate
if (bChildIsExecuting)
EnableMenuItem((HMENU)wParam, IDM_WINEXECNOTEPAD, MF_GRAYED);
else EnableMenuItem((HMENU)wParam, IDM_WINEXECNOTEPAD, MF_ENABLED);
break;

case WM_DESTROY:
PostQuitMessage(0);
return 0;
}
return DefWindowProc(hwnd, msg, wParam, lParam);
}

//*************************************************************
// NotifyRegisterCallback
//
// Purpose: Callback procedure for NotifyRegister
//
// Parameters:
// wID = Type of notification
// dwData = data or pointer to data depending on value of wID
//
// Comments:
//
// History: Date Author Reason
// 4/17/92 Vinoo Cherian Created
//****************************************************************************

BOOL FAR PASCAL NotifyRegisterCallback (WORD wID, DWORD dwData)
{
HTASK hTask; // handle of the task that called the notification call back
TASKENTRY te;


// Check for task exiting
switch (wID)
{
case NFY_EXITTASK:
// Obtain info about the task that is terminating
hTask = GetCurrentTask();
te.dwSize = sizeof(TASKENTRY);
TaskFindHandle(&te, hTask);

// Check if the task that is terminating is our child task.
// Also check if the hInstance of the task that is terminating
// in the same as the hInstance of the task that was WinExec'd by us
// earlier in this file. This additional check is added because
// the Task List that is brought up by selecting 'Switch To ...'
// from the system menu is also run as a child task of the application and
// consequently the hInstance needs to be checked to determine which
// child task is terminating.

if (te.hTaskParent == ghtaskParent && te.hInst == ghInstChild)
PostMessage(ghwnd, PM_TASKEND, (WORD)hTask, dwData );
break;

default:
break;
}

// Pass notification to other callback functions
return FALSE;

}

//****************************************************************************
// Function: AfterChildHasTerminated
//
// Purpose: Code that MUST be executed after child has terminated
//
// Parameters:
// hwnd == handle to window
//
// History: Date Author Reason
// 4/17/92 Vinoo Cherian Created
//****************************************************************************

void AfterChildHasTerminated(HWND hwnd)
{
MessageBox(hwnd, "Notepad, which I launched, has been terminated",
"Notification", MB_OK);
}

//****************************************************************************
// Function: AboutDlg
//
// Purpose: About dialog box function.
//
// Parameters:
// hwndDlg == Handle to _this_ window.
// msg == Message to process.
// wParam == WORD parameter -- depends on message
// lParam == LONG parameter -- depends on message
//
// Returns: Depends on message.
//
// Comments:
//
// History: Date Author Reason
// 1/27/92 Created
//****************************************************************************

BOOL CALLBACK AboutDlg (HWND hwndDlg, UINT msg, WPARAM wParam, LPARAM lParam)
{
switch (msg)
{
case WM_INITDIALOG:
return (TRUE);

case WM_COMMAND:
if ((wParam == IDOK) || // "OK" box selected?
(wParam == IDCANCEL)) // System menu close command?
{
EndDialog(hwndDlg, TRUE); // Exits the dialog box
return (TRUE);
}
break;
}

return (FALSE); // Didn't process a message
}