www.pudn.com > Winmobile.zip > EventGrabber.cpp

//-------------------------------------------------------------- 
// EventGrabber.cpp : Maintains grabber linked-list 
// 
// Code from _Programming the .NET Compact Framework with C#_ 
// and _Programming the .NET Compact Framework with VB_ 
// (c) Copyright 2002-2003 Paul Yao and David Durant.  
// All rights reserved. 
//-------------------------------------------------------------- 
#include "stdafx.h" 
#include "YaoDurantControls.h" 
 
EventGrabberList::EventGrabberList() 
{ 
   m_pegHead = NULL; 
   m_pegTail = NULL; 
} 
 
//----------------------------------------------------------- 
// Add new handler for control. 
//----------------------------------------------------------- 
BOOL EventGrabberList::AddEventGrabber( 
   HWND hwndCtrl,  
   HWND hwndGrabber,  
   int flags,  
   WNDPROC lpfn) 
{ 
   // Allocate memory for event grabber. 
   LPEVENTGRABBER peg; 
   peg = (LPEVENTGRABBER)malloc(sizeof(EVENTGRABBER)); 
   if (peg == NULL) 
      return FALSE; 
 
   peg->hwndControl = hwndCtrl; 
   peg->hwndGrabber = hwndGrabber; 
   peg->fEvents = flags; 
   peg->lpfn = lpfn; 
 
   // First time called? 
   if (m_pegHead == NULL && m_pegTail == NULL) 
   { 
      m_pegHead = peg; 
      m_pegTail = peg; 
      peg->pPrev = NULL; 
      peg->pNext = NULL; 
   } 
   else 
   { 
      // Last becomes second to last. 
      m_pegTail->pNext = peg; 
 
      // Last becomes our previous item. 
      peg->pPrev = m_pegTail; 
 
      // New item is now last item. 
      m_pegTail = peg; 
      peg->pNext = NULL; 
   } 
 
   return TRUE; 
} // AddEventGrabber() 
 
//----------------------------------------------------------- 
// Find handler for control. 
//----------------------------------------------------------- 
LPEVENTGRABBER WINAPI EventGrabberList::FindEventGrabber(HWND hwnd) 
{ 
   LPEVENTGRABBER peg; 
   for (peg = m_pegHead;  
        peg != NULL;  
        peg = peg->pNext) 
   { 
      if (peg->hwndControl == hwnd) 
         return peg; 
   } 
 
   return peg; 
} // FindEventGrabber() 
 
//----------------------------------------------------------- 
// Find first grabber in list (cleanup helper). 
//----------------------------------------------------------- 
LPEVENTGRABBER WINAPI EventGrabberList::FindFirstEventGrabber() 
{ 
   return m_pegHead; 
} // FindFirstEventGrabber 
 
//----------------------------------------------------------- 
// Remove grabber for control. 
//----------------------------------------------------------- 
BOOL WINAPI EventGrabberList::RemoveEventGrabber(HWND hwnd) 
{ 
   LPEVENTGRABBER peg = FindEventGrabber(hwnd); 
   if (peg == NULL) 
      return FALSE; 
 
   // Cleanup singleton entry on list 
   if (peg->pPrev == NULL && peg->pNext == NULL) 
   { 
      m_pegHead = NULL; 
      m_pegTail = NULL; 
   } 
   else 
   { 
      // Fix-up pointer to previous grabber. 
      if (peg->pPrev == NULL) 
      { 
         // Previous item is now head of list. 
         m_pegHead = peg->pNext; 
      } 
      else 
      { 
         // Previous item gets our next ptr. 
         peg->pPrev->pNext = peg->pNext; 
      } 
      // Fix-up pointer to next grabber. 
      if (peg->pNext == NULL) 
      { 
         m_pegTail = peg->pPrev; 
      } 
      else 
      { 
         // Next item gets our previous ptr. 
         peg->pNext->pPrev = peg->pPrev; 
      } 
   } 
 
   // Free memory for grabber. 
   free(peg); 
 
   return TRUE; 
} // RemoveEventGrabber