Win32编程点滴:消息循环(Message loop)
2010-01-10 09:37:13 来源:WEB开发网第五个版本?
我想我暂时是想不出第五个版本了,即便是一个简简单单的消息循环,也 还有很多深层次的东西可以挖掘。我们平时用惯了MFC/ATL/WTL之类的框架,它们已经将消息循环封装的 很好了,很多东西都已经自动处理了。我想,虽然有些东西我们不需要亲自处理,但是还是需要对此有 一定了解的。
最后,就已WTL的消息循环的源代码,结束这篇文章吧:
////////////////////////////////////////////////////////////////////////////// /
// CMessageLoop - message loop implementation
class CMessageLoop
{
public:
ATL::CSimpleArray<CMessageFilter*> m_aMsgFilter;
ATL::CSimpleArray<CIdleHandler*> m_aIdleHandler;
MSG m_msg;
// Message filter operations
BOOL AddMessageFilter(CMessageFilter* pMessageFilter)
{
return m_aMsgFilter.Add (pMessageFilter);
}
BOOL RemoveMessageFilter (CMessageFilter* pMessageFilter)
{
return m_aMsgFilter.Remove(pMessageFilter);
}
// Idle handler operations
BOOL AddIdleHandler(CIdleHandler* pIdleHandler)
{
return m_aIdleHandler.Add(pIdleHandler);
}
BOOL RemoveIdleHandler(CIdleHandler* pIdleHandler)
{
return m_aIdleHandler.Remove(pIdleHandler);
}
#ifndef _ATL_NO_OLD_NAMES
// for compatilibility with old names only
BOOL AddUpdateUI(CIdleHandler* pIdleHandler)
{
ATLTRACE2(atlTraceUI, 0, _T("CUpdateUIObject and AddUpdateUI are deprecated. Please change your code to use CIdleHandler and OnIdle\n"));
return AddIdleHandler(pIdleHandler);
}
BOOL RemoveUpdateUI(CIdleHandler* pIdleHandler)
{
ATLTRACE2 (atlTraceUI, 0, _T("CUpdateUIObject and RemoveUpdateUI are deprecated. Please change your code to use CIdleHandler and OnIdle\n"));
return RemoveIdleHandler(pIdleHandler);
}
#endif // ! _ATL_NO_OLD_NAMES
// message loop
int Run()
{
BOOL bDoIdle = TRUE;
int nIdleCount = 0;
BOOL bRet;
for(;;)
{
while(bDoIdle && !::PeekMessage(&m_msg, NULL, 0, 0, PM_NOREMOVE))
{
if(! OnIdle(nIdleCount++))
bDoIdle = FALSE;
}
bRet = ::GetMessage (&m_msg, NULL, 0, 0);
if(bRet == -1)
{
ATLTRACE2(atlTraceUI, 0, _T ("::GetMessage returned -1 (error)\n"));
continue; // error, don't process
}
else if(!bRet)
{
ATLTRACE2(atlTraceUI, 0, _T("CMessageLoop::Run - exiting\n"));
break; // WM_QUIT, exit message loop
}
if(!PreTranslateMessage (&m_msg))
{
::TranslateMessage(&m_msg);
::DispatchMessage (&m_msg);
}
if (IsIdleMessage(&m_msg))
{
bDoIdle = TRUE;
nIdleCount = 0;
}
}
return (int) m_msg.wParam;
}
static BOOL IsIdleMessage(MSG* pMsg)
{
// These messages should NOT cause idle processing
switch(pMsg->message)
{
case WM_MOUSEMOVE:
#ifndef _WIN32_WCE
case WM_NCMOUSEMOVE:
#endif // !_WIN32_WCE
case WM_PAINT:
case 0x0118: // WM_SYSTIMER (caret blink)
return FALSE;
}
return TRUE;
}
// Overrideables
// Override to change message filtering
virtual BOOL PreTranslateMessage(MSG* pMsg)
{
// loop backwards
for(int i = m_aMsgFilter.GetSize() - 1; i >= 0; i--)
{
CMessageFilter* pMessageFilter = m_aMsgFilter[i];
if(pMessageFilter != NULL && pMessageFilter->PreTranslateMessage(pMsg))
return TRUE;
}
return FALSE; // not translated
}
// override to change idle processing
virtual BOOL OnIdle(int /*nIdleCount*/)
{
for(int i = 0; i < m_aIdleHandler.GetSize(); i++)
{
CIdleHandler* pIdleHandler = m_aIdleHandler[i];
if (pIdleHandler != NULL)
pIdleHandler->OnIdle();
}
return FALSE; // don't continue
}
};
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