CWinThread Can't Receive Custom Message in some case
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From: Joseph M. Newcomer on 20 Sep 2009 12:01 Thread messages can only be used to a UI thread which has no visible windows and which uses only the MFC message pump in the secondary thread for its dispatching. You should never, ever, create user-visible interface objects in a secondary thread (the rules about what must be done and how it must be done are largely undocumented folklore, and a good hint about their usability is the fact that nobody with any serious Windows experience ever thinks this would be a good idea). A sure way to tell a beginner from an expert is that a beginner tends to think about creating UI objects in secondary threads; an expert would not consider this except under the most extreme circumstances. I have no idea what you mean by "try to printf" since that is a waste of time; there is no place printf can code. And you would not be using sprintf, or wsprintf because these are obsolete and dangerous. Presumably you are using CString::Format. To maintain counts like you are suggesting, you would create a modeless dialog owned by the main GUI thread. joe On Mon, 14 Sep 2009 01:25:51 -0700 (PDT), "Jason .Y" <lin.yang.jason(a)gmail.com> wrote: > >Hi,I have come to meet a strange question in my application: > >I have 2 Thread, which are both created by AfxBeginThread function >with a parameter of a derived class of CWinThread: >MsgCenterThread >MainTestThread > >and the MainTestThread is always trying to post thread messages to >MsgCenterThread, The messages are defined as below: >#define APPMSG_SHOWDLG (WM_USER + 211) >#define APPMSG_DATA (WM_USER + 212) > >The APPMSG_DATA is send 1 time per second, and the lParam is the count >of sending. > >In case of APPMSG_SHOWDLG, the MsgCenterThread will create a CDialog >object and call the DoModal method.and in another case, The >MsgCenterThread will try to printf the sending count, which is >attached with the APPMSG_DATA as lParam . > >The application seems to work fine,but once the MsgCenter has received >the APPMSG_SHOWDLG and show the Dialog, the MsgCenterThread can't >receive the APPMSG_DATA message for sometimes when I just clicked on >the Dialog very frequently. > >By the way, My coding environment is :Windows XP + VS2005 > >Any suggestion will be appriciated. > >Jason Joseph M. Newcomer [MVP] email: newcomer(a)flounder.com Web: http://www.flounder.com MVP Tips: http://www.flounder.com/mvp_tips.htm
From: Jason .Y on 20 Sep 2009 22:02
On 9æ21æ¥, ä¸å12æ¶01å, Joseph M. Newcomer <newco...(a)flounder.com> wrote: > Thread messages can only be used to a UI thread which has no visible windows and which > uses only the MFC message pump in the secondary thread for its dispatching.  You should > never, ever, create user-visible interface objects in a secondary thread (the rules about > what must be done and how it must be done are largely undocumented folklore, and a good > hint about their usability is the fact that nobody with any serious Windows experience > ever thinks this would be a good idea).  A sure way to tell a beginner from an expert is > that a beginner tends to think about creating UI objects in secondary threads; an expert > would not consider this except under the most extreme circumstances. > > I have no idea what you mean by "try to printf" since that is a waste of time; there is no > place printf can code.  And you would not be using sprintf, or wsprintf because these are > obsolete and dangerous.  Presumably you are using CString::Format. > > To maintain counts like you are suggesting, you would create a modeless dialog owned by > the main GUI thread. >                 joe > > > > > > On Mon, 14 Sep 2009 01:25:51 -0700 (PDT), "Jason .Y" <lin.yang.ja...(a)gmail.com> wrote: > > >Hi,I have come to meet a strange question in my application: > > >I have 2 Thread, which are both created by AfxBeginThread function > >with a parameter of a derived class of CWinThread: > >MsgCenterThread > >MainTestThread > > >and the MainTestThread is always trying to post thread messages to > >MsgCenterThread, The messages are defined as below: > >#define APPMSG_SHOWDLG (WM_USER + 211) > >#define APPMSG_DATA (WM_USER + 212) > > >The APPMSG_DATA is send 1 time per second, and the lParam is the count > >of sending. > > >In case of APPMSG_SHOWDLG, the MsgCenterThread will create a CDialog > >object and call the DoModal method.and in another case, The > >MsgCenterThread will try to printf the sending count, which is > >attached with the APPMSG_DATA as lParam . > > >The application seems to work fine,but once the MsgCenter has received > >the APPMSG_SHOWDLG and show the Dialog, the MsgCenterThread can't > >receive the APPMSG_DATA message for sometimes when I just clicked on > >the Dialog very frequently. > > >By the way, My coding environment is :Windows XP + VS2005 > > >Any suggestion will be appriciated. > > >Jason > > Joseph M. Newcomer [MVP] > email: newco...(a)flounder.com > Web:http://www.flounder.com > MVP Tips:http://www.flounder.com/mvp_tips.htm Thank you very much for your help. now I get to realize that's not a good way to post thread message to another thread, which creates user- visible interface objects. This strange question is by design. |