PostMessage problem

tataxin

I want to send a string between 2 dialog. So I try to use SendMessage() with WM_COPYDATA message Here is the code in send dialog

COPYDATASTRUCT cds;
.... // insert data here

::SendMessage(hWnd, WM_COPYDATA, (WPARAM) m_hWnd, (LPARAM) &cds );

And receive dialog code:

BEGIN_MESSAGE_MAP(RcvDlg, CDialog)
.....
ON_WM_COPYDATA()
END_MESSAGE_MAP()

BOOL RcvDlg::OnCopyData(){
... // get data here
}

It works, but while sending messeage, it locks the send dialog. So I want to change to another way, PostMessage. But I don't know how to implement. I tried to look on the internet, but cannot find what I want. Can anyone help me? Thanks in advance, :)

Naveen

Don't you see the following comments just below the help of WM_COPYDATA in MSDN[^] _An application must use the SendMessage function to send this message, not the PostMessage function_.

nave [OpenedFileFinder]

tataxin

oh, that's why I wasn't success. thank you very much, Naveen. So this means that when dialog A sends a string message to dialog B, it must be locked until receive the reply. Is it correct??

Hamid Taebi

And see Inter-Process Communication using WM_COPYDATA[^].

Naveen

tataxin wrote:

So this means that when dialog A sends a string message to dialog B, it must be locked until receive the reply. Is it correct??

Yes. :(

nave [OpenedFileFinder]

Jijo Raj

tataxin wrote:

It works, but while sending messeage, it locks the send dialog.

Since SendMessage is blocking call, it will return only after the WM_COPYMESSAGE handler returns. So don't do any heavy processing in your WM_COPYMESSAGE handler. The best method is copy the data and trigger the processing in another thread so that the handler can return immediately.

tataxin wrote:

It works, but while sending messeage, it locks the send dialog. So I want to change to another way, PostMessage.

You should not use PostMessage for WM_COPYDATA, since its asynchronous. This article might be helpful - http://www.codeguru.com/cpp/w-p/win32/article.php/c1429/[^] Regards, Jijo.

_____________________________________________________ http://weseetips.com[^] Visual C++ tips and tricks. Updated daily.

tataxin

thank you everyone, I will do like that

bonkers

You need a class that handles the post msgs....

void FACTORY::addWindow(HWND hWnd)
{
m_Windows.push_back(hWnd);
}

thus, regsiter all the windows with this class with the function above. (FACTORY::instance().addWindow(m_hWnd);) then, you send these messages to the different classes that registered to this via the PostMessage function....

void FACTORY::PostMessage(UINT Msg, WPARAM wParam, LPARAM lParam)
{

list<HWND>::iterator i;
int count = 0;

HWND hWnd;
for( i = m\_Windows.begin(); i != m\_Windows.end(); i++)
{
  hWnd = \*i;

  ::PostMessage(hWnd, Msg, wParam, lParam);
}

}

Then simply post the message and catch it in the class....

FACTORY::instance().PostMessage(THE_MESSAGE, (long)VAL1, (long)VAL2);

and "catch" it in you PretranslateMessage functions....

if(pMsg->message == THE_MESSAGE)

then get the vals...

int VAL1 = (long)pMsg->wParam;
int VAL2 = (long)pMsg->lParam;

OR SOMETHING LIKE THAT....

modified on Tuesday, June 24, 2008 3:04 AM

tataxin

Oh ha', thank you Naveen

tataxin · modified on Tuesday, June 24, 2008 3:04 AM

Thank you, bonkers. I just wonder if the receive dialog can get a string message ("Hello" for example) by this way?