52b
Subj : TWMNCHitTest
To   : borland.public.cpp.borlandcpp
From : "Richard Kavanagh" <r.kavanagh@daelnet.net>
Date : Tue Jul 15 2003 11:20 am

I needed to drag a Form with no title bar accross the screen. So I used the
following Macro

BEGIN_MESSAGE_MAP
VCL_MESSAGE_HANDLER(WM_NCHITTEST, TWMNCHitTest, WMNCHitTest)
END_MESSAGE_MAP(TForm)

together with this private function

void __fastcall TForm1::WMNCHitTest(TWMNCHitTest &Message)
// needed to move the form as it has no titlebar
{
 TForm::Dispatch(&Message);
 if (Message.Result == HTCLIENT)
  Message.Result = HTCAPTION;
}
// -------------------------------------------------

An annoying compiler warning to do with switch statements  not expanding
inline occurred. So I translated the Macro to

protected:
 virtual inline void __fastcall Dispatch(void* message);

and

void __fastcall TForm1::Dispatch(void* message)
{
 if(static_cast<TMessage*>(message)->Msg == WM_NCHITTEST)
  WMNCHitTest( *static_cast<TWMNCHitTest*>(message) );
 else
  TForm::Dispatch(message);
}
// -------------------------------------------------

and everything worked fine. However I can find no documentation to describe
the object type TWMNCHitTest. I hate using things I do not understand. Is
there anybody who can enlighten me.
Richard K

.

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