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--== Alain ==--
Guest
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 Posted: Tue Sep 26, 2006 12:38 am Post subject: detect adding column and repaint header |
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Hi,
i'm still working on my component and i would like to repaint the header.
i was thinking to trap a message for that purpose. However, i do not
know this message. Could you tell me which message is sent when a new
column is added ?
thanks a lot,
Alain |
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JD
Guest
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| Posted: Tue Sep 26, 2006 4:10 am Post subject: Re: detect adding column and repaint header |
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--== Alain ==-- <nospam (AT) noemail (DOT) com> wrote:
| Quote: |
i'm still working on my component and i would like to
repaint the header.
|
I presume that you're talking about a TListView descendent.
If that's that case, then you need to understand that a
TListView is just a wrapper arounf MicroSoft's ListView
control which actually consist of 2 controls. The Header
is a seperate window and while some messages (WM_NOTIFY)
can be intercepted in the ListViews WndProc, you'll need to
subclass the Header's WndProc to catch the others.
//-------------------------------------------------------------
#ifdef STRICT
#define HEADERWNDPROC WNDPROC
#else
#define HEADERWNDPROC FARPROC
#endif
//-------------------------------------------------------------
class TGradientListView : public TListView
{
typedef TListView inherited;
protected:
private:
HWND hHeader;
LONG HeaderWndProcPtr;
HEADERWNDPROC OldHeaderWndProc;
void __fastcall SubclassHeaderWndProc();
void __fastcall HeaderWndProc( TMessage &Message );
MESSAGE void __fastcall CMRecreateWnd( TMessage &Message );
public:
BEGIN_MESSAGE_MAP
VCL_MESSAGE_HANDLER( CM_RECREATEWND, TMessage, CMRecreateWnd )
END_MESSAGE_MAP( inherited )
__fastcall TGradientListView( TComponent* Owner );
__fastcall ~TGradientListView();
__published:
};
//-------------------------------------------------------------
//-------------------------------------------------------------
__fastcall TGradientListView::TGradientListView(TComponent* Owner) : TListView( Owner )
{
HeaderWndProcPtr = reinterpret_cast<LONG>( MakeObjectInstance(HeaderWndProc) );
SubclassHeaderWndProc();
}
//-------------------------------------------------------------
__fastcall TGradientListView::~TGradientListView()
{
if( hHeader ) ::SetWindowLong( hHeader, GWL_WNDPROC, reinterpret_cast<LONG>(OldHeaderWndProc) );
FreeObjectInstance( reinterpret_cast<void*>(HeaderWndProcPtr) );
}
//-------------------------------------------------------------
MESSAGE void __fastcall TGradientListView::CMRecreateWnd( TMessage &Message )
{
inherited::Dispatch( &Message );
SubclassHeaderWndProc();
}
//-------------------------------------------------------------
void __fastcall TGradientListView::SubclassHeaderWndProc()
{
hHeader = ListView_GetHeader( Handle );
if( hHeader ) OldHeaderWndProc = reinterpret_cast<HEADERWNDPROC>( ::SetWindowLong(hHeader, GWL_WNDPROC, HeaderWndProcPtr) );
}
//-------------------------------------------------------------
void __fastcall TGradientListView::HeaderWndProc( TMessage &Message )
{
switch( Message.Msg )
{
case WM_DESTROY: Message.Result = ::CallWindowProc(OldHeaderWndProc, hHeader, Message.Msg, Message.WParam, Message.LParam );
::SetWindowLong( hHeader, GWL_WNDPROC, reinterpret_cast<LONG>(OldHeaderWndProc) );
hHeader = NULL;
return;
}
Message.Result = ::CallWindowProc( OldHeaderWndProc, hHeader, Message.Msg, Message.WParam, Message.LParam );
}
//-------------------------------------------------------------
| Quote: | Could you tell me which message is sent when a new
column is added ?
|
You need to search MSN to see if there is a specific message
for that:
http://windowssdk.msdn.microsoft.com/en-us/library/ms670560.aspx
However, adding a column is only done programatically so you
should know when that's happening anyway.
~ JD |
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