Let's say you have to create a window inside a window or a hole, just to look outside and say: "Hi" ;-).
It's not so difficult to accomplish - actually, it's pretty easy. The keyword is
SetWindowRgn - which sets the window border to the specified
CRgn. You can also invert the
RGN_XOR) and create a hole inside the window. I've created 2 functions for this:
void CreateHole(CRgn& rgn) - creates the hole in the shape of
void ClearHoles() - clear the holes and return the window to its usual shape
void CHolesDlg::CreateHole(CRgn& rgn)
static CRgn ThisRgn;
static bool Start = true;
GetWindowRect (WindowRect); WindowRgn.CreateRectRgn (0,0,WindowRect.Width (), WindowRect.Height());
ThisRgn.CombineRgn (&ThisRgn, &rgn, RGN_OR);
Start = false;
HoleRgn.CombineRgn (&ThisRgn, &WindowRgn, RGN_XOR);
SetWindowRgn ((HRGN__*)HoleRgn.m_hObject, TRUE);
WindowRgn.CreateRectRgn (0,0,WindowRect.Width (), WindowRect.Height());
SetWindowRgn ((HRGN__*)WindowRgn.m_hObject, TRUE);
GetDlgItem (IDC_CLEAR)->GetWindowText (s);
if (s == "Clear Holes")
GetDlgItem (IDC_CLEAR)->SetWindowText ("Show Holes");
if (s == "Show Holes")
GetDlgItem (IDC_CLEAR)->SetWindowText ("Clear Holes");
In my example, I show 4 shaped holes in a dialog-based application (VC++ 6.0, Windows 98). It should work well for other controls as well.
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