Background color of your controls

[TickTick]

I want to make a label that works with your controls, but I am unable to get the background color in a trustworthy way.

I tried this

Dim lBackColor&
If UserControl.ContainerHwnd = UserControl.Parent.hWnd Then 'we are sitting right on top of the form
lBackColor = UserControl.Parent.BackColor
Else 'we are inside a container
Dim lDC&
lDC = GetDC(UserControl.ContainerHwnd)
lBackColor = GetBkColor(lDC)
ReleaseDC UserControl.ContainerHwnd, lDC
End If
UserControl.BackColor = lBackColor

... and it works fine for the TabControl, but for your frame, I am also getting a white-background color, so I am having a white label on a grey-like frame...

Can you give me a hint how to retrieve the "correct" background color?

Thank you!

[TiKu]

... and it works fine for the TabControl

It doesn't, at least it does not if the tab control is themed. Themed tab controls (actually that's true for any themed control) do not necessarily have a solid background. Take the Luna theme of Windows XP: With this theme the tab control has a gradient background, not a single solid back color.

To support themes properly, you must use the DrawThemeParentBackground API function.
My CheckBox control uses this code to react to the WM_CTLCOLORSTATIC message:

Code: Select all

LRESULT CheckBox::OnReflectedCtlColorStatic(UINT /*message*/, WPARAM wParam, LPARAM lParam, BOOL& /*wasHandled*/)
{
	SetBkColor(reinterpret_cast<HDC>(wParam), OLECOLOR2COLORREF(properties.backColor));
	SetTextColor(reinterpret_cast<HDC>(wParam), OLECOLOR2COLORREF(properties.foreColor));
	if(IsComctl32Version600OrNewer()) {
		if(flags.invalidBackBrush) {
			WTL::CRect clientRectangle;
			::GetClientRect(reinterpret_cast<HWND>(lParam), &clientRectangle);

			CDC memoryDC;
			memoryDC.CreateCompatibleDC(reinterpret_cast<HDC>(wParam));
			CBitmap memoryBitmap;
			memoryBitmap.CreateCompatibleBitmap(reinterpret_cast<HDC>(wParam), clientRectangle.Width(), clientRectangle.Height());
			HBITMAP hPreviousBitmap = memoryDC.SelectBitmap(memoryBitmap);
			memoryDC.SetViewportOrg(-clientRectangle.left, -clientRectangle.top);

			CTheme themingEngine;
			if(flags.usingThemes) {
				themingEngine.OpenThemeData(*this, VSCLASS_BUTTON);
			}
			if(themingEngine.IsThemeNull()) {
				if(hBackColorBrush) {
					memoryDC.FillRect(&clientRectangle, hBackColorBrush);
				} else {
					memoryDC.FillRect(&clientRectangle, GetSysColorBrush(properties.backColor & 0x0FFFFFFF));
				}
			} else {
				memoryDC.FillRect(&clientRectangle, GetSysColorBrush(COLOR_3DFACE));
			}
			DrawThemeParentBackground(reinterpret_cast<HWND>(lParam), memoryDC, &clientRectangle);

			memoryDC.SelectBitmap(hPreviousBitmap);
			if(!themedBackBrush.IsNull()) {
				themedBackBrush.DeleteObject();
			}
			themedBackBrush.CreatePatternBrush(memoryBitmap);
			flags.invalidBackBrush = FALSE;
		}
		return reinterpret_cast<LRESULT>(static_cast<HBRUSH>(themedBackBrush));
	}
	if(hBackColorBrush) {
		return reinterpret_cast<LRESULT>(hBackColorBrush);
	} else {
		return reinterpret_cast<LRESULT>(GetSysColorBrush(properties.backColor & 0x0FFFFFFF));
	}
}