- 1 year ago
Controls on top of a tab have the incorrect background in Win32 GUI
If controls on top of a tab have the incorrect background in a Win32 GUI, it is likely because the control is not being redrawn correctly. Here are a few troubleshooting steps you can try:
Use the WS_EX_COMPOSITED style: Try setting the
WS_EX_COMPOSITED
style on the tab control and the parent window. This style can help reduce flickering and improve control redraws.Force redraws: If setting the
WS_EX_COMPOSITED
style does not work, you can try forcing the controls to redraw themselves. You can do this by sending aWM_ERASEBKGND
message to the control and then sending aWM_PAINT
message to trigger a repaint. Here is an example:scssHWND hWndTab = GetDlgItem(hwndParent, IDC_TAB1);
HDC hdc = GetDC(hWndTab);
SendMessage(hWndTab, WM_ERASEBKGND, (WPARAM)hdc, 0);
ReleaseDC(hWndTab, hdc);
InvalidateRect(hWndTab, NULL, TRUE);
UpdateWindow(hWndTab);
This code gets the handle of the tab control, gets its device context, sends a
WM_ERASEBKGND
message to erase the control's background, releases the device context, and then invalidates the control and triggers a repaint.Use a custom drawing function: If neither of the above methods work, you can try using a custom drawing function to manually draw the controls on top of the tab. This can be more complex, but gives you full control over the appearance of the controls. Here is an example:
scss// Define a custom drawing function
LRESULT CALLBACK TabCustomDrawProc(HWND hWnd, UINT message, WPARAM wParam, LPARAM lParam, UINT_PTR uIdSubclass, DWORD_PTR dwRefData)
{
// Handle the drawing message
if (message == WM_PAINT)
{
// Get the device context
PAINTSTRUCT ps;
HDC hdc = BeginPaint(hWnd, &ps);
// Draw the control
// ...
// Release the device context
EndPaint(hWnd, &ps);
return 0;
}
// Pass other messages to the default window procedure
return DefSubclassProc(hWnd, message, wParam, lParam);
}
// Subclass the tab control and set the custom drawing function
HWND hWndTab = GetDlgItem(hwndParent, IDC_TAB1);
SetWindowSubclass(hWndTab, TabCustomDrawProc, 0, 0);
This code defines a custom drawing function that handles the
WM_PAINT
message, draws the control manually, and then releases the device context. The code then subclasses the tab control and sets the custom drawing function.
By following these steps, you should be able to resolve issues with controls on top of a tab having the incorrect background in a Win32 GUI.