Change Window Background Color on timer

Im having trouble trying to figure out how to change the background color of a button every second. Go from one color to another. This is how I create My Button. or possibly how can you change the color of a HWND instance outside of onPaint if possible?

hButton = CreateWindowEx(WS_EX_TRANSPARENT, "Button","B",
    WS_CHILD | WS_VISIBLE | BS_PUSHBUTTON,
    20, 30, 20, 20, hwnd, (HMENU)ID_BUTTON,
    hInst, NULL);

Here is the changing color case inside the WndProc.

case WM_ERASEBKGND:

     RECT rc;
     GetClientRect(hButton, &rc);
     SetBkColor((HDC)wParam, 0x000000ff); // red
     ExtTextOut((HDC)wParam, 0, 0, ETO_OPAQUE, &rc, 0, 0, 0);
     return 1;

Here is how I set my timer.

if (!SetTimer(hwnd, TIMER1, 20, NULL))
{
    MessageBox(hwnd, "No Timers Available", "Info", MB_OK);
    return FALSE;
}

The button seems to chagne colors but it is to quickl. I am not sure how to fix this.

I prefer using CMFCButton in such cases, provided your are using MFC.

The steps are very simple:

1. Add a member variable (control type) of type CMFCButton. Say you declared variable as CMFCButton m_hButton2;

2. Modify the OnInitDialog() function and add these lines:

   m_hButton2.m_nFlatStyle = CMFCButton::BUTTONSTYLE_NOBORDERS;
   m_hButton2.m_bTransparent = false;
   SetTimer(255, 1000, NULL);
   

3. Implement the OnTime() function to change color of choice. I have implemented something like below.

   void CMFCApplicationDialogDlg::OnTimer(UINT_PTR nIDEvent)
    {
       if(nIDEvent == 255)
       {
           static int nRedColor = 0;
           m_hButton2.SetFaceColor(RGB(nRedColor++,0,0), true);
       }
       CDialogEx::OnTimer(nIDEvent);
    }
   

The above implementation helps me increase Red part of color gradually every second and after few seconds (after 100 seconds or so) button will start looking Red.