Drawing a child window on top of another child window? - c++

Question

I have different screens serving different purposes in my win32 app, each screen having a different background. The main window have its own static background.
I am drawing screen background on a custom window using following code.
panelBackground = LoadBitmap ( hInstance, MAKEINTRESOURCE ( bitmap ) );
WNDCLASSEX wincl;
wincl.hInstance = hInstance;
wincl.lpszClassName = "jPanel";
wincl.lpfnWndProc = WndProc;
wincl.style = CS_BYTEALIGNWINDOW;// | CS_HREDRAW | CS_VREDRAW;
wincl.cbSize = sizeof (WNDCLASSEX);
wincl.hIcon = 0;
wincl.hIconSm = 0;
wincl.hCursor = LoadCursor (NULL, IDC_ARROW);
wincl.lpszMenuName = NULL;
wincl.cbClsExtra = 0;
wincl.cbWndExtra = 4;
wincl.hbrBackground = ( HBRUSH ) GetStockObject( BLACK_BRUSH );
RegisterClassEx (&wincl);
hwnd = CreateWindowEx ( 0, "jPanel", txt.c_str(), WS_CLIPSIBLINGS | WS_CHILD, x, y, width, height, parent, 0, hInstance, 0) ;
SetWindowLong( hwnd , 0 , ( LONG ) this ) ;
SetWindowPos ( hwnd , HWND_BOTTOM, 0, 0, 0, 0, SWP_NOSIZE | SWP_NOMOVE ) ;
Then in the WndProc :
view::jPanel* panel = ( view::jPanel* ) GetWindowLong( hwnd , 0 ) ;
case WM_PAINT:
{
if ( ! panel )
return 0 ;
HDC hdc ;
PAINTSTRUCT ps ;
RECT rect ;
GetClientRect( hwnd , &rect ) ;
hdc = BeginPaint( hwnd , &ps ) ;
HDC dcSkin = CreateCompatibleDC ( hdc ); // memory dc for skin
HDC hMemDc = CreateCompatibleDC ( hdc ); // memory dc for painting
HBITMAP hmemBmp = CreateCompatibleBitmap ( hdc, rect.right - rect.left, rect.bottom - rect.top ); // Create bitmap to draw on
HBITMAP hOldMemBmp = (HBITMAP)SelectObject ( hMemDc, hmemBmp ); // select memory bitmap in memory dc
HBITMAP hOldSkinBmp = (HBITMAP)SelectObject ( dcSkin, panel->panelBackground ); //select skin bitmap in skin memory dc
BitBlt ( hMemDc, 0, 0, rect.right - rect.left, rect.bottom - rect.top, dcSkin, 0, 0, SRCCOPY ); // Paint Skin on Memory DC
BitBlt ( hdc, 0, 0, rect.right - rect.left, rect.bottom - rect.top, hMemDc, 0, 0, SRCCOPY ); // Paint Skin on Window DC
//<<<... DeleteDC will leak memory if it holds a resource, so lets select the old bitmap back in the memory DCs
SelectObject ( hMemDc, hOldMemBmp ); // select old bitmaps back to their respective DCs before deleting
SelectObject ( dcSkin, hOldSkinBmp ); // select old bitmaps back to their respective DCs before deleting
DeleteObject ( hOldSkinBmp );
DeleteObject ( hOldMemBmp );
DeleteObject( hmemBmp );
DeleteDC ( hMemDc );
DeleteDC ( dcSkin );
EndPaint( hwnd , &ps ) ;
}
break ;
Problem : The child windows(buttons, edit controls) belonging to that screen don't show up, I am guessing
that they are below the screen background window. Moving the controls up the z-order with WS_EX_TOPMOST style doesn't work neither moving the screen background window at the bottom of z-order with SetWindowPos ( hwnd , HWND_BOTTOM, 0, 0, 0, 0, SWP_NOSIZE | SWP_NOMOVE ) ; works.
And yes buttons are BS_BITMAP styled.

Answer 1

Add the WS_CLIPCHILDREN style when you create the parent window.