This method allows an application to fill a surface with a given pixel color in a given rectangle. Do not use this method to clear the swap chain. You can accomplish this task more effectively by calling the IDirect3DMobileDevice::Clear method instead. Also, the IDirect3DMobileDevice::ColorFill method does not allow the application to fill the depth buffer.
HRESULT ColorFill( IDirect3DMobileSurface* pSurface, CONST RECT* pRect, D3DMCOLOR Color );
[in] A pointer to an IDirect3DMobileSurface interface representing the surface that will be contain the rectangle. Setting this parameter to NULL fills the entire surface. This surface must be a render target or a render target texture.
[in] A pointer to a RECT structure that defines the rectangular region.
[in] A D3DMCOLOR value that defines the color to fill the rectangle with.