he GetDC function retrieves a handle of a display device context (DC) for the client area of the specified window. The display device context can be used in subsequent GDI functions to draw in the client area of the window.
This function retrieves a common, class, or private device context depending on the class style specified for the specified window. For common device contexts, GetDC assigns default attributes to the device context each time it is retrieved. For class and private device contexts, GetDC leaves the previously assigned attributes unchanged.
HDC GetDC(
HWND hWnd // handle of window );
Parameters
hWnd
Identifies the window whose device context is to be retrieved.