You cannot use setdcbrushcolor undeclared identifier.

Set

# DEFINE _ win32_winnt 0x0501

Add to you # include Before

If it is an MFC project, add it to the beginning of # include.

This function can only be supported in windows and later versions.
Therefore, platform SDK adopts this method. You must display and define a macro in the program to tell the Windows version of the platform SDK program to run so that you can use the macro definitions and function
In fact, # DEFINE _ win32_winnt 0x0500 can be used (Win2000)
You can see this definition in wingdi. h.
# If (_ win32_winnt> = 0x0500)
# Define dc_brush 18
# Define dc_pen 19
# Endif

# If (_ win32_winnt> = 0x0500)
Wingdiapi colorref winapi setdcbrushcolor (HDC, colorref );
Wingdiapi colorref winapi setdcpencolor (HDC, colorref );
# Endif