DirectDraw supports all of the screen resolutions and depths supported by the display device driver. DirectDraw allows an application to change the mode to any one supported by the computer's display driver, including all supported 24- and 32-bpp (true-color) modes.
DirectDraw also supports HEL blitting in true-color surfaces. If the display device driver supports blitting at these resolutions, the hardware blitter will be used for display-memory-to-display-memory blits. Otherwise, the HEL will be used to perform the blits.
Window 95 and Windows NT allow you to specify the type of monitor being used. DirectDraw checks a list of known display modes against the display restrictions of the installed monitor. If DirectDraw determines that the requested mode is not compatible with the monitor, the call to the IDirectDraw2::SetDisplayMode method fails. Only modes that are supported on the installed monitor will be enumerated when you call the IDirectDraw2::EnumDisplayModes method.