IDirectDraw Interface

Microsoft DirectShow 9.0

IDirectDraw Interface

The IDirectDraw interface is exposed on DirectDraw objects used in the DirectShow multimedia streaming APIs and is included in the DirectShow documentation for convenience.

The DirectDraw object represents the display hardware. The object is hardware-accelerated if the display device for which it was instantiated has hardware acceleration. The three objects which can be created by a DirectDraw object are the DirectDrawSurface, DirectDrawPalette, and DirectDrawClipper objects. 

The DirectDraw object manages all of the objects it creates. It controls the default palette if the primary surface is in 8-bpp mode, the default color key values, and the hardware's display mode. It knows what resources have been allocated and what resources remain to be allocated.

Changing the display mode is an important piece of the functionality of DirectDraw. The display mode resolution can be changed at any time unless another application has obtained exclusive access to DirectDraw. The pixel depth of the display mode can only be changed if the application requesting the change has obtained exclusive access to the DirectDraw object. All DirectDrawSurface objects lose their surface memory and become inoperative when the mode is changed. These surfaces' memory must be reallocated using the Restore method

In addition to the methods inherited from IUnknown, the IDirectDraw interface includes the following methods.

Method Description
Compact Not yet implemented.
CreateClipper Creates a DirectDrawClipper object.
CreatePalette Creates a DirectDrawPalette object for this DirectDraw object.
CreateSurface Creates a DirectDrawSurface object for this DirectDraw object.
DuplicateSurface Duplicates a DirectDrawSurface object.
EnumDisplayModes Enumerates all of the display modes the hardware exposes through the DirectDraw object that are compatible with a provided surface description.
EnumSurfaces Enumerates all of the existing or possible surfaces that meet the search criterion specified.
FlipToGDISurface Makes the surface that GDI writes to the primary surface.
GetCaps Fills in the raw (not remaining) capabilities of the device driver (the hardware) and/or the Hardware Emulation Layer (HEL).
GetDisplayMode Returns the current display mode.
GetFourCCCodes Gets the FourCCCodes supported by the DirectDraw object.
GetGDISurface Returns the DirectDrawSurface object that currently represents the surface memory that GDI treats as the primary surface.
GetMonitorFrequency Returns the frequency of the monitor being driven by the DirectDraw object.
GetScanLine Returns the scan line that the monitor is currently updating to the display.
GetVerticalBlankStatus Returns the status of the vertical blank.
Initialize Initializes the DirectDraw object.
RestoreDisplayMode Resets the mode of the display device hardware for the primary surface to what it was before the SetDisplayMode method was called to change it.
SetCooperativeLevel Determines the top-level behavior of the application.
SetDisplayMode Sets the mode of the display device hardware. SetCooperativeLevel must be used to set exclusive level access before the mode can be changed.
WaitForVerticalBlank Used to help the caller synchronize itself with the vertical blank interval.