## CAggDirectDraw Class

This class aggregates an IDirectDraw interface. Although DirectDraw® interfaces (IDirectDraw and IDirectDrawSurface) potentially have the ability to be aggregated, this feature is not yet implemented. Various parts of Microsoft® DirectShow™ require aggregation of the DirectDraw interfaces. In particular, the video renderer passes out media samples that expose IDirectDraw and IDirectDrawSurface. This class and the CAggDrawSurface class republish the methods of the DirectDraw class so that they can be aggregated.

Each member function in this class, with the exception of the constructor, SetDirectDraw, and NonDelegatingQueryInterface, simply calls the corresponding method on the IDirectDraw interface with the parameters passed to it.

Protected Data Members

Name | Description
m_pDirectDraw | DirectDraw object.

Member Functions

Name | Description
CAggDirectDraw | Constructs a CAggDirectDraw object.
SetDirectDraw | Sets the DirectDraw object to be aggregated by this class.

Overridable Member Functions

Name | Description
NonDelegatingQueryInterface | Returns an interface and increments the reference count.

Implemented IDirectDraw Methods

Name | Description
Compact | Moves all the pieces of surface memory on the video card to a contiguous block to make the largest chunk of free memory available.
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 the display modes the hardware exposes through the DirectDraw object that are compatible with a provided surface description.
EnumSurfaces | Enumerates all 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 FOURCC codes supported by the DirectDraw object.
GetGDISurface | Returns the DirectDrawSurface object that currently represents the surface memory that GDI treats as the primary surface.
GetMonitorFrequency | Points to a DirectDrawSurface pointer that will be made to point to the DirectDrawSurface object currently controlling GDI's primary surface memory.
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 CAggDirectDraw::SetDisplayMode member function was called.
SetCooperativeLevel | Determines the top-level behavior of the application.
SetDisplayMode | Sets the mode of the display device hardware.
WaitForVerticalBlank | Helps the caller synchronize itself with the vertical blank interval.

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CAggDirectDraw::CAggDirectDraw

CAggDirectDraw Class

Constructs a CAggDirectDraw object.

CAggDirectDraw(
TCHAR *pName,
LPUNKNOWN pUnk
);

##### Parameters

pName
  Name of the object; used for debugging purposes.
pUnk
  Pointer to the owner of this object. If non-NULL, IUnknown calls are delegated to this object.

##### Return Values

No return value.

##### Remarks

This member function calls the CUnknown::CUnknown base class constructor and sets the m_pDirectDraw member variable to NULL.

###

CAggDirectDraw::NonDelegatingQueryInterface

CAggDirectDraw Class

Returns an interface and increments the reference count.

HRESULT NonDelegatingQueryInterface(
REFIID riid,
void ** ppv
);

##### Parameters

riid
  Reference identifier.
ppv
  Pointer to the interface.

##### Return Values

Returns E_POINTER if ppv is invalid. Returns NOERROR if the query is successful or E_NOINTERFACE if it is not.

##### Remarks

This member function provides an implementation of the INonDelegatingUnknown::NonDelegatingQueryInterface method. By default it passes out references to IDirectDraw and then calls the CUnknown::NonDelegatingQueryInterface member function for base class interface references. Override this class to return interfaces added in the derived class.

###

CAggDirectDraw::SetDirectDraw

CAggDirectDraw Class

Sets the DirectDraw object to be aggregated by this class.

void SetDirectDraw(
LPDIRECTDRAW pDirectDraw
);

##### Parameters

pDirectDraw
  IDirectDraw object to be aggregated.

##### Return Values

No return value.

##### Remarks

This member function sets the m_pDirectDraw data member to the pDirectDraw parameter.

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