CAggDirectDraw Class

The CAggDirectDraw class aggregates an IDirectDraw interface. Although Microsoft® 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

m_pDirectDraw

DirectDraw object.

Member Functions

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

Overridable Member Functions

NonDelegatingQueryInterface

Retrieves an interface and increments the reference count.

Implemented IDirectDraw Methods

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	Retrieves the current display mode.
GetFourCCCodes	Retrieves the FOURCC codes supported by the DirectDraw object.
GetGDISurface	Retrieves the DirectDrawSurface object that currently represents the surface memory that GDI treats as the primary surface.
GetMonitorFrequency	Retrieves the frequency of the monitor being driven by the DirectDraw object.
GetScanLine	Retrieves the scan line that the monitor is currently updating to the display.
GetVerticalBlankStatus	Retrieves 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.

CAggDirectDraw::CAggDirectDraw

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CAggDirectDraw Class

Constructs a CAggDirectDraw object.

Syntax

CAggDirectDraw(
    TCHAR *pName,
    LPUNKNOWN pUnk
    );

Parameters

pName

Pointer to the object's name; used for debugging purposes.

pUnk

Pointer to the owner of this object. If non-NULL, IUnknown calls are delegated to this object.

Return Value

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

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CAggDirectDraw Class

Retrieves an interface and increments the reference count.

Syntax

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

Parameters

riid

Reference identifier.

ppv

Address of a pointer to the interface.

Return Value

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

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CAggDirectDraw Class

Sets the DirectDraw object to be aggregated by this class.

Syntax

void SetDirectDraw(
    LPDIRECTDRAW pDirectDraw
    );

Parameters

pDirectDraw

Pointer to the IDirectDraw object to be aggregated.

Return Value

No return value.

Remarks

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

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