VMRALPHABITMAP structure (strmif.h)

[The feature associated with this page, DirectShow, is a legacy feature. It has been superseded by MediaPlayer, IMFMediaEngine, and Audio/Video Capture in Media Foundation. Those features have been optimized for Windows 10 and Windows 11. Microsoft strongly recommends that new code use MediaPlayer, IMFMediaEngine and Audio/Video Capture in Media Foundation instead of DirectShow, when possible. Microsoft suggests that existing code that uses the legacy APIs be rewritten to use the new APIs if possible.]

The VMRALPHABITMAP structure is used in the VMR-7 filter's IVMRMixerBitmap methods when the application is providing a static alpha-blended bitmap to be displayed on the composited video frame.

Syntax

typedef struct _VMRALPHABITMAP {
  DWORD                dwFlags;
  HDC                  hdc;
  LPDIRECTDRAWSURFACE7 pDDS;
  RECT                 rSrc;
  NORMALIZEDRECT       rDest;
  FLOAT                fAlpha;
  COLORREF             clrSrcKey;
} VMRALPHABITMAP, *PVMRALPHABITMAP;

Members

dwFlags

Flags that instruct the mixer where to find the bitmap. The following values are defined.

Value	Meaning
VMRBITMAP_DISABLE 0x00000001	Disable the bitmap. This flag cannot be combined with other flags.
VMRBITMAP_HDC 0x00000002	Obtain the bitmap from the HDC. If this flag is set, the hdc member must specify a valid handle to a device context, and the pDDS member must be NULL. If this flag is absent, the pDDS member must point to a valid DirectDraw surface, and the hdc member must be NULL.
VMRBITMAP_ENTIREDDS 0x00000004	Take the entire DirectDraw surface. When this flag is specified, rSrc is ignored. This flag cannot be combined with the VMRBITMAP_HDC flag.
VMRBITMAP_SRCCOLORKEY 0x00000008	The clrSrcKey value is valid and should be used when blending.
VMRBITMAP_SRCRECT 0x00000010	Indicates that the rSrc rectangle is valid and specifies a sub-rectangle of the original app image to be blended. This flag is only valid for the IVMRMixerBitmap::UpdateAlphaBitmapParameters method. For the IVMRMixerBitmap::SetAlphaBitmap method, the rSrc member must refer to the entire bitmap.

hdc

The handle to the device context for the bitmap. Specify NULL if the bitmap is located in a DirectDraw surface.

pDDS

Pointer to a DirectDraw surface that contains the bitmap. Specify NULL if the bitmap is to be obtained from a GDI device context. If a DirectDraw surface is specified, the pixel format must be ARGB-32 or RGB-32. If the surface contains per-pixel alpha, do not set the VMRBITMAP_SRCCOLORKEY flag in dwFlags.

rSrc

Specifies the source rectangle in either the GDI device context or the DirectDraw surface.

rDest

Specifies the destination rectangle in composition space.

fAlpha

Specifies the alpha blending value; must be a value from 0.0 to 1.0 (inclusive).

clrSrcKey

Specifies the source color key.

Requirements

Requirement	Value
Minimum supported client	Windows XP [desktop apps only]
Minimum supported server	Windows Server 2003 [desktop apps only]
Header	strmif.h (include Dshow.h)

See also

DirectShow Structures