DDPIXELFORMAT

The DDPIXELFORMAT structure describes the pixel format of a DirectDrawSurface object for the IDirectDrawSurface7::GetPixelFormat method.

typedef struct _DDPIXELFORMAT{ 
    DWORD dwSize; 
    DWORD dwFlags; 
    DWORD dwFourCC; 
    union 
    { 
        DWORD dwRGBBitCount; 
        DWORD dwYUVBitCount; 
        DWORD dwZBufferBitDepth; 
        DWORD dwAlphaBitDepth; 
        DWORD dwLuminanceBitCount;
        DWORD dwBumpBitCount;
    } DUMMYUNIONNAMEN(1);
    union 
    { 
        DWORD dwRBitMask; 
        DWORD dwYBitMask; 
        DWORD dwStencilBitDepth;
        DWORD dwLuminanceBitMask;
        DWORD dwBumpDuBitMask;
    } DUMMYUNIONNAMEN(2);
    union 
    { 
        DWORD dwGBitMask; 
        DWORD dwUBitMask; 
        DWORD dwZBitMask;
        DWORD dwBumpDvBitMask;
    } DUMMYUNIONNAMEN(3);
    union 
    { 
        DWORD dwBBitMask; 
        DWORD dwVBitMask; 
        DWORD dwStencilBitMask;
        DWORD dwBumpLuminanceBitMask;
    } DUMMYUNIONNAMEN(4);
    union 
    { 
        DWORD dwRGBAlphaBitMask; 
        DWORD dwYUVAlphaBitMask; 
        DWORD dwLuminanceAlphaBitMask;
        DWORD dwRGBZBitMask; 
        DWORD dwYUVZBitMask; 
    } DUMMYUNIONNAMEN(5);
} DDPIXELFORMAT, FAR* LPDDPIXELFORMAT; 

Members

dwSize

Size of the structure, in bytes. This member must be initialized before the structure is used.

dwFlags

The following optional control flags:

DDPF_ALPHA

The pixel format describes an alpha-only surface.

DDPF_ALPHAPIXELS

The surface has alpha channel information in the pixel format.

DDPF_ALPHAPREMULT

The surface uses the premultiplied alpha format. That is, the color components in each pixel are premultiplied by the alpha component.

DDPF_BUMPLUMINANCE

The luminance data in the pixel format is valid, and the dwLuminanceBitMask member describes valid luminance bits for a luminance-only or luminance-alpha surface.

DDPF_BUMPDUDV

Bump-map data in the pixel format is valid. Bump-map information is in the dwBumpBitCount, dwBumpDuBitMask, dwBumpDvBitMask, and dwBumpLuminanceBitMask members.

DDPF_COMPRESSED

The surface accepts pixel data in the specified format and compress it during the write operation.

DDPF_FOURCC

The dwFourCC member is valid and contains a FOURCC code describing a non-RGB pixel format.

DDPF_LUMINANCE

The pixel format describes a luminance-only or luminance-alpha surface.

DDPF_PALETTEINDEXED1

DDPF_PALETTEINDEXED2

DDPF_PALETTEINDEXED4

DDPF_PALETTEINDEXED8

The surface is 1-, 2-, 4-, or 8-bit color-indexed.

DDPF_PALETTEINDEXEDTO8

The surface is 1-, 2-, or 4-bit color-indexed to an 8-bit palette.

DDPF_RGB

The RGB data in the pixel format structure is valid.

DDPF_RGBTOYUV

The surface accepts RGB data and translates it during the write operation to YUV data. The format of the data to be written is contained in the pixel format structure. The DDPF_RGB flag is set.

DDPF_STENCILBUFFER

The surface encodes stencil and depth information in each pixel of the z-buffer. This flag can be used only if the DDPF_ZBUFFER flag is also specified.

DDPF_YUV

The YUV data in the pixel format structure is valid.

DDPF_ZBUFFER

The pixel format describes a z-buffer surface.

DDPF_ZPIXELS

The surface contains z information in the pixels.

dwFourCC

FourCC code. For more information see, Four-Character Codes (FOURCC).

dwRGBBitCount

RGB bits per pixel (4, 8, 16, 24, or 32).

dwYUVBitCount

YUV bits per pixel (4, 8, 16, 24, or 32).

dwZBufferBitDepth

Z-buffer bit depth (8, 16, 24, or 32).

dwAlphaBitDepth

Alpha channel bit depth (1, 2, 4, or 8) for an alpha-only surface (DDPF_ALPHA). For pixel formats that contain alpha information interleaved with color data (DDPF_ALPHAPIXELS), count the bits in the dwRGBAlphaBitMask member to obtain the bit depth of the alpha component. For more information, see Remarks.

dwLuminanceBitCount

Total luminance bits per pixel. This member applies only to luminance-only and luminance-alpha surfaces.

dwBumpBitCount

Total bump-map bits per pixel in a bump-map surface.

dwRBitMask

Mask for red bits.

dwYBitMask

Mask for Y bits.

dwStencilBitDepth

Bit depth of the stencil buffer. This member specifies how many bits are reserved within each pixel of the z-buffer for stencil information (the total number of z-bits is equal to dwZBufferBitDepth minus dwStencilBitDepth).

dwLuminanceBitMask

Mask for luminance bits.

dwBumpDuBitMask

Mask for bump-map U-delta bits.

dwGBitMask

Mask for green bits.

dwUBitMask

Mask for U bits.

dwZBitMask

Mask for z bits.

dwBumpDvBitMask

Mask for bump-map V-delta bits.

dwBBitMask

Mask for blue bits.

dwVBitMask

Mask for V bits.

dwStencilBitMask

Mask for stencil bits within each z-buffer pixel.

dwBumpLuminanceBitMask

Mask for luminance in a bump-map pixel.

dwRGBAlphaBitMask and dwYUVAlphaBitMask and dwLuminanceAlphaBitMask

Masks for the alpha channel.

dwRGBZBitMask and dwYUVZBitMask

Masks for the z channel.

Remarks

The dwAlphaBitDepth member reflects the bit depth of an alpha-only pixel format (DDPF_ALPHA). For pixel formats that include the alpha component with color components (DDPF_ALPHAPIXELS), the alpha bit depth is obtained by counting the bits in the various mask members. The following code example returns the number of bits set in a given bitmask:

WORD GetNumberOfBits( DWORD dwMask )
{
    WORD wBits = 0;
    while( dwMask )
    {
        dwMask = dwMask & ( dwMask - 1 );  
        wBits++;
    }
    return wBits;
}

The unions in this structure have been updated to work with compilers that do not support nameless unions. If your compiler does not support nameless unions, define the NONAMELESSUNION token before including the Ddraw.h header file.

Requirements

  Windows NT/2000: Requires Windows NT 4.0 SP3 or later.
  Windows 95/98: Requires Windows 95 or later. Available as a redistributable for Windows 95.
  Header: Declared in ddraw.h.

See Also

Off-Screen Surface Formats