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HT_Get8BPPMaskPalette function

The HT_Get8BPPMaskPalette function returns a mask palette for an 8-bits-per-pixel device type.

Syntax


LONG HT_Get8BPPMaskPalette(
  _Inout_  LPPALETTEENTRY pPaletteEntry,
  _In_     BOOL Use8BPPMaskPal,
  _In_     BYTE CMYMask,
  _In_     USHORT RedGamma,
  _In_     USHORT GreenGamma,
  _In_     USHORT BlueGamma
);

Parameters

pPaletteEntry [in, out]

Pointer to the array of PALETTEENTRY structures (described in the Windows SDK documentation) to be filled in. GDI assumes that it points to valid memory space in which GDI can place the entire 8-bit-per-pixel halftone palette.

For a driver that runs on Windows XP and later operating system versions, GDI checks pPaletteEntry[0] to determine how to return the composed CMY palette. If pPaletteEntry[0] is set to 'RGB0', the palette will be in one of the CMY_INVERTED modes and will have its indexes inverted. That is, index 0 in the palette is black, and index 255 is white. If pPaletteEntry[0] is not set to 'RGB0', the palette is a normal CMY palette, with index 0 being white and index 255 being black. See Using GDI 8-Bit-Per-Pixel CMY Mask Modes for new requirements and details on how to use this parameter.

Windows 2000 ignores any value the driver places in pPaletteEntry[0]. For this reason, if your driver is intended to run on Windows 2000 and on Windows XP or later versions, and your driver sets pPaletteEntry[0] to 'RGB0', the bitmaps your driver receives from Windows XP and later might have their colors inverted, relative to those received from Windows 2000. Therefore, such a driver must examine the palette before downloading a bitmap.

Use8BPPMaskPal [in]

Indicates which type of palette should be returned. When Use8BPPMaskPal is TRUE, HT_Get8BPPMaskPalette sets the pPaletteEntry parameter with the address of a CMY palette (an array of PALETTEENTRY structures) that is described by the bitmask specified in CMYMask. When Use8BPPMaskPal is FALSE, the function sets pPaletteEntry with the address of a standard RGB 8-bit-per-pixel halftone palette.

CMYMask [in]

Specifies information about the array of PALETTEENTRY structures pointed to by pPaletteEntry. This parameter can have one of the following values:

ValueMeaning

0

Gray scale with 256 levels

1

Five levels each of cyan, magenta, and yellow (each ranging from 0 to 4), for a total of 125 colors

2

Six levels each of cyan, magenta, and yellow (each ranging from 0 to 5), for a total of 216 colors

3 to 255

A bitmask that specifies that maximum number of levels of cyan, magenta, and yellow, respectively.

 

Drivers running on Windows 2000 should be restricted to 8-bits-per-pixel monochrome. That is, the value of CMYMask used should be 0.

For Windows XP and later operating system versions, and for all values of CMYMask, the value in pPaletteEntry[0] determines whether the palette that follows pPaletteEntry[0] is a normal CMY palette, or one of the CMY_INVERTED mode palettes. For more information, see the description of the pPaletteEntry parameter.

For values of CMYMask from 3 to 255, inclusive, the value is a bitmask in which groups of bits have the following meanings:

  • The three highest bits (bits 7,6,5) specify the number of levels of cyan. At most, seven levels of cyan (levels 1 to 7) are possible.

  • The middle three bits (bits 4,3,2) specify the number of levels of magenta. At most, seven levels of magenta (levels 1 to 7) are possible.

  • The two lowest bits (bits 1,0) specify the number of levels of yellow. At most, three levels of yellow (levels 1 to 3) are possible.

For values of CMYMask ranging from 3 to 255, any bitmask combination in which the cyan, magenta, or yellow level bits are zero is invalid. In such cases, HT_Get8BPPMaskPalette returns a palette count of zero. See Using GDI 8-Bit-Per-Pixel CMY Mask Modes for more information.

RedGamma [in]

If Use8BPPMaskPal is TRUE, the value of this parameter is not used. In that case, gamma values will be specified in the ciDevice member of the GDIINFO structure.

If Use8BPPMaskPal is FALSE, the value of this parameter specifies the red gamma value, out of the red, green and blue gamma values that GDI is to use to gamma-correct the palette. The USHORT value is interpreted as a real number whose four least-significant digits are to the right of the decimal point. For example, a gamma value of 10000 represents the real number 1.0000, and 12345 represents 1.2345. The minimum gamma value allowed is 0.0000, and the maximum allowable value is 6.5535.

GreenGamma [in]

If Use8BPPMaskPal is TRUE, the value of this parameter is not used. In that case, gamma values will be specified in the ciDevice member of the GDIINFO structure.

If Use8BPPMaskPal is FALSE, the value of this parameter specifies the green gamma value, out of the red, green and blue gamma values that GDI is to use to gamma-correct the palette. The USHORT value is interpreted as a real number whose four least-significant digits are to the right of the decimal point. For example, a gamma value of 10000 represents the real number 1.0000, and 12345 represents 1.2345. The minimum gamma value allowed is 0.0000, and the maximum allowable value is 6.5535.

BlueGamma [in]

If Use8BPPMaskPal is TRUE, the value of this parameter is not used. In that case, gamma values will be specified in the ciDevice member of the GDIINFO structure.

If Use8BPPMaskPal is FALSE, the value of this parameter specifies the blue gamma value, out of the red, green and blue gamma values that GDI is to use to gamma-correct the palette. The USHORT value is interpreted as a real number whose four least-significant digits are to the right of the decimal point. For example, a gamma value of 10000 represents the real number 1.0000, and 12345 represents 1.2345. The minimum gamma value allowed is 0.0000, and the maximum allowable value is 6.5535.

Return value

If pPaletteEntry is not NULL, HT_Get8BPPMaskPalette returns the number of PALETTEENTRY structures that GDI filled out in the array to which pPaletteEntry points. If pPaletteEntry is NULL, the value returned is the total count of PALETTEENTRY structures required to store the halftone palette.

If an illegal value of the CMYMask parameter is used in the call to this function, HT_Get8BPPMaskPalette returns a value of zero.

Remarks

The PALETTEENTRY structure is documented in the Windows SDK documentation.

Calling HT_Get8BPPMaskPalette with Use8BPPMaskPal set FALSE is equivalent to calling HT_Get8BPPFormatPalette.

See Using GDI 8-Bit-Per-Pixel CMY Mask Modes for more information about this function and how its parameters are used.

Requirements

Version

Available in Windows 2000 and later versions of the Windows operating systems.

Header

Winddi.h (include Winddi.h)

Library

Win32k.lib

DLL

Win32k.sys

See also

HT_Get8BPPFormatPalette

 

 

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