LBitmapBase::ColorRes

#include "ltwrappr.h"

virtual L_INT LBitmapBase::ColorRes(nBitsPerPixel, uFlags=CRF_FIXEDPALETTE|CRF_FLOYDSTEINDITHERING, pPalette=NULL, hPalette=NULL, uColors=0)

virtual L_INT LBitmapBase::ColorRes(BitmapSrc, nBitsPerPixel, uFlags=CRF_FIXEDPALETTE|CRF_FLOYDSTEINDITHERING, pPalette=NULL, hPalette=NULL, uColors=0)

L_UINT nBitsPerPixel;	/* the number of bits per pixel */
L_UINT32 uFlags;	/* flag that indicates the processing options */
LPRGBQUAD pPalette;	/* custom palette */
HPALETTE hPalette;	/* custom palette handle to use */
L_UINT uColors;	/* number of colors in the palette */
LBitmapBase& BitmapSrc;	/* the source bitmap */

Converts a class object’s bitmap from any bits-per-pixel to any bits-per-pixel.

Parameter	Description
nBitsPerPixel	The number of bits per pixel to increase or decrease the bitmap to. Valid values are 1, 2, 3, 4, 5, 6, 7, 8, 12, 16, 24, 32, 48, and 64.
uFlags	Processing options. Note that the palette and dithering options are useful only when the resulting bitmap requires a palette (when it is 8 bits per pixel or less). You can combine values when appropriate by using a bitwise OR ( \| ). Possible values are:
	Value	Meaning
	CRF_FIXEDPALETTE	[0x01] Use the fixed palette.
	CRF_OPTIMIZEDPALETTE	[0x02] Create an optimized palette, or if you supply a palette in the pPalette parameter, supply optimized colors for specified entries in the palette.
	CRF_NETSCAPEPALETTE	[0x40] Use the fixed palette that is employed by Netscape Navigator and by Microsoft Internet Explorer.
	CRF_USERPALETTE	[0x10] Use the palette specified in the pPalette parameter, without supplying optimized colors.
	CRF_IDENTITYPALETTE	[0x08] Insert the Windows system palette.
	CRF_FASTMATCHPALETTE	[0x20] Use a predefined table to speed conversion using your own palette. Refer to LBitmapSettings::CreateUserMatchTable.
	CRF_BYTEORDERBGR	[0x04] Use BGR color order. This flag only has meaning when going to 16 bits per pixel or higher.
	CRF_BYTEORDERRGB	[0x00] Use RGB color. This flag only has meaning when going to 16 bits per pixel or higher.
	CRF_BYTEORDERGRAY	[0x80] Grayscale.Destination bitmap should be 12 or 16-bit grayscale. 12 and 16-bit grayscale images are only supported in the Document/Medical toolkits.
	CRF_NODITHERING	[0x00000000] Use nearest color matching.
	CRF_FLOYDSTEINDITHERING	[0x00010000] Use Floyd-Steinberg dithering.
	CRF_STUCKIDITHERING	[0x00020000] Use Stucki dithering.
	CRF_BURKESDITHERING	[0x00030000] Use Burkes dithering.
	CRF_SIERRADITHERING	[0x00040000] Use Sierra dithering.
	CRF_STEVENSONARCEDITHERING	[0x00050000] Use Stevenson Arce dithering.
	CRF_JARVISDITHERING	[0x00060000] Use Jarvis dithering.
	CRF_ORDEREDDITHERING	[0x00070000] Use ordered dithering, which is faster but less accurate than other dithering methods.
	CRF_CLUSTEREDDITHERING	[0x00080000] Use clustered dithering.
pPalette	The custom palette to use. Specify this parameter as follows:
	$image\sqrblit.gif$ If you want to use the fixed palette or a fully optimized palette, pass NULL in this parameter and in hPalette.
	$image\sqrblit.gif$ If you want to supply the entire palette, specify CRF_USERPALETTE in the uFlags parameter and pass the address of your palette. Click here to see how to fill in the palette.
	$image\sqrblit.gif$ If you want the function to fill part of your palette with optimized colors, specify CRF_OPTIMIZEDPALETTE in the uFlags parameter and pass the address of your palettein pPalette and NULL in hPalette. Click here to see how to fill in the palette.
hPalette	The custom palette to use. Specify this parameter as follows:
	$image\sqrblit.gif$ If you want to use the fixed palette or a fully optimized palette, pass NULL in this parameter and in pPalette.
	$image\sqrblit.gif$ If you want to supply the entire palette, specify CRF_USERHPALETTE in the uFlags parameter and pass the handle of your palette. Click here to see how to fill in the palette.
	$image\sqrblit.gif$ If you want the function to fill part of your palette with optimized colors, specify CRF_OPTIMIZEDPALETTE in the uFlags parameter and pass NULL for pPalette and the handle of your palette in hPalette. Click here to see how to fill in the palette.
uColors	The number of colors in the palette. Pass 0 to get the default (such as 256 for 8 bits per pixel). Otherwise, do one of the following:
	$image\sqrblit.gif$ If you specify a palette in the pPalette or hPalette parameter, pass the number of entries in your palette (including reserved entries).
	$image\sqrblit.gif$ If you specify NULL in the pPalette and in the hPalette parameters and you specify CRF_OPTIMIZEDPALETTE in the uFlags parameter, you can use this parameter to limit the number of colors that the function maps in the optimized palette.
BitmapSrc	The source bitmap on which the conversion will be done.

Returns

SUCCESS	The function was successful.
< 1	An error occurred. Refer to Return Codes.

Comments

Call this function to do a color resolution on the source class object's bitmap and place the result in the calling object's bitmap. Note that if the callback functions are enabled, then the LBitmapBase::ColorResBitmapCallBack function of the calling object will be called for the color resolution operation.

For general information about dithering, refer to Color Resolution and Dithering.

In specifying the output destination, you can convert the bitmap in place, create a new converted bitmap, or let your callback function handle the output.

In specifying a palette, you can use simple palette options, or you can specify a palette that is tailored to your needs. The tailored palette can be any size that you specify. It can include specific colors, reserved blank entries, and open entries that this function fills with optimized colors.

If you use the same tailored palette more than once, you can improve performance by creating a table, as explained in LBitmapSettings::CreateUserMatchTable.

Note:

The BitmapSrc parameter is passed by reference, and is a required parameter.

This function does not support signed data images. It returns the error code ERROR_SIGNED_DATA_NOT_SUPPORTED if a signed data image is passed to this function.

Required DLLs and Libraries

LTDIS
LTFIL

For a listing of the exact DLLs and Libraries needed, based on the toolkit version, refer to Files To Be Included With Your Application.

Elements:	LBitmapBase::ColorResBitmapCallBack, LBase::EnableCallBack, LBase::IsCallBackEnabled, Class Members
Topics:	Raster Image Functions: Doing Color Expansion or Reduction
	Raster Image Functions: Doing Color Space Conversions
	Raster Image Functions: Palettes
	Color Resolution and Dithering