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Diffstat (limited to 'pcl/pcwhtidx.h')
| -rw-r--r-- | pcl/pcwhtidx.h | 126 |
1 files changed, 126 insertions, 0 deletions
diff --git a/pcl/pcwhtidx.h b/pcl/pcwhtidx.h new file mode 100644 index 000000000..c5c438292 --- /dev/null +++ b/pcl/pcwhtidx.h @@ -0,0 +1,126 @@ +/* Portions Copyright (C) 2001 artofcode LLC. + Portions Copyright (C) 1996, 2001 Artifex Software Inc. + Portions Copyright (C) 1988, 2000 Aladdin Enterprises. + This software is based in part on the work of the Independent JPEG Group. + All Rights Reserved. + + This software is distributed under license and may not be copied, modified + or distributed except as expressly authorized under the terms of that + license. Refer to licensing information at http://www.artifex.com/ or + contact Artifex Software, Inc., 101 Lucas Valley Road #110, + San Rafael, CA 94903, (415)492-9861, for further information. */ +/*$Id$ */ + +/* pcwhtindx.c - interface to code for finding white index of a palette */ + +#ifndef pcwhtindx_INCLUDED +#define pcwhtindx_INCLUDED + +#include "gx.h" +#include "gsbitmap.h" +#include "pcindxed.h" + +/* + * To implement transparency in PCL colored patterns and rasters, it is + * necessary to identify those pixels which should be considered white, as + * those are the pixels which should be transparent. + * + * "White" in the sense of PCL means white in the device color space, just + * prior to dithering. Hence, the effect of normalization, color lookup tables, + * and conversion from the source to device color lookup table are taken into + * account before determining if a given pixel is (potentially) transparent. + * + * Such a mechanism is, unfortunately, not easily implemented via the existing + * graphic library, as raster transparency is implemented via PostScript + * ImageType 4 images. For these images, the single color or range of colors + * required that identify pixels as transparent are specified in the source + * color space, before any conversion. + * + * In this implementation, normalization of colors for black and white + * reference points occurs before the raw data is ever considered a color, + * so at least that part of the problem is handled correctly. Beyond this + * canonical white--(1.0, 1.0, 1.0) in all color spaces--is assumed to yield + * white; if it does not (due to color lookup tables), the results will be + * incorrect. + * + * Where appropriate, this implementation also uses the graphic library's + * support for indexed color spaces. Creating potentially transparent rasters + * with these color spaces requires us to identify which entries in the + * color palette are white. When there is only one such entry, this is simple. + * When several palette entries are involved, life is more difficult. It is + * then necessary to remap all raster values which map to a white palette + * entry to the same white entry. + * + * For straight rasters, this is can be done in-place, as the raster will + * never be rendered with another color space. Patterns are not so easily + * handled, as they may be rendered subsequently with other color spaces. + * Hence, for those it is necessary to copy the data. + */ + +/* + * Determine the white entry in the color palette of an indexed color space, + * and perform any remapping that is required. + * + * The must_copy operand indicates if the raster data can be overwritten in + * place (false) or if a new array must be allocated. + * + * Returns 0 if successful, < 0 in the event of an error. + */ +int pcl_cmap_map_raster( + const pcl_cs_indexed_t * pindexed, + int * pfirst_white, + const gs_depth_bitmap * pin_pixinfo, + gs_depth_bitmap * pout_pixinfo, + bool must_copy, + gs_memory_t * pmem +); + +/* + * An alternative interface to the remapping capability, this one more suited + * to working with rasters. + * + * Because rasters are provided in a large number of pieces (typically one + * sanline is an individual piece), and all pieces are rendered using the + * the same color palette, it does not make sense to re-derive the mapping + * table for each raster. Consequently, the code below can be used to get + * the mapping table once, re-use it for each piece, and then free it. + * + * This code is specifically intended for rasters, and will only create a + * remap table if: + * + * source transparency is required + * the current palette uses an indexed pixel encoding (by plane or + * by pixel) + * there is more than one "white" in the current palette. + * + * Note that the macros for apply and free a remapping array will check for + * a null-pointer inline. Hence, the caller need not provide any other check + * of whether or nor remapping is necessary. + */ +const void * pcl_cmap_create_remap_ary( + pcl_state_t * pcs, + int * pfirst_white +); + +void pcl_cmap_int_apply_ary( + const void * vpmap, /* remap array pointer */ + byte * prast, /* array of bytes to be mapped */ + int b_per_p, /* bits per pixel */ + int npixels +); + +#define pcl_cmap_apply_remap_ary(pmap, prast, b_per_p, npixels) \ + BEGIN \ + if ((pmap) != 0) \ + pcl_cmap_int_apply_ary((pmap), (prast), (b_per_p), (npixels)); \ + END + +#define pcl_cmap_free_remap_ary(pmap, pcs) \ + BEGIN \ + if ((pmap) != 0) \ + gs_free_object( (pcs)->memory, \ + (void *)(pmap), \ + "pcl_cmap_free_remap_ary"); \ + END + +#endif /* pcwhtindx_INCLUDED */ |