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/*
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Copyright (C) 2001 artofcode LLC.
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This software is provided AS-IS with no warranty, either express or
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implied.
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This software is distributed under license and may not be copied,
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modified or distributed except as expressly authorized under the terms
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of the license contained in the file LICENSE in this distribution.
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For more information about licensing, please refer to
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http://www.ghostscript.com/licensing/. For information on
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commercial licensing, go to http://www.artifex.com/licensing/ or
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contact Artifex Software, Inc., 101 Lucas Valley Road #110,
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San Rafael, CA 94903, U.S.A., +1(415)492-9861.
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Author: Raph Levien <raph@artofcode.com>
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*/
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/* $Id: gxblend.h,v 1.3 2002/02/21 22:24:53 giles Exp $ */
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/* PDF 1.4 blending functions */
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#ifndef gxblend_INCLUDED
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# define gxblend_INCLUDED
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typedef bits16 ArtPixMaxDepth;
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#define ART_MAX_CHAN 16
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/**
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* art_blend_pixel: Compute PDF 1.4 blending function.
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* @dst: Where to store resulting pixel.
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* @backdrop: Backdrop pixel color.
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* @src: Source pixel color.
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* @n_chan: Number of channels.
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* @blend_mode: Blend mode.
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*
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* Computes the blend of two pixels according the PDF 1.4 transparency
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* spec (section 3.2, Blend Mode). A few things to keep in mind about
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* this implementation:
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*
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* 1. This is a reference implementation, not a high-performance one.
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* Blending using this function will incur a function call and switch
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* statement per pixel, and will also incur the extra cost of 16 bit
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* math.
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*
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* 2. Zero is black, one is white. In a subtractive color space such
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* as CMYK, all pixels should be represented as "complemented", as
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* described in section 3.1 (Blending Color Space) of the PDF 1.4
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* transparency spec.
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*
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* 3. I haven't really figured out how to handle the Compatible blend
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* mode. I wouldn't be surprised if it required an API change.
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**/
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void
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art_blend_pixel(ArtPixMaxDepth * dst, const ArtPixMaxDepth * backdrop,
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const ArtPixMaxDepth * src, int n_chan,
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gs_blend_mode_t blend_mode);
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/**
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* art_blend_pixel_8: Compute PDF 1.4 blending function on 8-bit pixels.
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* @dst: Where to store resulting pixel.
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* @backdrop: Backdrop pixel color.
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* @src: Source pixel color.
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* @n_chan: Number of channels.
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* @blend_mode: Blend mode.
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*
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* Computes the blend of two pixels according the PDF 1.4 transparency
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* spec (section 3.2, Blend Mode). A few things to keep in mind about
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* this implementation:
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*
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* 1. This is a reference implementation, not a high-performance one.
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* Blending using this function will incur a function call and switch
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* statement per pixel, and will also incur the extra cost of 16 bit
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* math.
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*
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* 2. Zero is black, one is white. In a subtractive color space such
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* as CMYK, all pixels should be represented as "complemented", as
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* described in section 3.1 (Blending Color Space) of the PDF 1.4
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* transparency spec.
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*
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* 3. I haven't really figured out how to handle the Compatible blend
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* mode. I wouldn't be surprised if it required an API change.
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**/
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void
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art_blend_pixel_8(byte *dst, const byte *backdrop,
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const byte *src, int n_chan, gs_blend_mode_t blend_mode);
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/**
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* art_pdf_union_8: Union together two alpha values.
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* @alpha1: One alpha value.
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* @alpha2: Another alpha value.
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*
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* Return value: Union (@alpha1, @alpha2).
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**/
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byte art_pdf_union_8(byte alpha1, byte alpha2);
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/**
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* art_pdf_union_mul_8: Union together two alpha values, with mask.
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* @alpha1: One alpha value.
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* @alpha2: Another alpha value.
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* @alpha_mask: A mask alpha value;
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*
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* Return value: Union (@alpha1, @alpha2 * @alpha_mask).
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**/
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byte art_pdf_union_mul_8(byte alpha1, byte alpha2, byte alpha_mask);
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/**
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* art_pdf_composite_pixel_alpha_8: Composite two alpha pixels.
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* @dst: Where to store resulting pixel, also initially backdrop color.
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* @src: Source pixel color.
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* @n_chan: Number of channels.
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* @blend_mode: Blend mode.
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*
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* Composites two pixels using the basic compositing operation. A few
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* things to keep in mind:
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*
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* 1. This is a reference implementation, not a high-performance one.
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*
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* 2. All pixels are assumed to have a single alpha channel.
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*
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* 3. Zero is black, one is white.
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*
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* Also note that src and dst are expected to be allocated aligned to
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* 32 bit boundaries, ie bytes from [0] to [(n_chan + 3) & -4] may
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* be accessed.
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**/
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void
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art_pdf_composite_pixel_alpha_8(byte *dst, const byte *src, int n_chan,
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gs_blend_mode_t blend_mode);
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/**
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* art_pdf_uncomposite_group_8: Uncomposite group pixel.
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* @dst: Where to store uncomposited pixel.
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* @backdrop: Backdrop.
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* @src: Composited source pixel.
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* @src_alpha_g: alpha_g value associated with @src.
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* @n_chan: Number of channels.
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*
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* Performs uncompositing operation as described in 5.3 of the Adobe spec.
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**/
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void
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art_pdf_uncomposite_group_8(byte *dst,
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const byte *backdrop,
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const byte *src, byte src_alpha_g, int n_chan);
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/**
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* art_pdf_recomposite_group_8: Recomposite group pixel.
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* @dst: Where to store pixel, also initial backdrop of group.
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* @dst_alpha_g: Optional pointer to alpha g value associated with @dst.
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* @alpha: Alpha mask value.
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* @src_alpha_g: alpha_g value associated with @src.
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* @blend_mode: Blend mode for compositing.
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*
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* Note: this is only for non-isolated groups. This covers only the
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* single-alpha case. A separate function is needed for dual-alpha,
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* and that probably needs to treat knockout separately.
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*
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* @src_alpha_g corresponds to $\alpha g_n$ in the Adobe notation.
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*
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* @alpha corresponds to $fk_i \cdot fm_i \cdot qk_i \cdot qm_i$.
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**/
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void
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art_pdf_recomposite_group_8(byte *dst, byte *dst_alpha_g,
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const byte *src, byte src_alpha_g,
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int n_chan,
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byte alpha, gs_blend_mode_t blend_mode);
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/**
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* art_pdf_composite_group_8: Composite group pixel.
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* @dst: Where to store pixel, also initial backdrop of group.
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* @dst_alpha_g: Optional pointer to alpha g value.
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* @alpha: Alpha mask value.
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*
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* Note: this is only for isolated groups. This covers only the
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* single-alpha case. A separate function is needed for dual-alpha,
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* and that probably needs to treat knockout separately.
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*
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* @alpha corresponds to $fk_i \cdot fm_i \cdot qk_i \cdot qm_i$.
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**/
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void
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art_pdf_composite_group_8(byte *dst, byte *alpha_g,
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const byte *src,
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int n_chan, byte alpha, gs_blend_mode_t blend_mode);
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/**
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* art_pdf_composite_knockout_simple_8: Simple knockout compositing.
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* @dst: Destination pixel.
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* @dst_shape: Shape associated with @dst.
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* @src: Source pixel.
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* @n_chan: Number of channels.
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* @opacity: Opacity.
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*
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* This function handles the simplest knockout case: an isolated
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* knockout group, and an elementary shape. The alpha channel of @src
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* is interpreted as shape.
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**/
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void
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art_pdf_composite_knockout_simple_8(byte *dst,
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byte *dst_shape,
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const byte *src,
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int n_chan, byte opacity);
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/**
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* art_pdf_composite_knockout_isolated_8: Simple knockout compositing.
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* @dst: Destination pixel.
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* @dst_shape: Shape associated with @dst.
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* @src: Source pixel.
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* @n_chan: Number of channels.
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* @shape: Shape.
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* @alpha_mask: Alpha mask.
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* @shape_mask: Shape mask.
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*
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* This function handles compositin in an isolated knockout case. The
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* alpha channel of @src is interpreted as alpha.
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**/
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void
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art_pdf_composite_knockout_isolated_8(byte *dst,
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byte *dst_shape,
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const byte *src,
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int n_chan,
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byte shape,
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byte alpha_mask, byte shape_mask);
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/**
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* art_pdf_composite_knockout_8: General knockout compositing.
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* @dst: Destination pixel.
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* @dst_alpha_g: Pointer to alpha g value associated with @dst.
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* @backdrop: Backdrop pixel (initial backdrop of knockout group).
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* @src: Source pixel.
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* @n_chan: Number of channels.
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* @shape: Shape.
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* @alpha_mask: Alpha mask.
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* @shape_mask: Shape mask.
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* @blend_mode: Blend mode for compositing.
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*
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* This function handles compositing in the case where the knockout
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* group is non-isolated. If the @src pixels themselves come from a
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* non-isolated group, they should be uncomposited before calling this
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* routine.
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**/
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void
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art_pdf_composite_knockout_8(byte *dst,
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byte *dst_alpha_g,
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const byte *backdrop,
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const byte *src,
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int n_chan,
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byte shape,
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byte alpha_mask,
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byte shape_mask, gs_blend_mode_t blend_mode);
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#endif /* gxblend_INCLUDED */
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