shade.h

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// Copyright (C) 2004-2025 Artifex Software, Inc.
//
// This file is part of MuPDF.
//
// MuPDF is free software: you can redistribute it and/or modify it under the
// terms of the GNU Affero General Public License as published by the Free
// Software Foundation, either version 3 of the License, or (at your option)
// any later version.
//
// MuPDF is distributed in the hope that it will be useful, but WITHOUT ANY
// WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
// FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
// details.
//
// You should have received a copy of the GNU Affero General Public License
// along with MuPDF. If not, see <https://www.gnu.org/licenses/agpl-3.0.en.html>
//
// Alternative licensing terms are available from the licensor.
// For commercial licensing, see <https://www.artifex.com/> or contact
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// CA 94129, USA, for further information.
 
#ifndef MUPDF_FITZ_SHADE_H
#define MUPDF_FITZ_SHADE_H
 
#include "mupdf/fitz/system.h"
#include "mupdf/fitz/context.h"
#include "mupdf/fitz/geometry.h"
#include "mupdf/fitz/store.h"
#include "mupdf/fitz/pixmap.h"
#include "mupdf/fitz/compressed-buffer.h"

 
enum
{
    FZ_FUNCTION_BASED = 1,
    FZ_LINEAR = 2,
    FZ_RADIAL = 3,
    FZ_MESH_TYPE4 = 4,
    FZ_MESH_TYPE5 = 5,
    FZ_MESH_TYPE6 = 6,
    FZ_MESH_TYPE7 = 7
};

typedef struct
{
    fz_storable storable;
 
    fz_rect bbox;       /* can be fz_infinite_rect */
    fz_colorspace *colorspace;
 
    fz_matrix matrix;   /* matrix from pattern dict */
    int use_background; /* background color for fills but not 'sh' */
    float background[FZ_MAX_COLORS];
 
    /* Just to be confusing, PDF Shadings of Type 1 (Function Based
     * Shadings), do NOT use function, but all the others do. This
     * is because Type 1 shadings take 2 inputs, whereas all the
     * others (when used with a function take 1 input. The type 1
     * data is in the 'f' field of the union below. */
    /* If function_stride = 0, then function is not used. Otherwise
     * function points to 256*function_stride entries. */
    int function_stride;
    float *function;
 
    int type; /* function, linear, radial, mesh */
    union
    {
        struct
        {
            int extend[2];
            float coords[2][3]; /* (x,y,r) twice */
        } l_or_r;
        struct
        {
            int vprow;
            int bpflag;
            int bpcoord;
            int bpcomp;
            float x0, x1;
            float y0, y1;
            float c0[FZ_MAX_COLORS];
            float c1[FZ_MAX_COLORS];
        } m;
        struct
        {
            fz_matrix matrix;
            int xdivs;
            int ydivs;
            float domain[2][2];
            float *fn_vals;
        } f;
    } u;
 
    fz_compressed_buffer *buffer;
} fz_shade;

fz_shade *fz_keep_shade(fz_context *ctx, fz_shade *shade);

void fz_drop_shade(fz_context *ctx, fz_shade *shade);

fz_rect fz_bound_shade(fz_context *ctx, fz_shade *shade, fz_matrix ctm);
 
typedef struct fz_shade_color_cache fz_shade_color_cache;
 
void fz_drop_shade_color_cache(fz_context *ctx, fz_shade_color_cache *cache);

void fz_paint_shade(fz_context *ctx, fz_shade *shade, fz_colorspace *override_cs, fz_matrix ctm, fz_pixmap *dest, fz_color_params color_params, fz_irect bbox, const fz_overprint *eop, fz_shade_color_cache **cache);

typedef struct
{
    fz_point p;
    float c[FZ_MAX_COLORS];
} fz_vertex;

typedef void (fz_shade_prepare_fn)(fz_context *ctx, void *arg, fz_vertex *v, const float *c);

typedef void (fz_shade_process_fn)(fz_context *ctx, void *arg, fz_vertex *av, fz_vertex *bv, fz_vertex *cv);

void fz_process_shade(fz_context *ctx, fz_shade *shade, fz_matrix ctm, fz_rect scissor,
            fz_shade_prepare_fn *prepare,
            fz_shade_process_fn *process,
            void *process_arg);
 
 
/* Implementation details: subject to change. */

void fz_drop_shade_imp(fz_context *ctx, fz_storable *shade);
 
#endif