--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/source/pdf/pdf-shade.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,531 @@
+// Copyright (C) 2004-2021 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
+// Artifex Software, Inc., 39 Mesa Street, Suite 108A, San Francisco,
+// CA 94129, USA, for further information.
+
+#include "mupdf/fitz.h"
+#include "mupdf/pdf.h"
+
+/* Sample various functions into lookup tables */
+
+static void
+pdf_sample_composite_shade_function(fz_context *ctx, float *shade, int n, pdf_function *func, float t0, float t1)
+{
+	int i;
+	float t;
+
+	for (i = 0; i < 256; i++)
+	{
+		t = t0 + (i / 255.0f) * (t1 - t0);
+		pdf_eval_function(ctx, func, &t, 1, shade, n);
+		shade += n;
+		*shade++ = 1;
+	}
+}
+
+static void
+pdf_sample_component_shade_function(fz_context *ctx, float *shade, int funcs, pdf_function **func, float t0, float t1)
+{
+	int i, k;
+	float t;
+
+	for (i = 0; i < 256; i++)
+	{
+		t = t0 + (i / 255.0f) * (t1 - t0);
+		for (k = 0; k < funcs; k++)
+			pdf_eval_function(ctx, func[k], &t, 1, shade++, 1);
+		*shade++ = 1;
+	}
+}
+
+void
+pdf_sample_shade_function(fz_context *ctx, float *samples, int n, int funcs, pdf_function **func, float t0, float t1)
+{
+	if (funcs == 1)
+		pdf_sample_composite_shade_function(ctx, samples, n, func[0], t0, t1);
+	else
+		pdf_sample_component_shade_function(ctx, samples, funcs, func, t0, t1);
+}
+
+static void
+make_sampled_shade_function(fz_context *ctx, fz_shade *shade, int funcs, pdf_function **func, float t0, float t1)
+{
+	int n = shade->colorspace->n;
+	if (funcs != 1)
+		n = funcs;
+	shade->function_stride = n + 1;
+	shade->function = Memento_label(fz_malloc(ctx, sizeof(float) * 256 * shade->function_stride), "shade samples");
+
+	pdf_sample_shade_function(ctx, shade->function, n, funcs, func, t0, t1);
+}
+
+/* Type 1-3 -- Function-based, linear and radial shadings */
+
+#define FUNSEGS 64 /* size of sampled mesh for function-based shadings */
+
+static void
+pdf_load_function_based_shading(fz_context *ctx, pdf_document *doc, fz_shade *shade, pdf_obj *dict, int funcs, pdf_function **func)
+{
+	pdf_obj *obj;
+	float x0, y0, x1, y1;
+	float fv[2];
+	int xx, yy, zz;
+	float *p;
+	int n = fz_colorspace_n(ctx, shade->colorspace);
+
+	x0 = y0 = 0;
+	x1 = y1 = 1;
+	obj = pdf_dict_get(ctx, dict, PDF_NAME(Domain));
+	if (obj)
+	{
+		x0 = pdf_array_get_real(ctx, obj, 0);
+		x1 = pdf_array_get_real(ctx, obj, 1);
+		y0 = pdf_array_get_real(ctx, obj, 2);
+		y1 = pdf_array_get_real(ctx, obj, 3);
+	}
+
+	shade->u.f.matrix = pdf_dict_get_matrix(ctx, dict, PDF_NAME(Matrix));
+	shade->u.f.xdivs = FUNSEGS;
+	shade->u.f.ydivs = FUNSEGS;
+	shade->u.f.fn_vals = Memento_label(fz_malloc(ctx, (FUNSEGS+1)*(FUNSEGS+1)*n*sizeof(float)), "shade_fn_vals");
+	shade->u.f.domain[0][0] = x0;
+	shade->u.f.domain[0][1] = y0;
+	shade->u.f.domain[1][0] = x1;
+	shade->u.f.domain[1][1] = y1;
+
+	p = shade->u.f.fn_vals;
+	if (funcs == 1)
+	{
+		for (yy = 0; yy <= FUNSEGS; yy++)
+		{
+			fv[1] = y0 + (y1 - y0) * yy / FUNSEGS;
+
+			for (xx = 0; xx <= FUNSEGS; xx++)
+			{
+				fv[0] = x0 + (x1 - x0) * xx / FUNSEGS;
+
+				pdf_eval_function(ctx, func[0], fv, 2, p, n);
+				p += n;
+			}
+		}
+	}
+	else
+	{
+		if (funcs != n)
+			fz_throw(ctx, FZ_ERROR_SYNTAX, "Expected 1 2in, n-out function, or n 2 in, 1-out functions");
+
+		for (yy = 0; yy <= FUNSEGS; yy++)
+		{
+			fv[1] = y0 + (y1 - y0) * yy / FUNSEGS;
+
+			for (xx = 0; xx <= FUNSEGS; xx++)
+			{
+				fv[0] = x0 + (x1 - x0) * xx / FUNSEGS;
+
+				for (zz = 0; zz < n; zz++)
+				{
+					pdf_eval_function(ctx, func[zz], fv, 2, p, 1);
+					p ++;
+				}
+			}
+		}
+	}
+}
+
+static void
+pdf_load_linear_shading(fz_context *ctx, pdf_document *doc, fz_shade *shade, pdf_obj *dict, int funcs, pdf_function **func)
+{
+	pdf_obj *obj;
+	float d0, d1;
+	int e0, e1;
+
+	obj = pdf_dict_get(ctx, dict, PDF_NAME(Coords));
+	shade->u.l_or_r.coords[0][0] = pdf_array_get_real(ctx, obj, 0);
+	shade->u.l_or_r.coords[0][1] = pdf_array_get_real(ctx, obj, 1);
+	shade->u.l_or_r.coords[1][0] = pdf_array_get_real(ctx, obj, 2);
+	shade->u.l_or_r.coords[1][1] = pdf_array_get_real(ctx, obj, 3);
+
+	d0 = 0;
+	d1 = 1;
+	obj = pdf_dict_get(ctx, dict, PDF_NAME(Domain));
+	if (obj)
+	{
+		d0 = pdf_array_get_real(ctx, obj, 0);
+		d1 = pdf_array_get_real(ctx, obj, 1);
+	}
+
+	e0 = e1 = 0;
+	obj = pdf_dict_get(ctx, dict, PDF_NAME(Extend));
+	if (obj)
+	{
+		e0 = pdf_array_get_bool(ctx, obj, 0);
+		e1 = pdf_array_get_bool(ctx, obj, 1);
+	}
+
+	make_sampled_shade_function(ctx, shade, funcs, func, d0, d1);
+
+	shade->u.l_or_r.extend[0] = e0;
+	shade->u.l_or_r.extend[1] = e1;
+}
+
+static void
+pdf_load_radial_shading(fz_context *ctx, pdf_document *doc, fz_shade *shade, pdf_obj *dict, int funcs, pdf_function **func)
+{
+	pdf_obj *obj;
+	float d0, d1;
+	int e0, e1;
+
+	obj = pdf_dict_get(ctx, dict, PDF_NAME(Coords));
+	shade->u.l_or_r.coords[0][0] = pdf_array_get_real(ctx, obj, 0);
+	shade->u.l_or_r.coords[0][1] = pdf_array_get_real(ctx, obj, 1);
+	shade->u.l_or_r.coords[0][2] = pdf_array_get_real(ctx, obj, 2);
+	shade->u.l_or_r.coords[1][0] = pdf_array_get_real(ctx, obj, 3);
+	shade->u.l_or_r.coords[1][1] = pdf_array_get_real(ctx, obj, 4);
+	shade->u.l_or_r.coords[1][2] = pdf_array_get_real(ctx, obj, 5);
+
+	d0 = 0;
+	d1 = 1;
+	obj = pdf_dict_get(ctx, dict, PDF_NAME(Domain));
+	if (obj)
+	{
+		d0 = pdf_array_get_real(ctx, obj, 0);
+		d1 = pdf_array_get_real(ctx, obj, 1);
+	}
+
+	e0 = e1 = 0;
+	obj = pdf_dict_get(ctx, dict, PDF_NAME(Extend));
+	if (obj)
+	{
+		e0 = pdf_array_get_bool(ctx, obj, 0);
+		e1 = pdf_array_get_bool(ctx, obj, 1);
+	}
+
+	make_sampled_shade_function(ctx, shade, funcs, func, d0, d1);
+
+	shade->u.l_or_r.extend[0] = e0;
+	shade->u.l_or_r.extend[1] = e1;
+}
+
+/* Type 4-7 -- Triangle and patch mesh shadings */
+
+struct mesh_params
+{
+	int vprow;
+	int bpflag;
+	int bpcoord;
+	int bpcomp;
+	float x0, x1;
+	float y0, y1;
+	float c0[FZ_MAX_COLORS];
+	float c1[FZ_MAX_COLORS];
+};
+
+static void
+pdf_load_mesh_params(fz_context *ctx, pdf_document *doc, fz_shade *shade, pdf_obj *dict)
+{
+	pdf_obj *obj;
+	int i, n;
+
+	shade->u.m.x0 = shade->u.m.y0 = 0;
+	shade->u.m.x1 = shade->u.m.y1 = 1;
+	for (i = 0; i < FZ_MAX_COLORS; i++)
+	{
+		shade->u.m.c0[i] = 0;
+		shade->u.m.c1[i] = 1;
+	}
+
+	shade->u.m.vprow = pdf_dict_get_int(ctx, dict, PDF_NAME(VerticesPerRow));
+	shade->u.m.bpflag = pdf_dict_get_int(ctx, dict, PDF_NAME(BitsPerFlag));
+	shade->u.m.bpcoord = pdf_dict_get_int(ctx, dict, PDF_NAME(BitsPerCoordinate));
+	shade->u.m.bpcomp = pdf_dict_get_int(ctx, dict, PDF_NAME(BitsPerComponent));
+
+	obj = pdf_dict_get(ctx, dict, PDF_NAME(Decode));
+	if (pdf_array_len(ctx, obj) >= 6)
+	{
+		n = fz_mini(FZ_MAX_COLORS, (pdf_array_len(ctx, obj) - 4) / 2);
+		shade->u.m.x0 = pdf_array_get_real(ctx, obj, 0);
+		shade->u.m.x1 = pdf_array_get_real(ctx, obj, 1);
+		shade->u.m.y0 = pdf_array_get_real(ctx, obj, 2);
+		shade->u.m.y1 = pdf_array_get_real(ctx, obj, 3);
+		for (i = 0; i < n; i++)
+		{
+			shade->u.m.c0[i] = pdf_array_get_real(ctx, obj, 4 + i * 2);
+			shade->u.m.c1[i] = pdf_array_get_real(ctx, obj, 5 + i * 2);
+		}
+	}
+
+	if (shade->u.m.vprow < 2 && shade->type == 5)
+	{
+		fz_warn(ctx, "Too few vertices per row (%d)", shade->u.m.vprow);
+		shade->u.m.vprow = 2;
+	}
+
+	if (shade->u.m.bpflag != 2 && shade->u.m.bpflag != 4 && shade->u.m.bpflag != 8 &&
+		shade->type != 5)
+	{
+		fz_warn(ctx, "Invalid number of bits per flag (%d)", shade->u.m.bpflag);
+		shade->u.m.bpflag = 8;
+	}
+
+	if (shade->u.m.bpcoord != 1 && shade->u.m.bpcoord != 2 && shade->u.m.bpcoord != 4 &&
+		shade->u.m.bpcoord != 8 && shade->u.m.bpcoord != 12 && shade->u.m.bpcoord != 16 &&
+		shade->u.m.bpcoord != 24 && shade->u.m.bpcoord != 32)
+	{
+		fz_warn(ctx, "Invalid number of bits per coordinate (%d)", shade->u.m.bpcoord);
+		shade->u.m.bpcoord = 8;
+	}
+
+	if (shade->u.m.bpcomp != 1 && shade->u.m.bpcomp != 2 && shade->u.m.bpcomp != 4 &&
+		shade->u.m.bpcomp != 8 && shade->u.m.bpcomp != 12 && shade->u.m.bpcomp != 16)
+	{
+		fz_warn(ctx, "Invalid number of bits per component (%d)", shade->u.m.bpcomp);
+		shade->u.m.bpcomp = 8;
+	}
+}
+
+static void
+pdf_load_type4_shade(fz_context *ctx, pdf_document *doc, fz_shade *shade, pdf_obj *dict, int funcs, pdf_function **func)
+{
+	pdf_load_mesh_params(ctx, doc, shade, dict);
+
+	if (funcs > 0)
+		make_sampled_shade_function(ctx, shade, funcs, func, shade->u.m.c0[0], shade->u.m.c1[0]);
+
+	shade->buffer = pdf_load_compressed_stream(ctx, doc, pdf_to_num(ctx, dict), 0);
+}
+
+static void
+pdf_load_type5_shade(fz_context *ctx, pdf_document *doc, fz_shade *shade, pdf_obj *dict, int funcs, pdf_function **func)
+{
+	pdf_load_mesh_params(ctx, doc, shade, dict);
+
+	if (funcs > 0)
+		make_sampled_shade_function(ctx, shade, funcs, func, shade->u.m.c0[0], shade->u.m.c1[0]);
+
+	shade->buffer = pdf_load_compressed_stream(ctx, doc, pdf_to_num(ctx, dict), 0);
+}
+
+/* Type 6 & 7 -- Patch mesh shadings */
+
+static void
+pdf_load_type6_shade(fz_context *ctx, pdf_document *doc, fz_shade *shade, pdf_obj *dict, int funcs, pdf_function **func)
+{
+	pdf_load_mesh_params(ctx, doc, shade, dict);
+
+	if (funcs > 0)
+		make_sampled_shade_function(ctx, shade, funcs, func, shade->u.m.c0[0], shade->u.m.c1[0]);
+
+	shade->buffer = pdf_load_compressed_stream(ctx, doc, pdf_to_num(ctx, dict), 0);
+}
+
+static void
+pdf_load_type7_shade(fz_context *ctx, pdf_document *doc, fz_shade *shade, pdf_obj *dict, int funcs, pdf_function **func)
+{
+	pdf_load_mesh_params(ctx, doc, shade, dict);
+
+	if (funcs > 0)
+		make_sampled_shade_function(ctx, shade, funcs, func, shade->u.m.c0[0], shade->u.m.c1[0]);
+
+	shade->buffer = pdf_load_compressed_stream(ctx, doc, pdf_to_num(ctx, dict), 0);
+}
+
+/* Load all of the shading dictionary parameters, then switch on the shading type. */
+
+static fz_shade *
+pdf_load_shading_dict(fz_context *ctx, pdf_document *doc, pdf_obj *dict, fz_matrix transform)
+{
+	fz_shade *shade = NULL;
+	pdf_function *func[FZ_MAX_COLORS] = { NULL };
+	pdf_obj *obj;
+	int funcs = 0;
+	int type = 0;
+	int i, in, out, n;
+
+	fz_var(shade);
+	fz_var(func);
+	fz_var(funcs);
+	fz_var(type);
+
+	fz_try(ctx)
+	{
+		shade = fz_malloc_struct(ctx, fz_shade);
+		FZ_INIT_STORABLE(shade, 1, fz_drop_shade_imp);
+		shade->type = FZ_MESH_TYPE4;
+		shade->use_background = 0;
+		shade->function_stride = 0;
+		shade->matrix = transform;
+		shade->bbox = fz_infinite_rect;
+
+		shade->colorspace = NULL;
+
+		funcs = 0;
+
+		obj = pdf_dict_get(ctx, dict, PDF_NAME(ShadingType));
+		type = pdf_to_int(ctx, obj);
+
+		obj = pdf_dict_get(ctx, dict, PDF_NAME(ColorSpace));
+		if (!obj)
+			fz_throw(ctx, FZ_ERROR_SYNTAX, "shading colorspace is missing");
+		shade->colorspace = pdf_load_colorspace(ctx, obj);
+		n = fz_colorspace_n(ctx, shade->colorspace);
+
+		obj = pdf_dict_get(ctx, dict, PDF_NAME(Background));
+		if (obj)
+		{
+			shade->use_background = 1;
+			for (i = 0; i < n; i++)
+				shade->background[i] = pdf_array_get_real(ctx, obj, i);
+		}
+
+		obj = pdf_dict_get(ctx, dict, PDF_NAME(BBox));
+		if (pdf_is_array(ctx, obj))
+			shade->bbox = pdf_to_rect(ctx, obj);
+
+		obj = pdf_dict_get(ctx, dict, PDF_NAME(Function));
+		if (pdf_is_dict(ctx, obj))
+		{
+			funcs = 1;
+
+			if (type == 1)
+				in = 2;
+			else
+				in = 1;
+			out = n;
+
+			func[0] = pdf_load_function(ctx, obj, in, out);
+			if (!func[0])
+				fz_throw(ctx, FZ_ERROR_SYNTAX, "cannot load shading function (%d 0 R)", pdf_to_num(ctx, obj));
+		}
+		else if (pdf_is_array(ctx, obj))
+		{
+			funcs = pdf_array_len(ctx, obj);
+			if (funcs != 1 && funcs != n)
+			{
+				funcs = 0;
+				fz_throw(ctx, FZ_ERROR_SYNTAX, "incorrect number of shading functions");
+			}
+			if (funcs > FZ_MAX_COLORS)
+			{
+				funcs = 0;
+				fz_throw(ctx, FZ_ERROR_SYNTAX, "too many shading functions");
+			}
+
+			if (type == 1)
+				in = 2;
+			else
+				in = 1;
+			out = 1;
+
+			for (i = 0; i < funcs; i++)
+			{
+				func[i] = pdf_load_function(ctx, pdf_array_get(ctx, obj, i), in, out);
+				if (!func[i])
+					fz_throw(ctx, FZ_ERROR_SYNTAX, "cannot load shading function (%d 0 R)", pdf_to_num(ctx, obj));
+			}
+		}
+		else if (type < 4)
+		{
+			/* Functions are compulsory for types 1,2,3 */
+			fz_throw(ctx, FZ_ERROR_SYNTAX, "cannot load shading function (%d 0 R)", pdf_to_num(ctx, obj));
+		}
+
+		shade->type = type;
+		switch (type)
+		{
+		case 1: pdf_load_function_based_shading(ctx, doc, shade, dict, funcs, func); break;
+		case 2: pdf_load_linear_shading(ctx, doc, shade, dict, funcs, func); break;
+		case 3: pdf_load_radial_shading(ctx, doc, shade, dict, funcs, func); break;
+		case 4: pdf_load_type4_shade(ctx, doc, shade, dict, funcs, func); break;
+		case 5: pdf_load_type5_shade(ctx, doc, shade, dict, funcs, func); break;
+		case 6: pdf_load_type6_shade(ctx, doc, shade, dict, funcs, func); break;
+		case 7: pdf_load_type7_shade(ctx, doc, shade, dict, funcs, func); break;
+		default:
+			fz_throw(ctx, FZ_ERROR_SYNTAX, "unknown shading type: %d", type);
+		}
+	}
+	fz_always(ctx)
+	{
+		for (i = 0; i < funcs; i++)
+			pdf_drop_function(ctx, func[i]);
+	}
+	fz_catch(ctx)
+	{
+		fz_drop_shade(ctx, shade);
+		fz_rethrow(ctx);
+	}
+	return shade;
+}
+
+static size_t
+fz_shade_size(fz_context *ctx, fz_shade *s)
+{
+	size_t f = 0;
+	if (s == NULL)
+		return 0;
+	if (s->function_stride)
+		f = sizeof(float) * s->function_stride * 256;
+	if (s->type == FZ_FUNCTION_BASED)
+		return sizeof(*s) + sizeof(float) * s->u.f.xdivs * s->u.f.ydivs * fz_colorspace_n(ctx, s->colorspace) + f;
+	return sizeof(*s) + fz_compressed_buffer_size(s->buffer) + f;
+}
+
+fz_shade *
+pdf_load_shading(fz_context *ctx, pdf_document *doc, pdf_obj *dict)
+{
+	fz_matrix mat;
+	pdf_obj *obj;
+	fz_shade *shade;
+
+	if ((shade = pdf_find_item(ctx, fz_drop_shade_imp, dict)) != NULL)
+	{
+		return shade;
+	}
+
+	/* Type 2 pattern dictionary */
+	if (pdf_dict_get(ctx, dict, PDF_NAME(PatternType)))
+	{
+		mat = pdf_dict_get_matrix(ctx, dict, PDF_NAME(Matrix));
+
+		obj = pdf_dict_get(ctx, dict, PDF_NAME(ExtGState));
+		if (obj)
+		{
+			if (pdf_dict_get(ctx, obj, PDF_NAME(CA)) || pdf_dict_get(ctx, obj, PDF_NAME(ca)))
+			{
+				fz_warn(ctx, "shading with alpha not supported");
+			}
+		}
+
+		obj = pdf_dict_get(ctx, dict, PDF_NAME(Shading));
+		if (!obj)
+			fz_throw(ctx, FZ_ERROR_SYNTAX, "missing shading dictionary");
+
+		shade = pdf_load_shading_dict(ctx, doc, obj, mat);
+	}
+
+	/* Naked shading dictionary */
+	else
+	{
+		shade = pdf_load_shading_dict(ctx, doc, dict, fz_identity);
+	}
+
+	pdf_store_item(ctx, dict, shade, fz_shade_size(ctx, shade));
+
+	return shade;
+}