--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/mupdf-source/source/xps/xps-gradient.c	Mon Sep 15 11:43:07 2025 +0200
@@ -0,0 +1,551 @@
+// 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 "xps-imp.h"
+
+#include <string.h>
+#include <math.h>
+#include <float.h>
+#include <stdlib.h>
+
+#define MAX_STOPS 256
+
+enum { SPREAD_PAD, SPREAD_REPEAT, SPREAD_REFLECT };
+
+/*
+ * Parse a list of GradientStop elements.
+ * Fill the offset and color arrays, and
+ * return the number of stops parsed.
+ */
+
+struct stop
+{
+	float offset;
+	float r, g, b, a;
+	int index;
+};
+
+static int cmp_stop(const void *a, const void *b)
+{
+	const struct stop *astop = a;
+	const struct stop *bstop = b;
+	float diff = astop->offset - bstop->offset;
+	if (diff < 0)
+		return -1;
+	if (diff > 0)
+		return 1;
+	return astop->index - bstop->index;
+}
+
+static inline float lerp(float a, float b, float x)
+{
+	return a + (b - a) * x;
+}
+
+static int
+xps_parse_gradient_stops(fz_context *ctx, xps_document *doc, char *base_uri, fz_xml *node,
+	struct stop *stops, int maxcount)
+{
+	fz_colorspace *colorspace;
+	float sample[FZ_MAX_COLORS];
+	float rgb[3];
+	int before, after;
+	int count;
+	int i;
+
+	/* We may have to insert 2 extra stops when postprocessing */
+	maxcount -= 2;
+
+	count = 0;
+	while (node && count < maxcount)
+	{
+		if (fz_xml_is_tag(node, "GradientStop"))
+		{
+			char *offset = fz_xml_att(node, "Offset");
+			char *color = fz_xml_att(node, "Color");
+			if (offset && color)
+			{
+				stops[count].offset = fz_atof(offset);
+				stops[count].index = count;
+
+				xps_parse_color(ctx, doc, base_uri, color, &colorspace, sample);
+
+				fz_convert_color(ctx, colorspace, sample+1, fz_device_rgb(ctx), rgb, NULL, fz_default_color_params);
+
+				stops[count].r = rgb[0];
+				stops[count].g = rgb[1];
+				stops[count].b = rgb[2];
+				stops[count].a = sample[0];
+
+				count ++;
+			}
+		}
+		node = fz_xml_next(node);
+	}
+
+	if (count == 0)
+	{
+		fz_warn(ctx, "gradient brush has no gradient stops");
+		stops[0].offset = 0;
+		stops[0].r = 0;
+		stops[0].g = 0;
+		stops[0].b = 0;
+		stops[0].a = 1;
+		stops[1].offset = 1;
+		stops[1].r = 1;
+		stops[1].g = 1;
+		stops[1].b = 1;
+		stops[1].a = 1;
+		return 2;
+	}
+
+	if (count == maxcount)
+		fz_warn(ctx, "gradient brush exceeded maximum number of gradient stops");
+
+	/* Postprocess to make sure the range of offsets is 0.0 to 1.0 */
+
+	qsort(stops, count, sizeof(struct stop), cmp_stop);
+
+	before = -1;
+	after = -1;
+
+	for (i = 0; i < count; i++)
+	{
+		if (stops[i].offset < 0)
+			before = i;
+		if (stops[i].offset > 1)
+		{
+			after = i;
+			break;
+		}
+	}
+
+	/* Remove all stops < 0 except the largest one */
+	if (before > 0)
+	{
+		memmove(stops, stops + before, (count - before) * sizeof(struct stop));
+		count -= before;
+	}
+
+	/* Remove all stops > 1 except the smallest one */
+	if (after >= 0)
+		count = after + 1;
+
+	/* Expand single stop to 0 .. 1 */
+	if (count == 1)
+	{
+		stops[1] = stops[0];
+		stops[0].offset = 0;
+		stops[1].offset = 1;
+		return 2;
+	}
+
+	/* First stop < 0 -- interpolate value to 0 */
+	if (stops[0].offset < 0)
+	{
+		float d = -stops[0].offset / (stops[1].offset - stops[0].offset);
+		stops[0].offset = 0;
+		stops[0].r = lerp(stops[0].r, stops[1].r, d);
+		stops[0].g = lerp(stops[0].g, stops[1].g, d);
+		stops[0].b = lerp(stops[0].b, stops[1].b, d);
+		stops[0].a = lerp(stops[0].a, stops[1].a, d);
+	}
+
+	/* Last stop > 1 -- interpolate value to 1 */
+	if (stops[count-1].offset > 1)
+	{
+		float d = (1 - stops[count-2].offset) / (stops[count-1].offset - stops[count-2].offset);
+		stops[count-1].offset = 1;
+		stops[count-1].r = lerp(stops[count-2].r, stops[count-1].r, d);
+		stops[count-1].g = lerp(stops[count-2].g, stops[count-1].g, d);
+		stops[count-1].b = lerp(stops[count-2].b, stops[count-1].b, d);
+		stops[count-1].a = lerp(stops[count-2].a, stops[count-1].a, d);
+	}
+
+	/* First stop > 0 -- insert a duplicate at 0 */
+	if (stops[0].offset > 0)
+	{
+		memmove(stops + 1, stops, count * sizeof(struct stop));
+		stops[0] = stops[1];
+		stops[0].offset = 0;
+		count++;
+	}
+
+	/* Last stop < 1 -- insert a duplicate at 1 */
+	if (stops[count-1].offset < 1)
+	{
+		stops[count] = stops[count-1];
+		stops[count].offset = 1;
+		count++;
+	}
+
+	return count;
+}
+
+static void
+xps_sample_gradient_stops(fz_context *ctx, xps_document *doc, fz_shade *shade, struct stop *stops, int count)
+{
+	float offset, d;
+	int i, k;
+
+	shade->function = fz_malloc(ctx, sizeof(float) * 256 * 4);
+
+	k = 0;
+	for (i = 0; i < 256; i++)
+	{
+		offset = i / 255.0f;
+		while (k + 1 < count && offset > stops[k+1].offset)
+			k++;
+
+		d = (offset - stops[k].offset) / (stops[k+1].offset - stops[k].offset);
+
+		shade->function[4*i + 0] = lerp(stops[k].r, stops[k+1].r, d);
+		shade->function[4*i + 1] = lerp(stops[k].g, stops[k+1].g, d);
+		shade->function[4*i + 2] = lerp(stops[k].b, stops[k+1].b, d);
+		shade->function[4*i + 3] = lerp(stops[k].a, stops[k+1].a, d);
+	}
+}
+
+/*
+ * Radial gradients map more or less to Radial shadings.
+ * The inner circle is always a point.
+ * The outer circle is actually an ellipse,
+ * mess with the transform to squash the circle into the right aspect.
+ */
+
+static void
+xps_draw_one_radial_gradient(fz_context *ctx, xps_document *doc, fz_matrix ctm,
+	struct stop *stops, int count,
+	int extend,
+	float x0, float y0, float r0,
+	float x1, float y1, float r1)
+{
+	fz_device *dev = doc->dev;
+	fz_shade *shade;
+
+	shade = fz_malloc_struct(ctx, fz_shade);
+	FZ_INIT_STORABLE(shade, 1, fz_drop_shade_imp);
+	shade->colorspace = fz_keep_colorspace(ctx, fz_device_rgb(ctx));
+	shade->bbox = fz_infinite_rect;
+	shade->matrix = fz_identity;
+	shade->use_background = 0;
+	shade->function_stride = 4;
+	shade->type = FZ_RADIAL;
+	shade->u.l_or_r.extend[0] = extend;
+	shade->u.l_or_r.extend[1] = extend;
+
+	shade->u.l_or_r.coords[0][0] = x0;
+	shade->u.l_or_r.coords[0][1] = y0;
+	shade->u.l_or_r.coords[0][2] = r0;
+	shade->u.l_or_r.coords[1][0] = x1;
+	shade->u.l_or_r.coords[1][1] = y1;
+	shade->u.l_or_r.coords[1][2] = r1;
+
+	fz_try(ctx)
+	{
+		xps_sample_gradient_stops(ctx, doc, shade, stops, count);
+		fz_fill_shade(ctx, dev, shade, ctm, 1, fz_default_color_params);
+	}
+	fz_always(ctx)
+		fz_drop_shade(ctx, shade);
+	fz_catch(ctx)
+		fz_rethrow(ctx);
+}
+
+/*
+ * Linear gradients.
+ */
+
+static void
+xps_draw_one_linear_gradient(fz_context *ctx, xps_document *doc, fz_matrix ctm,
+	struct stop *stops, int count,
+	int extend,
+	float x0, float y0, float x1, float y1)
+{
+	fz_device *dev = doc->dev;
+	fz_shade *shade;
+
+	shade = fz_malloc_struct(ctx, fz_shade);
+	FZ_INIT_STORABLE(shade, 1, fz_drop_shade_imp);
+	shade->colorspace = fz_keep_colorspace(ctx, fz_device_rgb(ctx));
+	shade->bbox = fz_infinite_rect;
+	shade->matrix = fz_identity;
+	shade->use_background = 0;
+	shade->function_stride = 4;
+	shade->type = FZ_LINEAR;
+	shade->u.l_or_r.extend[0] = extend;
+	shade->u.l_or_r.extend[1] = extend;
+
+	shade->u.l_or_r.coords[0][0] = x0;
+	shade->u.l_or_r.coords[0][1] = y0;
+	shade->u.l_or_r.coords[0][2] = 0;
+	shade->u.l_or_r.coords[1][0] = x1;
+	shade->u.l_or_r.coords[1][1] = y1;
+	shade->u.l_or_r.coords[1][2] = 0;
+
+	fz_try(ctx)
+	{
+		xps_sample_gradient_stops(ctx, doc, shade, stops, count);
+		fz_fill_shade(ctx, dev, shade, ctm, doc->opacity[doc->opacity_top], fz_default_color_params);
+	}
+	fz_always(ctx)
+		fz_drop_shade(ctx, shade);
+	fz_catch(ctx)
+		fz_rethrow(ctx);
+}
+
+/*
+ * We need to loop and create many shading objects to account
+ * for the Repeat and Reflect SpreadMethods.
+ * I'm not smart enough to calculate this analytically
+ * so we iterate and check each object until we
+ * reach a reasonable limit for infinite cases.
+ */
+
+static void
+xps_draw_radial_gradient(fz_context *ctx, xps_document *doc, fz_matrix ctm, fz_rect area,
+	struct stop *stops, int count,
+	fz_xml *root, int spread)
+{
+	float x0, y0, r0;
+	float x1, y1, r1;
+	float xrad = 1;
+	float yrad = 1;
+	float invscale;
+	int i, ma = 1;
+	fz_matrix inv;
+
+	char *center_att = fz_xml_att(root, "Center");
+	char *origin_att = fz_xml_att(root, "GradientOrigin");
+	char *radius_x_att = fz_xml_att(root, "RadiusX");
+	char *radius_y_att = fz_xml_att(root, "RadiusY");
+
+	x0 = y0 = 0.0f;
+	x1 = y1 = 1.0f;
+	xrad = 1.0f;
+	yrad = 1.0f;
+
+	if (origin_att)
+		xps_parse_point(ctx, doc, origin_att, &x0, &y0);
+	if (center_att)
+		xps_parse_point(ctx, doc, center_att, &x1, &y1);
+	if (radius_x_att)
+		xrad = fz_atof(radius_x_att);
+	if (radius_y_att)
+		yrad = fz_atof(radius_y_att);
+
+	xrad = fz_max(0.01f, xrad);
+	yrad = fz_max(0.01f, yrad);
+
+	/* scale the ctm to make ellipses */
+	if (fz_abs(xrad) > FLT_EPSILON)
+	{
+		ctm = fz_pre_scale(ctm, 1, yrad/xrad);
+	}
+
+	if (yrad != 0.0f)
+	{
+		invscale = xrad / yrad;
+		y0 = y0 * invscale;
+		y1 = y1 * invscale;
+	}
+
+	r0 = 0;
+	r1 = xrad;
+
+	inv = fz_invert_matrix(ctm);
+	area = fz_transform_rect(area, inv);
+	ma = fz_maxi(ma, ceilf(hypotf(area.x0 - x0, area.y0 - y0) / xrad));
+	ma = fz_maxi(ma, ceilf(hypotf(area.x1 - x0, area.y0 - y0) / xrad));
+	ma = fz_maxi(ma, ceilf(hypotf(area.x0 - x0, area.y1 - y0) / xrad));
+	ma = fz_maxi(ma, ceilf(hypotf(area.x1 - x0, area.y1 - y0) / xrad));
+
+	if (spread == SPREAD_REPEAT)
+	{
+		for (i = ma - 1; i >= 0; i--)
+			xps_draw_one_radial_gradient(ctx, doc, ctm, stops, count, 0, x0, y0, r0 + i * xrad, x1, y1, r1 + i * xrad);
+	}
+	else if (spread == SPREAD_REFLECT)
+	{
+		if ((ma % 2) != 0)
+			ma++;
+		for (i = ma - 2; i >= 0; i -= 2)
+		{
+			xps_draw_one_radial_gradient(ctx, doc, ctm, stops, count, 0, x0, y0, r0 + i * xrad, x1, y1, r1 + i * xrad);
+			xps_draw_one_radial_gradient(ctx, doc, ctm, stops, count, 0, x0, y0, r0 + (i + 2) * xrad, x1, y1, r1 + i * xrad);
+		}
+	}
+	else
+	{
+		xps_draw_one_radial_gradient(ctx, doc, ctm, stops, count, 1, x0, y0, r0, x1, y1, r1);
+	}
+}
+
+/*
+ * Calculate how many iterations are needed to cover
+ * the bounding box.
+ */
+
+static void
+xps_draw_linear_gradient(fz_context *ctx, xps_document *doc, fz_matrix ctm, fz_rect area,
+	struct stop *stops, int count,
+	fz_xml *root, int spread)
+{
+	float x0, y0, x1, y1;
+	int i, mi, ma;
+	float dx, dy, x, y, k;
+	fz_point p1, p2;
+	fz_matrix inv;
+
+	char *start_point_att = fz_xml_att(root, "StartPoint");
+	char *end_point_att = fz_xml_att(root, "EndPoint");
+
+	x0 = y0 = 0;
+	x1 = y1 = 1;
+
+	if (start_point_att)
+		xps_parse_point(ctx, doc, start_point_att, &x0, &y0);
+	if (end_point_att)
+		xps_parse_point(ctx, doc, end_point_att, &x1, &y1);
+
+	p1.x = x0; p1.y = y0; p2.x = x1; p2.y = y1;
+	inv = fz_invert_matrix(ctm);
+	area = fz_transform_rect(area, inv);
+	x = p2.x - p1.x; y = p2.y - p1.y;
+	k = ((area.x0 - p1.x) * x + (area.y0 - p1.y) * y) / (x * x + y * y);
+	mi = floorf(k); ma = ceilf(k);
+	k = ((area.x1 - p1.x) * x + (area.y0 - p1.y) * y) / (x * x + y * y);
+	mi = fz_mini(mi, floorf(k)); ma = fz_maxi(ma, ceilf(k));
+	k = ((area.x0 - p1.x) * x + (area.y1 - p1.y) * y) / (x * x + y * y);
+	mi = fz_mini(mi, floorf(k)); ma = fz_maxi(ma, ceilf(k));
+	k = ((area.x1 - p1.x) * x + (area.y1 - p1.y) * y) / (x * x + y * y);
+	mi = fz_mini(mi, floorf(k)); ma = fz_maxi(ma, ceilf(k));
+	dx = x1 - x0; dy = y1 - y0;
+
+	if (spread == SPREAD_REPEAT)
+	{
+		for (i = mi; i < ma; i++)
+			xps_draw_one_linear_gradient(ctx, doc, ctm, stops, count, 0, x0 + i * dx, y0 + i * dy, x1 + i * dx, y1 + i * dy);
+	}
+	else if (spread == SPREAD_REFLECT)
+	{
+		if ((mi % 2) != 0)
+			mi--;
+		for (i = mi; i < ma; i += 2)
+		{
+			xps_draw_one_linear_gradient(ctx, doc, ctm, stops, count, 0, x0 + i * dx, y0 + i * dy, x1 + i * dx, y1 + i * dy);
+			xps_draw_one_linear_gradient(ctx, doc, ctm, stops, count, 0, x0 + (i + 2) * dx, y0 + (i + 2) * dy, x1 + i * dx, y1 + i * dy);
+		}
+	}
+	else
+	{
+		xps_draw_one_linear_gradient(ctx, doc, ctm, stops, count, 1, x0, y0, x1, y1);
+	}
+}
+
+/*
+ * Parse XML tag and attributes for a gradient brush, create color/opacity
+ * function objects and call gradient drawing primitives.
+ */
+
+static void
+xps_parse_gradient_brush(fz_context *ctx, xps_document *doc, fz_matrix ctm, fz_rect area,
+	char *base_uri, xps_resource *dict, fz_xml *root,
+	void (*draw)(fz_context *ctx, xps_document *, fz_matrix, fz_rect, struct stop *, int, fz_xml *, int))
+{
+	fz_xml *node;
+
+	char *opacity_att;
+	char *spread_att;
+	char *transform_att;
+
+	fz_xml *transform_tag = NULL;
+	fz_xml *stop_tag = NULL;
+
+	struct stop stop_list[MAX_STOPS];
+	int stop_count;
+	int spread_method;
+
+	opacity_att = fz_xml_att(root, "Opacity");
+	spread_att = fz_xml_att(root, "SpreadMethod");
+	transform_att = fz_xml_att(root, "Transform");
+
+	for (node = fz_xml_down(root); node; node = fz_xml_next(node))
+	{
+		if (fz_xml_is_tag(node, "LinearGradientBrush.Transform"))
+			transform_tag = fz_xml_down(node);
+		if (fz_xml_is_tag(node, "RadialGradientBrush.Transform"))
+			transform_tag = fz_xml_down(node);
+		if (fz_xml_is_tag(node, "LinearGradientBrush.GradientStops"))
+			stop_tag = fz_xml_down(node);
+		if (fz_xml_is_tag(node, "RadialGradientBrush.GradientStops"))
+			stop_tag = fz_xml_down(node);
+	}
+
+	xps_resolve_resource_reference(ctx, doc, dict, &transform_att, &transform_tag, NULL);
+
+	spread_method = SPREAD_PAD;
+	if (spread_att)
+	{
+		if (!strcmp(spread_att, "Pad"))
+			spread_method = SPREAD_PAD;
+		if (!strcmp(spread_att, "Reflect"))
+			spread_method = SPREAD_REFLECT;
+		if (!strcmp(spread_att, "Repeat"))
+			spread_method = SPREAD_REPEAT;
+	}
+
+	ctm = xps_parse_transform(ctx, doc, transform_att, transform_tag, ctm);
+
+	if (!stop_tag) {
+		fz_warn(ctx, "missing gradient stops tag");
+		return;
+	}
+
+	stop_count = xps_parse_gradient_stops(ctx, doc, base_uri, stop_tag, stop_list, MAX_STOPS);
+	if (stop_count == 0)
+	{
+		fz_warn(ctx, "no gradient stops found");
+		return;
+	}
+
+	xps_begin_opacity(ctx, doc, ctm, area, base_uri, dict, opacity_att, NULL);
+
+	draw(ctx, doc, ctm, area, stop_list, stop_count, root, spread_method);
+
+	xps_end_opacity(ctx, doc, base_uri, dict, opacity_att, NULL);
+}
+
+void
+xps_parse_linear_gradient_brush(fz_context *ctx, xps_document *doc, fz_matrix ctm, fz_rect area,
+	char *base_uri, xps_resource *dict, fz_xml *root)
+{
+	xps_parse_gradient_brush(ctx, doc, ctm, area, base_uri, dict, root, xps_draw_linear_gradient);
+}
+
+void
+xps_parse_radial_gradient_brush(fz_context *ctx, xps_document *doc, fz_matrix ctm, fz_rect area,
+	char *base_uri, xps_resource *dict, fz_xml *root)
+{
+	xps_parse_gradient_brush(ctx, doc, ctm, area, base_uri, dict, root, xps_draw_radial_gradient);
+}