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diff --git a/gfx/cairo/libpixman/src/pixman-linear-gradient.c b/gfx/cairo/libpixman/src/pixman-linear-gradient.c
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+/* -*- Mode: c; c-basic-offset: 4; tab-width: 8; indent-tabs-mode: t; -*- */
+/*
+ * Copyright © 2000 SuSE, Inc.
+ * Copyright © 2007 Red Hat, Inc.
+ * Copyright © 2000 Keith Packard, member of The XFree86 Project, Inc.
+ * 2005 Lars Knoll & Zack Rusin, Trolltech
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation, and that the name of Keith Packard not be used in
+ * advertising or publicity pertaining to distribution of the software without
+ * specific, written prior permission. Keith Packard makes no
+ * representations about the suitability of this software for any purpose. It
+ * is provided "as is" without express or implied warranty.
+ *
+ * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
+ * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
+ * FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
+ * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
+ * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
+ * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
+ * SOFTWARE.
+ */
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+#include <stdlib.h>
+#include "pixman-private.h"
+
+#include "pixman-dither.h"
+
+static pixman_bool_t
+linear_gradient_is_horizontal (pixman_image_t *image,
+ int x,
+ int y,
+ int width,
+ int height)
+{
+ linear_gradient_t *linear = (linear_gradient_t *)image;
+ pixman_vector_t v;
+ pixman_fixed_32_32_t l;
+ pixman_fixed_48_16_t dx, dy;
+ double inc;
+
+ if (image->common.transform)
+ {
+ /* projective transformation */
+ if (image->common.transform->matrix[2][0] != 0 ||
+ image->common.transform->matrix[2][1] != 0 ||
+ image->common.transform->matrix[2][2] == 0)
+ {
+ return FALSE;
+ }
+
+ v.vector[0] = image->common.transform->matrix[0][1];
+ v.vector[1] = image->common.transform->matrix[1][1];
+ v.vector[2] = image->common.transform->matrix[2][2];
+ }
+ else
+ {
+ v.vector[0] = 0;
+ v.vector[1] = pixman_fixed_1;
+ v.vector[2] = pixman_fixed_1;
+ }
+
+ dx = linear->p2.x - linear->p1.x;
+ dy = linear->p2.y - linear->p1.y;
+
+ l = dx * dx + dy * dy;
+
+ if (l == 0)
+ return FALSE;
+
+ /*
+ * compute how much the input of the gradient walked changes
+ * when moving vertically through the whole image
+ */
+ inc = height * (double) pixman_fixed_1 * pixman_fixed_1 *
+ (dx * v.vector[0] + dy * v.vector[1]) /
+ (v.vector[2] * (double) l);
+
+ /* check that casting to integer would result in 0 */
+ if (-1 < inc && inc < 1)
+ return TRUE;
+
+ return FALSE;
+}
+
+static uint32_t *
+linear_get_scanline_narrow (pixman_iter_t *iter,
+ const uint32_t *mask)
+{
+ pixman_image_t *image = iter->image;
+ int x = iter->x;
+ int y = iter->y;
+ int width = iter->width;
+ uint32_t * buffer = iter->buffer;
+
+ pixman_vector_t v, unit;
+ pixman_fixed_32_32_t l;
+ pixman_fixed_48_16_t dx, dy;
+ gradient_t *gradient = (gradient_t *)image;
+ linear_gradient_t *linear = (linear_gradient_t *)image;
+ uint32_t *end = buffer + width;
+ pixman_gradient_walker_t walker;
+
+ _pixman_gradient_walker_init (&walker, gradient, image->common.repeat);
+
+ /* reference point is the center of the pixel */
+ v.vector[0] = pixman_int_to_fixed (x) + pixman_fixed_1 / 2;
+ v.vector[1] = pixman_int_to_fixed (y) + pixman_fixed_1 / 2;
+ v.vector[2] = pixman_fixed_1;
+
+ if (image->common.transform)
+ {
+ if (!pixman_transform_point_3d (image->common.transform, &v))
+ return iter->buffer;
+
+ unit.vector[0] = image->common.transform->matrix[0][0];
+ unit.vector[1] = image->common.transform->matrix[1][0];
+ unit.vector[2] = image->common.transform->matrix[2][0];
+ }
+ else
+ {
+ unit.vector[0] = pixman_fixed_1;
+ unit.vector[1] = 0;
+ unit.vector[2] = 0;
+ }
+
+ dx = linear->p2.x - linear->p1.x;
+ dy = linear->p2.y - linear->p1.y;
+
+ l = dx * dx + dy * dy;
+
+ if (l == 0 || unit.vector[2] == 0)
+ {
+ /* affine transformation only */
+ pixman_fixed_32_32_t t, next_inc;
+ double inc;
+
+ if (l == 0 || v.vector[2] == 0)
+ {
+ t = 0;
+ inc = 0;
+ }
+ else
+ {
+ double invden, v2;
+
+ invden = pixman_fixed_1 * (double) pixman_fixed_1 /
+ (l * (double) v.vector[2]);
+ v2 = v.vector[2] * (1. / pixman_fixed_1);
+ t = ((dx * v.vector[0] + dy * v.vector[1]) -
+ (dx * linear->p1.x + dy * linear->p1.y) * v2) * invden;
+ inc = (dx * unit.vector[0] + dy * unit.vector[1]) * invden;
+ }
+ next_inc = 0;
+
+ if (((pixman_fixed_32_32_t )(inc * width)) == 0)
+ {
+ register uint32_t color;
+
+ color = _pixman_gradient_walker_pixel (&walker, t);
+ while (buffer < end)
+ *buffer++ = color;
+ }
+ else
+ {
+ int i;
+
+ i = 0;
+ while (buffer < end)
+ {
+ if (!mask || *mask++)
+ {
+ *buffer = _pixman_gradient_walker_pixel (&walker,
+ t + next_inc);
+ }
+ i++;
+ next_inc = inc * i;
+ buffer++;
+ }
+ }
+ }
+ else
+ {
+ /* projective transformation */
+ double t;
+
+ t = 0;
+
+ while (buffer < end)
+ {
+ if (!mask || *mask++)
+ {
+ if (v.vector[2] != 0)
+ {
+ double invden, v2;
+
+ invden = pixman_fixed_1 * (double) pixman_fixed_1 /
+ (l * (double) v.vector[2]);
+ v2 = v.vector[2] * (1. / pixman_fixed_1);
+ t = ((dx * v.vector[0] + dy * v.vector[1]) -
+ (dx * linear->p1.x + dy * linear->p1.y) * v2) * invden;
+ }
+
+ *buffer = _pixman_gradient_walker_pixel (&walker, t);
+ }
+
+ ++buffer;
+
+ v.vector[0] += unit.vector[0];
+ v.vector[1] += unit.vector[1];
+ v.vector[2] += unit.vector[2];
+ }
+ }
+
+ iter->y++;
+
+ return iter->buffer;
+}
+
+static uint32_t *
+linear_get_scanline_16 (pixman_iter_t *iter,
+ const uint32_t *mask)
+{
+ pixman_image_t *image = iter->image;
+ int x = iter->x;
+ int y = iter->y;
+ int width = iter->width;
+ uint16_t * buffer = (uint16_t*)iter->buffer;
+ pixman_bool_t toggle = ((x ^ y) & 1);
+
+ pixman_vector_t v, unit;
+ pixman_fixed_32_32_t l;
+ pixman_fixed_48_16_t dx, dy;
+ gradient_t *gradient = (gradient_t *)image;
+ linear_gradient_t *linear = (linear_gradient_t *)image;
+ uint16_t *end = buffer + width;
+ pixman_gradient_walker_t walker;
+
+ _pixman_gradient_walker_init (&walker, gradient, image->common.repeat);
+
+ /* reference point is the center of the pixel */
+ v.vector[0] = pixman_int_to_fixed (x) + pixman_fixed_1 / 2;
+ v.vector[1] = pixman_int_to_fixed (y) + pixman_fixed_1 / 2;
+ v.vector[2] = pixman_fixed_1;
+
+ if (image->common.transform)
+ {
+ if (!pixman_transform_point_3d (image->common.transform, &v))
+ return iter->buffer;
+
+ unit.vector[0] = image->common.transform->matrix[0][0];
+ unit.vector[1] = image->common.transform->matrix[1][0];
+ unit.vector[2] = image->common.transform->matrix[2][0];
+ }
+ else
+ {
+ unit.vector[0] = pixman_fixed_1;
+ unit.vector[1] = 0;
+ unit.vector[2] = 0;
+ }
+
+ dx = linear->p2.x - linear->p1.x;
+ dy = linear->p2.y - linear->p1.y;
+
+ l = dx * dx + dy * dy;
+
+ if (l == 0 || unit.vector[2] == 0)
+ {
+ /* affine transformation only */
+ pixman_fixed_32_32_t t, next_inc;
+ double inc;
+
+ if (l == 0 || v.vector[2] == 0)
+ {
+ t = 0;
+ inc = 0;
+ }
+ else
+ {
+ double invden, v2;
+
+ invden = pixman_fixed_1 * (double) pixman_fixed_1 /
+ (l * (double) v.vector[2]);
+ v2 = v.vector[2] * (1. / pixman_fixed_1);
+ t = ((dx * v.vector[0] + dy * v.vector[1]) -
+ (dx * linear->p1.x + dy * linear->p1.y) * v2) * invden;
+ inc = (dx * unit.vector[0] + dy * unit.vector[1]) * invden;
+ }
+ next_inc = 0;
+
+ if (((pixman_fixed_32_32_t )(inc * width)) == 0)
+ {
+ register uint32_t color;
+ uint16_t dither_diff;
+ uint16_t color16;
+ uint16_t color16b;
+
+ color = _pixman_gradient_walker_pixel (&walker, t);
+ color16 = dither_8888_to_0565(color, toggle);
+ color16b = dither_8888_to_0565(color, toggle^1);
+ // compute the difference
+ dither_diff = color16 ^ color16b;
+ while (buffer < end) {
+ *buffer++ = color16;
+ // use dither_diff to toggle between color16 and color16b
+ color16 ^= dither_diff;
+ toggle ^= 1;
+ }
+ }
+ else
+ {
+ int i;
+
+ i = 0;
+ while (buffer < end)
+ {
+ if (!mask || *mask++)
+ {
+ *buffer = dither_8888_to_0565(_pixman_gradient_walker_pixel (&walker,
+ t + next_inc),
+ toggle);
+ }
+ toggle ^= 1;
+ i++;
+ next_inc = inc * i;
+ buffer++;
+ }
+ }
+ }
+ else
+ {
+ /* projective transformation */
+ double t;
+
+ t = 0;
+
+ while (buffer < end)
+ {
+ if (!mask || *mask++)
+ {
+ if (v.vector[2] != 0)
+ {
+ double invden, v2;
+
+ invden = pixman_fixed_1 * (double) pixman_fixed_1 /
+ (l * (double) v.vector[2]);
+ v2 = v.vector[2] * (1. / pixman_fixed_1);
+ t = ((dx * v.vector[0] + dy * v.vector[1]) -
+ (dx * linear->p1.x + dy * linear->p1.y) * v2) * invden;
+ }
+
+ *buffer = dither_8888_to_0565(_pixman_gradient_walker_pixel (&walker, t),
+ toggle);
+ }
+ toggle ^= 1;
+
+ ++buffer;
+
+ v.vector[0] += unit.vector[0];
+ v.vector[1] += unit.vector[1];
+ v.vector[2] += unit.vector[2];
+ }
+ }
+
+ iter->y++;
+
+ return iter->buffer;
+}
+
+static uint32_t *
+linear_get_scanline_wide (pixman_iter_t *iter, const uint32_t *mask)
+{
+ uint32_t *buffer = linear_get_scanline_narrow (iter, NULL);
+
+ pixman_expand_to_float (
+ (argb_t *)buffer, buffer, PIXMAN_a8r8g8b8, iter->width);
+
+ return buffer;
+}
+
+void
+_pixman_linear_gradient_iter_init (pixman_image_t *image, pixman_iter_t *iter)
+{
+ // XXX: we can't use this optimization when dithering
+ if (0 && linear_gradient_is_horizontal (
+ iter->image, iter->x, iter->y, iter->width, iter->height))
+ {
+ if (iter->iter_flags & ITER_16)
+ linear_get_scanline_16 (iter, NULL);
+ else if (iter->iter_flags & ITER_NARROW)
+ linear_get_scanline_narrow (iter, NULL);
+ else
+ linear_get_scanline_wide (iter, NULL);
+
+ iter->get_scanline = _pixman_iter_get_scanline_noop;
+ }
+ else
+ {
+ if (iter->iter_flags & ITER_16)
+ iter->get_scanline = linear_get_scanline_16;
+ else if (iter->iter_flags & ITER_NARROW)
+ iter->get_scanline = linear_get_scanline_narrow;
+ else
+ iter->get_scanline = linear_get_scanline_wide;
+ }
+}
+
+PIXMAN_EXPORT pixman_image_t *
+pixman_image_create_linear_gradient (const pixman_point_fixed_t * p1,
+ const pixman_point_fixed_t * p2,
+ const pixman_gradient_stop_t *stops,
+ int n_stops)
+{
+ pixman_image_t *image;
+ linear_gradient_t *linear;
+
+ image = _pixman_image_allocate ();
+
+ if (!image)
+ return NULL;
+
+ linear = &image->linear;
+
+ if (!_pixman_init_gradient (&linear->common, stops, n_stops))
+ {
+ free (image);
+ return NULL;
+ }
+
+ linear->p1 = *p1;
+ linear->p2 = *p2;
+
+ image->type = LINEAR;
+
+ return image;
+}
+
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