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/*
*
* 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 "pixman-private.h"
void
_pixman_gradient_walker_init (pixman_gradient_walker_t *walker,
gradient_t * gradient,
pixman_repeat_t repeat)
{
walker->num_stops = gradient->n_stops;
walker->stops = gradient->stops;
walker->left_x = 0;
walker->right_x = 0x10000;
walker->a_s = 0.0f;
walker->a_b = 0.0f;
walker->r_s = 0.0f;
walker->r_b = 0.0f;
walker->g_s = 0.0f;
walker->g_b = 0.0f;
walker->b_s = 0.0f;
walker->b_b = 0.0f;
walker->repeat = repeat;
walker->need_reset = TRUE;
}
static void
gradient_walker_reset (pixman_gradient_walker_t *walker,
pixman_fixed_48_16_t pos)
{
int32_t x, left_x, right_x;
pixman_color_t *left_c, *right_c;
int n, count = walker->num_stops;
pixman_gradient_stop_t *stops = walker->stops;
float la, lr, lg, lb;
float ra, rr, rg, rb;
float lx, rx;
if (walker->repeat == PIXMAN_REPEAT_NORMAL)
{
x = (int32_t)pos & 0xffff;
}
else if (walker->repeat == PIXMAN_REPEAT_REFLECT)
{
x = (int32_t)pos & 0xffff;
if ((int32_t)pos & 0x10000)
x = 0x10000 - x;
}
else
{
x = pos;
}
for (n = 0; n < count; n++)
{
if (x < stops[n].x)
break;
}
left_x = stops[n - 1].x;
left_c = &stops[n - 1].color;
right_x = stops[n].x;
right_c = &stops[n].color;
if (walker->repeat == PIXMAN_REPEAT_NORMAL)
{
left_x += (pos - x);
right_x += (pos - x);
}
else if (walker->repeat == PIXMAN_REPEAT_REFLECT)
{
if ((int32_t)pos & 0x10000)
{
pixman_color_t *tmp_c;
int32_t tmp_x;
tmp_x = 0x10000 - right_x;
right_x = 0x10000 - left_x;
left_x = tmp_x;
tmp_c = right_c;
right_c = left_c;
left_c = tmp_c;
x = 0x10000 - x;
}
left_x += (pos - x);
right_x += (pos - x);
}
else if (walker->repeat == PIXMAN_REPEAT_NONE)
{
if (n == 0)
right_c = left_c;
else if (n == count)
left_c = right_c;
}
/* The alpha channel is scaled to be in the [0, 255] interval,
* and the red/green/blue channels are scaled to be in [0, 1].
* This ensures that after premultiplication all channels will
* be in the [0, 255] interval.
*/
la = (left_c->alpha * (1.0f/257.0f));
lr = (left_c->red * (1.0f/257.0f));
lg = (left_c->green * (1.0f/257.0f));
lb = (left_c->blue * (1.0f/257.0f));
ra = (right_c->alpha * (1.0f/257.0f));
rr = (right_c->red * (1.0f/257.0f));
rg = (right_c->green * (1.0f/257.0f));
rb = (right_c->blue * (1.0f/257.0f));
lx = left_x * (1.0f/65536.0f);
rx = right_x * (1.0f/65536.0f);
if (FLOAT_IS_ZERO (rx - lx) || left_x == INT32_MIN || right_x == INT32_MAX)
{
walker->a_s = walker->r_s = walker->g_s = walker->b_s = 0.0f;
walker->a_b = (la + ra) / 2.0f;
walker->r_b = (lr + rr) / 510.0f;
walker->g_b = (lg + rg) / 510.0f;
walker->b_b = (lb + rb) / 510.0f;
}
else
{
float w_rec = 1.0f / (rx - lx);
walker->a_b = (la * rx - ra * lx) * w_rec;
walker->r_b = (lr * rx - rr * lx) * w_rec * (1.0f/255.0f);
walker->g_b = (lg * rx - rg * lx) * w_rec * (1.0f/255.0f);
walker->b_b = (lb * rx - rb * lx) * w_rec * (1.0f/255.0f);
walker->a_s = (ra - la) * w_rec;
walker->r_s = (rr - lr) * w_rec * (1.0f/255.0f);
walker->g_s = (rg - lg) * w_rec * (1.0f/255.0f);
walker->b_s = (rb - lb) * w_rec * (1.0f/255.0f);
}
walker->left_x = left_x;
walker->right_x = right_x;
walker->need_reset = FALSE;
}
uint32_t
_pixman_gradient_walker_pixel (pixman_gradient_walker_t *walker,
pixman_fixed_48_16_t x)
{
float a, r, g, b;
uint8_t a8, r8, g8, b8;
uint32_t v;
float y;
if (walker->need_reset || x < walker->left_x || x >= walker->right_x)
gradient_walker_reset (walker, x);
y = x * (1.0f / 65536.0f);
a = walker->a_s * y + walker->a_b;
r = a * (walker->r_s * y + walker->r_b);
g = a * (walker->g_s * y + walker->g_b);
b = a * (walker->b_s * y + walker->b_b);
a8 = a + 0.5f;
r8 = r + 0.5f;
g8 = g + 0.5f;
b8 = b + 0.5f;
v = ((a8 << 24) & 0xff000000) |
((r8 << 16) & 0x00ff0000) |
((g8 << 8) & 0x0000ff00) |
((b8 >> 0) & 0x000000ff);
return v;
}
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