The Tor Browser / file revision

 /*

  *

  * 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->stepper   = 0;

     walker->left_ag   = 0;

     walker->left_rb   = 0;

     walker->right_ag  = 0;

     walker->right_rb  = 0;

     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;

     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;

     }

     walker->left_x   = left_x;

     walker->right_x  = right_x;

     walker->left_ag  = ((left_c->alpha >> 8) << 16)   | (left_c->green >> 8);

     walker->left_rb  = ((left_c->red & 0xff00) << 8)  | (left_c->blue >> 8);

     walker->right_ag = ((right_c->alpha >> 8) << 16)  | (right_c->green >> 8);

     walker->right_rb = ((right_c->red & 0xff00) << 8) | (right_c->blue >> 8);

     if (walker->left_x == walker->right_x                ||

         (walker->left_ag == walker->right_ag &&

 	 walker->left_rb == walker->right_rb))

     {

 	walker->stepper = 0;

     }

     else

     {

 	int32_t width = right_x - left_x;

 	walker->stepper = ((1 << 24) + width / 2) / width;

     }

     walker->need_reset = FALSE;

 }

 uint32_t

 _pixman_gradient_walker_pixel (pixman_gradient_walker_t *walker,

                                pixman_fixed_48_16_t      x)

 {

     int dist, idist;

     uint32_t t1, t2, a, color;

     if (walker->need_reset || x < walker->left_x || x >= walker->right_x)

 	gradient_walker_reset (walker, x);

     dist  = ((int)(x - walker->left_x) * walker->stepper) >> 16;

     idist = 256 - dist;

     /* combined INTERPOLATE and premultiply */

     t1 = walker->left_rb * idist + walker->right_rb * dist;

     t1 = (t1 >> 8) & 0xff00ff;

     t2  = walker->left_ag * idist + walker->right_ag * dist;

     t2 &= 0xff00ff00;

     color = t2 & 0xff000000;

     a     = t2 >> 24;

     t1  = t1 * a + 0x800080;

     t1  = (t1 + ((t1 >> 8) & 0xff00ff)) >> 8;

     t2  = (t2 >> 8) * a + 0x800080;

     t2  = (t2 + ((t2 >> 8) & 0xff00ff));

     return (color | (t1 & 0xff00ff) | (t2 & 0xff00));

 }