michael@0: /*
michael@0:  *
michael@0:  * Copyright © 2000 Keith Packard, member of The XFree86 Project, Inc.
michael@0:  *             2005 Lars Knoll & Zack Rusin, Trolltech
michael@0:  *
michael@0:  * Permission to use, copy, modify, distribute, and sell this software and its
michael@0:  * documentation for any purpose is hereby granted without fee, provided that
michael@0:  * the above copyright notice appear in all copies and that both that
michael@0:  * copyright notice and this permission notice appear in supporting
michael@0:  * documentation, and that the name of Keith Packard not be used in
michael@0:  * advertising or publicity pertaining to distribution of the software without
michael@0:  * specific, written prior permission.  Keith Packard makes no
michael@0:  * representations about the suitability of this software for any purpose.  It
michael@0:  * is provided "as is" without express or implied warranty.
michael@0:  *
michael@0:  * THE COPYRIGHT HOLDERS DISCLAIM ALL WARRANTIES WITH REGARD TO THIS
michael@0:  * SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND
michael@0:  * FITNESS, IN NO EVENT SHALL THE COPYRIGHT HOLDERS BE LIABLE FOR ANY
michael@0:  * SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
michael@0:  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN
michael@0:  * AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING
michael@0:  * OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS
michael@0:  * SOFTWARE.
michael@0:  */
michael@0: 
michael@0: #ifdef HAVE_CONFIG_H
michael@0: #include <config.h>
michael@0: #endif
michael@0: #include "pixman-private.h"
michael@0: 
michael@0: void
michael@0: _pixman_gradient_walker_init (pixman_gradient_walker_t *walker,
michael@0:                               gradient_t *              gradient,
michael@0:                               pixman_repeat_t		repeat)
michael@0: {
michael@0:     walker->num_stops = gradient->n_stops;
michael@0:     walker->stops     = gradient->stops;
michael@0:     walker->left_x    = 0;
michael@0:     walker->right_x   = 0x10000;
michael@0:     walker->stepper   = 0;
michael@0:     walker->left_ag   = 0;
michael@0:     walker->left_rb   = 0;
michael@0:     walker->right_ag  = 0;
michael@0:     walker->right_rb  = 0;
michael@0:     walker->repeat    = repeat;
michael@0: 
michael@0:     walker->need_reset = TRUE;
michael@0: }
michael@0: 
michael@0: static void
michael@0: gradient_walker_reset (pixman_gradient_walker_t *walker,
michael@0: 		       pixman_fixed_48_16_t      pos)
michael@0: {
michael@0:     int32_t x, left_x, right_x;
michael@0:     pixman_color_t *left_c, *right_c;
michael@0:     int n, count = walker->num_stops;
michael@0:     pixman_gradient_stop_t *stops = walker->stops;
michael@0: 
michael@0:     if (walker->repeat == PIXMAN_REPEAT_NORMAL)
michael@0:     {
michael@0: 	x = (int32_t)pos & 0xffff;
michael@0:     }
michael@0:     else if (walker->repeat == PIXMAN_REPEAT_REFLECT)
michael@0:     {
michael@0: 	x = (int32_t)pos & 0xffff;
michael@0: 	if ((int32_t)pos & 0x10000)
michael@0: 	    x = 0x10000 - x;
michael@0:     }
michael@0:     else
michael@0:     {
michael@0: 	x = pos;
michael@0:     }
michael@0:     
michael@0:     for (n = 0; n < count; n++)
michael@0:     {
michael@0: 	if (x < stops[n].x)
michael@0: 	    break;
michael@0:     }
michael@0:     
michael@0:     left_x =  stops[n - 1].x;
michael@0:     left_c = &stops[n - 1].color;
michael@0:     
michael@0:     right_x =  stops[n].x;
michael@0:     right_c = &stops[n].color;
michael@0: 
michael@0:     if (walker->repeat == PIXMAN_REPEAT_NORMAL)
michael@0:     {
michael@0: 	left_x  += (pos - x);
michael@0: 	right_x += (pos - x);
michael@0:     }
michael@0:     else if (walker->repeat == PIXMAN_REPEAT_REFLECT)
michael@0:     {
michael@0: 	if ((int32_t)pos & 0x10000)
michael@0: 	{
michael@0: 	    pixman_color_t  *tmp_c;
michael@0: 	    int32_t tmp_x;
michael@0: 
michael@0: 	    tmp_x   = 0x10000 - right_x;
michael@0: 	    right_x = 0x10000 - left_x;
michael@0: 	    left_x  = tmp_x;
michael@0: 
michael@0: 	    tmp_c   = right_c;
michael@0: 	    right_c = left_c;
michael@0: 	    left_c  = tmp_c;
michael@0: 
michael@0: 	    x = 0x10000 - x;
michael@0: 	}
michael@0: 	left_x  += (pos - x);
michael@0: 	right_x += (pos - x);
michael@0:     }
michael@0:     else if (walker->repeat == PIXMAN_REPEAT_NONE)
michael@0:     {
michael@0: 	if (n == 0)
michael@0: 	    right_c = left_c;
michael@0: 	else if (n == count)
michael@0: 	    left_c = right_c;
michael@0:     }
michael@0: 
michael@0:     walker->left_x   = left_x;
michael@0:     walker->right_x  = right_x;
michael@0:     walker->left_ag  = ((left_c->alpha >> 8) << 16)   | (left_c->green >> 8);
michael@0:     walker->left_rb  = ((left_c->red & 0xff00) << 8)  | (left_c->blue >> 8);
michael@0:     walker->right_ag = ((right_c->alpha >> 8) << 16)  | (right_c->green >> 8);
michael@0:     walker->right_rb = ((right_c->red & 0xff00) << 8) | (right_c->blue >> 8);
michael@0: 
michael@0:     if (walker->left_x == walker->right_x                ||
michael@0:         (walker->left_ag == walker->right_ag &&
michael@0: 	 walker->left_rb == walker->right_rb))
michael@0:     {
michael@0: 	walker->stepper = 0;
michael@0:     }
michael@0:     else
michael@0:     {
michael@0: 	int32_t width = right_x - left_x;
michael@0: 	walker->stepper = ((1 << 24) + width / 2) / width;
michael@0:     }
michael@0: 
michael@0:     walker->need_reset = FALSE;
michael@0: }
michael@0: 
michael@0: uint32_t
michael@0: _pixman_gradient_walker_pixel (pixman_gradient_walker_t *walker,
michael@0:                                pixman_fixed_48_16_t      x)
michael@0: {
michael@0:     int dist, idist;
michael@0:     uint32_t t1, t2, a, color;
michael@0: 
michael@0:     if (walker->need_reset || x < walker->left_x || x >= walker->right_x)
michael@0: 	gradient_walker_reset (walker, x);
michael@0: 
michael@0:     dist  = ((int)(x - walker->left_x) * walker->stepper) >> 16;
michael@0:     idist = 256 - dist;
michael@0: 
michael@0:     /* combined INTERPOLATE and premultiply */
michael@0:     t1 = walker->left_rb * idist + walker->right_rb * dist;
michael@0:     t1 = (t1 >> 8) & 0xff00ff;
michael@0: 
michael@0:     t2  = walker->left_ag * idist + walker->right_ag * dist;
michael@0:     t2 &= 0xff00ff00;
michael@0: 
michael@0:     color = t2 & 0xff000000;
michael@0:     a     = t2 >> 24;
michael@0: 
michael@0:     t1  = t1 * a + 0x800080;
michael@0:     t1  = (t1 + ((t1 >> 8) & 0xff00ff)) >> 8;
michael@0: 
michael@0:     t2  = (t2 >> 8) * a + 0x800080;
michael@0:     t2  = (t2 + ((t2 >> 8) & 0xff00ff));
michael@0: 
michael@0:     return (color | (t1 & 0xff00ff) | (t2 & 0xff00));
michael@0: }
michael@0: