michael@0: /*
michael@0:  * Copyright © 2000 SuSE, Inc.
michael@0:  * Copyright © 2007 Red Hat, Inc.
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: 
michael@0: #include <stdlib.h>
michael@0: #include <math.h>
michael@0: #include "pixman-private.h"
michael@0: 
michael@0: static force_inline double
michael@0: coordinates_to_parameter (double x, double y, double angle)
michael@0: {
michael@0:     double t;
michael@0: 
michael@0:     t = atan2 (y, x) + angle;
michael@0: 
michael@0:     while (t < 0)
michael@0: 	t += 2 * M_PI;
michael@0: 
michael@0:     while (t >= 2 * M_PI)
michael@0: 	t -= 2 * M_PI;
michael@0: 
michael@0:     return 1 - t * (1 / (2 * M_PI)); /* Scale t to [0, 1] and
michael@0: 				      * make rotation CCW
michael@0: 				      */
michael@0: }
michael@0: 
michael@0: static uint32_t *
michael@0: conical_get_scanline_narrow (pixman_iter_t *iter, const uint32_t *mask)
michael@0: {
michael@0:     pixman_image_t *image = iter->image;
michael@0:     int x = iter->x;
michael@0:     int y = iter->y;
michael@0:     int width = iter->width;
michael@0:     uint32_t *buffer = iter->buffer;
michael@0: 
michael@0:     gradient_t *gradient = (gradient_t *)image;
michael@0:     conical_gradient_t *conical = (conical_gradient_t *)image;
michael@0:     uint32_t       *end = buffer + width;
michael@0:     pixman_gradient_walker_t walker;
michael@0:     pixman_bool_t affine = TRUE;
michael@0:     double cx = 1.;
michael@0:     double cy = 0.;
michael@0:     double cz = 0.;
michael@0:     double rx = x + 0.5;
michael@0:     double ry = y + 0.5;
michael@0:     double rz = 1.;
michael@0: 
michael@0:     _pixman_gradient_walker_init (&walker, gradient, image->common.repeat);
michael@0: 
michael@0:     if (image->common.transform)
michael@0:     {
michael@0: 	pixman_vector_t v;
michael@0: 
michael@0: 	/* reference point is the center of the pixel */
michael@0: 	v.vector[0] = pixman_int_to_fixed (x) + pixman_fixed_1 / 2;
michael@0: 	v.vector[1] = pixman_int_to_fixed (y) + pixman_fixed_1 / 2;
michael@0: 	v.vector[2] = pixman_fixed_1;
michael@0: 
michael@0: 	if (!pixman_transform_point_3d (image->common.transform, &v))
michael@0: 	    return iter->buffer;
michael@0: 
michael@0: 	cx = image->common.transform->matrix[0][0] / 65536.;
michael@0: 	cy = image->common.transform->matrix[1][0] / 65536.;
michael@0: 	cz = image->common.transform->matrix[2][0] / 65536.;
michael@0: 
michael@0: 	rx = v.vector[0] / 65536.;
michael@0: 	ry = v.vector[1] / 65536.;
michael@0: 	rz = v.vector[2] / 65536.;
michael@0: 
michael@0: 	affine =
michael@0: 	    image->common.transform->matrix[2][0] == 0 &&
michael@0: 	    v.vector[2] == pixman_fixed_1;
michael@0:     }
michael@0: 
michael@0:     if (affine)
michael@0:     {
michael@0: 	rx -= conical->center.x / 65536.;
michael@0: 	ry -= conical->center.y / 65536.;
michael@0: 
michael@0: 	while (buffer < end)
michael@0: 	{
michael@0: 	    if (!mask || *mask++)
michael@0: 	    {
michael@0: 		double t = coordinates_to_parameter (rx, ry, conical->angle);
michael@0: 
michael@0: 		*buffer = _pixman_gradient_walker_pixel (
michael@0: 		    &walker, (pixman_fixed_48_16_t)pixman_double_to_fixed (t));
michael@0: 	    }
michael@0: 
michael@0: 	    ++buffer;
michael@0: 
michael@0: 	    rx += cx;
michael@0: 	    ry += cy;
michael@0: 	}
michael@0:     }
michael@0:     else
michael@0:     {
michael@0: 	while (buffer < end)
michael@0: 	{
michael@0: 	    double x, y;
michael@0: 
michael@0: 	    if (!mask || *mask++)
michael@0: 	    {
michael@0: 		double t;
michael@0: 
michael@0: 		if (rz != 0)
michael@0: 		{
michael@0: 		    x = rx / rz;
michael@0: 		    y = ry / rz;
michael@0: 		}
michael@0: 		else
michael@0: 		{
michael@0: 		    x = y = 0.;
michael@0: 		}
michael@0: 
michael@0: 		x -= conical->center.x / 65536.;
michael@0: 		y -= conical->center.y / 65536.;
michael@0: 
michael@0: 		t = coordinates_to_parameter (x, y, conical->angle);
michael@0: 
michael@0: 		*buffer = _pixman_gradient_walker_pixel (
michael@0: 		    &walker, (pixman_fixed_48_16_t)pixman_double_to_fixed (t));
michael@0: 	    }
michael@0: 
michael@0: 	    ++buffer;
michael@0: 
michael@0: 	    rx += cx;
michael@0: 	    ry += cy;
michael@0: 	    rz += cz;
michael@0: 	}
michael@0:     }
michael@0: 
michael@0:     iter->y++;
michael@0:     return iter->buffer;
michael@0: }
michael@0: 
michael@0: static uint32_t *
michael@0: conical_get_scanline_wide (pixman_iter_t *iter, const uint32_t *mask)
michael@0: {
michael@0:     uint32_t *buffer = conical_get_scanline_narrow (iter, NULL);
michael@0: 
michael@0:     pixman_expand_to_float (
michael@0: 	(argb_t *)buffer, buffer, PIXMAN_a8r8g8b8, iter->width);
michael@0: 
michael@0:     return buffer;
michael@0: }
michael@0: 
michael@0: void
michael@0: _pixman_conical_gradient_iter_init (pixman_image_t *image, pixman_iter_t *iter)
michael@0: {
michael@0:     if (iter->iter_flags & ITER_NARROW)
michael@0: 	iter->get_scanline = conical_get_scanline_narrow;
michael@0:     else
michael@0: 	iter->get_scanline = conical_get_scanline_wide;
michael@0: }
michael@0: 
michael@0: PIXMAN_EXPORT pixman_image_t *
michael@0: pixman_image_create_conical_gradient (const pixman_point_fixed_t *  center,
michael@0:                                       pixman_fixed_t                angle,
michael@0:                                       const pixman_gradient_stop_t *stops,
michael@0:                                       int                           n_stops)
michael@0: {
michael@0:     pixman_image_t *image = _pixman_image_allocate ();
michael@0:     conical_gradient_t *conical;
michael@0: 
michael@0:     if (!image)
michael@0: 	return NULL;
michael@0: 
michael@0:     conical = &image->conical;
michael@0: 
michael@0:     if (!_pixman_init_gradient (&conical->common, stops, n_stops))
michael@0:     {
michael@0: 	free (image);
michael@0: 	return NULL;
michael@0:     }
michael@0: 
michael@0:     angle = MOD (angle, pixman_int_to_fixed (360));
michael@0: 
michael@0:     image->type = CONICAL;
michael@0: 
michael@0:     conical->center = *center;
michael@0:     conical->angle = (pixman_fixed_to_double (angle) / 180.0) * M_PI;
michael@0: 
michael@0:     return image;
michael@0: }
michael@0: