summaryrefslogtreecommitdiffstats
path: root/gfx/cairo/libpixman/src/pixman-linear-gradient.c
blob: 3f528508a18843fd824c419f596cd8db481a88bb (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
/* -*- 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"

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 (pixman_iter_t                 *iter,
		     const uint32_t                *mask,
		     int                            Bpp,
		     pixman_gradient_walker_write_t write_pixel,
		     pixman_gradient_walker_fill_t  fill_pixel)
{
    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 * (Bpp / 4);
    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)
	{
	    fill_pixel (&walker, t, buffer, end);
	}
	else
	{
	    int i;

	    i = 0;
	    while (buffer < end)
	    {
		if (!mask || *mask++)
		{
		    write_pixel (&walker, t + next_inc, buffer);
		}
		i++;
		next_inc = inc * i;
		buffer += (Bpp / 4);
	    }
	}
    }
    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;
		}

		write_pixel (&walker, t, buffer);
	    }

	    buffer += (Bpp / 4);

	    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_narrow (pixman_iter_t  *iter,
			    const uint32_t *mask)
{
    return linear_get_scanline (iter, mask, 4,
				_pixman_gradient_walker_write_narrow,
				_pixman_gradient_walker_fill_narrow);
}


static uint32_t *
linear_get_scanline_wide (pixman_iter_t *iter, const uint32_t *mask)
{
    return linear_get_scanline (iter, NULL, 16,
				_pixman_gradient_walker_write_wide,
				_pixman_gradient_walker_fill_wide);
}

void
_pixman_linear_gradient_iter_init (pixman_image_t *image, pixman_iter_t  *iter)
{
    if (linear_gradient_is_horizontal (
	    iter->image, iter->x, iter->y, iter->width, iter->height))
    {
	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_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;
}