1 /* Libart_LGPL - library of basic graphic primitives
2 * Copyright (C) 1998 Raph Levien
3 *
4 * This library is free software; you can redistribute it and/or
5 * modify it under the terms of the GNU Library General Public
6 * License as published by the Free Software Foundation; either
7 * version 2 of the License, or (at your option) any later version.
8 *
9 * This library is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 * Library General Public License for more details.
13 *
14 * You should have received a copy of the GNU Library General Public
15 * License along with this library; if not, write to the
16 * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
17 * Boston, MA 02111-1307, USA.
18 */
20 /* Render a sorted vector path into a graymap. */
22 #include <string.h> /* for memset */
23 #include "art_misc.h"
25 #include "art_svp.h"
26 #include "art_svp_render_aa.h"
27 #include "art_gray_svp.h"
29 typedef struct _ArtGraySVPData ArtGraySVPData;
31 struct _ArtGraySVPData {
32 art_u8 *buf;
33 int rowstride;
34 int x0, x1;
35 };
37 static void
38 art_gray_svp_callback (void *callback_data, int y,
39 int start, ArtSVPRenderAAStep *steps, int n_steps)
40 {
41 ArtGraySVPData *data = (ArtGraySVPData *)callback_data;
42 art_u8 *linebuf;
43 int run_x0, run_x1;
44 int running_sum = start;
45 int x0, x1;
46 int k;
48 #if 0
49 printf ("start = %d", start);
50 running_sum = start;
51 for (k = 0; k < n_steps; k++)
52 {
53 running_sum += steps[k].delta;
54 printf (" %d:%d", steps[k].x, running_sum >> 16);
55 }
56 printf ("\n");
57 #endif
59 linebuf = data->buf;
60 x0 = data->x0;
61 x1 = data->x1;
63 if (n_steps > 0)
64 {
65 run_x1 = steps[0].x;
66 if (run_x1 > x0)
67 memset (linebuf, running_sum >> 16, run_x1 - x0);
69 for (k = 0; k < n_steps - 1; k++)
70 {
71 running_sum += steps[k].delta;
72 run_x0 = run_x1;
73 run_x1 = steps[k + 1].x;
74 if (run_x1 > run_x0)
75 memset (linebuf + run_x0 - x0, running_sum >> 16, run_x1 - run_x0);
76 }
77 running_sum += steps[k].delta;
78 if (x1 > run_x1)
79 memset (linebuf + run_x1 - x0, running_sum >> 16, x1 - run_x1);
80 }
81 else
82 {
83 memset (linebuf, running_sum >> 16, x1 - x0);
84 }
86 data->buf += data->rowstride;
87 }
89 /**
90 * art_gray_svp_aa: Render the vector path into the bytemap.
91 * @svp: The SVP to render.
92 * @x0: The view window's left coord.
93 * @y0: The view window's top coord.
94 * @x1: The view window's right coord.
95 * @y1: The view window's bottom coord.
96 * @buf: The buffer where the bytemap is stored.
97 * @rowstride: the rowstride for @buf.
98 *
99 * Each pixel gets a value proportional to the area within the pixel
100 * overlapping the (filled) SVP. Pixel (x, y) is stored at:
101 *
102 * @buf[(y - * @y0) * @rowstride + (x - @x0)]
103 *
104 * All pixels @x0 <= x < @x1, @y0 <= y < @y1 are generated. A
105 * stored value of zero is no coverage, and a value of 255 is full
106 * coverage. The area within the pixel (x, y) is the region covered
107 * by [x..x+1] and [y..y+1].
108 **/
109 void
110 art_gray_svp_aa (const ArtSVP *svp,
111 int x0, int y0, int x1, int y1,
112 art_u8 *buf, int rowstride)
113 {
114 ArtGraySVPData data;
116 data.buf = buf;
117 data.rowstride = rowstride;
118 data.x0 = x0;
119 data.x1 = x1;
120 art_svp_render_aa (svp, x0, y0, x1, y1, art_gray_svp_callback, &data);
121 }