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 */
19
20 /* Render a sorted vector path into a graymap. */
21
22 #include "config.h"
23 #include "art_gray_svp.h"
24
25 #include <string.h> /* for memset */
26 #include "art_misc.h"
27
28 #include "art_svp.h"
29 #include "art_svp_render_aa.h"
30
31 typedef struct _ArtGraySVPData ArtGraySVPData;
32
33 struct _ArtGraySVPData {
34 art_u8 *buf;
35 int rowstride;
36 int x0, x1;
37 };
38
39 static void
art_gray_svp_callback(void * callback_data,int y,int start,ArtSVPRenderAAStep * steps,int n_steps)40 art_gray_svp_callback (void *callback_data, int y,
41 int start, ArtSVPRenderAAStep *steps, int n_steps)
42 {
43 ArtGraySVPData *data = (ArtGraySVPData *)callback_data;
44 art_u8 *linebuf;
45 int run_x0, run_x1;
46 int running_sum = start;
47 int x0, x1;
48 int k;
49
50 #if 0
51 printf ("start = %d", start);
52 running_sum = start;
53 for (k = 0; k < n_steps; k++)
54 {
55 running_sum += steps[k].delta;
56 printf (" %d:%d", steps[k].x, running_sum >> 16);
57 }
58 printf ("\n");
59 #endif
60
61 linebuf = data->buf;
62 x0 = data->x0;
63 x1 = data->x1;
64
65 if (n_steps > 0)
66 {
67 run_x1 = steps[0].x;
68 if (run_x1 > x0)
69 memset (linebuf, running_sum >> 16, run_x1 - x0);
70
71 for (k = 0; k < n_steps - 1; k++)
72 {
73 running_sum += steps[k].delta;
74 run_x0 = run_x1;
75 run_x1 = steps[k + 1].x;
76 if (run_x1 > run_x0)
77 memset (linebuf + run_x0 - x0, running_sum >> 16, run_x1 - run_x0);
78 }
79 running_sum += steps[k].delta;
80 if (x1 > run_x1)
81 memset (linebuf + run_x1 - x0, running_sum >> 16, x1 - run_x1);
82 }
83 else
84 {
85 memset (linebuf, running_sum >> 16, x1 - x0);
86 }
87
88 data->buf += data->rowstride;
89 }
90
91 /**
92 * art_gray_svp_aa: Render the vector path into the bytemap.
93 * @svp: The SVP to render.
94 * @x0: The view window's left coord.
95 * @y0: The view window's top coord.
96 * @x1: The view window's right coord.
97 * @y1: The view window's bottom coord.
98 * @buf: The buffer where the bytemap is stored.
99 * @rowstride: the rowstride for @buf.
100 *
101 * Each pixel gets a value proportional to the area within the pixel
102 * overlapping the (filled) SVP. Pixel (x, y) is stored at:
103 *
104 * @buf[(y - * @y0) * @rowstride + (x - @x0)]
105 *
106 * All pixels @x0 <= x < @x1, @y0 <= y < @y1 are generated. A
107 * stored value of zero is no coverage, and a value of 255 is full
108 * coverage. The area within the pixel (x, y) is the region covered
109 * by [x..x+1] and [y..y+1].
110 **/
111 void
art_gray_svp_aa(const ArtSVP * svp,int x0,int y0,int x1,int y1,art_u8 * buf,int rowstride)112 art_gray_svp_aa (const ArtSVP *svp,
113 int x0, int y0, int x1, int y1,
114 art_u8 *buf, int rowstride)
115 {
116 ArtGraySVPData data;
117
118 data.buf = buf;
119 data.rowstride = rowstride;
120 data.x0 = x0;
121 data.x1 = x1;
122 art_svp_render_aa (svp, x0, y0, x1, y1, art_gray_svp_callback, &data);
123 }
124