source: libcaca/trunk/cucul/conic.c @ 811

Last change on this file since 811 was 811, checked in by Sam Hocevar, 14 years ago
  • Renamed caca_t into caca_display_t.
  • Renamed canvas handle variables from "c" to "cv". Eh ouais mon gros.
  • Property svn:keywords set to Id
File size: 6.0 KB
Line 
1/*
2 *  libcucul      Canvas for ultrafast compositing of Unicode letters
3 *  Copyright (c) 2002-2006 Sam Hocevar <sam@zoy.org>
4 *                All Rights Reserved
5 *
6 *  $Id: conic.c 811 2006-04-18 15:11:25Z sam $
7 *
8 *  This library is free software; you can redistribute it and/or
9 *  modify it under the terms of the Do What The Fuck You Want To
10 *  Public License, Version 2, as published by Sam Hocevar. See
11 *  http://sam.zoy.org/wtfpl/COPYING for more details.
12 */
13
14/*
15 *  This file contains ellipse and circle drawing functions, both filled
16 *  and outline.
17 */
18
19#include "config.h"
20
21#if !defined(__KERNEL__)
22#   include <stdlib.h>
23#endif
24
25#include "cucul.h"
26#include "cucul_internals.h"
27
28static void ellipsepoints(cucul_canvas_t *, int, int, int, int, uint32_t);
29
30/** \brief Draw a circle on the canvas using the given character.
31 *
32 *  \param cv The handle to the libcucul canvas.
33 *  \param x Center X coordinate.
34 *  \param y Center Y coordinate.
35 *  \param r Circle radius.
36 *  \param str UTF-8 string representing the character that should be used
37 *         to draw the circle outline.
38 *  \return void
39 */
40void cucul_draw_circle(cucul_canvas_t *cv, int x, int y, int r, char const *str)
41{
42    int test, dx, dy;
43    uint32_t ch = _cucul_utf8_to_utf32(str);
44
45    /* Optimized Bresenham. Kick ass. */
46    for(test = 0, dx = 0, dy = r ; dx <= dy ; dx++)
47    {
48        ellipsepoints(cv, x, y, dx, dy, ch);
49        ellipsepoints(cv, x, y, dy, dx, ch);
50
51        test += test > 0 ? dx - dy-- : dx;
52    }
53}
54
55/** \brief Fill an ellipse on the canvas using the given character.
56 *
57 *  \param cv The handle to the libcucul canvas.
58 *  \param xo Center X coordinate.
59 *  \param yo Center Y coordinate.
60 *  \param a Ellipse X radius.
61 *  \param b Ellipse Y radius.
62 *  \param str UTF-8 string representing the character that should be used
63 *         to fill the ellipse.
64 *  \return void
65 */
66void cucul_fill_ellipse(cucul_canvas_t *cv, int xo, int yo, int a, int b,
67                        char const *str)
68{
69    int d2;
70    int x = 0;
71    int y = b;
72    int d1 = b*b - (a*a*b) + (a*a/4);
73
74    while(a*a*y - a*a/2 > b*b*(x+1))
75    {
76        if(d1 < 0)
77        {
78            d1 += b*b*(2*x+1); /* XXX: "Computer Graphics" has + 3 here. */
79        }
80        else
81        {
82            d1 += b*b*(2*x*1) + a*a*(-2*y+2);
83            cucul_draw_line(cv, xo - x, yo - y, xo + x, yo - y, str);
84            cucul_draw_line(cv, xo - x, yo + y, xo + x, yo + y, str);
85            y--;
86        }
87        x++;
88    }
89
90    cucul_draw_line(cv, xo - x, yo - y, xo + x, yo - y, str);
91    cucul_draw_line(cv, xo - x, yo + y, xo + x, yo + y, str);
92
93    d2 = b*b*(x+0.5)*(x+0.5) + a*a*(y-1)*(y-1) - a*a*b*b;
94    while(y > 0)
95    {
96        if(d2 < 0)
97        {
98            d2 += b*b*(2*x+2) + a*a*(-2*y+3);
99            x++;
100        }
101        else
102        {
103            d2 += a*a*(-2*y+3);
104        }
105
106        y--;
107        cucul_draw_line(cv, xo - x, yo - y, xo + x, yo - y, str);
108        cucul_draw_line(cv, xo - x, yo + y, xo + x, yo + y, str);
109    }
110}
111
112/** \brief Draw an ellipse on the canvas using the given character.
113 *
114 *  \param cv The handle to the libcucul canvas.
115 *  \param xo Center X coordinate.
116 *  \param yo Center Y coordinate.
117 *  \param a Ellipse X radius.
118 *  \param b Ellipse Y radius.
119 *  \param str UTF-8 string representing the character that should be used
120 *         to draw the ellipse outline.
121 *  \return void
122 */
123void cucul_draw_ellipse(cucul_canvas_t *cv, int xo, int yo, int a, int b,
124                        char const *str)
125{
126    int d2;
127    int x = 0;
128    int y = b;
129    int d1 = b*b - (a*a*b) + (a*a/4);
130    uint32_t ch = _cucul_utf8_to_utf32(str);
131
132    ellipsepoints(cv, xo, yo, x, y, ch);
133
134    while(a*a*y - a*a/2 > b*b*(x+1))
135    {
136        if(d1 < 0)
137        {
138            d1 += b*b*(2*x+1); /* XXX: "Computer Graphics" has + 3 here. */
139        }
140        else
141        {
142            d1 += b*b*(2*x*1) + a*a*(-2*y+2);
143            y--;
144        }
145        x++;
146        ellipsepoints(cv, xo, yo, x, y, ch);
147    }
148
149    d2 = b*b*(x+0.5)*(x+0.5) + a*a*(y-1)*(y-1) - a*a*b*b;
150    while(y > 0)
151    {
152        if(d2 < 0)
153        {
154            d2 += b*b*(2*x+2) + a*a*(-2*y+3);
155            x++;
156        }
157        else
158        {
159            d2 += a*a*(-2*y+3);
160        }
161
162        y--;
163        ellipsepoints(cv, xo, yo, x, y, ch);
164    }
165}
166
167/** \brief Draw a thin ellipse on the canvas.
168 *
169 *  \param cv The handle to the libcucul canvas.
170 *  \param xo Center X coordinate.
171 *  \param yo Center Y coordinate.
172 *  \param a Ellipse X radius.
173 *  \param b Ellipse Y radius.
174 *  \return void
175 */
176void cucul_draw_thin_ellipse(cucul_canvas_t *cv, int xo, int yo, int a, int b)
177{
178    /* FIXME: this is not correct */
179    int d2;
180    int x = 0;
181    int y = b;
182    int d1 = b*b - (a*a*b) + (a*a/4);
183
184    ellipsepoints(cv, xo, yo, x, y, '-');
185
186    while(a*a*y - a*a/2 > b*b*(x+1))
187    {
188        if(d1 < 0)
189        {
190            d1 += b*b*(2*x+1); /* XXX: "Computer Graphics" has + 3 here. */
191        }
192        else
193        {
194            d1 += b*b*(2*x*1) + a*a*(-2*y+2);
195            y--;
196        }
197        x++;
198        ellipsepoints(cv, xo, yo, x, y, '-');
199    }
200
201    d2 = b*b*(x+0.5)*(x+0.5) + a*a*(y-1)*(y-1) - a*a*b*b;
202    while(y > 0)
203    {
204        if(d2 < 0)
205        {
206            d2 += b*b*(2*x+2) + a*a*(-2*y+3);
207            x++;
208        }
209        else
210        {
211            d2 += a*a*(-2*y+3);
212        }
213
214        y--;
215        ellipsepoints(cv, xo, yo, x, y, '|');
216    }
217}
218
219static void ellipsepoints(cucul_canvas_t *cv, int xo, int yo, int x, int y,
220                          uint32_t ch)
221{
222    uint8_t b = 0;
223
224    if(xo + x >= 0 && xo + x < (int)cv->width)
225        b |= 0x1;
226    if(xo - x >= 0 && xo - x < (int)cv->width)
227        b |= 0x2;
228    if(yo + y >= 0 && yo + y < (int)cv->height)
229        b |= 0x4;
230    if(yo - y >= 0 && yo - y < (int)cv->height)
231        b |= 0x8;
232
233    if((b & (0x1|0x4)) == (0x1|0x4))
234        _cucul_putchar32(cv, xo + x, yo + y, ch);
235
236    if((b & (0x2|0x4)) == (0x2|0x4))
237        _cucul_putchar32(cv, xo - x, yo + y, ch);
238
239    if((b & (0x1|0x8)) == (0x1|0x8))
240        _cucul_putchar32(cv, xo + x, yo - y, ch);
241
242    if((b & (0x2|0x8)) == (0x2|0x8))
243        _cucul_putchar32(cv, xo - x, yo - y, ch);
244}
245
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