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
|
#include <common.h>
#include <fb.h>
#include <gui/graphic_utils.h>
#include <linux/stat.h>
#include <fcntl.h>
#include <errno.h>
#include <fs.h>
#include <malloc.h>
static void __illuminate(struct fb_info *info,
int x, int y,
u8 r, u8 g, u8 b, u8 a)
{
void *pixel;
if (x < 0 || y < 0 || x >= info->xres || y >= info->yres)
return;
pixel = fb_get_screen_base(info);
pixel += y * info->line_length + x * (info->bits_per_pixel >> 3);
gu_set_rgba_pixel(info, pixel, r, g, b, a);
}
static void illuminate(struct fb_info *info,
bool invert,
int x, int y,
u8 r, u8 g, u8 b, u8 a)
{
if (invert)
__illuminate(info, y, x,
r, g, b, a);
else
__illuminate(info, x, y,
r, g, b, a);
}
static void draw_simple_line(struct screen *sc,
int x1, int y1,
int x2, int y2,
u8 r, u8 g, u8 b, u8 a,
unsigned int dash)
{
int x;
bool invert = false;
unsigned int pixel = 0;
BUG_ON(x1 != x2 &&
y1 != y2);
if (x1 == x2) {
swap(x1, y1);
swap(x2, y2);
invert = true;
}
if (x1 > x2) {
swap(x1, x2);
swap(y1, y2);
}
for (x = x1; x < x2 - 1; x++) {
if (!dash ||
(++pixel % (2 * dash)) < dash)
illuminate(sc->info,
invert,
x, y1,
r, g, b, a);
}
}
/**
* gl_draw_line - draw a 2D dashed line between (x1, y1) and (x2,y2)
*
* @sc: screen to draw on
* @x1, @y1: first point defining the line
* @x2, @y2: second point defining the line
* @r, @g, @b, @a: line's color
* @dash: dash length (0 denotes solid line)
*
* gl_draw_line() implements integer version of Bresenham's algoritm
* as can be found here:
*
* http://www.idav.ucdavis.edu/education/GraphicsNotes/Bresenhams-Algorithm.pdf
*/
void gu_draw_line(struct screen *sc,
int x1, int y1,
int x2, int y2,
u8 r, u8 g, u8 b, u8 a,
unsigned int dash)
{
int dx;
int dy;
int i, j, eps;
bool invert = false;
unsigned int pixel = 0;
BUG_ON(x1 < 0 || y1 < 0 ||
x2 < 0 || y2 < 0);
if (x1 == x2 || y1 == y2) {
draw_simple_line(sc,
x1, y1,
x2, y2,
r, g, b, a, dash);
return;
}
dx = abs(x2 - x1);
dy = abs(y2 - y1);
/*
* First thing we need to determine "Driving Axis", as can be
* seen below if Y-axis projection of the line is bigger than
* X-axis projection we swap axes and pretend the X is Y and
* vice versa
*/
if (dy > dx) {
swap(x1, y1);
swap(x2, y2);
swap(dx, dy);
invert = true;
}
/*
* Second, we need to make sure that we will be traversing
* driving axis in the direction of increment so we swap point
* 1 with point 2 if x1 is greater than x2
*/
if (x1 > x2) {
swap(x1, x2);
swap(y1, y2);
}
j = y1;
eps = dy - dx;
for (i = x1; i <= x2 - 1; i++) {
if (!dash ||
(++pixel % (2 * dash)) > dash) {
illuminate(sc->info,
invert,
j, i,
r, g, b, a);
} else {
printf("NOT illuminating pixel: %d\n", pixel);
}
if (eps >= 0) {
j += 1;
eps -= dx;
}
eps += dy;
}
}
/**
* gl_draw_circle - draw a 2D circle with center at (x0, y0)
*
* @sc: screen to draw on
* @x0, @y0: coordinates of circle's center
* @radius: circle's radius
* @r, @g, @b, @a: circle's color
*
* gu_draw_circle() implements midpoint circle algorithm as can be
* found here:
*
* https://en.wikipedia.org/wiki/Midpoint_circle_algorithm
*/
void gu_draw_circle(struct screen *sc,
int x0, int y0, int radius,
u8 r, u8 g, u8 b, u8 a)
{
int x = radius;
int y = 0;
int e = 0;
BUG_ON(x0 < 0 || y0 < 0 || radius < 0);
while (x >= y) {
__illuminate(sc->info, x0 + x, y0 + y, r, g, b, a);
__illuminate(sc->info, x0 + y, y0 + x, r, g, b, a);
__illuminate(sc->info, x0 - y, y0 + x, r, g, b, a);
__illuminate(sc->info, x0 - x, y0 + y, r, g, b, a);
__illuminate(sc->info, x0 - x, y0 - y, r, g, b, a);
__illuminate(sc->info, x0 - y, y0 - x, r, g, b, a);
__illuminate(sc->info, x0 + y, y0 - x, r, g, b, a);
__illuminate(sc->info, x0 + x, y0 - y, r, g, b, a);
y += 1;
e += 1 + 2 * y;
if (2 * (e - x) + 1 > 0) {
x -= 1;
e += 1 - 2 * x;
}
}
}
|
