Commit | Line | Data |
---|---|---|
af58ef32 SC |
1 | #include <stdio.h> |
2 | #include <math.h> | |
3 | #include <malloc.h> | |
17ba3e42 | 4 | #include <string.h> |
af58ef32 SC |
5 | |
6 | /* | |
7 | * adapted from Paul Heckbert's algorithm on p 657-659 of | |
8 | * Andrew S. Glassner's book, "Graphics Gems" | |
9 | * ISBN 0-12-286166-3 | |
10 | * | |
11 | */ | |
12 | ||
13 | #include "tickmarks.h" | |
14 | ||
15 | #define MAX(a, b) (((a) < (b)) ? (b) : (a)) | |
16 | ||
17 | static double nicenum(double x, int round) | |
18 | { | |
19 | int exp; /* exponent of x */ | |
20 | double f; /* fractional part of x */ | |
21 | ||
22 | exp = floor(log10(x)); | |
23 | f = x / pow(10.0, exp); | |
24 | if (round) { | |
25 | if (f < 1.5) | |
26 | return 1.0 * pow(10.0, exp); | |
27 | if (f < 3.0) | |
28 | return 2.0 * pow(10.0, exp); | |
29 | if (f < 7.0) | |
30 | return 5.0 * pow(10.0, exp); | |
31 | return 10.0 * pow(10.0, exp); | |
32 | } | |
33 | if (f <= 1.0) | |
34 | return 1.0 * pow(10.0, exp); | |
35 | if (f <= 2.0) | |
36 | return 2.0 * pow(10.0, exp); | |
37 | if (f <= 5.0) | |
38 | return 5.0 * pow(10.0, exp); | |
39 | return 10.0 * pow(10.0, exp); | |
40 | } | |
41 | ||
17ba3e42 SC |
42 | static void shorten(char *str) |
43 | { | |
44 | int l; | |
45 | ||
46 | l = strlen(str); | |
47 | if (l > 9 && strcmp(&str[l - 9], "000000000") == 0) { | |
48 | str[l - 9] = 'G'; | |
49 | str[l - 8] = '\0'; | |
b655c189 | 50 | } else if (l > 6 && strcmp(&str[l - 6], "000000") == 0) { |
17ba3e42 SC |
51 | str[l - 6] = 'M'; |
52 | str[l - 5] = '\0'; | |
b655c189 | 53 | } else if (l > 3 && strcmp(&str[l - 3], "000") == 0) { |
17ba3e42 SC |
54 | str[l - 3] = 'K'; |
55 | str[l - 2] = '\0'; | |
56 | } | |
57 | } | |
58 | ||
af58ef32 SC |
59 | int calc_tickmarks(double min, double max, int nticks, struct tickmark **tm) |
60 | { | |
61 | char str[100]; | |
62 | int nfrac; | |
63 | double d; /* tick mark spacing */ | |
64 | double graphmin, graphmax; /* graph range min and max */ | |
65 | double range, x; | |
66 | int count, i; | |
67 | ||
68 | /* we expect min != max */ | |
69 | range = nicenum(max - min, 0); | |
70 | d = nicenum(range / (nticks - 1), 1); | |
71 | graphmin = floor(min / d) * d; | |
72 | graphmax = ceil(max / d) * d; | |
73 | nfrac = MAX(-floor(log10(d)), 0); | |
74 | snprintf(str, sizeof(str)-1, "%%.%df", nfrac); | |
75 | ||
76 | count = ((graphmax + 0.5 * d) - graphmin) / d + 1; | |
77 | *tm = malloc(sizeof(**tm) * count); | |
78 | ||
79 | i = 0; | |
80 | for (x = graphmin; x < graphmax + 0.5 * d; x += d) { | |
81 | (*tm)[i].value = x; | |
82 | sprintf((*tm)[i].string, str, x); | |
17ba3e42 | 83 | shorten((*tm)[i].string); |
af58ef32 SC |
84 | i++; |
85 | } | |
86 | return i; | |
87 | } | |
88 | ||
89 | #if 0 | |
90 | ||
91 | static void test_range(double x, double y) | |
92 | { | |
93 | int nticks, i; | |
94 | ||
95 | struct tickmark *tm = NULL; | |
96 | printf("Testing range %g - %g\n", x, y); | |
97 | nticks = calc_tickmarks(x, y, 10, &tm); | |
98 | ||
99 | for (i = 0; i < nticks; i++) { | |
100 | printf(" (%s) %g\n", tm[i].string, tm[i].value); | |
101 | } | |
102 | printf("\n\n"); | |
103 | free(tm); | |
104 | } | |
105 | ||
106 | int main(int argc, char *argv[]) | |
107 | { | |
108 | test_range(0.0005, 0.008); | |
109 | test_range(0.5, 0.8); | |
110 | test_range(5.5, 8.8); | |
111 | test_range(50.5, 80.8); | |
112 | test_range(-20, 20.8); | |
113 | test_range(-30, 700.8); | |
114 | } | |
115 | #endif |