Commit | Line | Data |
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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 | ||
7175d91d SC |
42 | static void shorten(struct tickmark *tm, int nticks, int *power_of_ten, |
43 | int use_KMG_symbols) | |
17ba3e42 | 44 | { |
7175d91d | 45 | int i, l, minshorten; |
1e1ffcc4 SC |
46 | char *str; |
47 | char shorten_char = '?'; | |
48 | ||
49 | minshorten = 100; | |
50 | for (i = 0; i < nticks; i++) { | |
51 | str = tm[i].string; | |
52 | l = strlen(str); | |
53 | ||
c9e8d6e3 SC |
54 | if (strcmp(str, "0") == 0) |
55 | continue; | |
1e1ffcc4 | 56 | if (l > 9 && strcmp(&str[l - 9], "000000000") == 0) { |
7175d91d SC |
57 | *power_of_ten = 9; |
58 | shorten_char = use_KMG_symbols ? 'G' : '\0'; | |
1e1ffcc4 SC |
59 | } else if (6 < minshorten && l > 6 && |
60 | strcmp(&str[l - 6], "000000") == 0) { | |
7175d91d SC |
61 | *power_of_ten = 6; |
62 | shorten_char = use_KMG_symbols ? 'M' : '\0'; | |
1e1ffcc4 | 63 | } else if (l > 3 && strcmp(&str[l - 3], "000") == 0) { |
7175d91d SC |
64 | *power_of_ten = 3; |
65 | shorten_char = use_KMG_symbols ? 'K': '\0'; | |
1e1ffcc4 | 66 | } else { |
7175d91d | 67 | *power_of_ten = 0; |
1e1ffcc4 SC |
68 | } |
69 | ||
7175d91d SC |
70 | if (*power_of_ten < minshorten) |
71 | minshorten = *power_of_ten; | |
1e1ffcc4 SC |
72 | } |
73 | ||
74 | if (minshorten == 0) | |
75 | return; | |
76 | ||
77 | for (i = 0; i < nticks; i++) { | |
78 | str = tm[i].string; | |
79 | l = strlen(str); | |
80 | str[l - minshorten] = shorten_char; | |
81 | str[l - minshorten + 1] = '\0'; | |
17ba3e42 SC |
82 | } |
83 | } | |
84 | ||
7175d91d SC |
85 | int calc_tickmarks(double min, double max, int nticks, struct tickmark **tm, |
86 | int *power_of_ten, int use_KMG_symbols) | |
af58ef32 SC |
87 | { |
88 | char str[100]; | |
89 | int nfrac; | |
90 | double d; /* tick mark spacing */ | |
91 | double graphmin, graphmax; /* graph range min and max */ | |
92 | double range, x; | |
93 | int count, i; | |
94 | ||
95 | /* we expect min != max */ | |
96 | range = nicenum(max - min, 0); | |
97 | d = nicenum(range / (nticks - 1), 1); | |
98 | graphmin = floor(min / d) * d; | |
99 | graphmax = ceil(max / d) * d; | |
100 | nfrac = MAX(-floor(log10(d)), 0); | |
101 | snprintf(str, sizeof(str)-1, "%%.%df", nfrac); | |
102 | ||
103 | count = ((graphmax + 0.5 * d) - graphmin) / d + 1; | |
104 | *tm = malloc(sizeof(**tm) * count); | |
105 | ||
106 | i = 0; | |
107 | for (x = graphmin; x < graphmax + 0.5 * d; x += d) { | |
108 | (*tm)[i].value = x; | |
109 | sprintf((*tm)[i].string, str, x); | |
110 | i++; | |
111 | } | |
7175d91d | 112 | shorten(*tm, i, power_of_ten, use_KMG_symbols); |
af58ef32 SC |
113 | return i; |
114 | } | |
115 | ||
116 | #if 0 | |
117 | ||
118 | static void test_range(double x, double y) | |
119 | { | |
120 | int nticks, i; | |
121 | ||
122 | struct tickmark *tm = NULL; | |
123 | printf("Testing range %g - %g\n", x, y); | |
124 | nticks = calc_tickmarks(x, y, 10, &tm); | |
125 | ||
126 | for (i = 0; i < nticks; i++) { | |
127 | printf(" (%s) %g\n", tm[i].string, tm[i].value); | |
128 | } | |
129 | printf("\n\n"); | |
130 | free(tm); | |
131 | } | |
132 | ||
133 | int main(int argc, char *argv[]) | |
134 | { | |
135 | test_range(0.0005, 0.008); | |
136 | test_range(0.5, 0.8); | |
137 | test_range(5.5, 8.8); | |
138 | test_range(50.5, 80.8); | |
139 | test_range(-20, 20.8); | |
140 | test_range(-30, 700.8); | |
141 | } | |
142 | #endif |