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