Commit | Line | Data |
---|---|---|
af58ef32 SC |
1 | #include <stdio.h> |
2 | #include <math.h> | |
3 | #include <malloc.h> | |
17ba3e42 | 4 | #include <string.h> |
af58ef32 | 5 | |
3c3ed070 | 6 | /* |
af58ef32 SC |
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 | 42 | static void shorten(struct tickmark *tm, int nticks, int *power_of_ten, |
d8fbeefb | 43 | int use_KMG_symbols, int base_offset) |
17ba3e42 | 44 | { |
d8fbeefb JA |
45 | const char shorten_chr[] = { 0, 'K', 'M', 'G', 'P', 'E', 0 }; |
46 | int i, l, minshorten, shorten_idx = 0; | |
1e1ffcc4 | 47 | char *str; |
1e1ffcc4 SC |
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 | 57 | *power_of_ten = 9; |
d8fbeefb | 58 | shorten_idx = 3; |
1e1ffcc4 SC |
59 | } else if (6 < minshorten && l > 6 && |
60 | strcmp(&str[l - 6], "000000") == 0) { | |
7175d91d | 61 | *power_of_ten = 6; |
d8fbeefb | 62 | shorten_idx = 2; |
1e1ffcc4 | 63 | } else if (l > 3 && strcmp(&str[l - 3], "000") == 0) { |
7175d91d | 64 | *power_of_ten = 3; |
d8fbeefb | 65 | shorten_idx = 1; |
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; | |
d8fbeefb JA |
76 | if (!use_KMG_symbols) |
77 | shorten_idx = 0; | |
78 | else if (base_offset) | |
79 | shorten_idx += base_offset; | |
1e1ffcc4 SC |
80 | |
81 | for (i = 0; i < nticks; i++) { | |
82 | str = tm[i].string; | |
83 | l = strlen(str); | |
d8fbeefb JA |
84 | str[l - minshorten] = shorten_chr[shorten_idx]; |
85 | if (shorten_idx) | |
86 | str[l - minshorten + 1] = '\0'; | |
17ba3e42 SC |
87 | } |
88 | } | |
89 | ||
7175d91d | 90 | int calc_tickmarks(double min, double max, int nticks, struct tickmark **tm, |
d8fbeefb | 91 | int *power_of_ten, int use_KMG_symbols, int base_offset) |
af58ef32 SC |
92 | { |
93 | char str[100]; | |
94 | int nfrac; | |
95 | double d; /* tick mark spacing */ | |
96 | double graphmin, graphmax; /* graph range min and max */ | |
97 | double range, x; | |
98 | int count, i; | |
99 | ||
100 | /* we expect min != max */ | |
101 | range = nicenum(max - min, 0); | |
102 | d = nicenum(range / (nticks - 1), 1); | |
103 | graphmin = floor(min / d) * d; | |
104 | graphmax = ceil(max / d) * d; | |
105 | nfrac = MAX(-floor(log10(d)), 0); | |
106 | snprintf(str, sizeof(str)-1, "%%.%df", nfrac); | |
107 | ||
108 | count = ((graphmax + 0.5 * d) - graphmin) / d + 1; | |
109 | *tm = malloc(sizeof(**tm) * count); | |
110 | ||
111 | i = 0; | |
112 | for (x = graphmin; x < graphmax + 0.5 * d; x += d) { | |
113 | (*tm)[i].value = x; | |
114 | sprintf((*tm)[i].string, str, x); | |
115 | i++; | |
116 | } | |
d8fbeefb | 117 | shorten(*tm, i, power_of_ten, use_KMG_symbols, base_offset); |
af58ef32 SC |
118 | return i; |
119 | } | |
120 | ||
121 | #if 0 | |
122 | ||
123 | static void test_range(double x, double y) | |
124 | { | |
125 | int nticks, i; | |
126 | ||
127 | struct tickmark *tm = NULL; | |
128 | printf("Testing range %g - %g\n", x, y); | |
129 | nticks = calc_tickmarks(x, y, 10, &tm); | |
130 | ||
3c3ed070 | 131 | for (i = 0; i < nticks; i++) |
af58ef32 | 132 | printf(" (%s) %g\n", tm[i].string, tm[i].value); |
3c3ed070 | 133 | |
af58ef32 SC |
134 | printf("\n\n"); |
135 | free(tm); | |
136 | } | |
137 | ||
138 | int main(int argc, char *argv[]) | |
139 | { | |
3c3ed070 JA |
140 | test_range(0.0005, 0.008); |
141 | test_range(0.5, 0.8); | |
142 | test_range(5.5, 8.8); | |
143 | test_range(50.5, 80.8); | |
144 | test_range(-20, 20.8); | |
145 | test_range(-30, 700.8); | |
af58ef32 SC |
146 | } |
147 | #endif |