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
|
/* This header file gives the metrics for the vector fonts. */
/* Our choice for stroke width, in terms of virtual pixels. This number is
magic: just slightly greater than sqrt(2), so that adjacent strokes that
are inclined at a 45 degree angle will overlap as they should.
(According to ``Calligraphy for Computers'', the Hershey fonts were
designed to be drawn by an electron beam the intensity of which fell to
50% at a transverse displacement of one unit.) */
#define HERSHEY_STROKE_WIDTH 1.42
/* This value gives good results for the Japanese characters (Kana and
Kanji). */
#define HERSHEY_ORIENTAL_STROKE_WIDTH 1.175
/* According to Allen Hershey, 1 em = 32 virtual pixels for his alphabets
of principal size. But taking into account the width of the strokes
(nominally 1 virtual pixel), if the characters are thought of as resting
on a baseline, the baseline (and the capline, etc.) should be located at
half-integer values of the vertical coordinate. That changes things
slightly (an em should be 33 virtual pixels, not 32).
Incidentally his recommended spacing between lines is 40 pixels (24 for
indexical size), i.e., 1.2 em or so (1 em is the minimum possible
spacing).
*/
/* Dimensions for characters in principal [large] size. The `centerline'
is located at y=0, in the original coordinate system. The `topline' and
`bottomline' are determined by the tallest characters, which are
parentheses, brackets, and braces. */
#define HERSHEY_LARGE_BASELINE (-9.5) /* relative to centerline */
#define HERSHEY_LARGE_CAPLINE 12.5 /* relative to centerline */
#define HERSHEY_LARGE_TOPLINE 16.5 /* relative to centerline */
#define HERSHEY_LARGE_BOTTOMLINE -16.5 /* relative to centerline */
#define HERSHEY_LARGE_CAPHEIGHT 22 /* i.e. capline - baseline */
#define HERSHEY_LARGE_ASCENT 26 /* i.e. topline - baseline */
#define HERSHEY_LARGE_DESCENT 7 /* i.e. baseline - bottomline */
#define HERSHEY_LARGE_HEIGHT (HERSHEY_LARGE_ASCENT + HERSHEY_LARGE_DESCENT)
#define HERSHEY_LARGE_EM 33
/* Dimensions for characters in indexical [medium] size. The `centerline'
is located at y=0, in the original coordinate system. The `topline' and
`bottomline' are determined by the tallest characters, which are
parentheses, brackets, and braces. */
#define HERSHEY_MEDIUM_BASELINE (-6.5) /* relative to centerline */
#define HERSHEY_MEDIUM_CAPLINE 7.5 /* relative to centerline */
#define HERSHEY_MEDIUM_TOPLINE 10.5 /* relative to centerline */
#define HERSHEY_MEDIUM_BOTTOMLINE -10.5 /* relative to centerline */
#define HERSHEY_MEDIUM_CAPHEIGHT 14 /* i.e. capline - baseline */
#define HERSHEY_MEDIUM_ASCENT 17 /* i.e. topline - baseline */
#define HERSHEY_MEDIUM_DESCENT 4 /* i.e. baseline - bottomline */
#define HERSHEY_MEDIUM_HEIGHT (HERSHEY_MEDIUM_ASCENT + HERSHEY_MEDIUM_DESCENT)
#define HERSHEY_MEDIUM_EM 21
/* Dimensions for characters in cartographic [small] size. The
`centerline' is located at y=0, in the original coordinate system. The
`topline' and `bottomline' are determined by the tallest characters,
which are parentheses, brackets, and braces. In the cartographic size
there are only parentheses, and unlike the other two sizes they are not
symmetric about y=0 (since they will surround only upper-case letters;
there are no lower-case letters in cartographic). */
#define HERSHEY_SMALL_BASELINE (-4.5) /* relative to centerline */
#define HERSHEY_SMALL_CAPLINE 5.5 /* relative to centerline */
#define HERSHEY_SMALL_TOPLINE 6.5 /* relative to centerline */
#define HERSHEY_SMALL_BOTTOMLINE -5.5 /* relative to centerline */
#define HERSHEY_SMALL_CAPHEIGHT 10 /* i.e. capline - baseline */
#define HERSHEY_SMALL_ASCENT 11 /* i.e. topline - baseline */
#define HERSHEY_SMALL_DESCENT 1 /* i.e. baseline - bottomline */
#define HERSHEY_SMALL_HEIGHT (HERSHEY_SMALL_ASCENT + HERSHEY_SMALL_DESCENT)
#define HERSHEY_SMALL_EM 12
/* Vertical positionings (in alabel_str.c) are now based on the assumption
that all characters we are dealing with are of principal [large] size.
I see no graceful way to handle positionings relative to the baseline
for the other two sizes. Of course, centered positioning will work
perfectly, since the Hershey glyphs were designed for that. */
#define HERSHEY_BASELINE HERSHEY_LARGE_BASELINE
#define HERSHEY_CAPHEIGHT HERSHEY_LARGE_CAPHEIGHT
#define HERSHEY_ASCENT HERSHEY_LARGE_ASCENT
#define HERSHEY_DESCENT HERSHEY_LARGE_DESCENT
#define HERSHEY_HEIGHT HERSHEY_LARGE_HEIGHT
#define HERSHEY_EM HERSHEY_LARGE_EM
/* The scaling between distances in Hershey units and distances in user
coordinates. Idea is that the font size (i.e. the nominal minimum
inter-line spacing) corresponds to HERSHEY_LARGE_EM Hershey units. */
#define HERSHEY_UNITS_TO_USER_UNITS(size) \
((size)*(_plotter->drawstate->true_font_size)/(HERSHEY_EM))
/************************************************************************/
/* Some miscellaneous information on typesetting mathematics, taken from
Allen Hershey's 1969 TR (see g_her_glyph.c):
Subscripts and superscripts, in math text, should be in indexical size.
The centerline of subscripts/superscripts would be lowered/raised by 10
vertical units.
[In principal size the centerline is 9.5 units above the baseline; in
indexical size the centerline is 6.5 units above the baseline. So when
going to subscripts, the baseline should be lowered by 7 units; when
going to superscripts, the baseline should be raised by 13 units. This
is not actually the scheme we use; see alabel_str.c. -- rsm]
In math text the quantity being supplied with a sub/superscript is
typically an italic character. The transitions principal->superscript
and subscript->principal are accordingly accompanied by 2 add'l units of
horizontal space.
In math text, conjuctive/predicative signs should be given a extra
spacing of 1/2 en (i.e. 1/4 em), i.e. 8 units in principal size, to
either side. This is accomplished by glyph 2198 (or 1198, in indexical
size).
Case fractions (e.g. \frac34) are formed by raising/lowering
indexical-size characters by 12 vertical units; in mathematical text,
they should be given a small (4-unit) spacing to either side.
Simple limits, for sum and integral signs, are in indexical size, and
are raised/lowered by 24 units. */
/************************************************************************/
|
