If the family graphical parameter (see par)
has been set to one of the Hershey fonts (see ‘Details’)
Hershey vector fonts are used to render text.
When using the text and contour functions
Hershey fonts may be selected via the vfont argument, which is
a character vector of length 2 (see ‘Details’ for valid
values). This allows Cyrillic to be selected, which is not available
via the font families.
HersheyThe Hershey fonts have two advantages:
vector fonts describe each character in terms of a set of points; R renders the character by joining up the points with straight lines. This intimate knowledge of the outline of each character means that R can arbitrarily transform the characters, which can mean that the vector fonts look better for rotated text.
this implementation was adapted from the GNU libplot library which provides support for non-ASCII and non-English fonts. This means that it is possible, for example, to produce weird plotting symbols and Japanese characters.
Drawback:
You cannot use mathematical expressions (plotmath) with
Hershey fonts.
The Hershey characters are organised into a set of fonts. A
particular font is selected by specifying one of the following
font families via par(family) and specifying the desired font
face (plain, bold, italic, bold-italic) via par(font).
| family | faces available |
"HersheySerif" |
plain, bold, italic, bold-italic |
"HersheySans" |
plain, bold, italic, bold-italic |
"HersheyScript" |
plain, bold |
"HersheyGothicEnglish" |
plain |
"HersheyGothicGerman" |
plain |
"HersheyGothicItalian" |
plain |
"HersheySymbol" |
plain, bold, italic, bold-italic |
"HersheySansSymbol" |
plain, italic |
In the vfont specification for the text and
contour functions, the Hershey font is specified by a typeface
(e.g., serif or sans serif) and a fontindex or
‘style’ (e.g., plain or italic). The first
element of vfont specifies the typeface and the second element
specifies the fontindex. The first table produced by
demo(Hershey) shows the character a produced by each of
the different fonts.
The available typeface and fontindex values are
available as list components of the variable Hershey.
The allowed pairs for (typeface, fontindex) are:
| serif | plain |
| serif | italic |
| serif | bold |
| serif | bold italic |
| serif | cyrillic |
| serif | oblique cyrillic |
| serif | EUC |
| sans serif | plain |
| sans serif | italic |
| sans serif | bold |
| sans serif | bold italic |
| script | plain |
| script | italic |
| script | bold |
| gothic english | plain |
| gothic german | plain |
| gothic italian | plain |
| serif symbol | plain |
| serif symbol | italic |
| serif symbol | bold |
| serif symbol | bold italic |
| sans serif symbol | plain |
| sans serif symbol | italic |
and the indices of these are available as Hershey$allowed.
The string to be drawn can include escape sequences, which all begin with a \. When R encounters a \, rather than drawing the \, it treats the subsequent character(s) as a coded description of what to draw.
One useful escape sequence (in the current context) is of the
form: \123. The three digits following the \
specify an octal code for a character. For example, the octal
code for p is 160 so the strings "p" and
"\160" are equivalent. This is useful for producing
characters when there is not an appropriate key on your keyboard.
The other useful escape sequences all begin with \\. These are described below. Remember that backslashes have to be doubled in R character strings, so they need to be entered with four backslashes.
an entire string of Greek symbols can be produced by
selecting the HersheySymbol or HersheySansSymbol family or the
Serif Symbol or Sans Serif Symbol typeface. To allow Greek
symbols to be embedded in a string which uses a non-symbol
typeface, there are a set of symbol escape sequences of the form
\\ab. For example, the escape sequence \\*a
produces a Greek alpha. The second table in demo(Hershey)
shows all of the symbol escape sequences and the symbols that they
produce.
further escape sequences of the form
\\ab are provided for producing ISO Latin-1 characters.
Another option is to use the appropriate octal code. The
(non-ASCII) ISO Latin-1 characters are in the range 241…377.
For example, \366 produces the character o with an umlaut.
The third table in demo(Hershey) shows all of the ISO
Latin-1 escape sequences.
These characters can be used directly. (Characters not in Latin-1 are replaced by a dot.)
Several characters are missing, c-cedilla has no cedilla and
‘sharp s’ (U+00DF, also known as ‘esszett’)
is rendered as ss.
a set of characters are provided which
do not fall into any standard font. These can only be accessed by
escape sequence. For example, \\LI produces the zodiac sign for
Libra, and \\JU produces the astronomical sign for Jupiter.
The fourth table in demo(Hershey) shows all of the
special character escape sequences.
cyrillic characters are implemented
according to the K018-R encoding, and can be used directly in such
a locale using the Serif typeface and Cyrillic (or Oblique Cyrillic)
fontindex. Alternatively they can be specified via an octal code
in the range 300 to 337 for lower case characters or 340 to 377 for
upper case characters. The fifth table in demo(Hershey) shows the
octal codes for the available Cyrillic characters.
Cyrillic has to be selected via a ("serif", fontindex) pair
rather than via a font family.
83 Hiragana, 86 Katakana, and 603 Kanji characters are implemented according to the EUC-JP (Extended Unix Code) encoding. Each character is identified by a unique hexadecimal code. The Hiragana characters are in the range 0x2421 to 0x2473, Katakana are in the range 0x2521 to 0x2576, and Kanji are (scattered about) in the range 0x3021 to 0x6d55.
When using the Serif typeface and EUC fontindex, these characters can be produced by a pair of octal codes. Given the hexadecimal code (e.g., 0x2421), take the first two digits and add 0x80 and do the same to the second two digits (e.g., 0x21 and 0x24 become 0xa4 and 0xa1), then convert both to octal (e.g., 0xa4 and 0xa1 become 244 and 241). For example, the first Hiragana character is produced by \244\241.
It is also possible to use the hexadecimal code directly. This works for all non-EUC fonts by specifying an escape sequence of the form \\#J1234. For example, the first Hiragana character is produced by \\#J2421.
The Kanji characters may be specified in a third way, using the so-called "Nelson Index", by specifying an escape sequence of the form \\#N1234. For example, the (obsolete) Kanji for ‘one’ is produced by \\#N0001.
demo(Japanese) shows the available Japanese characters.
all of the characters in the Hershey
fonts are stored in a large array. Some characters are not
accessible in any of the Hershey fonts. These characters can only
be accessed via an escape sequence of the form \\#H1234.
For example, the fleur-de-lys is produced by \\#H0746.
The sixth and seventh tables of demo(Hershey) shows all of
the available raw glyphs.
demo(Hershey), par,
text, contour.
Japanese for the Japanese characters in the Hershey fonts.
# NOT RUN {
Hershey
## for tables of examples, see demo(Hershey)
# }
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