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- This directory contains supplementary documentation on GNU libplot, the
- drawing library on which several of the executables in the GNU plotting
- utilities ("plotutils") package, such as graph, plot, tek2plot, plotfont,
- and hersheydemo, are based.
- ./colors.txt: A listing of the color names recognized by libplot,
- and hence by each of the above plotting utilities.
- A 24-bit RGB representation for each color is given.
- For example, you may pop up a simple graph,
- drawn in a chocolate color, by typing the command
- echo 0 0 1 1 2 0 | graph -T X
- This is because "chocolate" is one of the listed color
- names. In the 24-bit RGB scheme, "chocolate" means
- (210,105,30). The strength of each of R (red), G
- (green), and B (blue) is represented as an 8-bit
- quantity, i.e., an integer in the range 0..255.
- ./h-fonts.txt: A listing of the 22 Hershey fonts supported by GNU
- libplot and executables based on it.
- Hershey fonts are vector ("stroked") fonts, in which each character is made
- up of thickened line segments. They can look good on high-resolution
- output devices (on which they have a hand-lettered appearance) and on
- medium-resolution output devices (where they may be competitive with other
- types of font). This is especially the case if anti-aliasing is used.
- To see a demo page illustrating the Hershey fonts, do
- hersheydemo -Tps > page.ps
- to produce the page in PS (Postscript format), or
- hersheydemo -Tsvg
- in SVG (scaled vector graphics) format. You can send the former to a
- printer, and display the latter from the command line by invoking on it,
- e.g., a Web browser such as firefox, or the `svgdisplay' or `display'
- executables. (They come respectively from KDE and the ImageMagick
- package.) The result should look good. If you do
- hersheydemo -TX
- to see the demo page (rotated) in a popped-up 800pixel-by-800pixel
- X window, the result may look less good, as your X display may not use
- anti-aliasing. That means that every pixel in the window will be either
- black or white, with no gradations that make characters more legible.
- The 22 Hershey fonts built into GNU libplot were assembled from glyphs in
- the large family of vector glyphs designed by Dr. Allen V. Hershey in the
- early days of computer graphics, beginning in the 1960s. His glyphs
- predate modern outline fonts, but are not just of historical interest. The
- demo page is taken from his 1972 article in Computer Graphics and Image
- Processing (vol. 1, no. 4, pp. 373-385).
- Plotting utilities such as `graph' can use Hershey fonts, as well as,
- e.g., such Postscript fonts as Times-Roman. By doing
- echo 0 0 1 1 2 0 | graph -T ps -F Times-Roman -L 'A Graph' > graph.ps
- echo 0 0 1 1 2 0 | graph -T ps -F HersheySerif -L 'A Graph' > graph.ps
- echo 0 0 1 1 2 0 | graph -T ps -F HersheyGothic-English -L 'A Graph' > graph.ps
- etc., you can generate graphs with labels and titles in various fonts. Use
- the
- output-format-specific (though Hershey fonts are supported in all output
- formats).
- The Hershey glyph repertory, built into GNU libplot, includes various
- symbols in addition to occidental and Japanese characters. Some symbol
- glyphs do not belong to any font. If the current font is a Hershey font,
- you may access any glyph by its number, even if it is not a character in
- the font, in the conventional sense. For instance,
- echo 0 0 1 1 2 0 | graph -T ps
- would label the graph being drawn with a title line consisting of
- two fleurs-de-lys. That is because the fleur-de-lys is Hershey glyph
- The following files are relevant to the Hershey glyph repertory built
- into GNU libplot. The
- ./h-glyphs.txt: A high-level survey of the `occidental' Hershey glyphs,
- in great detail. Includes an extensive comparison with earlier
- (pre-GNU) distributions of the Hershey glyphs, and an explanation
- of how the glyph array was assembled.
-
- ./hershey.bib: A bibliography, in BibTeX format, of publications
- dealing with the Hershey glyphs and with Allen Hershey's system for
- scientific typography, which was designed to use them. Most of the
- cited items are technical reports that are available from the
- U.S. National Technical Information Service (+1 703 487 4650).
- Stock numbers are given.
-
- ./kana.txt: The encodings used for the Hershey Hiragana and Katakana
- (syllabic Japanese characters). These are part of the HersheyEUC
- font, but may also be accessed by number.
-
- ./kanji.txt: The encoding of the 603 available Japanese Kanji
- (ideographic characters), and their meaning. These are part of the
- HersheyEUC font, but may also be accessed by number.
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