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- Path: sparky!uunet!cs.utexas.edu!qt.cs.utexas.edu!yale.edu!yale!mintaka.lcs.mit.edu!ai-lab!wheat-chex!bkph
- From: bkph@wheat-chex.ai.mit.edu (Berthold K.P. Horn)
- Newsgroups: comp.text.tex
- Subject: Re: HyperTeX
- Date: 23 Jan 1993 02:27:09 GMT
- Organization: MIT Artificial Intelligence Lab
- Lines: 207
- Message-ID: <1jqadtINN50f@life.ai.mit.edu>
- References: <16B569888.UPP201@rhrz.uni-bonn.de> <1j6g54INNcr8@life.ai.mit.edu> <ALIEN.93Jan18172626@vulcan.essex.ac.uk>
- NNTP-Posting-Host: wheat-chex.ai.mit.edu
- In-reply-to: alien@essex.ac.uk's message of 18 Jan 93 17:26:26 GMT
-
-
- In article <ALIEN.93Jan18172626@vulcan.essex.ac.uk> alien@essex.ac.uk ("Adrian F Clark") writes:
-
- ...
-
- BKH> Hyper text linkage is also supported by DVIWindo on the IBM PC.
- BKH> Great way to add a glossary to a manual, for example.
- BKH> Particularly since it is easy to highlight the words using
- BKH> a different font, different color, or reverse video, or colored
- BKH> background box. Hyper text buttons can be anywhere, even behind
- BKH> inserted TIFF images.
-
- Maybe someone could post definitions for the \specials involved, so
- that we can consider extending existing previewers in a compatible
- way.
-
- --
- Dr Adrian F. Clark JANET: alien@uk.ac.essex
- INTERNET: alien%uk.ac.essex@nsfnet-relay.ac.uk FAX: (+44) 206-872900
- BITNET: alien%uk.ac.essex@ac.uk PHONE: (+44) 206-872432 (direct)
- Dept ESE, University of Essex, Wivenhoe Park, Colchester, Essex, C04 3SQ, UK.
-
- OK, here is a brief summary of some of the relevant \special's supported
- by DVIWindo - along with some hype about `electronic publishing' :-*
-
- Some \specials for hyper-text linkage in DVI files:
- ===================================================
-
- Electronic publishing is upon us. Many files may rarely if ever be printed.
- `Pre'-viewers need to get better in terms of font rendering, faster, and more
- interactive --- since often they will be the only way a user interact with a
- document. This attitude to `pre'-viewers leads to the requirement for new
- capabilities that would not be thought of if the previewer was in fact merely
- there to make sure that there aren't any problems with a document, and that it
- is worth wasting paper to print it.
-
- At the minimum, a `pre'-viewer needs to support string search, and have
- the ability to display diagrams, figures and image of some sort.
- But more can be done if the user is given some interactive capabilities.
- Hyper-text linkage provides such ability. It makes it possible,
- for example, to high-light technical terms in order to alert the user to the
- fact that clicking on the word will show the corresponding glossary entry.
-
- Here are some simple \specials for implementing such a capability.
- Note that the end user would typically NOT use the \specials `raw', but
- via some macro package, as usual. So, for example, instead of explicitely
- changing text color, there might be macros like
-
- \def\lavender{\special{textcolor: 128 0 128}}
- \def\revert{\special{\textcolor: revert}}
-
- which could then be used in text:
-
- ... the {\lavender hyper-text \revert} button works by ...
-
-
- Summary of \specials:
- =====================
-
- (*) Hyper-text buttons are set up using:
-
- \special{button: <width> <height> <mark> [<file>]}
-
- This creates a sensitive area of specified width and height, with the
- lower left corner at TeX's current point. The semantics of this is
- that if the user clicks the left mouse button in the hypertext button
- area, viewing is transferred to the corresponding labelled mark
- (possibily in another DVI file).
-
- (*) Hyper-text marks are set using
-
- \special{mark: <label> [<xoff> <yoff>]}
-
- This is place to which control can be transferred. The optional offsets
- specify where the cursor is to appear relative to TeX's current point.
-
- Clicking the right mouse button returns control to the place where the left
- mouse button was last pushed. A limited push down stack of DVI file
- positions is maintained. The right mouse button push can come after the
- viewing scale, position or page has been changed.
-
- The hypertext button can be any rectangular area. Attention can be
- drawn to the button using rules, text or inserted TIFF images. The
- ability to control the color of rules and text and bi-level images
- is particularly useful in this connection.
-
- In some cases it makes sense for there to be just one (short) page per mark,
- particularly in the case of a glossary.
-
- NOTE: all dimensions are in TeX's scaled points (65536 per printer's
- point, of which there are 72.27 per inch). Hence they are easy to create
- using the usual dimension notations in TeX, including `pt', `cm', `in' etc.
-
- NOTE: hyper-text `labels' are sequences of non-white space characters --- or
- strings delimited by double-quote marks.
-
- There is no visible manifestation of the button itself (except in a mode
- designed for debugging hyper text linkage). This allows the user
- flexibility to show the button using words in some special font,
- colored text, colored rules in the background, or inserted TIFF images.
-
- (*) The color of text is controlled as follows:
-
- \special{textcolor: <r> <g> <b>} and \special{textcolor: revert}
-
- where <r> <g> and <b> are numbers in the 0 - 255 range specifying
- the amount red, green, and blue components of the color to be used for text.
-
- `textcolor: revert' returns the color to that in force before the previous
- textcolor change.
-
- Judicious use of a bit of colored text can be a useful adjunct to font
- changes in drawing attention. A good way to mark technical words with
- hyper text buttone behind them that lead to a glossary, for example.
-
-
- (*) The color of rules is controlled as follows:
-
- \special{rulecolor: <r> <g> <b>} and \special{rulecolor: revert}
-
- where <r> <g> and <b> are numbers in the 0 - 255 range specifying
- the amount red, green, and blue components of the color to be used for rules.
-
- `rulecolor: revert' returns the color to that in force before the previous
- rulecolor change.
-
- Rules are useful for colored backgrounds behind text, and for delineating
- hyper-text buttons.
-
-
- (*) Text can be shown in reverse video using:
-
- \special{reversevideo: on} and \special{reversevideo: off}
-
- The size of the rectangular area with reversed color on which the
- letter is placed depends on the ascent and descent of the font being used.
-
-
- (*) TIFF images (or EPSF images with TIFF preview) can be inserted using:
-
- \special{insertimage: <file-name> <width> [<height> [<ifdn>]]}
-
- The image is inserted with the lower left hand corner at TeX's current
- point. The current point is not affected by the image insertion. Here
- <ifdn>, if given, specifies the number of the image in the file.
- If omitted, the first (and often the only) image in the file is shown.
- <width> and <height> specify the space on the page to be used for the image.
- The image is scaled isotropically if height is omitted, otherwise it is
- stretched as needed.
-
-
- (*) In the case of `monochrome'/`bi-level'/`one-bit' images, one can
- control the color of the `figure' (1 bits) and the color of the
- `background' (0 bits) using:
-
- \special{figurecolor: <r-c> <g-c> <b-c> [<r-b> <g-b> <b-b>]}
-
- where the first three numbers specify the color of the `figure'
- and the last three the color of the `background'. The background
- is white (or rather the selected screen background color) if the
- background color is omitted.
-
-
- (*) TPIC specials can also be used to create device independent graphics,
- such as polygonal lines (solid, dashed, or dotted), quadratic splines,
- circlular disks and arcs, ellipses, pie slices and so on. The latter
- are particularly useful for drawing attention to hyper-text buttons.
-
-
- (*) The ten most popular schemes for insertion of EPS figures are also
- supported. If the EPS figure has a preview in EPSF or EPSI format, it
- will be shown on screen. On the IBM PC, most drawing applications create
- EPSF files with TIFF preview, for example. On Unix/NeXT EPSI preview is
- more popular.
-
-
- Some Limitations:
- =================
-
- One some display devices text colors will be `rounded' to the nearest
- `solid' color --- for example, one of 20 `system colors' in the case of VGA.
- (The colors of rules will not be so `rounded' --- dithered colors will be
- used if necessary).
-
- The push down stacks for saving text color and rule colors is limited.
-
- Positive kerning within a word can introduce gaps in reverse video.
- Often the desired effect can be achieved with better control by first
- using a rule to lay down a rectangular area behind the text in the
- background color and then writing the text over it in the desired
- foreground color.
-
- TIFF image files are binary and have a complex structure and so cannot be
- reliably read using TeX. So it is not possible to extract the number of rows
- and columns (the way BBox'es are read from EPS files) using TeX macros.
- Since the aspect ratioof the figure will not be know to TeX, it is safest to
- specify only the width of the figure to avoid anistropic scaling.
-
- For page independence, color of text and rules is NOT maintained
- across page breaks. This makes it a challenge to reliably change
- the color of a long section of text which may be broken across pages.
-
-
- Disclaimer: respondent has connections with Y&Y :=]
-
- Berthold K.P. Horn
- Cambridge, Massachusetts, USA
-