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Text Generation Method

                        Text Generation with LASI


  There is no "text" component (or object) in a LASI drawing system.
  Instead, recognizing that a limited amount of text often needs to be
  added to a drawing or layout, a method of text generation has been
  provided. The method makes text characters from path objects. The
  characters are the same as any other path object, an may be changed with
  normal path editing commands.

  Each character is read from the pattern file TXT.DBD. This file is a
  random access file which contains an single record of 128 bytes for each
  of 96 characters. At entry time, the position, size of the text and the
  character spacing is requested. The text string is then simply typed in
  and terminated by <enter>. The layer and width of the text are taken from
  the default path parameters.

  Using paths for text has advantages and disadvantages. Path and vertex
  space is used up. However, text may be manipulated the same as a path,
  and the conversion to other drawing systems is much easier.
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The Character Field

  Characters start as little cells containing a drawing of a character. The
  data format of the character drawing is quite different from a cell and
  will be describe later. A character is drawn as a rank 1 cell using paths
  (of 0 width) on a 16x16 field of basic drawing units. The lower left
  corner of the field is position 0,0. The vertices of the paths fall on
  the basic unit grid points. The vertices may be on any grid point except
  15,15.


                                              15
                . . . . . . . . . . . . . . . x 15  (15,15 not used)
                . . . . . . . . . . . . . . . .
                . . . . . . . . . . . . . . . .
                . . . . . . . . . . . . . . . .
                . . . . . . . . . . . . . . . .
                . . . . . . . . . . . . . . . .
                . . . . . . . . . . . . . . . .
                . . . . . . . . . . . . . . . .  ^
                . . . . . . . . . . . . . . . .  |
                . . . . . . . . . . . . . . . .  Y
                . . . . . . . . . . . . . . . .
                . . . . . . . . . . . . . . . .
                . . . . . . . . . . . . . . . .
                . . . . . . . . . . . . . . . .
                . . . . . . . . . . . . . . . .
      (origin)0 . . . . . . . . . . . . . . . .
                0
                            X -->

                Character Drawing Field in basic units


  Once a character cell is drawn, the program MAKETXT.EXE is used to
  install the character in the TXT.DBD file.

  There can be any character drawing in the pattern file corresponding to a
  given typed character. In fact, different TXT.DBD files (with different
  names) with different drawings or fonts can be kept for different uses.
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The TXT.DBD File

  The pattern file TXT.DBD is ninety-six 128 byte records long. Each record
  corresponds to an ASCII character starting at decimal 32 (space) and
  ending at decimal 127 (delete, non-printing). When a character is typed
  under LASI, the correct record is found and the information is used to
  make path objects in the drawing. The records are randomly written by the
  MAKETXT.EXE program by typing the desired character and then giving the
  name of the cell which contains the character drawing.

  The vertices of the path pattern are written in a single byte of a record
  in the form of the X-coordinate as the upper 4 bits and the Y-coordinate
  as the lower 4 bits (nibbles). The coordinates may then be only the
  numbers 0-15. The coordinate combination (15,15) is however prohibited
  because it is used to indicate the end of a path.

  A record therefore contains vertex coordinate bytes from 0-254, with 255
  decimal (or FF in Hex) bytes marking the end of a path. The remaining
  bytes in a record are always filled with FF bytes to prevent further
  paths being made as the record is read.

  The maximum number of vertices that a record can hold is dependent on the
  number of independent paths, but can be determined from:

              total no. vertices = 128 - total no. paths
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Text and the CALMA

  The text made by LASI is treated like any path or poly object by the
  CALMA when converted using LASI2CSF.EXE. Paths of 0 width or poly are
  converted to boundaries. Boundaries however are automatically closed by
  the CALMA itself, which will cause characters made from poly to be
  distorted by the CALMA. The solution is of course to give a character
  some width. This then will make the CALMA think that the character is a
  path and it will not be closed. If characters are to be converted to
  CALMA, then one should create a TXT.DBD file that contains characters
  that look good with the desired width.
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Character Cell Collection

  The cell collection that contains all the cells that are used to make the
  text characters is not usually included with the LASI System
  distribution. If you don't have a copy of this collection, and it is not
  available from your distribution source, it will be sent on request.
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