  TkTeXCAD -- Short description
  Hilmar Straube, hilmstr@web.de
  Aug 16, 2001

  Short description for TkTeXCAD, a Python/Tkinter-Script to interac-
  tively create LaTeX picture environments.
  ______________________________________________________________________

  Table of Contents


  1. Introduction

  2. (Not-)Features

     2.1 Saved picture parts
     2.2 Inclusion of EPS pictures

  3. Notes on the user interface

     3.1 The display menu
     3.2 The menu picture parts

  4. The file menu


  ______________________________________________________________________

  11..  IInnttrroodduuccttiioonn

  TkTeXCAD means to make creation of standard LaTeX picture environments
  easy.  It knows about LaTeX' limitations and attempts to preview the
  dvi output.  It is able to save and load pictures in its own format
  (realized using the module pickle provided with Python), but only
  exports LaTeX source.  Special focus is laid on processing reusable
  picture parts.


  22..  ((NNoott--))FFeeaattuurreess

  The program uses the unit pt and the picture environment without
  additional extension packages (except graphicx for .eps inclusion).

  So, the program only generates these: \circle (empty circle; stepped
  up to 40 pt), \circle* (filled, only up to 15 pt), lines and vectors
  (limited elevations; a very bold version is used to implement filled
  rectangles), various text boxes, the \qbezier splines,
  \includegraphics (requieres \usepackage{graphicx} in the preamble) and
  of course commands to insert saved picture parts.

  Moreover, it is possible to show the same object several times by
  using \multiput.


  22..11..  SSaavveedd ppiiccttuurree ppaarrttss

  The program makes a difference between classes of pictures and
  instances of these picture classes. A picture class contains some
  objects with their individual properties.  An instance of a picture
  class can then be an object inside other picture classes where it
  appears as a special, user-defined objects. Whenever the inner picture
  class changes, all instances of this class will be changed as well.

  The object "instance of a picture class" can be scaled (\unitlength).
  This may cause the diameters of the arcs of \oval and the circles to
  change un-proportional, but the program will (hopefully) preview that.

  So a picture for TkTeXCAD consists of several picture classes. There
  is a main picture, that will be inserted directly into the LaTeX
  source. All other classes will be referenced to (possibly indirectly)
  from the main picture. When exporting, the program creates a file for
  every exported picture class _w_i_t_h _e_x_a_c_t_l_y _t_h_e _s_a_m_e _n_a_m_e_; _s_o _y_o_u _h_a_v_e
  _t_o _t_a_k_e _c_a_r_e _t_h_a_t _t_h_i_s _n_a_m_e _w_i_l_l _b_e _l_e_g_a_l _o_n _y_o_u_r _s_y_s_t_e_m_.


  22..22..  IInncclluussiioonn ooff EEPPSS ppiiccttuurreess

  As noted above, the program is able to include EPS files. It will
  preview their contents, but will need the help of the Python Imaging
  Library (PIL).  This library then uses Ghostscript to render the
  pictures, but only on UNIX derivates with Ghostscript installed.  If
  you have already installed the PIL on another platform, append some
  letters to the line "import Image" in tktc.py.  This will raise an
  "ImportError" exception and thus tell the programm that there is no
  EPS support on your system.

  With no EPS support, every EPS picture will appear as a striked out
  rectangle whose aspect ratio is unknown.  The programm will assume 1/1
  which is probably wrong.

  The EPSs will not be saved, neiter in the .pic files of tkTeXCad nor
  in the exported files.  So, you should copy them with your whole LaTeX
  document.  (The exported files contain absolute paths to the files.)


  33..  NNootteess oonn tthhee uusseerr iinntteerrffaaccee

  33..11..  TThhee ddiissppllaayy mmeennuu

  Every click into the canvas will be transformed into LaTeX
  coordinates.  Additionally it will be placed onto the nearest point in
  the grid.  This grid can be hidden, but this does not change that
  behavior.  If you don't want it, just make the grid spacing small
  enough.

  To change the coordinate system, the data in the upper field of the
  menu is used.  It denotes the number of points on the screen that will
  be one TeX pt.


  33..22..  TThhee mmeennuu ppiiccttuurree ppaarrttss

  To create a new picture class, select the objects you want to transfer
  into (elements/... mark) and select "create new picture class". These
  objects will be deleted in the picture class you are just editing and
  pasted into the newly created class.  Then, the program places the
  first instance of this newly created picture class exactly to where it
  took the objects from.

  The next menu items are the picture classes that you have already
  created.  Some of them may be grayed to make it impossible to insert
  them into classes whose instances they contain (to avoid circular
  references).

  The last menu item gives access to editing all classes.

  This does not really fit in here, but probably needs some explanation:
  Objects that are \multiputted can be changed into several stand-alone
  objects by selecting "create count simple objects".  The same thing
  can be done with an instance of a picture class.  This detaches it
  from its picture class; changes to the picture class will not affect
  the newly created objects any more.


  44..  TThhee ffiillee mmeennuu

  Load, save and import refer to the files created by TkTeXCAD and
  pickle.  Import will only work, if the imported file does not contain
  any picture classes whose names are ambiguous with those already in
  memory.  The imported classes can then be selected in the menu picture
  classes.

  Exporting creates for every picture class a .tex file with the same
  name.  These refer to one another and can be placed into your LaTeX
  source using \import{_n_a_m_e>