@techreport{TR-DCC-93-24,
  number = {DCC-93-24},
  author = {Patrocínio, Eduardo A. and de Rezende, Pedro J.},
  title = {{EGOLib}: {Uma} Biblioteca Orientada a Objetos Gráficos},
  month = {September},
  year = {1993}, 
  institution = {Department of Computer Science, University of Campinas},
  note = {In Portuguese, 25 pages.
    \par\selectlanguage{english}\textbf{Abstract}
      We present a description of a library of functions ({\em EGOlib})
      built on the {\em X-Window} system for the manipulation of
      graphics objects, which provides facilities for the update of such
      objects while modifications of attributes of the objects are made.
      This library constitutes a level above the {\em xlib} library,
      allowing the user a higher level access to modifications of
      various attributes on a homogeneous and uniform way, resulting in
      more elegant code than is possible using purely {\em xlib}
      functions.
    \par
      The concept of class hierarchy, present in object oriented
      languages, is used for creating the classes of graphics objects,
      from some simple ones up to composed objects such as binary trees.
    \par
      Applications of {\em EGOlib} are abundant, and in particular, this
      library has been used for the implementation of algorithm
      animations.
  }
}