NAME
    CAD::Drawing::IO::DWGI - Perl bindings to the OpenDWG toolkit

WARNING
    This module is intended to serve as a backend to CAD::Drawing and is not
    guaranteed to remain interface stable. Do not use this module directly
    unless you have a need for higher-speed access than that which is
    provided by CAD::Drawing (which also provides loads of other features.)

    Just

      use CAD::Drawing 

AUTHOR
      Eric L. Wilhelm
      ewilhelm AT sbcglobal DOT net
      http://pages.sbcglobal.net/mycroft

COPYRIGHT
    This module is copyright 2003 by Eric L. Wilhelm and A. Zahner Co.

    This is module is free software as described under the terms below.
    Permission to use, modify and distribute this module shall be governed
    by these terms (the module code is distributed and licensed
    independently from the OpenDWG consortium's code.) All notices and
    disclaimers must remain intact with any copies of this software.

LICENSE
    This module is distributed under the same terms as Perl. See the Perl
    source package for details.

REQUIREMENTS
    You must obtain and install the OpenDWG libraries from the OpenDWG
    consortium in order to use this module. By using this module, you have
    the responsibility to adhere to both the licensing of this module and
    the licensing of the OpenDWG consortium.

SYNOPSIS
      use CAD::Drawing::IO::DWGI;
      $dwg = CAD::Drawing::IO::DWGI->new();
      $dwg->loadfile("file.dwg");
      $dwg->getentinit();
      while(my($layer, $color, $type) = $dwg->getent()) {
        my $type = $dwg->entype($type);
        if($type eq "lines") {
          $line = $dwg->getLine();
          }
        }
  
      $dxf = CAD::Drawing::IO::DWGI->new();
      $dxf->newfile(1);
      $dxf->getentinit();
      $dxf->writeCircle({"pt"=>[$x, $y], "rad" => 1.125, "color" => 9});
      $dxf->savefile("check.dxf", 1);

SPEED
    Wow! This is fast! I had originally implemented this with a
    function-call based wrapper which had the drawback that the layerhandle
    had to be found for every object which was being saved. See the
    writeLayer() and setLayer() functions below for details of the improved
    methods. Also note that while the speed is amazing from this level, very
    little speed is lost by moving up a level to using CAD::Drawing (please
    do this.)

Accuracy
    The dxf file accuracy is set internally at 14 digits after the decimal
    place. Providing an interface to set this would take a bit of coding in
    C, so you are more than welcome to submit a patch.

Changes
      0.08 First public release
      0.09 Fixed error reading image size
      0.10 Added Ellipse read

Constructor
  new

    Creates a new blessed reference which gives access to the following
    object methods.

      $d = CAD::Drawing::IO::DWGI->new();

File Actions
  loadfile

    Loads a file from disk into the toolkit data structure.

      $d->loadfile("filename.dxf|dwg");

  newfile

    Creates an empty data structure and initializes some default values.

      $d->newfile($version);

  savefile

    Writes the data to disk.

      $d->savefile($name, $type);

Layer Actions
  listlayers

    Returns a list of layers in the loaded object.

      @layers = $d->listlayers();

  writeLayer

    Add a new layer to the database and set it as the current layer. A
    newfile() starts with layer "0" as the default.

      %layer_opt = (
        name => $name,  # limit of 255 characters?
        color => 9,     # must be 0-256
        );
      $dwg->writeLayer(\%layer_opt)

    Currently, the only parameter supported is the name and color.

  setLayer

    Set layer as the default. Layer must have been previously created with
    writeLayer().

      $dwg->setLayer($name) or die "layer not in drawing yet";

Typed Entity Functions
    NOTE that all getThing methods must be part of a getent() loop.

  getCircle

    Reads a circle from the current entity.

      $circle = $d->getCircle();
      print "point:  ", join(",", @{$circle->{pt}}), "\n";
      print "rad:    $circle->{rad}\n";

  writeCircle

    Writes a circle to the object structure.

      $d->writeCircle({"pt"=>[$x,$y,$z], "rad"=>$rad, "color"=>$color});

  getEllipse

    Reads an ellipse from the current entity.

      $el = $d->getEllipse();
      print "center:  ", join(",", @{$el->{pt}}), "\n";
      print "offset:  ", join(",", @{$el->{off}}), "\n";
      print "minor / major ratio:   $el->{ratio}\n";
      print "start / end:  ", join(",", @{$el->{angs}}), "\n";

    There is (as usual) some discrepency between the odwg docs and the adesk
    dxf ref as to wtf this parameter thing is. There are some undocumented
    functions in the toolkit, which seem to only reduce the arc-angles. NOTE
    that the angles given are relative to the baseline described by the
    vector stored in $el->{off}.

  getArc

    Reads an arc from the current entity.

      $arc = $d->getArc();
      print "point:  ", join(",", @{$arc->{pt}}), "\n";
      print "rad:    $arc->{rad}\n";
      print "radian angles: ", join(",", @{$arc->{angs}}), "\n";

  writeArc

    Writes an arc to the object structure.

      %ArcOpts = (
        "pt" => [$x,$y,$z],
        "rad" => $rad,
        "angs" => [$start, $end],
        "color" => $color,
        );
      $d->writeArc(\%ArcOpts);

  getLine

    Reads a line from the current entity.

      $line = $d->getLine();
      print "endpoints:  ",
        join("\n", 
          map({join(",", @{$_})}
            @{$line->{pts}}
          )
        ), "\n";

  writeLine

    Writes a line to the object structure.

      %LineOpts = (
        "pts" => [ [$x1,$y1,$z1], [$x2,$y2,$z2] ],
        "color" => $color,
        );
      $d->writeLine(\%LineOpts);

  getText

      $text = $d->getText();
      print "point:  ", join(",", @{$text->{pt}}), "\n";
      print "string: ", $text->{string}, "\n";
      print "height: ", $text->{height}, "\n";

  writeText

      %TextOpts = (
        "pt" => [$x, $y, $z],
        "string" => $string,
        "height" => $height,
        "color" => $color,
        );
      $d->writeText(\%TextOpts);

  getSolid

  getPoint

      $point = $d->getPoint();
      print "point:  ", join(",", @{$point->{pt}}), "\n";

  writePoint

      %PointOpts = (
        "pt" => [$x, $y, $z],
        "color" => $color,
        );
      $d->writePoint(\%PointOpts);

  getLWPline

      $pline = $d->getLWPline();
      print "points:\n\t", 
        join("\n\t", 
            map({join(",", @{$_})}
              @{$pline->{pts}}
               )
          ), "\n";
      print $pline->{closed} ? "closed" : "open" , "\n";

  writeLWPline

      @pts = (
        [0,1],
        [5,-2.25],
        [7,9],
        [4,6],
        [-2,7.375],
         );
      %PlineOpts = (
        "pts" => \@pts,
        "closed" => 1,
        "color" => 255,
        );
      $d->writeLWPline(\%PlineOpts);

  getImage

    Reads an image from the current entity.

Entity List handling
    Entities are read and written from a list, which must be initialized on
    both read and write operations.

  getentinit

    Initializes the entity list. Call this before adding anything to a
    newfile() or before calling getent() after loadfile()

  getent

    Returns the next entity. This is paired with getentinit() and the two
    act as a pair much like the Perl open() and $line = <FILEHANDLE> setup.

Utilities
  get_extrusion

    Returns the extrusion vector of the current entity as an array
    reference. Returns undef if extrusion is not set.

      if(my $extrusion = $dwg->get_extrusion()) {
        print "extrusion is @$extrusion\n";
      }

  set_extrusion

    Sets the extrusion direction of the current entity. Not intended to be
    used from Perl (each write<entity> function calls this itself if the
    value of $opts{extrusion} is set.)

  entype

    Return a text string for the entity type code.

      $type = $d->entype($type);
      if($type eq "plines") {
        $pline = $d->getLWPline();
        }

  DESTROY

    This function is called under the hood by perl when variables created by
    new() go out of scope. You should never call this from your code, but
    you can undef() your object and it will get called.

    Note that you may in fact need to undef($dwg) to kill your object before
    trying to use another one. The toolkit doesn't like to be opened and
    closed while objects are in-use, and each object has no way of knowing
    whether or not there are other objects in-use. Since I don't feel like
    leaking memory with a BEGIN and END setup, you'll just have to live with
    this (or make a suggestion for a better setup.)