#!/usr/bin/perl

use strict;
use warnings;
use Gtk2 '-init';
use Gnome2::Canvas;
use Data::Dumper;


my ($win,$canvas)=create_window();

create_box($canvas,{
  x=>10,
  y=>10,
  text=>'verschieben mit der mittleren Maustaste',
  on_event=>\&box_event
});
create_box($canvas,{
  x=>10,
  y=>100,
  text=>'Mit der linken Maustase erzeugt man Verbindungen',
  on_event=>\&box_event
});
create_box($canvas,{
  x=>300,
  y=>300,
  text=>'Nur ein TestText',
  on_event=>\&box_event
});
create_box($canvas,{
  x=>300,
  y=>200,
  text=>'Noch etwas mehr Text',
  on_event=>\&box_event
});

$win->show_all();

Gtk2->main();

########################################################################
sub create_window
{
 my $w_top = Gtk2::Window->new;
 $w_top->signal_connect(destroy => \&quit);

 my $vbox = Gtk2::VBox->new(0,0);
 $w_top->add($vbox);

 my $w_canvas = Gnome2::Canvas->new_aa();
 $vbox->pack_start($w_canvas, 1,1,0);
 $w_canvas->set_size_request(600,600);
 $w_canvas->set_scroll_region (0, 0, 600, 600);

 my $quit = Gtk2::Button->new("Quit");
 $quit->signal_connect(clicked => \&quit);
 $vbox->pack_start($quit, 0, 0, 0);

 return $w_top,$w_canvas;
}

sub create_box
{
  my $canvas=shift;
  my $opts=shift;
  return undef unless(ref($opts) eq 'HASH');

  $opts->{x}=0 unless($opts->{x});
  $opts->{y}=0 unless($opts->{y});
  $opts->{on_event}=sub{1} unless($opts->{on_event});

  $opts->{box_fill}='white' unless($opts->{fill});
  $opts->{box_outline}='black' unless($opts->{line});

  $opts->{text}='???' unless($opts->{text});
  $opts->{text_color}='black' unless($opts->{text_color});
  $opts->{text_font}='Sans 12' unless($opts->{text_font});
  $opts->{text_anchor}='GTK_ANCHOR_NW' unless($opts->{text_anchor});

  my $root = $canvas->root;
  my $text = Gnome2::Canvas::Item->new(
                                      $root, 'Gnome2::Canvas::Text',
                                      x => $opts->{x}+2,
                                      y => $opts->{y}+2,
                                      fill_color => $opts->{text_color},
                                      font => $opts->{text_font},
                                      anchor => 'GTK_ANCHOR_NW',
                                      text => $opts->{text} );

  my (undef,undef,$px,$py)=$text->get_bounds();

  my $box = Gnome2::Canvas::Item->new(
                                      $root, 'Gnome2::Canvas::Rect',
                                      x1 => $opts->{x},
                                      y1 => $opts->{y},
                                      x2 => $px+4,
                                      y2 => $py+4,
                                      fill_color=> $opts->{box_fill},
                                      outline_color => $opts->{box_outline});

  $box->{TEXT_ELEMENT}=$text;
  $box->go_to_top();

  my $id=$canvas->add_item($box);
  $text->set_item_id($id);
  my $cmd_ext=$opts->{on_event};

  my $cmd=sub{
    my $box=shift;

    # rise to top
    $box->go_to_top() if($_[0]->type eq 'button-press');

    # runn event
    my $bb=$box->canvas()->get_item($box->get_item_id);
    $cmd_ext->($bb,@_);
  };

  $box->signal_connect("event", $cmd);
  $text->signal_connect("event", $cmd);

  return $box;
}

sub create_line
{
  my $start_box=shift;
  my $end_box=shift;
  my $size=shift || 4;
  my $color=shift || 'green';

  # only one line!
  if( defined($start_box->{LINE_START_ID}) || defined($end_box->{LINE_END_ID}) )
  { return undef; }

  # diffent boxes
  return undef if( $start_box eq $end_box );


  my($pa_x1,$pa_y1,$pa_x2,$pa_y2)=$start_box->get_bounds();
  my($pb_x1,$pb_y1,$pb_x2,$pb_y2)=$end_box->get_bounds();

  my $line = Gnome2::Canvas::Item->new(
                                        $start_box->canvas->root, "Gnome2::Canvas::Line",
                                        points       => [
                                                          $pa_x1+int(($pa_x2-$pa_x1)/2),
                                                          $pa_y1+int(($pa_y2-$pa_y1)/2),
                                                          $pb_x1+int(($pb_x2-$pb_x1)/2),
                                                          $pb_y1+int(($pb_y2-$pb_y1)/2)],
                                        width_pixels => $size,
                                        fill_color   => $color);


  my $id=$start_box->canvas()->add_item($line);
  $start_box->{LINE_START_ID}=$id;
  $end_box->{LINE_END_ID}=$id;
  $line->{BOX_START_ID}=$start_box->get_item_id();
  $line->{BOX_END_ID}=$end_box->get_item_id();

  $start_box->go_to_top();
  $end_box->go_to_top();

  return $line;
}

sub quit{ exit; }

#-----------------------------------------------------------------------

# moving boxes (middle Mouse)
# create Line (left mouse)
{
  my $moving;
  my $line;
  sub box_event
  {
    my $box=shift;
    my $event=shift;

    # move Box
    if($event->type eq 'button-press' && $event->button() == 2)
    { $moving=[$event->x(),$event->y()]; }
    elsif($event->type eq 'button-release' && $moving)
    { $moving=undef; }
    elsif($event->type eq 'motion-notify' && $moving)
    {
      my $dx=$event->x()-$moving->[0];
      my $dy=$event->y()-$moving->[1];
      $moving=[$event->x(),$event->y()];
      $box->move($dx, $dy);
      $box->{TEXT_ELEMENT}->move($dx, $dy);
      update_line($box);
    }

    # connect_boxes
    elsif($event->type eq 'button-press' && $event->button() == 1)
    {
      my($px1,$py1,$px2,$py2)=$box->get_bounds();
      $line = Gnome2::Canvas::Item->new(
                                        $box->canvas->root, "Gnome2::Canvas::Line",
                                        points       => [
                                                          $px1+int(($px2-$px1)/2),
                                                          $py1+int(($py2-$py1)/2),
                                                          $event->x(),
                                                          $event->y(),
                                                        ],
                                        width_pixels => 4,
                                        fill_color   => 'red');
      $box->go_to_top();
    }
    elsif($event->type eq 'motion-notify' && $line)
    {
      my $p=$line->get('points');
      $p->[-2]=$event->x();
      $p->[-1]=$event->y();
      $line->set('points',$p);
    }
    elsif($event->type eq 'button-release' && $line)
    {
      $line->destroy();
      $line=undef;

      my $item=$box->canvas->get_item_at($event->x(), $event->y());

      create_line($box,$box->canvas->get_item($item->get_item_id)) if($item && defined($item->get_item_id));

    }
  }
}

sub update_line
{
  my $box=shift;
  if(defined($box->{LINE_START_ID}))
  {
    my($px1,$py1,$px2,$py2)=$box->get_bounds();

    my $line=$box->canvas->get_item($box->{LINE_START_ID});

    if($line->isa('Gnome2::Canvas::Line'))
    {
      my $p=$line->get('points');
      $p->[0]=$px1+int(($px2-$px1)/2);
      $p->[1]=$py1+int(($py2-$py1)/2);
      $line->set('points',$p);
    }
  }

  if(defined($box->{LINE_END_ID}))
  {
    my($px1,$py1,$px2,$py2)=$box->get_bounds();

    my $line=$box->canvas->get_item($box->{LINE_END_ID});

    if($line->isa('Gnome2::Canvas::Line'))
    {
      my $p=$line->get('points');
      $p->[-2]=$px1+int(($px2-$px1)/2);
      $p->[-1]=$py1+int(($py2-$py1)/2);
      $line->set('points',$p);
    }
  }
}

#=======================================================================
# Canvas
#=======================================================================

sub Gnome2::Canvas::get_item
{
  my $canvas=shift;
  my $id=shift;
  return undef unless(defined($id) && $canvas->{ELMENT_LIST});
  return $canvas->{ELMENT_LIST}->[$id];
}

sub Gnome2::Canvas::add_item
{
  my $canvas=shift;
  my $item=shift;
  $canvas->{ELMENT_LIST}=[] unless($canvas->{ELMENT_LIST});
  my $id=@{$canvas->{ELMENT_LIST}};
  $item->{ELEMENT_ID}=$id;
  push(@{$canvas->{ELMENT_LIST}}, $item);
  return $id;
}

sub Gnome2::Canvas::delete_item
{
  my $canvas=shift;
  my $item=shift;
  if($canvas->{ELMENT_LIST})
  {
    if(ref($item) && $item->isa('Gnome2::Canvas::Item'))
    {
      for(0..$#{$canvas->{ELMENT_LIST}})
      {
        if($canvas->{ELMENT_LIST}->[$_] eq $item)
        {
          $canvas->delete_item($_);
          last;
        }
      }
    }
    elsif($item=~/^\d+$/)
    {
      $canvas->{ELMENT_LIST}->[$item]->destroy();
      $canvas->{ELMENT_LIST}->[$item]=undef;
    }
  }
}

#=======================================================================
# Canvas::Item
#=======================================================================

sub Gnome2::Canvas::Item::go_to_top
{
  my $item=shift;
  $item=$item->canvas->get_item($item->{ELEMENT_ID}) if(defined($item->{ELEMENT_ID}));
  $item->raise_to_top();
  $item->{TEXT_ELEMENT}->raise_to_top() if(defined($item->{TEXT_ELEMENT}));
}

sub Gnome2::Canvas::Item::get_item_id
{
  my $item=shift;
  return $item->{ELEMENT_ID};
}

sub Gnome2::Canvas::Item::set_item_id
{
  my $item=shift;
  my $id=shift;
  return unless(defined($id) && $id=~/^\d+$/);
  $item->{ELEMENT_ID}=$id;
}