in reply to Re^2: Drawing Shapefiles in Goo::Canvas
in thread Drawing Shapefiles in Goo::Canvas

As far as I can tell, you are still doing it wrong. Unless I'm missing some deep magic you are trying to use, the following is not right 
 my $way_lines = Goo::Canvas::Polyline->new($way_group,
  TRUE, $num_points, [\@points]);

#here you have both the $points (assuming its an array_ref of points)
# AND you have a nested array_ref in an array_ref ???
# [ \@points]   ????  where did you come up with that?

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You can only specify 1 array_ref, like $points = \@points and just use $points.

Look closely at the example in Goo::Canvas Waypoint marker w zoom/save to svg and pdf and the man page for PolyLine. There are 2 ways to specify points when creating the PolyLine. One is to drop in an anonymous array_ref of x,y pairs. The other is to set the anonymous array_ref to undef, when creating the PolyLine, then after creation, set the points option to an array_ref. Additionally, if you later want to change(update) the points, the points must be a Goo::Canvas::Points object. The Goo::Canvas::Points object is just an object wrapper around the array_ref (look at my waypoint example closely), but the Goo::Canvas wants it that way.

Remember, the Goo::Canvas is still in development, and the author hasn't tightened up those dangling inconsistencies yet. But you can get it to work, with the steps outlined above.

I'm not really a human, but I play one on earth CandyGram for Mongo

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Re^4: Drawing Shapefiles in Goo::Canvas
by deadpickle (Pilgrim) on Jun 18, 2008 at 03:38 UTC
    I have to say, thank you very much for the help!! I must be missing something cause it still is not displaying any lines at all I can't figure why. Its probably something I have overlooked and it may take another pair of eyes to remedy this. 
    #!/usr/bin/perl -w
use strict;
use Glib qw/TRUE FALSE/;
use Gtk2 -init;
use Goo::Canvas;

#variables
my $ellipsoid = 23; #static WSG83
my $zone;
my @mtp;
my @ps;
my @cs;
my $count = 1;
my $way_ref = [340, 170,340, 230];

#Create Window
my $window = new Gtk2::Window ( "toplevel" );
$window->signal_connect ("delete_event", sub { Gtk2->main_quit; });
$window->set_border_width (10);
$window->set_size_request(640,480);
$window->set_position('center');

#Create Scrolled Window
my $scwin = Gtk2::ScrolledWindow->new();
$scwin->set_policy('always','always');
$window->add($scwin);

#add canvas
my $canvas = Goo::Canvas->new();
$scwin->add($canvas);
my $root = $canvas->get_root_item();

#waypoint lines group
my $way_group = Goo::Canvas::Group->new($root);

#add Background image
my $pixbuf = Gtk2::Gdk::Pixbuf->new_from_file ($filename);
my $image = Goo::Canvas::Image->new($root, $pixbuf, 0, 0,
    'width' => $pixbuf->get_width, 
    'height' => $pixbuf->get_height);

#handle the events
$canvas->signal_connect (event => \&event_handler);

#Start the waypoint connector
my $way_lines = Goo::Canvas::Polyline->new($way_group,TRUE,undef,
    stroke_color => 'black',
    line_width => 3,
    );

$window->show_all;

Gtk2->main;

#------------------------------------------------
#handle the mosue events
sub event_handler {
    my ( $widget, $event ) = @_;
    
    #on 2 mouse presses
    if ( $event->type eq "2button-press" ) {
        my ($x,$y) = ($event->x,$event->y);
        print 'x->',$x,'  ','y->',$y;
        
        #Drop waypoint icon
        my $tgroup = Goo::Canvas::Group->new ($root);
        Goo::Canvas::Ellipse->new($tgroup,$x,$y,7.5,7.5,
            fill_color => 'purple',
            stroke_color => 'black');
        Goo::Canvas::Text->new ($tgroup,$count,$x,$y,-1,'GTK_ANCHOR_CE
+NTER',
            font => 'Sans Bold 15',
            fill_color => 'pink',
        );
        print " $count\n";
        
        push @$way_ref,$x,$y;
        my $points = Goo::Canvas::Points->new($way_ref);
        $way_lines->set(points => $points);
        $count++;
        print "$way_lines\n";
        return;
    }
}
#------------------------------------------------

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[reply]
[d/l]
      Man, you seem to do everything so as to make it as hard as possible to figure out. :-)

      Look at this code, with comments to show fixes. 

      #!/usr/bin/perl -w
use strict;
use Glib qw/TRUE FALSE/;
use Gtk2 -init;
use Goo::Canvas;

#variables
my $ellipsoid = 23; #static WSG83
my $zone;
my @mtp;
my @ps;
my @cs;
my $count = 1;

# changed to bring more into field of view
my $way_ref = [40, 70,140, 130];

#Create Window
my $window = new Gtk2::Window ( "toplevel" );
$window->signal_connect ("delete_event", sub { Gtk2->main_quit; });
$window->set_border_width (10);
$window->set_size_request(640,480);
$window->set_position('center');

#Create Scrolled Window
my $scwin = Gtk2::ScrolledWindow->new();
$scwin->set_policy('always','always');
$window->add($scwin);

#add canvas
my $canvas = Goo::Canvas->new();
$scwin->add($canvas);
my $root = $canvas->get_root_item();


# this group isn't doing anything, so when you add
# your PolyLines to it, it isn't there. You need to place
# the group somewhere on the canvas
#waypoint lines group
my $way_group = Goo::Canvas::Group->new($root);

#add Background image
my $filename = shift or die "no image $!\n";
my $pixbuf = Gtk2::Gdk::Pixbuf->new_from_file ($filename);
my $image = Goo::Canvas::Image->new($root, $pixbuf, 0, 0,
    'width' => $pixbuf->get_width, 
    'height' => $pixbuf->get_height);

#handle the events
$canvas->signal_connect (event => \&event_handler);


# your TRUE option below creates closed lines, you may want FALSE
#Start the waypoint connector, notice group is $root, NOT $way_group

my $way_lines = Goo::Canvas::Polyline->new($root,TRUE,undef,
    stroke_color => 'pink',  #make more visible
    line_width => 5,
    );

# PolyLine wants an Points object
my $points = Goo::Canvas::Points->new($way_ref);

# setting after line creation, sets the 'points' property by name
$way_lines->set(points => $points);


$window->show_all;

Gtk2->main;

#------------------------------------------------
#handle the mosue events
sub event_handler {
    my ( $widget, $event ) = @_;
    
    #on 2 mouse presses, a doubleclick
    if ( $event->type eq "2button-press" ) {
        my ($x,$y) = ($event->x,$event->y);
        print 'x->',$x,'  ','y->',$y;
        
        #Drop waypoint icon
        my $tgroup = Goo::Canvas::Group->new ($root);
        Goo::Canvas::Ellipse->new($tgroup,$x,$y,7.5,7.5,
            fill_color => 'purple',
            stroke_color => 'black');
        Goo::Canvas::Text->new ($tgroup,$count,$x,$y,-1,'GTK_ANCHOR_CE
+NTER',
            font => 'Sans Bold 15',
            fill_color => 'pink',
        );
        print " $count\n";
        
        push @$way_ref,$x,$y;
        my $points = Goo::Canvas::Points->new($way_ref);
        $way_lines->set(points => $points);
        $count++;
        print "$way_lines\n";
        return;
    }
}
#------------------------------------------------

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      I'm not really a human, but I play one on earth CandyGram for Mongo
[reply]
[d/l]

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