http://www.perlmonks.org?node_id=1063582


in reply to Re^4: Question about embedded Tk::Canvas
in thread Question about embedded Tk::Canvas

Right. So your issue is retrieving a reference to the canvas object. The easiest approach would probably be to store a reference to it when you create it. You seem to be creating a module anyway...so perhaps something like: 
package YourPackage;
use strict;use warnings;
use Tk;
use Tk::Canvas;
sub new {
   my $class = shift;
   my $self = bless {}, $class;
   my $mw = MainWindow->new();
   $self->{'mainwin'}=$mw;
   $self->{'mycanvas'}=$mw->Canvas();
   return $self;
}
sub getcanvas {
   my $self=shift;
   printf "Returning a %s\n",ref($self->{'mycanvas'});
   return $self->{'mycanvas'}
}
package main;
my $YP = YourPackage->new();
my $canvas=$YP->getcanvas();

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Re^6: Question about embedded Tk::Canvas
by emilbarton (Scribe) on Nov 20, 2013 at 19:39 UTC
    Ok, it seems quite a bit of a modification on my script. I don't understand why retrieving a reference aftewards should disturb but I'll apply this solution.

    Thank you very much for your help.
[reply]
      Looking at your code on github, it's because of this: 
      my $canvas = $Mainwin->Scrolled('Canvas')->grid;
my $real = $canvas->Subwidget("canvas");

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      Based on your choice of the variable name $real, you seem to already know what the issue is here :) $canvas isn't a 'Canvas'.
[reply]
[d/l]
        Hey, I always wondered was real meant in this way.. I think I just copied from TextUndo tricks I had to use somewhere else. Maybe it's not of any use here.
[reply]
        No I'm sorry, removing this workaround doesn't change anything, and I'll have to try your first proposal... In the meantime I found where this comes from: I had experienced key-binding problems in Scrolled TextUndo widgets and could apply with success Zentara's tip given here Re^3: Tk hidden binding, so to be on the safe side, as my canvas is scrolled too, I just applied the same here in prevision of possible key-bindings and problems. Anyway, I must acknowledge I often copy and paste bits of code without always being sure they're appropriate, when it works no further verification is made (shame on me!).
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