Re: Help with TixGrid, segfault in Tix_LinkListNext

Hi Norbert

I tried running your example under perl on WinXP, but it crashes everytime the first click of the Update Grid button.


Changing this line:

$g->deleteRow(0, $curlines+1);

to this:

$g->deleteRow(1, $curlines);

lets it get a bit further, until it tries to return from update_grid the 3rd time.  It was clearing the header row too.

Adding the line below at the top of the 'for my $p' loop lets it continue to pop letters off of @packs until the last visible one (nine remaining on winxp running with activestate's perl not counting the header lines- need to compare this to a linux perl) is removed and the program flow returns to MainLoop:

print $Packages{$p}{'cb'},"\n";

When it tries to return to MainLoop (or $g->update()) with less rows showing than the minimal amount it first displays,  -height changes that, then it crashes.

A possible bug is that the deleteRow method doesn't change how many rows that the index method returns for a 'max' value.  They're blank but still there so $curlines always gets the value of 26.

Changing the cell values from the Checkbox widgets to a text itemvalue lets it delete everything without crashing...

Tested on perl v5.10.1 - Binary build 1006 [291086] from activestate.

Phil Hartfield
phil681@yahoo / [email protected]


----- Original Message ----
From: Norbert Preining <[email protected]>
To: [email protected]
Sent: Sat, December 5, 2009 11:38:24 PM
Subject: Help with TixGrid, segfault in Tix_LinkListNext

Hi everyone,

I am having a problem with TixGrid. I want to embedd a check button
in the first column and at certain points update the grid (the list 
of items to be shown).

I have code that actually works, but there is a problem with the selection.
As soon as I update the grid and scroll down the checkbuttons are 
drawn incorrectly, namely some are selected that should not be.

Ok, that sounds rather complicted, I agree, so I tried to create a 
minimal example, but that, even worse, made Tk segfault in 
Tix_LinkListNext.

Here the code:
$^W = 1;
use strict;

use Tk;
use Tk::TixGrid;

my $mw = MainWindow->new();
my $g = $mw->TixGrid(-topmargin => 1);

my @packs = qw/a b c d e f g h i j k l m n o p q r s t u v w x y z/;
my %Packages;

$g->set(0,0, -itemtype => 'text', -text => "CB");
$g->set(1,0, -itemtype => 'text', -text => "Name");

my $i = 1;
for my $p (@packs) {
  $Packages{$p}{'selected'} = $i%2;
  $Packages{$p}{'cb'} = $g->Checkbutton(-variable => \$Packages{$p}{'selected'});
  $g->set(0,$i, -itemtype => 'window', -widget => $Packages{$p}{'cb'});
  $g->set(1,$i, -itemtype => 'text', -text => $p);
  $i++;
}

$g->pack;
  
$mw->Button(-text => "Update Grid", -command => \&update_grid)->pack;

MainLoop;

sub update_grid {
  my (undef, $curlines) = $g->index(0, 'max');
  $g->deleteRow(1, $curlines+1);
  pop @packs;
  my $i = 1;
  for my $p (@packs) {
    $g->set(0,$i, -itemtype => 'window', -widget => $Packages{$p}{'cb'});
    $g->set(1,$i, -itemtype => 'text', -text => $p);
    $i++;
  }
  print "Foo\n";
}
    


Interestingly it crashes not always at the first time, but sometimes
at the n-th time I press the update grid button.
It is not the $g->set in the update_grid, because I always come around
the print "Foo\n"; but after that segfaults occur.

So I wonder if something is wrong with the above code, or some bug in
TixGrid I am hitting?

Thanks a lot for any suggestion

Norbert
------------------------------------------------------------------------
Norbert Preining            preining@{jaist.ac.jp, logic.at, debian.org}
JAIST, Japan            TU Wien, Austria           Debian TeX Task Force
DSA: 0x09C5B094   fp: 14DF 2E6C 0307 BE6D AD76  A9C0 D2BF 4AA3 09C5 B094
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