Problem with Tk::chooseColor on Win32

jdtoronto has asked for the wisdom of the Perl Monks concerning the following question:

Esteemed monks,

It was time to add some colour choices to various things in my monster Perl/Tk application. So I added a simple little method using chooseColor, but alas it was a dismal failure. Oh, I could choose a colour alright, but alas, if you wanted to close the colour picker window ir click on the 'Cancel' button, it crashes the application.

Here is a minimal test case that I can make crash on my machine.

use strict;
use warnings;

use Tk;

my $cfg;
my $font_colour;
my $wd = MainWindow->new();

$wd->Label(
  -text    => 'Color',
  -justify => 'right',
  )->grid(
  -column => 0,
  -row    => 4,
  -pady   => 20,
  -padx   => 20,
  -sticky => 'e'
  );
my $colour_button = $wd->Button(
  -width   => 6,
  -command => sub { $font_colour = colour_picker() },
  )->grid(
  -column => 2,
  -row    => 4,
  -pady   => 20,
  -padx   => 20,
  -sticky => 'e'
  );

if ($font_colour) {
  $colour_button->configure( -background => $font_colour, -activebackg
+round => $font_colour );
}

MainLoop;

sub colour_picker {

  my $colour = $wd->chooseColor( -title => 'Color Picker', -initialcol
+or => '#000000' );
  print "Colour chosen: " . $colour . "\n" if $colour;
  $colour_button->configure( -background => $colour, -activebackground
+ => $colour );
  return $colour;

}
[download]

In the event viewer the error is always:

Faulting application perl.exe, version 5.8.8.820, faulting module msvc
+rt.dll, version 7.0.2600.2180, fault address 0x000378c0.
[download]

I am using Perl 5.8.8.820 Activestate build, Windows XP-SP2.

I am not knowledgable enough to know how to troubleshoot this any further myself, so any assistance would be appreciated.

jdtoronto

Comment on Problem with Tk::chooseColor on Win32 Select or Download Code

Replies are listed 'Best First'.
Re: Problem with Tk::chooseColor on Win32 by thundergnat (Deacon) on May 24, 2007 at 17:45 UTC
If you cancel the dialog, the $colour variable is undefined. You then try to set the -background and -activebackground to an undefined value. CRASH!! You need to check that $colour is defined before using it. use strict; use warnings; use Tk; my $cfg; my $font_colour; my $wd = MainWindow->new(); $wd->Label( -text => 'Color', -justify => 'right', )->grid( -column => 0, -row => 4, -pady => 20, -padx => 20, -sticky => 'e' ); my $colour_button = $wd->Button( -width => 6, -command => sub { $font_colour = colour_picker() }, )->grid( -column => 2, -row => 4, -pady => 20, -padx => 20, -sticky => 'e' ); if ($font_colour) { $colour_button->configure( -background => $font_colour, -activebackg +round => $font_colour ); } MainLoop; sub colour_picker { my $colour = $wd->chooseColor( -title => 'Color Picker', -initialcol +or => '#000000' ); $colour ? print "Colour chosen: " . $colour . "\n" : return; $colour_button->configure( -background => $colour, -activebackground + => $colour ); return $colour; } [download]	[reply] [d/l]
Re^2: Problem with Tk::chooseColor on Win32 by jdtoronto (Prior) on May 24, 2007 at 18:42 UTC
Thank you thundergnat, that is indeed the problem. Another senior moment on my part! jdtoronto	[reply]
Re^2: Problem with Tk::chooseColor on Win32 by ldln (Pilgrim) on May 24, 2007 at 18:09 UTC
...just curious : Is there an similar command to bring out the font-selection-window on win32 from perl/Tk also?	[reply]
Re^3: Problem with Tk::chooseColor on Win32 by thundergnat (Deacon) on May 24, 2007 at 19:15 UTC
Not that I am aware of. It isn't too hard to fake it though... and you could probably access it through Win32::API with a little tinkering.	[reply]
Re: Problem with Tk::chooseColor on Win32 by ldln (Pilgrim) on May 24, 2007 at 16:28 UTC
Works fine here. perl5.8.8 (build 817), Tk804.027, WinXP SP2. UPDATE Sorry, didn't read text closely enough. Yeah, ugly bug here also if "Cancel" button is pressed. Sorry. UPDATE Ok, simple fix. Just make sure you don't try to assign "undef color", if user press cancel. Maybe add simple if test: `... if ($colour) { $colour_button->configure( -background => $colour, -activeback +ground => $colour ); } ...` [download]	[reply] [d/l]
Re^2: Problem with Tk::chooseColor on Win32 by jdtoronto (Prior) on May 24, 2007 at 17:43 UTC
Thanks for the update ldln, yeah, it is kinda ugly! Now all I have to do is figure out how get the nasty little critter back on his feet instead of lying around on his back! jdtoronto	[reply]
Re: Problem with Tk::chooseColor on Win32 by zentara (Archbishop) on May 24, 2007 at 17:14 UTC
Works fine on linux too. I'm not really a human, but I play one on earth. Cogito ergo sum a bum	[reply]
Re^2: Problem with Tk::chooseColor on Win32 by jdtoronto (Prior) on May 24, 2007 at 17:41 UTC
Thanks, ldln & zentara and also Albannach who responded in the CB. I know it works fine on Linux! But Linux doesn't use the Win32 native colour chooser, nor does it have msvcrt.dll! I have tried it on 3 machines now, two are XP-XP2, the other is Win2k - all are very up to date. I have some others I can try, but ti is looking pretty consistent. My tech support guy has the same failure on his machine too. jdtoronto	[reply]

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