Button Basics

[edpatterson]

Please let me know if this belongs in the Perl area.

I can not get the button background color to change based upon button selection. The button should be gree for start and red for stop. It stays green no matters what the textvailable is.

[tt]
#!/usr/bin/perl -w

use strict;
use Tk;

my $mode = 'Start';
my $color = 'green';

my $mw = MainWindow->new;
my $lbl = $mw->Label(-text=>'Button Basics')->pack;
my $btn = $mw->Button(-textvariable=>\$mode,
-background =>$color,
-command=> sub {
if($mode eq 'Start'){
$color = 'red';
$mode = 'Stop';
}else{
$color = 'green';
$mode = 'Start';
}
}
)->pack(-side=>'bottom');

MainLoop;
[/tt]

Thanks,
Ed

 

[Bong]

Sometimes I find that the scope of an embedded command is lower than the scope in which the button is initiated. Try putting the command in a proc with "color" and "mode" as arguments and calling the proc with the -command option of the button.

Also, you have to use $btn configure -background $color each time you change the background.

_________________
Bob Rashkin
rrashkin@csc.com