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

Good morning. I've had some production code in effect for a few years using TKX under ActiveState Perl, but had to move to Strawberry because of Windows 10 at work. I'm now using Tk and have a problem. Under TKx, it was easy to change the botton's background color, but under Tk, I'm not seeing how. The background =>"yellow" did not work. Here's my code: 
#!/usr/bin/perl -w

use Tk;

open(OUTFILE, '>>forecast.txt') or die "Cannot open forecast.txt: $!";

my $mw = MainWindow->new;
$mw->geometry("150x700");
$mw->title("Multiple Windows Test");

my $button1 = $mw->Button(-text => "18-Letters",
                          -command => sub {print OUTFILE "18L\n", back
+ground => "yellow"})->pack(-side => "top");
my $button2 = $mw->Button(-text => "07-Orders",
                          -command => sub {print OUTFILE "07O\n"})->pa
+ck(-side => "top");
my $button3 = $mw->Button(-text => "36-Letters",
                          -command => sub {print OUTFILE "36L\n"})->pa
+ck(-side => "top");
my $button4 = $mw->Button(-text => "38-Letters",
                          -command => sub {print OUTFILE "38L\n"})->pa
+ck(-side => "top");
my $button5 = $mw->Button(-text => "11-Orders",
                          -command => sub {print OUTFILE "11O\n"})->pa
+ck(-side => "top");
my $button6 = $mw->Button(-text => "99-Letters",
                          -command => sub {print OUTFILE "99L\n"})->pa
+ck(-side => "top");
my $button7 = $mw->Button(-text => "21-Letters",
                          -command => sub {print OUTFILE "21L\n"})->pa
+ck(-side => "top");
my $button8 = $mw->Button(-text => "23-Letters",
                          -command => sub {print OUTFILE "23L\n"})->pa
+ck(-side => "top");
my $button9 = $mw->Button(-text => "Return to L&I",
                          -command => sub {print OUTFILE "OOO\n"})->pa
+ck(-side => "top");
my $button10 = $mw->Button(-text => "D1008235",
                          -command => sub {print OUTFILE "D1008235 08\
+n"})->pack(-side => "top");
my $button11 = $mw->Button(-text => "D2008235",
                          -command => sub {print OUTFILE "D2008235 08\
+n"})->pack(-side => "top");
my $button12 = $mw->Button(-text => "D2108235",
                          -command => sub {print OUTFILE "D2108235 08\
+n"})->pack(-side => "top");
my $button13 = $mw->Button(-text => "D2208235",
                          -command => sub {print OUTFILE "D2208235 08\
+n"})->pack(-side => "top");
my $button14 = $mw->Button(-text => "D2608235",
                          -command => sub {print OUTFILE "D2608235 08\
+n"})->pack(-side => "top");
my $button15 = $mw->Button(-text => "D6108 CMPRT09",
                          -command => sub {print OUTFILE "D6108235-1\n
+"})->pack(-side => "top");
my $button16 = $mw->Button(-text => "D6108 CMPRT10",
                          -command => sub {print OUTFILE "D6108235-2\n
+"})->pack(-side => "top");
my $button17 = $mw->Button(-text => "D6308 CMPRT03",
                          -command => sub {print OUTFILE "D6308235-1\n
+"})->pack(-side => "top");
my $button18 = $mw->Button(-text => "D6408235 CMPRT03",
                          -command => sub {print OUTFILE "D6408235-1\n
+"})->pack(-side => "top");
my $button19 = $mw->Button(-text => "D6608 CMPRT06",
                          -command => sub {print OUTFILE "D6608235-06\
+n"})->pack(-side => "top");
my $button20 = $mw->Button(-text => "D6608 CMPRT25",
                          -command => sub {print OUTFILE "D6608235-25\
+n"})->pack(-side => "top");
my $button21 = $mw->Button(-text => "D6608 CMPRT26",
                          -command => sub {print OUTFILE "D6608235-26\
+n"})->pack(-side => "top");
my $button22 = $mw->Button(-text => "D6608 CMPRT27",
                          -command => sub {print OUTFILE "D6608235-27\
+n"})->pack(-side => "top");
my $button23 = $mw->Button(-text => "X6108235",
                          -command => sub {print OUTFILE "X6108235 08\
+n"})->pack(-side => "top");
my $button25 = $mw->Button(-text => "D8815235",
                          -command => sub {print OUTFILE "D8815235 15\
+n"})->pack(-side => "top");
my $button26 = $mw->Button(-text => "M1915235",
                          -command => sub {print OUTFILE "M1915235 15\
+n"})->pack(-side => "top");
my $button27 = $mw->Button(-text => "M9015235",
                          -command => sub {print OUTFILE "M9015235 15\
+n"})->pack(-side => "top");
my $button28 = $mw->Button(-text => "M9115235",
                          -command => sub {print OUTFILE "M9115235 15\
+n"})->pack(-side => "top");
my $button29 = $mw->Button(-text => "WR115235",
                          -command => sub {print OUTFILE "WR115235 15\
+nWR415235 15\n"})->pack(-side => "top");
$mw->Button(-text => "Exit", -command => sub{$mw->destroy})->pack();



MainLoop;

[download]

Replies are listed 'Best First'.
Re: Change button color with Tk
by roboticus (Chancellor) on Oct 31, 2017 at 19:29 UTC

    PerlCowboy:

    I think it's because you need to change:

    my $button1 = $mw->Button(-text => "18-Letters",
                          -command => sub {print OUTFILE "18L\n", back
+ground => "yellow"})->pack(-side =>"top");

    [download]

    to this:

    my $button1 = $mw->Button(-text => "18-Letters",
                          -command => sub {print OUTFILE "18L\n" },
                          -background => "yellow"})->pack(-side =>"top
+");

    [download]

    I don't use Tk or Tkx, but it seems to me that:

    sub { print OUTFILE "18L\n", background => "yellow" }

    [download]

    Can't possibly do what you're expecting. The print statement doesn't know anything about colors. In fact, the code is essentially equal to:

    sub { print OUTFILE "18L\n", "background", "yellow" }

    [download]

    So if you look at the file you're printing to, I'd expect you'll see some unexpected "backgroundyellow" strings in there.

    ...roboticus

    When your only tool is a hammer, all problems look like your thumb.

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      This got me a little farther, but now I need to call the subroutine when the button is clicked. 
      my $button1 = $mw->Button(-text => "18-Letters",
                   -command => sub {print OUTFILE "18L\n",\&onclick,}
                          ,)
                          ->pack(-side => "top");
sub onclick{
   $button1->configure(-background=>"yellow")
}

      [download]
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Re: Change button color with Tk
by kcott (Archbishop) on Nov 01, 2017 at 06:30 UTC

    G'day PerlCowboy,

    All (I can't think of any exceptions off the top of my head) Tk widget options start with a "-". See your first post here for a plethora of examples.

    All widget documentation is laid out in much the same manner. Looking at Tk::Button, you'll see Standard Options followed by Widget-Specific Options.

    The Standard Options are just a list. Their details can be found in Tk::options. At the start of that page, you'll find the cget() and configure() methods: these are what you use to query and change options (both Standard and Widget-Specific ones).

    It's unclear precisely what you want to do. If you just want to change the default background colour for your GUI when it's first presented, then ++roboticus is quite correct, you don't include them in a sub; instead, you'll want code like this: 

    $parent->Button(
    -text => '...',
    -background => '...',
    -command => ...
)

    [download]

    If, however, you want a colour to change in response to an event (e.g. a button press), then you will want code in a sub, but using the configure() method I indicated above.

    — Ken

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      I have some working code now, but my buttons are each a unique name. They are $button1 through $button28. Here's the code that works and the sub for the first button: 
      my $button1 = $mw->Button(-text => "18-Letters",
                          -command => sub {print OUTFILE "18L\n"},
                          -command => \&change)->pack(-side => "top");
sub change {
 $button1->configure(-background=>"yellow")
}

      [download]
      Aside from coding a sub for each button, could I use a if then to configure for an array? The goal is to change the color of the button once it is pressed. 
       
my @btn = $button1-$button28;

      [download]
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        Hello PerlCowboy,

        you can use a brutal method like storing all buttons into an hash:

        my $mw = MainWindow->new;

my %buttons;

for (1..9){
           $buttons{$_} = $mw->Button(-text=>"Button $_",-command=>[\&
+colorize,$_])->pack;
}

MainLoop;

sub colorize{
             $buttons{$_[0]}->configure(-bg=>'yellow');
             print $buttons{$_[0]}->cget('-text')," button is yellow n
+ow\n";
}

        [download]

        Or you can use Canvas tagging facility to select the current one

        L*

        There are no rules, there are no thumbs..
        Reinvent the wheel, then learn The Wheel; may be one day you reinvent one of THE WHEELS.
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