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

I'm trying to understand Tk's customization with optionAdd. I can get it to work on a global level, but not on a more specific level (without undesired side effects). The comments in the code below explain what I'm after and what I get: 
use warnings;
use strict;
use Tk;

my $mw = MainWindow->new();
$mw->geometry('200x200');

### Globally, I want the font to be this...
$mw->optionAdd('*font', 'helvr12');

### ...but I want my LabFrame's to be bold.
### This does not make the label for the frame bold, but
### oddly enough the print statement below returns 'helvb12'!
$mw->optionAdd('*LabFrame.font', 'helvb12');

### The line below will make the label for the frame bold, but
### it also changes its child (the Label), which I don't want.
#$mw->optionAdd('*LabFrame*font', 'helvb12');

my $lab_frm = $mw->LabFrame(-label => 'LabFrame Test')->pack;
$lab_frm->Label(-text => 'Label Test')->pack;

print STDERR $lab_frm->optionGet('font', ref $lab_frm), "\n";

MainLoop;

[download]
Questions:
  1. Why does the LabFrame report its font as 'helvb12' when it doesn't appear bold?
  2. How can I get the LabFrame to appear bold without changing its children?

Replies are listed 'Best First'.
Re: Tk and optionAdd's scope
by PeterPeiGuo (Hermit) on Apr 16, 2010 at 02:17 UTC

    Try to run the following and it proves that optionAdd does deliver the expected "scope":

    use warnings;
use strict;
use Tk;
use Tk::LabFrame;

my $mw = new MainWindow ( ) ;


$mw->optionAdd('*foo*font' => '-adobe-courier-plain-r-normal-*-30-*-*-
+*-*-*-*');
$mw->optionAdd('*bar*font' => '-adobe-courier-bold-r-normal-*-30-*-*-*
+-*-*-*');
$mw->optionAdd('*foo*foreground' => 'red');
$mw->optionAdd('*foo*background' => 'green');
$mw->optionAdd('*bar*foreground' => 'white');
$mw->optionAdd('*bar*background' => 'yellow');

my $frame = $mw->LabFrame(-label => 'Frame', Name => "foo")->pack;
$frame->Label ( -text => 'foo', Name => "bar")->pack(-padx=>5, -pady=>
+5) ;
MainLoop();

    [download]

    Peter (Guo) Pei

[reply]
[d/l]
      Peter,

      This works, but the reason I turned to optionAdd was to avoid extra code within the widgets (laziness). Luckily, I've only a few LabFrames, but say I had 25. I would have to add 25 lines of Name = ... rather than (what I had hoped) one line of $mw->optionAdd('the font of every LabFrame', 'the font');. I thought "LabFrame" was already an identifier in itself, but apparently not.

      Thanks.
[reply]
[d/l]
[select]

        optionAdd looks buggy, and I think you should just avoid it entirely. For example, it supposed to support -class, but apparently does not. If it supports -class as expected, you can simply put all 25 in the same class.

        Peter (Guo) Pei

[reply]
Re: Tk and optionAdd's scope
by Khen1950fx (Canon) on Apr 16, 2010 at 07:01 UTC
    Here's my stab at it:
    #!/usr/bin/perl

use strict;
use warnings;
use Tk;
require Tk::LabFrame;
require Tk::LabEntry;

my $mw = MainWindow->new;
$mw->geometry("150x80");
#$mw->optionAdd( "LabFrame.font", "helvb12" );

my $canvas_total = "Label Test";
my $le_t_text    = "LabFrame Test";
my $le           = $mw->LabEntry(
    -textvariable  => \$canvas_total,
    -labelVariable => \$le_t_text,
    -labelPack     => [ -anchor => "center" ]
);
$le->pack( -expand => 1, -fill => "y" );

#print STDERR $le->optionGet( "font", ref $le ), "\n";

MainLoop;

    [download]
    I used the labelpack example from the source as a starting point. Note that I commented out the optionAdd because it didn't make any difference. Also the print statement.
[reply]
[d/l]
      This works because LabFrames are bold by default. In my example I'm changing the default font at a global level: 
      $mw->optionAdd('*font', 'helvr12');

      [download]
      As a result the LabFrame's are no longer bold and I'm trying to revert them.
[reply]
[d/l]
        I understand. I went as far as I could without having to modify my own option database setup. You should probably try Tk::Xrm.
[reply]
Re: Tk and optionAdd's scope
by stefbv (Priest) on Apr 17, 2010 at 17:18 UTC
    I can get it to work on a global level, but not on a more specific level ...

    I believe that "optionAdd" is meant to be used only on a global level, for "more specific level" you have to use the widget options.

    Regards, Stefan

[reply]

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