Tk::Gauge Module Borked?

[beretboy]

The Tk::Gauge module generates all manner of gee-whiz analog graphs. Sadly, as far as I can tell, this is all it's doing at the moment. Repeated attemps to have it draw a needle on said graphs have failed. Having run several of the example scripts to no avail, I asked monks on the CB and bart confirmed my results.

What I've found is that if I try to graph my own needle, using Tk::Canvas (of which Tk::Gauge is a MegaWidget) methods, the line is drawn "behind" the Gauge. I expect this is what's happening to the lines the module draws as well.

So the question is, how do I bring lines I draw to the foreground, and is the Tk::Gauge module really broken?

Example code can be found in the link above, and below I will include my code that draws a line "behind" the gauge (based on the thermometer example).

#!/usr/local/bin/perl -w
use Tk;
use Tk::Gauge;
use strict;
use warnings;

my $mw = MainWindow->new;

our($temperature);

my $thermo = $mw->Gauge(
    -from                 => -20,
    -to                   => 40,
    -huboutline           => 'red',
    -majorticklabelskip   => [-20,40],
    -minortickinterval    => 5,
    -finetickinterval     => 1,
    -style                 => 'pieslice',
    -margin            => 20,
    -bandwidth           => 5,
    -bands           => [
                {
                   -minimum  => -20,
                   -maximum  => -5,
                   -arccolor => '#aa00aa',
                },
                {
                   -minimum  => -5,
                   -maximum  =>  5,
                   -arccolor => '#0000ff',
                },
                {
                   -minimum  =>  5,
                   -maximum  => 15,
                   -arccolor => '#00ff00',
                },
                {
                   -minimum  => 15,
                   -maximum  => 25,
                   -arccolor => '#ffff00',
                },
                {
                   -minimum  => 25,
                   -maximum  => 35,
                   -arccolor => '#ff8800',
                },
                {
                   -minimum  => 35,
                   -maximum  => 40,
                   -arccolor => '#ff0000',
                },
                  ],
     -needles              =>[
                      {
                  -arrowshape => [0,0,0],
                          -radius     => 60,
                          -variable   => \$temperature,
                  -color      => 'black',
                  -width      => 2,
                  -showvalue  => 1,
                  -format     => '%.1f C',
                      },
                 ],
)->pack;

$mw->after( 1000, sub{ $temperature = 18.2 } );

$thermo->createLine(0,0,200,200, -width => 5); # Line should go right 
+across gauge!

MainLoop;

[zentara]

I don't know what exactly your problem is with Tk::Gauge, but does it have anything to do with

 Failed to AUTOLOAD 'Tk::Gauge::traceVdelete'

If so, there is something in the source about that, a supplied diff file must be applied to Trace.pm, and it states it will be included in the next Tk release. Without the patch, the lines won't move.

As far as your question about raising the line, it is usually done with tags like

$thermo->createLine(0,0,200,200,
                     -width => 5,
                     -tags => ['topline'],
                     ); # Line should go right across gauge! 


$thermo->raise('topline','gauge');
#where 'gauge' is supposed to be an advertised tag , but
# it dosn't seem to work.

So I guess I have to agree with you, the module is not ready for widespread use yet.

[Anonymous Monk]

Oh, for some examples see:

http://www.lehigh.edu/~sol0/ptk/my-tk-apps.html

janitored by ybiC: Linkified URL

[beretboy]

Thank you Mr. Lidie! (The above anonymous monk is the author of the module, who I emailed earlier)

[beretboy]

Yeah, I've been trying:

$thermo->raise('needle', 'gauge');

Both of which are advertised tags, neither of which work! Also, why doesn't this work?

$thermo->raise('needle', 'all');

[Anonymous Monk]

Apply the Tk::Trace patch supplied in the Tk::Gauge package - needles will then work!

S. Lidie

janitored by ybiC: Linkified CPAN module name

[zentara]

Hi again, I was trying to figure out why the needles didn't show up in the Tk::Gauge examples, (and your code above). Anyways, it seems that Tk::Trace needs to be pre-loaded into Tk, before you load Tk. This is shown, but poorly described in the perldoc for Tk::Trace. Also see Simple Tk Gauge.

Anyways, change the top of your script to this, and see the needle appear( on linux anyways).

#!/usr/local/bin/perl -w
package Tk;
use Tk::Trace;

package main;
use Tk;
use Tk::Gauge;
use strict;
use warnings;
......
.......