Re^2: Tk Buttons

[PilotinControl]

The question is right here: Why is it that when you press that button again it starts counting where it left off when it should be reset to 0 to start counting by 10s again. Thanks.

[Athanasius]

Hello PilotinControl,

In the snippet you’ve posted, I can’t see any code to count or reset a value. Please provide a minimal but complete example that reproduces the problem. See How do I post a question effectively? and the SSCCE.

Cheers,

[PilotinControl]

It has been figured out....I needed to add another Bind function in order to set the opposite button back to speed stop 0....otherwise when pressed again it would continue onto the next sub routine in line

[choroba]

That's weird. Why are you changing the binding? You should just change the speed. Here's how I understood your description:

#!/usr/bin/perl
use warnings;
use strict;

use Tk;

{   my $speed = 0;

    sub change_speed {
        my $diff  = shift;
        my $state = $speed <=> 0;
        if (! $state || $state == ($diff <=> 0)) {
            $speed += $diff if abs($speed + $diff) <= 100;
        } else {
            $speed = 0;
        }
    }

    sub create_label {
        my $parent = shift;
        return $parent->Label(-textvariable => \$speed,
                              -relief       => 'sunken',
                             )->pack(-ipadx => 5)
    }
}

my $mw = 'MainWindow'->new(-title => 'Motor');
my $mf = $mw->Frame->pack;

$mf->Label(-text => 'Tk Motor Controller')->pack;

my $l  = create_label($mf);

my $bf = $mf->Frame->pack;
$bf->Button(-text    => '<',
            -command => [ \&change_speed, -10 ],
           )->pack(-side => 'left');
$bf->Button(-text => '>',
            -command => [ \&change_speed, 10 ],
           )->pack(-side => 'right');

my $qb = $mf->Button(-text      => 'Quit',
                     -underline => 0,
                     -command   => sub { Tk::exit() },
                    )->pack( -pady => 10);
$mw->bind('<Alt-q>', sub { $qb->invoke });


MainLoop();

Update: Used closure over the $speed variable.

[PilotinControl]

And to further explain, the buttons, when pressed control the speed and direction of a motor connected to the laptop via a usb cable using the Win32::SerialPort module....that part works. What is happening when the direction button is pressed it gets faster in the forward direction and when pressed again it gets faster and faster...and when the reverse button is pressed the motor stops and proceeds to going in the reverse direction and each time that button is pressed it gets faster and faster....here is what is happening....if the forward button is pressed again....instead of starting at speed 0....it picks up where the last forward button press left off...lets say it stopped at 40 when we first pressed the reverse button....when the forward button is pressed again it goes to speed 50 instead of starting back at zero....same holds true if the reverse button was pressed again.

[fishmonger]

The info regarding the controlling of the motor and use of Win32::SerialPort is completely irrelevant to the problem you're asking about.

As has already been mentioned, your posted code does not include anything that would change/rest the value. I will repeat the request that Athanasius made. Please post a short but complete script that demonstrates the problem you're having with the setting/resetting of the values so that we can run some tests. With that info we should be able to point out problem and solution. It would also be helpful if you would use proper code formatting so that your code is more readable.