Simple front end using Perl/Tk

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Introduction

This article shows how to use Perl to write a simple graphical user interface.

Installation

Install the latest version of Perl and Tk from the ActiveState download page.

Using the code

We begin by declaring the MainWindow object and configuring the object properties.

# Create the main window
my $x_win = MainWindow->new();
$x_win->configure(-title=>'Test');
$x_win->geometry('+200+100');

The application is divided into four frames: one on the top (personInfo), one in the middle (midFrame), and two at the bottom for "Load and Save Data" buttons. personInfo is divided into a left frame for labels and right frame for fields.

my $personInfo = $x_win->Frame(-background=>'cyan')->pack(-side=>'top',
                   -fill=>'x');
my $personLeft = $personInfo->Frame(-background=>'cyan')->pack(-side=>'left',
                   -fill=>'x');
my $personRight = $personInfo->Frame(-background=>'cyan')->pack(-side=>'left',
                   -fill=>'x',-padx=>20,-pady=>20);

# Labels
$personLeft->Label(-text=>'Personal Information',-background=>'cyan')->pack();
$personLeft->Label(-text=>'',-background=>'cyan')->pack();
$personLeft->Label(-text=>'Name',-background=>'cyan')->pack();
$personLeft->Label(-text=>'Age',-background=>'cyan')->pack();
$personLeft->Label(-text=>'Address',-background=>'cyan')->pack();
$personLeft->Label(-text=>'Occupation',-background=>'cyan')->pack();

Variables are bound to the labels in the midFrame frame. This implies that when the state of the label control changes, the variable is updated to reflect the new state and vice-versa.

# Fields
$personRight->Label(-text=>'',-background=>'cyan')->pack();
$personRight->Label(-text=>'',-background=>'cyan')->pack();
$personRight->Entry(-background=>'green',-width=>20,-borderwidth=>2,
    -relief=>'sunken',-textvariable=>\$perInfo->{NAME})->pack();
$personRight->Entry(-background=>'green',-width=>20,-borderwidth=>2,
    -relief=>'sunken',-textvariable=>\$perInfo->{AGE})->pack();
$personRight->Entry(-background=>'green',-width=>20,-borderwidth=>2,
    -relief=>'sunken',-textvariable=>\$perInfo->{ADDR})->pack();
$personRight->Entry(-background=>'green',-width=>20,-borderwidth=>2,
    -relief=>'sunken',-textvariable=>\$perInfo->{OCCUPATION})->pack();

midFrame is used to put some sort of separator between the "Personal Information" and the "Load and Save Data" buttons.

# Separator Bar
my $midFrame = $x_win->Frame(-borderwidth=>3,-relief=>'groove',
                             -background=>'purple',
)->pack(-side=>'top');
$midFrame->Label(width=>100,height=>0,-foreground=>'white',
-background=>'purple')->pack();

# Process frame
my $saveFrame = $x_win->Frame(-background=>'cyan')->pack(-side=>'top',
                              -fill=>'x');
$saveFrame->Button(-text => 'Save Data',-command => \&saveinfo,
              )->grid(qw/-row 2 -column 0 -sticky nesw/);

# Process frame
my $loadFrame = $x_win->Frame(-background=>'cyan')->pack(-side=>'top',
                              -fill=>'x');
$loadFrame->Button(-text => 'Load Data',-command => \&loadinfo,
              )->grid(qw/-row 2 -column 0 -sticky nesw/);

MainLoop() signals the end of TK widgets building, and the code that follows will be subroutines. saveInfo dumps the state of perInfo hash, loadInfo does the opposite. Note that perInfo is bound to the controls in the personRight frame.

MainLoop();

sub saveinfo
{
    open(OUT,">test.txt");
    print OUT "Name" . "=" . $perInfo->{NAME} . "<br>\n";
    print OUT "Age" .  "=" . $perInfo->{AGE} . "<br>\n";
    print OUT "Address" .  "=" . $perInfo->{ADDR} . "<br>\n";
    print OUT "Occupation:" . "=" . $perInfo->{OCCUPATION} . "<br>\n";
    close(OUT);

    $file = $x_win->getSaveFile(-filetypes => \@types);
    open(OUT,">$file");
    #print OUT "Content-type:text/html\n\n";
    print OUT $perInfo->{NAME} . "\n";
    print OUT $perInfo->{AGE} . "\n";
    print OUT $perInfo->{ADDR} . "\n";
    print OUT $perInfo->{OCCUPATION} . "\n";
    close(OUT);
}

sub loadinfo
{
    my $file;
    
    # Types are listed in the dialog widget
    my @types = (["Config Files", '.txt', 'TEXT'],
               ["All Files", "*"] );

    $file = $x_win->getOpenFile(-filetypes => \@types);

    open IN,$file;
    my @tfile = <IN>;
    chop @tfile;
    close (IN);

    $perInfo->{NAME} = $tfile[0];
    $perInfo->{AGE} = $tfile[1];
    $perInfo->{ADDR} = $tfile[2];
    $perInfo->{OCCUPATION} = $tfile[3];
}

This article introduced the basics of installing the Perl interpreter and writing a visual application using the Tk. I encourage you to explore further on the web as well as try out simple programs.

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