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Drawing with Perl/Tk


use Tk;

$mw = MainWindow->new(
    -title => "Draw",
);

$canvas = $mw->Canvas(
    -height     => 300,
    -width      => 400,
    -background => "white",
)->pack;

$canvas->createLine(0, 0, 100, 150,
    -fill  => "red",
    -width => 2,
);

MainLoop;
The above code creates a 300x400 white canvas and draws a red line of width 2 on it. The coordinate system is a little backwards - with (0, 0) at the upper left. This is what it looks like:
Let's add an oval behind the line. Changes are in green. 

use Tk;

$mw = MainWindow->new(
    -title => "Draw",
);

$canvas = $mw->Canvas(
    -height     => 300,
    -width      => 400,
    -background => "white",
)->pack;


$oval = $canvas->createOval(30, 50, 140, 180,
    -fill    => "#4510a3",        # RGB hex values
    -outline => "lightgreen",
    -width   => 5,
); 
$canvas->createLine(0, 0, 100, 150,
    -fill  => "red",
    -width => 2,
);

MainLoop;
As a final demonstration let's add a button that when pressed will cause the oval to move! 

use Tk;

$mw = MainWindow->new(
    -title => "Draw",
);

$canvas = $mw->Canvas(
    -height     => 300,
    -width      => 400,
    -background => "white",
)->pack;

$oval = $canvas->createOval(30, 50, 140, 180,
    -fill    => "#4510a3",
    -outline => "lightgreen",
    -width   => 5,
);
$canvas->createLine(0, 0, 100, 150,
    -fill  => "red",
    -width => 2,
);


$mw->Button(
    -text => "Move",
    -command => sub {
        $canvas->move($oval, 40, 80);
    },
)->pack;

MainLoop;
This is what the screen will look like after pressing the button:
Do you sense the possiblities? Play! Try it! The canvas widget is one of the most sophisticated of them all. Very useful for all kinds of things. And fun!

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