How to Add a Download Progress Bar to WWW::Mechanize in Perl

# Fetch the URL ($u) and specify a callback function to handle the content as it downloads in chunks

$m->get($u, ":content_cb" => \&callback);

# Open a new file to save the downloaded video (e.g., an FLV file). 

# If the file cannot be opened, the script will terminate (die) and print the error message ($!).

open (VID,">$i.flv") or die "$!";

# Initialize a variable to track the total number of bytes downloaded so far

$total = 0;

# Define the callback subroutine that is triggered for each chunk of data received

sub callback

{

    # Extract the arguments passed to the callback:

    # $data - the current chunk of data downloaded

    # $response - the HTTP::Response object

    # $proto - the LWP::Protocol object

    my( $data, $response, $proto ) = @_;

    

    # Write the current chunk of data to the opened file

    print VID "$data"; 

    

    # Add the length (in bytes) of the current chunk to the running total

    $total += length($data);

    

    # Retrieve the total expected size of the file from the HTTP response headers

    $size = $response->header('Content-Length');

    

    # Calculate the percentage of the file downloaded so far, round it down (floor), and print it

    print floor(($total/$size)*100), "% downloaded\n"; 

}