Lee ♫ Goddard

NAME

CGI::ProgressBar - CGI.pm sub-class with a progress bar object

SYNOPSIS

        use lib '..';

        use CGI::ProgressBar qw/:standard/;
        $| = 1; # Do not buffer output

        my $steps = 10;

        print header,
                start_html('A Simple Example'),
                h1('A Simple Example'),
                p('This example will fill the screen with nonsense between updates to a progress bar.'),
                progress_bar( -from=>1, -to=>$steps, -blocks=>$steps );

        for (1..$steps){
                print update_progress_bar;
                # Simulate being busy/sleep 2;
                print rand>0.5 ? chr 47 : chr 92 for 0 .. 100000;
        }
        print hide_progress_bar;
        print p('All done.');
        print end_html;
        exit;

DESCRIPTION

This module provides a progress bar for web browsers.

It aims to require that the recipient client have a minimum of JavaScript 1.0, HTML 4.0, ancd CSS/1, but this has yet to be tested.

All feedback would be most welcome. Address at the end of the POD.

DEPENDENCIES

        CGI

EXPORT

        progress_bar
        update_progress_bar
        hide_progress_bar

USE

The module sub-classes CGI.pm, providing three additional methods (or functions, depending on your taste), each of which are detailed below.

Simply replace your "use CGI qw//;" with "use CGI::ProgressBar qw//;".

Treat each new function as any other CGI.pm HTML-producing routine with the exception that the arguments should be supplied as in OOP form. In other words, the following are all the same:

        my $html = $query->progress_bar;
        my $html = progress_bar;
        my $html = progress_bar(from=>1, to=>10);
        my $html = $query->progress_bar(from=>1, to=>10);
        my $html = $query->progress_bar(-to=>10);

This will probably change if someone would like it to.

FUNCTIONS/METHODS

FUNCTION/METHOD progress_bar

Returns mark-up that instantiates a progress bar. Currently that is HTML and JS, but perhaps the JS ought to go into the head.

The progress bar itself is an object in this class, stored in the calling (CGI) object - specifically in the field progress_bar, which we create as an array.

from
to

Values which the progress bar spans. Defaults: 0, 100.

blocks

The number of blocks to appear in the progress bar. Default: 100. You probably want to link this to from and to.

width
height

The width and height of the progress bar, in pixels. Cannot accept percentages (yet). Defaults: 400, 20.

gap

The amount of space between blocks, in pixels. Default: 1.

label

Supply this parameter with a true value to have a numerical display of progress.

layer_id

Most HTML elements on the page have id attributes. These can be accessed through the layer_id field, which is a hash with the follwoing keys relating to the id value:

form

The form which contains everything we display.

container

The div containing everything we display.

block

This value is used as a prefixed for the id of each block of the bar, with the suffix being a number incremented from 1.

number

The digits being updated as the bar progresses, if the option is enabled.

FUNCTION/METHOD update_progress_bar

Updates the progress bar.

FUNCTION/METHOD hide_progress_bar

Hides the progress bar.

CSS STYLE CLASS EMPLOYED

pblib_bar

A DIV containing the whole progress bar, including any accessories (such as the label). The only attribute used by this module is width, which is set dynamically. The rest is up to you. A good start is:

        padding:    2 px;
        border:     solid black 1px;
        text-align: center;
pblib_block

An individual block within the status bar. The following attributes are set dynamically: width, height, margin-right.

pblib_number

Formatting for the label text (part of which is actually an input type='text' element. border and text-align are used here, and the whole appears centred within a table.

BUGS, CAVEATS, TODO

One bar per page

This may change.

Parameter passing doesn't match CGI.pm

But it will in the next release if you ask me for it.

colors not implimented

I'd like to see here something like the Tk::ProgressBar::colors; not because I've ever used it, but because it might be cool.

Horizontal orientation only

You can get around this by adjusting the CSS, but you'd rather not. And even if you did, the use of -label might not look very nice. So the next version will support an -orientation option.

Inline CSS and JS

Because it's easiest for me. I suppose some kind of over-loading of the CGI::start_html would be possible, but then I'd have to check it, and maybe update it, every time CGI.pm was updated, which I don't fancy.

AUTHOR

Lee Goddard <lgoddard -at- cpan -dot- org>

Copyright (C) Lee Goddard, 2002-2003. All Rights Reserved. This software is made available under the same terms as Perl itself. You may use and redistribute this software under the same terms as Perl itself.

KEYWORDS

HTML, CGI, progress bar, widget

SEE ALSO

perl. CGI, Tk::ProgressBar,

MODIFICATIONS

25 March 2004

  • Updated the POD

3 POD Errors

The following errors were encountered while parsing the POD:

Around line 242:

'=item' outside of any '=over'

Around line 343:

You forgot a '=back' before '=head1'

Around line 378:

You forgot a '=back' before '=head1'