NAME

PBar.pm -- An AppleEvent Module for Progress Bar 1.0.1

DESCRIPTION

Progress Bar is a small AppleScriptable utility written by Gregory H. Dow. This module, PBar.pm, generates Apple Event calls using AEBuild in place of AppleScript. Because the Apple Event Manager is not involved, Progress Bar updates more quickly.

In most applications the time taken to up date the Progress Bar must be kept to a minimum. On this machine (68030 CPU) An AppleScript update to the progress bar takes about 0.72 seconds. Using PBar.pm the time is reduced to 0.10 seconds; a seven-fold improvement.

Progress Bar 1.0.1 is found by a search for the creator type PBar and launched automatically. To minimise the time taken for the search, Progress Bar 1.0.1 should be kept in the same volume as PBar.pm.

SYNOPSIS

        use Mac::AppleEvents
        use Mac::Processes
        use Mac::MoreFiles
        

Install "PBar.pm" in a folder named "Apps" in the "Mac" folder in MacPerl's library path.

TEST PROGRAM

The following script (ideally saved as a MacPerl droplet) shows 10 increments of the bar at 1 second intervals. The window is closed when the bar is full after a final five second pause.

        #!perl
        # Droplet "Run_PBar"

        use Mac::Apps::PBar;

        $bar = Mac::Apps::PBar->new('FTP DOWNLOAD', '100, 50');
        $bar->data(Cap1, 'file: BigFile.tar.gz');
        $bar->data(Cap2, 'size: 1,230K');
        $bar->data(MinV, '0');
        $bar->data(MaxV, '1230');
        for(0..10) {
                $n = $_*123;
                $bar->data(Valu, $n);
                sleep(1);
        }
        sleep(5);
        $bar->close_window;

CREATING A NEW PROGRESS BAR

Progress Bar 1.0.1 is launced and a new Progress bar created by:

         $bar = Mac::Apps::PBar->new('NAME', 'xpos, ypos');

where the arguments to the new constructor have the following meanings:

First argument:

is a string for the title bar of the Progress Bar window.

Second argument:

is a string 'xpos, ypos' defining the position of the top left-hand corner of the window in pixels. The pair of numbers and the comma should be enclosed in single quotes as shown.

SENDING DATA

Values are sent to the Progress Bar by the data sub-routine using the variable names in the aete resource for each of the Progress Bar properties. There are five property values for the PBar class. The syntax is:

        $bar->data('property', 'value')

Values, whether numeric or not, should be single quoted strings.

Minimum value 'MinV'

This is the value of the displayed parameter corresponding to the origin of the bar. Often it is zero, but may take other values (for instance a temperature bar in degrees Fahrenheit might start at 32).

Maximum value 'MaxV'

This is the value corresponding to the full extent of the bar. It can take any value, such as the size of a file in KB, or 100 for a percentage variable. Bar increments are integers, hence discrimination is finer the larger the value of MaxV.

Current value 'Valu'

This is the value which sets the progress bar to the position corresponding to the current value of the parameter displayed. The value must obviously lie somewhere between MinV and MaxV.

Upper caption 'Cap1'

This string, immediately under the title bar, can be set to anything appropriate for the application.

Lower caption 'Cap2'

The lower caption string can either be set to a constant value (e.g. File size = 1234K) or up-dated with the bar. For instance it might be appropriate to set 'Cap2' as follows:

        $n = $max_value - $current_value;
        $bar->data('Cap2', "remaining $n");

Note the double quotes so that the value of $n is interpolated.

It should be remembered however that it will take twice as long to update both Cap2 and Valu as just to update the bar Valu by itself. In applications where speed is of the essence, just the bar value Valu should be changed.

REFERENCES

The following documents, which are relevant to AEBuild, may be of interest:

AEGizmos_1.4.1

Written by Jens Peter Alfke this gives a description of AEBuild on which the MacPerl AEBuildAppleEvent is based. Available from:

        ftp://dev.apple.com/
        devworld/Tool_Chest/Interapplication_Communication/
        AE_Tools_/AEGizmos_1.4.1

aete.convert

A fascinating MacPerl script by David C. Schooley which extracts the aete resources from scriptable applications. It is an invaluable aid for the construction ofAEBuild events. Available from:

        ftp://ftp.ee.gatech.edu/
        pub/mac/Widgets/
        aete.converter_1.1.sea.hqx

AE_Tracker

This a small control panel which allows some or all AE Events to be tracked at various selectable levels of information. It is relatively difficult to decipher the output but AE_Tracker can be helpful. Available from:

        ftp://ftp.amug.org/
        pub/amug/bbs-in-a-box/files/system7/a/
        aetracker2.0.sit.hqx

Inside Macintosh

Chapter 6 "Resolving and Creating Object Specifier Records" . The summary can be obtained from:

        http://gemma.apple.com/
        dev/techsupport/insidemac/IAC/
        IAC-287.html

Progress Bar 1.0.1

Obtainable from Info-Mac archives as:

        info-mac/dev/osa/progress-bar-1.0.1.hqx

References are valid as at May 1997.

COPYRIGHT

Copyright (c) 1997 by Chris Nandor and Alan Fry. All rights reserved.

This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.

AUTHORS

Chris Nandor <pudge@pobox.com> is responsible for the AEBuild techniques, and particularly for evolving the AE object specifications. He wrote the first working script on which this module is largely based.

Alan Fry <ajf@afco.demon.co.uk> wrote the module and this documentation.

HISTORY

Version 1.0.0 15 May 1997

cpanm Mac::Apps::PBar

perl -MCPAN -e shell
install Mac::Apps::PBar