/ 
Image-Base-1.00
River stage two • 14 direct dependents • 16 total dependents
/ Image::Base

NAME

Image::Base - base class for loading, manipulating and saving images.

SYNOPSIS

This class should not be used directly. Known inheritors are Image::Xbm and Image::Xpm.

An example of the generalised functionality that this class could provide is the new_from_image() method (described later) which can be used to copy an image of one type to an image of another type.

If you want to create algorithms which manipulate 2D images in terms of (x,y,colour) then you could extend this class (without changing the file), like this:

# Filename: mylibrary.pl
package Image::Base ; # Switch to this class to build on it.

sub mytransform {
    my $self  = shift ;
    my $class = ref( $self ) || $self ;

    # Perform your transformation here; might be drawing a line or filling
    # a rectangle or whatever... getting/setting pixels using $self->xy().
}

package main ; # Switch back to the default package.

Now if you require mylibrary.pl after you've used Image::Xpm or any other Image::Base inheriting classes then all these classes will inherit your mytransform() method.

DESCRIPTION

new_from_image()

my $bitmap = Image::Xbm->new( -file => 'bitmap.xbm' ) ;
my $pixmap = $bitmap->new_from_image( 'Image::Xpm', -cpp => 1 ) ;
$pixmap->save( 'pixmap.xpm' ) ;

Note that the above will only work if you've installed Image::Xbm and Image::Xpm, but will work correctly for any image object that inherits from Image::Base and respects its API.

You can use this method to transform an image to another image of the same type but with some different characteristics, e.g.

my $p = Image::Xpm->new( -file => 'test1.xpm' ) ;
my $q = $p->new_from_image( ref $p, -cpp => 2, -file => 'test2.xpm' ) ;
$q->save ;

new()

Virtual - must be overridden.

Recommend that it at least supports -file (filename), -width and -height.

get()

my $width = $i->get( -width ) ;
my( $hotx, $hoty ) = $i->get( -hotx, -hoty ) ;

Get any of the object's attributes. Multiple attributes may be requested in a single call.

See xy get/set colours of the image itself.

set()

Virtual - must be overridden.

Set any of the object's attributes. Multiple attributes may be set in a single call; some attributes are read-only.

See xy get/set colours of the image itself.

xy()

Virtual - must be overridden. Expected to provide the following functionality:

$i->xy( 4, 11, '#123454' ) ;    # Set the colour at point 4,11
my $v = $i->xy( 9, 17 ) ;       # Get the colour at point 9,17

Get/set colours using x, y coordinates; coordinates start at 0.

When called to set the colour the value returned is class specific; when called to get the colour the value returned is the colour name, e.g. 'blue' or '#f0f0f0', etc, e.g.

$colour = xy( $x, $y ) ;  # e.g. #123456 
xy( $x, $y, $colour ) ;   # Return value is class specific

We don't normally pick up the return value when setting the colour.

load()

Virtual - must be overridden. Expected to provide the following functionality:

$i->load ;
$i->load( 'test.xpm' ) ;

Load the image whose name is given, or if none is given load the image whose name is in the -file attribute.

save()

Virtual - must be overridden. Expected to provide the following functionality:

$i->save ;
$i->save( 'test.xpm' ) ;

Save the image using the name given, or if none is given save the image using the name in the -file attribute. The image is saved in xpm format.

CHANGES

2000/05/04

Created.

AUTHOR

Mark Summerfield. I can be contacted as <summer@perlpress.com> - please include the word 'imagebase' in the subject line.

COPYRIGHT

Copyright (c) Mark Summerfield 2000. All Rights Reserved.

This module may be used/distributed/modified under the LGPL.