gimp/plug-ins/perl/Gimp/OO.pod

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=head1 NAME
Gimp::OO - Pseudo-OO for Gimp functions.
=head1 SYNOPSIS
use Gimp; # Gimp::OO is now part of Gimp.
=head1 DESCRIPTION
As you might have noticed, you can sort most gimp functions fall into three
groups, depending on the name-prefix: C<gimp_>, C<plug_in_>, C<extension_>
etc..
Whats more, there are functions groups like C<gimp_image_> or
C<gimp_selection_>, operating on a common object, B<Images> and B<Selection>
in this case.
If you only had the plain syntax, your scripts would quickly aquire
the "vertical gimp syndrome":
gimp_palette_set_foreground(...)
gimp_layer_new(...)
gimp_palette_set_background(...)
gimp_image_add_layer(...)
etc. Of course, your fingers will suffer from severe injuries as well.
A solution to this situation is to use OO-syntax. Gimp plays some (very)
dirty tricks and provides a number of classes, like C<Gimp::Image> and
C<Gimp::Palette> that allow shorter identifiers to be used (all these appear
with the C<Gimp::> prefix as well as without, i.e. C<Gimp::Palette> is the
same class as C<Palette>).
If you call a method, C<Gimp> tries to find a gimp function by
prepending a number of prefixes until it finds a valid function:
$image = Gimp->image_new(...); # calls gimp_image_new(...)
$image = Image->new(...); # calls gimp_image_new as well
$image = new Image(...); # the same in green
Palette->set_foreground(...) # calls gimp_palette_set_foreground(..)
Return values from functions are automatically blessed (through
The Magic Autobless feature ;) to their corresponding classes, i.e.
$image = new Image(...); # $image is now blessed to Gimp::Image
$image->height; # calls gimp_image_height($image)
$image->flatten; # likewise gimp_flatten($image)
$image->histogram(...); # calls gimp_histogram($image,...), since
# gimp_image_histogram does not exist
The class argument (C<$image> in the above examples) is prepended to the
argument list.
Another shortcut: many functions want a (redundant) image argument, like
$image->shear ($layer, ...)
Since all you want is to shear the C<$layer>, not the C<$image>, this is
confusing as well. In cases like this, Gimp allows you to write:
$layer->shear (...)
And automatically infers the additional IMAGE-type argument.
As the (currently) last goodie, if the first argument is of type INT32, its
name is "run_mode" and there are no other ambiguties, you can omit it, i.e.
these three calls are equivalent:
plug_in_gauss_rle (RUN_NONINTERACTIVE, $image, $layer, 8, 1, 1);
plug_in_gauss_rle ($image, $layer, 8, 1, 1);
plug_in_gauss_rle ($layer, 8, 1, 1);
You can call all sorts of sensible and not-so-sensible functions,
so this feature can be abused:
patterns_list Image; # will call gimp_patterns_list
quit Plugin; # will quit the Gimp, not an Plugin.
there is no image involved here whatsoever...
=head1 AVAILABLE CLASSES
The following classes (with and without Gimp::) are available. The prefixes
that are checked are shown as well (the null prefix "" is implicit).
=over 4
=item Gimp (there is no Gimp::Gimp, only Gimp::)
gimp_
=item Layer
gimp_layer_
gimp_drawable_
gimp_floating_sel_
gimp_image_
gimp_
plug_in_
perl_fu_
=item Image
gimp_image_
gimp_drawable_
gimp_
plug_in_
perl_fu_
=item Drawable
gimp_drawable_
gimp_layer_
gimp_image_
gimp_
plug_in_
perl_fu_
=item Selection
gimp_selection_
=item Channel
gimp_channel_
gimp_drawable_
gimp_selection_
gimp_image_
gimp_
plug_in_
perl_fu_
=item Display
gimp_display_
gimp_
=item Palette
gimp_palette_
=item Plugin
plug_in_
=item Gradients
gimp_gradients_
=item Edit
gimp_edit_
=item Progress
gimp_progress_
=item Region
(none except the implicit null prefix)
=item Tile
gimp_tile_
=item PixelRgn
gimp_pixel_rgn_
=item GDrawable
gimp_gdrawable_
=item Brushes
gimp_brushes_
=item Patterns
gimp_patterns_
=back
=head1 AUTHOR
Marc Lehmann <pcg@goof.com>
=head1 SEE ALSO
perl(1), L<Gimp>.