Gimp::Fu - ``easy to use'' framework for Gimp scripts
SYNOPSIS
use Gimp;
use Gimp::Fu;
(this module uses Gtk, so make sure it's correctly installed)
DESCRIPTION
Currently, there are only three functions in this module. This
fully suffices to provide a professional interface and the
ability to run this script from within the Gimp and standalone
from the commandline.
(This distribution comes with example scripts. One is
"examples/example-fu.pl", which is small Gimp::Fu-script you can take as
starting point for your experiments)
THE REGISTER FUNCTION
register
"function_name",
"blurb", "help",
"author", "copyright",
"date",
"menu path",
"image types",
[
[PF_TYPE,name,desc,optional-default,optional-extra-args],
[PF_TYPE,name,desc,optional-default,optional-extra-args],
# etc...
],
[
# like above, but for return values (optional)
],
['feature1', 'feature2'...], # optionally check for features
sub { code };
function name
The pdb name of the function, i.e. the name under which is will be
registered in the Gimp database. If it doesn't start with ``perl_fu_'',
``file_'', ``plug_in_'' or ``extension_'', it will be prepended. If you
don't want this, prefix your function name with a single ``+''. The idea
here is that every Gimp::Fu plug-in will be found under the common
"perl_fu_"-prefix.
blurb
A small description of this script/plug-in. Defaults to ``=pod(NAME)'' (see
the section on EMBEDDED POD DOCUMENTATION for an explanation of this
string).
help
A help text describing this script. Should be longer and more verbose than
"blurb". Default is ``=pod(HELP)''.
author
The name (and also the e-mail address if possible!) of the
script-author. Default is ``=pod(AUTHOR)''.
copyright
The copyright designation for this script. Important! Safe your intellectual
rights! The default is ``=pod(AUTHOR)''.
date
The ``last modified'' time of this script. There is no strict syntax here, but
I recommend ISO format (yyyymmdd or yyyy-mm-dd). Default value is ``=pod(DATE)''.
menu path
The menu entry Gimp should create. It should start either with <Image>, if
you want an entry in the image menu (the one that opens when clicking into
an image), <Xtns>, for the Xtns menu or <None> for none.
image types
The types of images your script will accept. Examples are ``RGB'', ``RGB*'',
``GRAY, RGB'' etc... Most scripts will want to use ``*'', meaning ``any type''.
the parameter array
An array ref containing parameter definitions. These are similar to the
parameter definitions used for "gimp_install_procedure", but include an
additional default value used when the caller doesn't supply one, and
optional extra arguments describing some types like "PF_SLIDER".
Each array element has the form "[type, name, description, default_value, extra_args]".
<Image>-type plugins get two additional parameters, image ("PF_IMAGE") and
drawable ("PF_DRAWABLE"). Do not specify these yourself. Also, the
"run_mode" argument is never given to the script, but its value canm be
accessed in the package-global $run_mode. The name is used in the
dialog box as a hint, the description will be used as a tooltip.
See the section PARAMETER TYPES for the supported types.
the return values
This is just like the parameter array, just that it describes the return
values. Of course, default values and the enhanced Gimp::Fu parameter
types don't make much sense here. (Even if they did, it's not implemented
anyway..). This argument is optional.
If you supply a parameter type (e.g. "PF_IMAGE") instead of a full
specification ("[PF_IMAGE, ...]"), Gimp::Fu might supply some default
values. This is only implemented for "PF_IMAGE" at the moment.
the features requirements
See Gimp::Features for a description of which features can be checked
for. This argument is optional (but remember to specify an empty return
value array, "[]", if you want to specify it).
the code
This is either a anonymous sub declaration ("sub { your code here; }", or a
coderef, which is called when the script is run. Arguments (including the
image and drawable for <Image> plug-ins) are supplied automatically.
It is good practise to return an image, if the script creates one, or
"undef", since the return value is interpreted by Gimp::Fu (like displaying
the image or writing it to disk). If your script creates multiple pictures,
return an array.
Are all mapped to a string entry, since perl doesn't really distinguish
between all these datatypes. The reason they exist is to help other scripts
(possibly written in other languages! really!). It's nice to be able to
specify a float as 13.45 instead of ``13.45'' in C! "PF_VALUE" is synonymous
to "PF_STRING", and <PF_INT> is synonymous to <PF_INT32>.
PF_COLOR, PF_COLOUR
Will accept a colour argument. In dialogs, a colour preview will be created
which will open a colour selection box when clicked.
PF_IMAGE
A gimp image.
PF_DRAWABLE
A gimp drawable (image, channel or layer).
PF_TOGGLE, PF_BOOL
A boolean value (anything perl would accept as true or false). The description
will be used for the toggle-button label!
PF_SLIDER
Uses a horizontal scale. To set the range and stepsize, append an array ref
(see Gtk::Adjustment for an explanation) "[range_min, range_max, step_size,
page_increment, page_size]" as ``extra argument'' to the description array.
Default values will be substitued for missing entries, like in:
The same as PF_SLIDER, except that this one uses a spinbutton instead of a scale.
PF_RADIO
In addition to a default value, an extra argument describing the various
options must be provided. That extra argument must be a reference
to an array filled with "Option-Name =" Option-Value> pairs. Gimp::Fu
will then generate a horizontal frame with radio buttons, one for each
alternative. For example:
[PF_RADIO, "direction", "the direction to move to", 5, [Left => 5, Right => 7]]]
draws two buttons, when the first (the default, ``Left'') is activated, 5
will be returned. If the second is activated, 7 is returned.
PF_FONT
Lets the user select a font and returns a X Logical Font Descriptor (XLFD).
The default argument, if specified, must be a full XLFD specification, or a
warning will be printed. Please note that the gimp text functions using
these fontnames (gimp_text_..._fontname) ignore the size. You can extract
the size and dimension by using the "xlfd_size" function.
In older Gimp-Versions a user-supplied string is returned.
PF_BRUSH, PF_PATTERN, PF_GRADIENT
Lets the user select a brush/pattern/gradient whose name is returned as a
string. The default brush/pattern/gradient-name can be preset.
PF_CUSTOM
PF_CUSTOM is for those of you requiring some non-standard-widget. You have
to supply a code reference returning three values as the extra argument:
(widget, settor, gettor)
"widget" is Gtk widget that should be used.
"settor" is a function that takes a single argument, the new value for
the widget (the widget should be updated accordingly).
"gettor" is a function that should return the current value of the widget.
While the values can be of any type (as long as it fits into a scalar),
you should be prepared to get a string when the script is started from the
commandline or via the PDB.
PF_FILE
This represents a file system object. It usually is a file, but can be
anything (directory, link). It might not even exist at all.
PF_TEXT
Similar to PF_STRING, but the entry widget is much larger and has Load and
Save buttons.
EMBEDDED POD DOCUMENTATION
The register functions expects strings (actually scalars) for
documentation, and nobody wants to embed long parts of documentation into
a string, cluttering the whole script.
Therefore, Gimp::Fu utilizes the Gimp::Pod module to display the full text
of the pod sections that are embedded in your scripts (see perlpod for
an explanation of the POD documentation format) when the user hits the
``Help'' button in the dialog box.
Since version 1.094, you can embed specific sections or the full pod
text into any of the blurb, help, author, copyright and date arguments
to the register functions. Gimp::Fu will look into all these strings
for sequences of the form ``=pod(section-name)''. If found, they will
be replaced by the text of the corresponding section from the pod
documentation. If the named section is not found (or is empty, as in
``=pod()''), the full pod documentation is embedded.
Most of the mentioned arguments have default values (see THE REGISTER
FUNCTION) that are used when the arguments are either undefined or empty
strings, making the register call itself much shorter and, IMHO, more
readable.
MISC. FUNCTIONS
save_image(img,options_and_path)
This is the internal function used to save images. As it does more than just
gimp_file_save, I thought it would be handy in other circumstances as well.
The "img" is the image you want to save (which might get changed during
the operation!), "options_and_path" denotes the filename and optinal
options. If there are no options, "save_image" tries to deduce the filetype
from the extension. The syntax for options is
[IMAGETYPE[OPTIONS...]:]filespec
IMAGETYPE is one of GIF, JPG, JPEG, PNM or PNG, options include
options valid for all images
+F flatten the image (default depends on the image)
-F do not flatten the image
options for GIF and PNG images
+I do save as interlaced (GIF only)
-I do not save as interlaced (default)
options for GIF animations (use with -F)
+L save as looping animation
-L save as non-looping animation (default)
-Dn default frame delay (default is 0)
-Pn frame disposal method: 0=don't care, 1 = combine, 2 = replace
options for PNG images
-Cn use compression level n
-E Do not skip ancillary chunks (default)
+E Skip ancillary chunks
options for JPEG images
-Qn use quality "n" to save file (JPEG only)
-S do not smooth (default)
+S smooth before saving
some examples:
test.jpg save the image as a simple jpeg
JPG:test.jpg same
JPG-Q70:test.jpg the same but force a quality of 70
GIF-I-F:test.jpg save a gif image(!) named test.jpg
non-inerlaced and without flattening