Image::Magick::Iterator - sequentially read Image::Magick object from a filehandle.
use strict;
use Image::Magick::Iterator;
my $iter = Image::Magick::Iterator->new();
#assume PPM stream is coming from STDIN;
$iter->handle(\*STDIN);
#explicitly set format to PPM, there is no auto-detection built in
$iter->format('PPM');
while(my $image = $iter->next){
print $image->Get('height'),"\n"; #access height attribute of each
#Image::Magick object
}
Image::Magick::Iterator adds iteration support to Image::Magick. This means that if you have a stream of concatenated images, you can access each image in the stream as an independent Image::Magick object.
Iteration functionality is not present in Image::Magick itself as of version 5.56. Passing a stream of concatenated images would result in essentially a "stack" of images which would all be manipulated in parallel by any Image::Magick calls. Calls to Write() either output an animated series of image (a la animated GIFs), or the first image in the series.
Image::Magick::Iterator is extensible to support many different image filetypes. Currently only PPM support is implemented. See /SYNOPSIS for an example.
Currently only PPM images can be iterated. It's not difficult to add new image types though, and I'm receptive to new classes for handling more formats. To add another format:
1. Have a look at the source of Image::Magick::Iterator::PPM to get an idea of how to write a new format handling class. It is basically a class with one method, read_image, that when given a filehandle reference reads an image from it and passes back the raw data.
2. add a mapping to "_delegate()" that maps the desired value of "format()" to your image reading class.
Email the author.
Allen Day <allenday@ucla.edu>
Copyright (C) 2004 by Allen Day, allenday@ucla.edu
This library is released under GPL, the GNU General Public License
The rest of the documentation details each of the object methods. Internal methods are usually preceded with a '_'. Methods are in alphabetical order for the most part.
my $obj = new Image::Magick::Iterator();
Builds a new Image::Magick::Iterator object
an instance of Image::Magick::Iterator
None
$obj->init(%arg);
Internal method to initialize a new Image::Magick::Iterator object
true on success
Arguments passed to "new()"
$obj->format(); #get existing value $obj->format($newval); #set new value
stores a scalar value of the fileformat to be read from "handle()". currently supported formats are:
* PPM
value of format (a scalar)
(optional) on set, a scalar
$obj->handle(); #get existing value $obj->handle($newval); #set new value
stores a filehandle reference (eg \*STDIN, or an IO::Handle.
value of handle (a scalar)
(optional) on set, a scalar
$obj->next(); #get next Image::Magick from stream
reads an Image::Magick object from a filehandle.
a Image::Magick object, or undef if the filehandle is EOF or contains only a partial image.
none, read-only
