Image::Magick::Iterator - sequentially read Image::Magick object from a filehandle.

NAME

Image::Magick::Iterator - sequentially read Image::Magick object from a filehandle.

SYNOPSIS

  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
  }

DESCRIPTION

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.

SUPPORTED FORMATS

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.

FEEDBACK

Email the author.

AUTHOR

Allen Day <allenday@ucla.edu>

COPYRIGHT AND LICENSE

This library is released under GPL, the GNU General Public License

APPENDIX

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.

`new()`

Usage

  my $obj = new Image::Magick::Iterator();

Function

Builds a new Image::Magick::Iterator object

Returns

an instance of Image::Magick::Iterator

Arguments

None

`init()`

Usage

  $obj->init(%arg);

Function

Internal method to initialize a new Image::Magick::Iterator object

Returns

true on success

Arguments

Arguments passed to new()

`format()`

Usage

  $obj->format();        #get existing value

  $obj->format($newval); #set new value

Function

stores a scalar value of the fileformat to be read from handle(). currently supported formats are:

  * PPM

Returns

value of format (a scalar)

Arguments

(optional) on set, a scalar

`handle()`

Usage

  $obj->handle();        #get existing value

  $obj->handle($newval); #set new value

Function

stores a filehandle reference (eg \*STDIN, or an IO::Handle.

Returns

value of handle (a scalar)

Arguments

(optional) on set, a scalar

`next()`

Usage

  $obj->next(); #get next Image::Magick from stream

Function

reads an Image::Magick object from a filehandle.

Returns

a Image::Magick object, or undef if the filehandle is EOF or contains only a partial image.

Arguments

none, read-only

`_delegate()`

Usage

  $obj->_delegate($format);

Function

internal method, maps format names to class names

Returns

class to be delegated to for reading an image of the specified format

Arguments

name of an image format

Image::Magick::Iterator - sequentially read Image::Magick object from a filehandle.