Aaron Crane

NAME

Image::JPEG::Size - find the size of JPEG images

SYNOPSIS

    use Image::JPEG::Size;

    my $jpeg_sizer = Image::JPEG::Size->new;
    my ($width, $height) = $jpeg_sizer->file_dimensions($filename);

DESCRIPTION

This module uses libjpeg to rapidly determine the size of one or more JPEG images.

CONSTRUCTOR

First create an instance of the class:

    my $jpeg_sizer = Image::JPEG::Size->new;

The constructor initialises internal libjpeg structures; if that fails, an exception is thrown.

The constructor takes attributes as either a hash reference or a listified hash. Unknown attributes are ignored. The following attributes are understood:

error

Specifies the action to take on encountering a non-recoverable error in an image; see "ERROR HANDLING". Defaults to fatal.

warning

Specifies the action to take on encountering a recoverable error in an image; see "ERROR HANDLING". Defaults to warn.

METHODS

file_dimensions

You can repeatedly call file_dimensions in list context to find the width and height of your JPEG images:

    my ($width, $height) = $jpeg_sizer->file_dimensions($filename);

For now, the JPEG images must be supplied as a filename.

file_dimensions_hash

In some cases, you may prefer to get the image dimensions as a hash. The file_dimensions_hash takes a single filename argument, and returns a listified hash with keys width and height.

ERROR HANDLING

By default, recoverable errors in the image are reported using Perl's warning mechanism, and non-recoverable errors cause an exception to be thrown. However, this behaviour can be changed when creating an Image::JPEG::Size instance. The options are:

fatal

Throw an exception with information about the error, and stop processing this image immediately.

warn

Emit a Perl warning with information about the error. If the error is non-recoverable, image processing stops immediately, and its dimensions are reported as 0×0 pixels.

quiet

Suppress the error entirely. If the error is non-recoverable, image processing stops immediately, and its dimensions are reported as 0×0 pixels.

AUTHOR

Aaron Crane, <arc@cpan.org>

The initial development of this module was sponsored by Science Photo Library https://www.sciencephoto.com/.

COPYRIGHT

Copyright 2017 Aaron Crane.

LICENSE

This library is free software and may be distributed under the same terms as perl itself. See http://dev.perl.org/licenses/.