NAME

   Plack::Middleware::Image::Scale - Resize jpeg and png images on the fly

VERSION

   version 0.011

SYNOPSIS

       ## example1.psgi
       use Plack::Builder;
       use Plack::Middleware::Image::Scale;
       my $app = sub { return [200,[],[]] };

       builder {
           enable 'ConditionalGET';
           enable 'Image::Scale';
           enable 'Static', path => qr{^/images/};
           $app;
       };

   A request to /images/foo_40x40.png will use
   images/foo.(png|jpg|gif|jpeg) as original, scale it to 40x40 px size
   and convert to PNG format.

       ## example2.psgi
       use Plack::Builder;
       use Plack::App::File;
       use Plack::Middleware::Image::Scale;
       my $app = sub { return [200,['Content-Type'=>'text/plain'],['hello']] };

       my $thumber = builder {
           enable 'ConditionalGET';
           enable 'Image::Scale',
               width => 200, height => 100,
               flags => { fill => 'ff00ff' };
           Plack::App::File->new( root => 'images' );
       };

       builder {
           mount '/thumbs' => $thumber;
           mount '/' => $app;
       };

   A request to /thumbs/foo.png will use images/foo.(png|jpg|gif|jpeg) as
   original, scale it small enough to fit 200x100 px size, fill extra
   borders (top/down or left/right, depending on the original image aspect
   ratio) with cyan background, and convert to PNG format. Also clipping
   is available, see "CONFIGURATION".

DESCRIPTION

   Scale and convert images to the requested format on the fly. By default
   the size and other scaling parameters are extracted from the request
   URI. Scaling is done with Image::Scale.

   The original image is not modified or even accessed directly by this
   module. The converted image is not cached, but the request can be
   validated (If-Modified-Since) against original image without doing the
   image processing. This middleware should be used together a cache
   proxy, that caches the converted images for all clients, and implements
   content validation.

   The response headers (like Last-Modified or ETag) are from the original
   image, but body is replaced with a PSGI content filter to do the image
   processing. The original image is fetched from next middleware layer or
   application with a normal PSGI request. You can use
   Plack::Middleware::Static, or Catalyst::Plugin::Static::Simple for
   example.

   See "CONFIGURATION" for various size/format specifications that can be
   used in the request URI, and "ATTRIBUTES" for common configuration
   options that you can use when constructing the middleware.

ATTRIBUTES

path

   Must be a RegexpRef, CodeRef, Str or Undef.

   The PATH_INFO is compared against this value to evaluate if the request
   should be processed. Undef (the default) will match always. PATH_INFO
   is topicalized by settings it to $_, and it may be rewritten during
   CodeRef matching. Rewriting can be used to relocate image paths, much
   like path parameter for Plack::Middleware::Static.

   If path matches, next it will be compared against "name". If path
   doesn't match, the request will be delegated to the next middleware
   layer or application.

match

   Must be a RegexpRef, or CodeRef.

   The PATH_INFO, possibly rewritten during "path" matching, is compared
   against this value to extract name, size and ext. The default value is:

       qr{^(.+)(?:_(.+?))?(?:\.(jpe?g|png|image))$}

   The expression is evaluated in array context and may return three
   elements: name, size and ext. Returning an empty array means no match.
   Non-matching requests are delegated to the next middleware layer or
   application.

   If the path matches, the original image is fetched from
   name."orig_ext", scaled with parameters extracted from size and
   converted to the content type defined by ext. See also "any_ext".

size

   Must be a RegexpRef, CodeRef, HashRef, Undef.

   The size extracted by "match" is compared against this value to
   evaluate if the request should be processed, and to map it into width,
   height and flags for image processing. Undef will match always and use
   default width, height and flags as defined by the "ATTRIBUTES". The
   default value is:

       qr{^(\d+)?x(\d+)?(?:-(.+))?$}

   The expression is evaluated in array context and may return three
   elements; width, height and flags. Returning an empty array means no
   match. Non-matching requests are delegated to the next middleware layer
   or application.

   Optionally a hash reference can be returned. Keys width, height, and
   any remaining keys as an hash reference, will be unrolled from the hash
   reference.

any_ext

   If defined and request ext is equal to this, the content type of the
   original image is used in the output. This means that the image format
   of the original image is preserved. Default is image.

orig_ext

   ArrayRef of possible original image formats. See "fetch_orig".

memory_limit

   Memory limit for the image scaling in bytes, as defined in
   Image::Scale.

jpeg_quality

   JPEG quality, as defined in Image::Scale.

width

   Use this to set and override image width.

height

   Use this to set and override image height.

flags

   Use this to set and override image processing flags.

METHODS

fetch_orig

   Call parameters: PSGI request HashRef $env, Str $basename. Return
   value: PSGI response ArrayRef $res.

   The original image is fetched from the next layer or application. All
   possible extensions defined in "orig_ext" are tried in order, to search
   for the original image. All other responses except a straight 404 (as
   returned by Plack::Middleware::Static for example) are considered
   matches.

body_scaler

   Call parameters: @args. Return value: PSGI content filter CodeRef $cb.

   Create the content filter callback and return a CodeRef to it. The
   filter will buffer the data and call "image_scale" with parameters
   @args when EOF is received, and finally return the converted data.

image_scale

   Call parameters: ScalarRef $buffer, String $ct, Int $width, Int
   $height, HashRef|Str $flags. Return value: $imagedata

   Read image from $buffer, scale it to $width x $height and return as
   content-type $ct. Optional $flags to specify image processing options
   like background fills or cropping.

CONFIGURATION

   The default match pattern for URI is "..._widthxheight-flags.ext".

   If URI doesn't match, the request is passed through. Any number of
   flags can be specified, separated with -. Flags can be boolean (exists
   or doesn't exist), or have a numerical value. Flag name and value are
   separated with a zero-width word to number boundary. For example z20
   specifies flag z with value 20.

width

   Width of the output image. If not defined, it can be anything (to
   preserve the image aspect ratio).

height

   Height of the output image. If not defined, it can be anything (to
   preserve the image aspect ratio).

flags: fill

   Image aspect ratio is preserved by scaling the image to fit within the
   specified size. This means scaling to the smaller or the two possible
   sizes that preserve aspect ratio. Extra borders of background color are
   added to fill the requested image size exactly.

       /images/foo_400x200-fill.png

   If fill has a value, it specifies the background color to use.
   Undefined color with png output means transparent background.

flags: crop

   Image aspect ratio is preserved by scaling and cropping from middle of
   the image. This means scaling to the bigger of the two possible sizes
   that preserve the aspect ratio, and then cropping to the exact size.

flags: fit

   Image aspect ratio is preserved by scaling the image to the smaller of
   the two possible sizes. This means that the resulting picture may have
   one dimension smaller than specified, but cropping or filling is
   avoided.

   See documentation in distribution directory doc for a visual
   explanation.

flags: z

   Zoom the original image N percent bigger. For example z20 to zoom 20%.
   Zooming applies only to explicitly defined width and/or height, and it
   does not change the crop size.

       /images/foo_40x-z20.png

EXAMPLES

       ## see example4.psgi

       my %imagesize = Config::General->new('imagesize.conf')->getall;

       # ...

       enable 'Image::Scale', size => \%imagesize;

   A request to /images/foo_medium.png will use
   images/foo.(png|jpg|gif|jpeg) as original. The size and flags are taken
   from the configuration file as parsed by Config::General.

       ## imagesize.conf

       <medium>
           width   200
           height  100
           crop
       </medium>
       <big>
           width   300
           height  100
           crop
       </big>
       <thumbred>
           width   50
           height  100
           fill    ff0000
       </thumbred>

   For more examples, browse into directory eg
   <http://cpansearch.perl.org/src/PNU/> inside the distribution directory
   for this version.

CAVEATS

   The cropping requires Imager. This is a run-time dependency, and
   fallback is not to crop the image to the expected size.

SEE ALSO

   Image::Scale

   Imager

   Plack::App::ImageMagick

AUTHOR

   Panu Ervamaa <[email protected]>

COPYRIGHT AND LICENSE

   This software is copyright (c) 2011-2016 by Panu Ervamaa.

   This is free software; you can redistribute it and/or modify it under
   the same terms as the Perl 5 programming language system itself.

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