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

VERSION
   version 0.006

SYNOPSIS
       ## example1.psgi

       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) as
   original, scale it to 40x40 px size and convert to PNG format.

       ## example2.psgi

       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_x.png will use images/foo.(png|jpg|gif) 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".

       ## 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) 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>

   But you might want to use a simple config format if writing it in-line.

       ## see example3.psgi

       my $imagesize = {
           small   => [ 40,100],
           medium  => [140,200],
           big     => [240,300],
       };

       # ...

       enable 'Image::Scale', size => $imagesize;

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
 match
   Must be a RegexpRef, "CodeRef", "HashRef" or "Undef".

   The PATH_INFO is compared against this value to extract the size
   parameter for image processing. Undef means match always. "PATH_INFO" is
   topicalized by settings it to $_, and it may be rewritten during the
   match. The rewritten path is used for fetching the original image.

   The return value is evaluated in array context and may contain one
   element, the size. Returning an empty array means no match. Non-matching
   requests are delegated to the next middleware layer or application.

 size
   Must be a RegexpRef, "CodeRef", "HashRef" or "Undef".

   The "size" extracted by "path" match is compared against this value to
   extract width, height and flags for image processing. Undef means match
   always.

   The return value is evaluated in array context and may contain 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 an array or hash reference can be returned. Keys "width",
   "height" and flags as an hash reference will be unrolled from a hash
   reference.

 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
   "*...*_*width*x*height*-*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: 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

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 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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