NAME Plack::Middleware::Image::Scale - Resize jpeg and png images on the fly VERSION version 0.003 SYNOPSIS # app.psgi builder { enable 'ConditionalGET'; enable 'Image::Scale'; enable 'Static', path => qr{^/images/}; $app; }; DESCRIPTION Suppose that you have images/foo.jpg in your filesystem. With above setup you can make request to /images/foo_40x40.png, to receive it as scaled to 40x40 and converted to png format. Scaling is done with Image::Scale module. The converted and/or scaled version is not stored. This middleware implements a PSGI content filter to do the processing. The response headers (like Last-Modified or ETag) will be from the original image, but the image processing happens only if the body is actually used. This middleware doesn't access the filesystem at all. The original image is fetched from next middleware layer or application. The image requests should return a filehandle body for optimal results. You can use Plack::Middleware::Static, or "Catalyst::Plugin::Static::Simple" for example. This means that the response can be validated (with If-Modified-Since or If-None-Match) against original image, without doing the expensive image processing, or even reading the file content at all. This module should be used with a proxy cache that implements validation. See below for various size/format specifications that can be used in the request URI. See "ATTRIBUTES" for common configuration options that you can give as named parameters to the "enable". With default configuration, the format of the URI is *basename*_*width*x*height*-*flags*.*ext* Only *basename*, "x" and *ext* are required. 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. basename Original image is requested from URI *basename*.*orig_ext*, where *orig_ext* is list of filename extensions. See "orig_ext". 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. /images/foo_40x20-fill0xff0000.png ## red 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 specified width or height N percent bigger. For example "z20" to zoom 20%. The zooming applies only to width and/or height defined in the URI, and does not change the crop size. Image is always cropped to the specified pixel width, height or both. /images/foo_40x-crop-z20.png ATTRIBUTES match_path Only matching URIs are processed with this module. The match is done against PATH_INFO. Non-matching requests are delegated to the next middleware layer or application. The value must be a RegexpRef, that returns 3 captures. Default value is: qr<^(.+)_(.+)\.(png|jpg|jpeg)$> First capture is the path and basename of the requested image. The original image will be fetched by "fetch_orig" with this argument. See "call". Second capture is the size specification for the requested image. See "match_spec". Third capture is the extension for the desired output format. This extension is mapped with Plack::MIME to the Content-Type to be used in the HTTP response. The content type defined the output format used in image processing. Currently only jpeg and png format are supported. See "call". match_spec The size specification captured by "match_path" is matched against this. Only matching URIs are processed with this module. The value must be a RegexpRef. Default values is: qr<^(\d+)?x(\d+)?(?:-(.+))?$> First and second captures are the desired width and height of the resulting image. Both are optional, but note that the "x" between is required. Third capture is an optional flag. This value is parsed in the "image_scale" method during the conversion. 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. METHODS call Process the request. The original image is fetched from the backend if "match_path" and "match_spec" match as specified. Normally you should use Plack::Middleware::Static or similar backend, that returns a filehandle or otherwise delayed body. Content-Type of the response is set according the request. The body of the response is replaced with a streaming body that implements a content filter to do the actual resizing for the original body. This means that if response body gets discarded due to header validation (If-Modified-Since or If-None-Match for example), the body never needs to be processed. However, if the original image has been modified, for example the modification date has been changed, the streaming body gets passed to the HTTP server (or another middleware layer that needs to read it in), and the conversion happens. fetch_orig The original image is fetched from the next layer or application. The basename of the request URI, as matched by "match_path", and all possible extensions defined in "orig_ext" are used 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 Create a content filter callback to do the conversion with specified arguments. The callback binds to a closure with a buffer and the image_scale arguments. The callback will buffer the response and call "image_scale" after an EOF. image_scale Do the actual scaling and cropping of the image. Arguments are width, height and flags, as parsed in "call". See "DESCRIPTION" for description of various sizes and flags. CAVEATS The cropping requires Imager. This is a run-time dependency, and fallback is not to crop the image to the desired size. SEE ALSO Image::Scale Imager Plack::App::ImageMagick AUTHOR Panu Ervamaa 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.