README


# Image manipulation made even easier - sfImageTransformExtraPlugin

![sfImageTransformExtraPlugin](http://www.symfony-project.org/uploads/plugins/4366ffec3f32548c30e31094c3dcbcea.png)

## Table of Contents

*   [About](#about)
*   [Installation](#installation)
*   [Configuring the image formats you need](#formats)
*   [Configuring the location of the original image](#sources)
    * [Your source image is a local file referenced by the filename](#file-source)
    * [Your source image is a local file which location is stored in the database (Doctrine and Propel)](#database-source)
    * [Your source image is a remote file accessed over HTTP](#http-source)
    * [Your source image is different - write your own source class](#custom-source)
*   [Caching the generated images](#caching)
    * [Verifying your cache settings](#verify-caching)
    * [Invalidating the cached images manually](#manual-invalidation)
    * [Invalidating the cached images automatically](#auto-invalidation)
    * [Optimising the Invalidating process](#optimise-invalidation)
*   [Demonstration](#demo)
*   [How does it work?](#internals)

- - -

## <a name="about">About</a>

On a website you ususally find lots of images and a set of formats.

For example let's say a user avatar is always ``80x80 PNG`` while a homepage top image is always ``320x140 JPG`` with 
round corners.

As it is far too costly to prepare all these different formats by hand there are automated ways to generate them from 
source images uploaded by a user. One of the best tools for this in the symfony world is 
[sfImageTransformPlugin](http://www.symfony-project.org/plugins/sfImageTransformPlugin) which enables you to perform 
many sophisticated transformations on your images such as resizing, color manipulation, overlays and much much more. It 
is not only easy to use but easy to extend as well. Writing your own transformation is a bliss.

Using such an automatism means you have to write code and perform all necessary transformation - usually on upload, no 
matter if the generated files are ever requested. It also means that design changes that change the formats as well lead 
to a change of business logic rather than just templates.

This is where sfImageTransformExtraPlugin springs into action as it provides a way to configure formats with multiple 
transformations.

In your templates you only refer to the format by name which results in an SEO friendly image URL (a URL that you have 
full control over). The image itself will be generated on first request and (in production environments) written to the 
filesystem.

Here are some of the key features:

*   Configure image transformation for your thumbnail formats
*   Format changes without the need to change code
*   Unobstrusive implementation (No need to write code)
*   Generating images on request
*   Can be run as a web service for a content delivery network (CDN)
*   Supporting image file sources stored in databases via Doctrine or Propel, remote files and more
*   Full control over the thumbnail URLs and therefor easy to adapt to your SEO requirements
*   Generated API documentation
*   Unit tested
*   Easy to extend

To get an idea what you can do you might want to check out a quick [demonstration](#demo) or see [how it works internally](#internals).

## <a name="installation">Installation</a>

To install the plugin for a symfony project, the usual process is to use the symfony command line:

    $ php symfony plugin:install sfImageTransformExtraPlugin

Alternatively, if you don't have PEAR installed, you can download the latest package attached to this plugin's wiki page 
and extract it under your project's ``plugins/`` directory.

Activate the plugin in your ``ProjectConfiguration.class.php``.

    // /config/ProjectConfiguration.class.php
    ...
    $this->enablePlugins(..., 'sfImageTransformPlugin', 'sfImageTransformExtraPlugin');
    ...

Enable the generating module in your ``settings.yml``.

    // /apps/yourapplication/config/settings.yml
    all:
      .settings:
        enabled_modules:        [ ..., sfImageTransformator ]
    ...

You also need to configure automatic mime detection for sfImageTransformPlugin in your applications ``app.yml``.

    // /apps/yourapplication/config/app.yml
    all:
      sfImageTransformPlugin:
        mime_type:
          auto_detect:  true
          library:    gd_mime_type #  gd_mime_type (GD), Fileinfo (PECL), MIME_Type (PEAR)
        font_dir:     %SF_PLUGINS_DIR%/sfImageTransformExtraPlugin/data/example-resources/fonts
    ...

Automatic mime detection is absolutely necessary!
Of course you can point the ``font_dir`` to your own location containing True Type Fonts.

Clear the cache to enable the autoloading to find the new classes:

    $ php symfony cc

> Note: The plugin requires sfImageTransformPlugin to be installed as well. The dependencies described there apply as 
well so please follow the [README](http://www.symfony-project.org/plugins/sfImageTransformPlugin?tab=plugin_readme 
"sfImageTransformPlugin README").

The default routes of the plugin expect all thumbails to be called from the relative URL ``/thumbnails/..``. So you have 
to make sure, that this folder (``SF_ROOT_DIR/web/thumbnails``) exists and is writable to the web server.

    $ mkdir SF_ROOT_DIR/web/thumbnails
    $ chmod 777 SF_ROOT_DIR/web/thumbnails

The ``/thumbnails`` path is specified in your routes. If you make changes to the routes you have to make sure that the 
equivalent path exists and is writable.

To ensure that the caching of your generated files works please also have a look at [verifying your cache settings](#verify-caching).

## <a name="formats">Configuring the image formats you need</a>

The best way to learn how you configure your format transformations is to walk through a rather complex format configuration.

Of course you can chain transformations. In fact most of the above thumbnails have two transformations applied one for resizing and another for the effect.

All these format settings have to be made in a file called `thumbnailing.yml`. It starts like this.

    all:
      .settings:
        formats:

Let's see how it works and start with the original again. The format looks like this.

          star0:
            quality:                25
            mime_type:              image/png
            transformations:        ~

With the following result.

![star0](http://stat.ical.ly/thumbnails/star0.png "No Transformation")

Now let's add a ``crop`` transformation to get to the correct dimensions.

          star1:
            quality:                25
            mime_type:              image/png
            transformations:
              - { adapter: GD, transformation: crop, param: { left: 90, top: 72, width: 120, height: 120 }}

![star1](http://stat.ical.ly/thumbnails/star1.png "Just cropped")

And just to be a bit different we want to rotate.

          star2:
            quality:                25
            mime_type:              image/png
            transformations:
              - { adapter: GD, transformation: crop, param: { left: 90, top: 72, width: 120, height: 120 }}
              - { adapter: GD, transformation: rotate, param: { angle: 20, background: '#FFFFFF' }}

![star2](http://stat.ical.ly/thumbnails/star2.png "Now it's rotated as well")

The blank spots are not what we want so let's crop it again.

          star3:
            quality:                25
            mime_type:              image/png
            transformations:
              - { adapter: GD, transformation: crop, param: { left: 90, top: 72, width: 120, height: 120 }}
              - { adapter: GD, transformation: rotate, param: { angle: 20, background: '#FFFFFF' }}
              - { adapter: GD, transformation: crop, param: { left: 17, top: 17, width: 120, height: 120 }}

![star3](http://stat.ical.ly/thumbnails/star3.png "Cropped again")

So we are back to the dimensions we wanted. Now we want a watermark on top of it.

          star4:
            quality:                25
            mime_type:              image/png
            transformations:
              - { adapter: GD, transformation: crop, param: { left: 90, top: 72, width: 120, height: 120 }}
              - { adapter: GD, transformation: rotate, param: { angle: 20, background: '#FFFFFF' }}
              - { adapter: GD, transformation: crop, param: { left: 17, top: 17, width: 120, height: 120 }}
              - { adapter: GD, transformation: overlay, param: { overlay: sfImage|overlays/logo.png, position: center }}

              
![star4](http://stat.ical.ly/thumbnails/star4.png "Watermarked")

Of course this is not "Web 2.0" enough yet..

          star5:
            quality:                25
            mime_type:              image/png
            transformations:
              - { adapter: GD, transformation: crop, param: { left: 90, top: 72, width: 120, height: 120 }}
              - { adapter: GD, transformation: rotate, param: { angle: 20, background: '#FFFFFF' }}
              - { adapter: GD, transformation: crop, param: { left: 17, top: 17, width: 120, height: 120 }}
              - { adapter: GD, transformation: overlay, param: { overlay: sfImage|overlays/logo.png, position: center }}

                            - { adapter: GD, transformation: overlay, param: { overlay: sfImage|overlays/star_frame.png, position: 
              center }}

![star5](http://stat.ical.ly/thumbnails/star5.png "Star frame added")

Now we want to get rid of the bits that stick out by applying an alpha mask.

          star6:
            quality:                25
            mime_type:              image/png
            transformations:
              - { adapter: GD, transformation: crop, param: { left: 90, top: 72, width: 120, height: 120 }}
              - { adapter: GD, transformation: rotate, param: { angle: 20, background: '#FFFFFF' }}
              - { adapter: GD, transformation: crop, param: { left: 17, top: 17, width: 120, height: 120 }}
              - { adapter: GD, transformation: overlay, param: { overlay: sfImage|overlays/logo.png, position: center }}

                            - { adapter: GD, transformation: overlay, param: { overlay: sfImage|overlays/star_frame.png, position: 
              center }}
              - { adapter: GD, transformation: alphaMask, param: { mask: sfImage|masks/star_mask.gif }}

![star6](http://stat.ical.ly/thumbnails/star6.png "Stamped out")

Done! ;)

> Please note that for overlay and alphaMask transformations
> you need to prefix the resource path with "sfImage|" as this
> automatically converts the path into an sfImage object.

## <a name="sources">Configuring the location of the original image</a>

sfImageTransformExtraPlugins uses custom PHP stream wrappers to map your images URLs to the real location of the source images. There are a few sources already available but of course you can easily add your own.

### <a name="file-source">Your source image is a local file referenced by the filename</a>

Your image sources lie in a directory accessible to your web server and you want to keep the filenames.

Create a route like the following in your applications ``routing.yml``.

    // /apps/yourapplication/config/routing.yml
    sf_image:
      class: sfImageTransformRoute
      url:   /thumbnails/:format/:filepath.:sf_format
      param: { module: sfImageTransformator, action: index }
      requirements:
        format:    '[\w_-]+'
        filepath:  '[\w/]+'
        sf_format: 'gif|png|jpg'
        sf_method: [ get ]
      options:
        image_source: File
    ...

You can now generate ``<img />`` tags to these images like this.

    <?php
    echo image_tag(url_for('sf_image_file', array('format' => 'pixelate', 'filepath' => 'logo.png')));
  // resulting in: http://localhost/thumbnails/pixelate/logo.png.jpg
  ?>

> Please note that the prefix filepath - ``/thumbnails`` in the above example - is required to exist and be writable for 
the webserver!

### <a name="database-source">Your source image is a local file which location is stored in the database (Doctrine and Propel)</a>

When you develop on symfony chances are that uploaded image files are located in the ``sf_upload_dir`` and their 
filenames are stored in the database. sfImageTransformExtraPlugin comes with two images source classes that you can use 
to work with these files.

Your image sources are located in a directory accessible to your web server and you want to keep the filenames.

Create a route like the following in your applications ``routing.yml``.

    // /apps/yourapplication/config/routing.yml
    sf_image:
      class: sfImageTransformRoute
      url:   /thumbnails/:type/:format/:path/:slug-:id.:sf_format
      param: { module: sfImageTransformator, action: index, attribute: file }
      requirements:
        format:    '[\w_-]+'
        path:      '[\w/]+'
        slug:      '[\w_-]+'
        id:        '\d+(?:,\d+)?'
        sf_format: 'gif|png|jpg'
        sf_method: [ get ]
      options:
        image_source: Doctrine # or Propel
        segment_separators: [ '/', '.', '-' ]
    ...

You can now generate ``<img />`` tags to these images like this.

    <?php
    echo image_tag(url_for('sf_image_doctrine', array('format' => 'pixelate', 'sf_subject' => $record)));
    // resulting in: http://localhost/thumbnails/News/pixelate/01/00/00/mytest-1.jpg
    ?>

``$record`` in this example is either a Doctrine or Propel record.

The ``:path`` attribute is provided by the sfImageTransformExtraPlugins own route class ``sfImageTransformRoute``. It 
will take the ``id`` attribute and form a three level deep path from it.

    // examples
    1 => 01/00/00
    37410 = 10/74/03
    ..

This path can ensure that you won't store more than 100 files per directory which is necessary to avoid imperformance 
from the filesystem.

### <a name="http-source">Your source image is a remote file accessed over HTTP</a>

If you plan to build a content delivery network (CDN) and run sfImageTransformExtraPlugin as a webservice your image 
sources will not be available locally but instead over HTTP.

Your image sources are located in a directory not accessible to your web server and you want to keep the filenames.

Create a route like the following in your applications ``routing.yml``.

    // /apps/yourapplication/config/routing.yml
    sf_image:
      class: sfImageTransformRoute
      url:   /thumbnails/sfweb/:format/:filepath.:sf_format
      param: { module: sfImageTransformator, action: index, protocol: http, domain: www.symfony-project.org }
      requirements:
        format:    '[\w_-]+'
        protocol:  'http|https'
        domain:    '[\w-_.]+'
        filepath:  '[\w/-_.]+'
        sf_format: 'gif|png|jpg'
        sf_method: [ get ]
      options:
        image_source: HTTP
  ...

You can now generate ``<img />`` tags to these images like this.

    <?php
    echo image_tag(url_for('sf_image_http', array('format' => 'pixelate', 'filepath' => 
    'images/symfony-reloaded.png')));
    // resulting in: http://localhost/thumbnails/sfweb/pixelate/images/symfony-reloaded.png.jpg
    ?>

### <a name="custom-source">Your source image is different - write your own source class</a>

It doesn't matter where your source images are stored and how you need to receive the filepath/URL you can easily 
implement a solution by following two easy steps:

1. Write a new route

When defining the URL of the new route the only thing you need to care about is the list of parameters. You have to 
provide all parameters that are necessary to retrieve the images location.

In the case of a Doctrine model storing the filename of a local file you need to know the model type (i.e. 
NewsBulletin), the ID of the object (i.e. 123) and the model attribute or field which stores the filename (i.e. file). 
Depending on your requirements you might need different parameters to identify the source.

You will also most certainly need a parameter for the desired format.

    sf_image:
      class: sfImageTransformRoute
      url:   /thumbnails/:format/:special.sf_format
    param: { module: sfImageTransformator, action: index }
      requirements:
        format:    '[\w_-]+'
        sf_format: http|https
        somespecialparameter:    '[\w-_.]+'
        sf_method: [ get ]
      options:
        image_source: Special

2. Write a new sfImageSource class

Once you defined the parameters you can implement the sfImageSource class by implementing ``sfImageSourceInterface`` and 
``barfoo``.

If the image source files are stored on the local filesystem accessible to the webserver your need to implement 
``sfImageSourceLocalAbstract``. For all other locations please use ``sfImageSourceRemote`` as PHP functions like ``stat()`` only 
work with local files and therefor need to be faked .

    class sfImageSourceSpecial extends sfImageSourceRemote implements sfImageSourceInterface
    {
      /**
       * Returns an sfImageSource:// URL specific to the implementing stream wrapper
       *
       * @param  array  $parameters Current request parameters
       * @return string sfImageSource:// URI
       * @throws InvalidArgumentException
       */
      public static function buildURIfromParameters(array $parameters)
      {
        ...
      }

      /**
       * Translates the given stream URL to the abolute path of the source image
       *
       * @param  string $path The given stream URL
       * @return string
       */
      private function translatePathToFilename($path)
      {
        ...
      }

    }

In most cases you only have to change/adapt the methods in the above example. That is all you have to do.

Please make sure that the base URL (in the above example ``/thumbnails``) exists and is writable. See [verifying your cache settings](#verify-caching) for details.

## <a name="caching">Caching the generated images</a>

sfImageTransformExtraPlugin provides functionality to cache your generated images so that instead of processing the images from scratch per request they get stored on the local filesystem from where your webserver can serve them statically without even spawning a PHP process.

### <a name="verify-caching">Verifying your settings</a>

sfImageTransformExtraPlugin provides a symfony task to check your settings to ensure that caching is working properly.

    $ ./symfony help transforms:check-caching
    Usage:
     symfony transforms:check-caching [--env="..."] [--route-name="..."] application
    
    Arguments:
     application   The application name
    
    Options:
     --env         The environment (default: prod)
     --route-name  The sfImageTransform routename (default: sf_image)
    
    Description:
     The transforms:check-caching task performs a series of tests on your project to verify the thumbnail caching to work.
     Call it with:
    
       php symfony transforms:check-caching application
    
       Please read the output carefully especially if one or more checks fail.
    
       You can also run the tests for a specific environment by providing the env option. It defaults to prod which in most cases is the only environment you want your cache to be enabled.
    
       php symfony transforms:check-caching application --env=prod
    
       The tasks assumes the default route name sf_image for your thumbnails. If you use a different one you can specify it with the route-name option.
    
       php symfony transforms:check-caching application --route-name=your_thumbnail_route
    
       Please note that the permission checks can not be reliable as they are performed with the system permissions of your current user account while your web server should run with a different user account which might have different priviledges.

### <a name="manual-invalidation">Invalidating the cached images manually</a>

Sometimes you want to remove already generated images from your filesystem i.e. if the original source image was 
changed.

For this there is a symfony task which takes two mandatory arguments.

    $ ./symfony help transforms:remove
    Usage:
     symfony transforms:remove  application route

     Aliases: remove-thumbnails

     Arguments:
      application  The application name
      sf_route     The symfony route name that generated the image(s) you want to remove

     Description:
      Removes thumbnails generated by sfImageTransformExtraPlugin.

Let's take a route from the previous examples.

    // /apps/yourapplication/config/routing.yml
    sf_image:
      class: sfImageTransformRoute
      url:   /thumbnails/:format/:filepath.:sf_format
      param: { module: sfImageTransformator, action: index }
      requirements:
        format:    '[\w_-]+'
        filepath:  '[\w/]+'
        sf_format: 'gif|png|jpg'
        sf_method: [ get ]
      options:
        image_source: File

Assuming that this route is active for your frontend application you can now do the following to remove all images 
generated by that route.

    $ ./symfony transforms:remove frontend sf_image_file
     Do you really want to delete all generated images?
    y
    >> files-    Generated images removed.

To be more specific you can provide all attributes available for the route.

To remove only images for this route that used the ``default`` format:

    $ ./symfony transforms:remove frontend sf_image_file --format=default
    >> files-    Generated images removed.

To remove only images for this route that are of type ``jpg``:

    $ ./symfony transforms:remove frontend sf_image_file --sf_format=jpg
    >> files-    Generated images removed.

Of course you can combine all available attributes. In this case to remove all ``jpg`` images that were generated using 
the ``default`` format (for example if you changed the mimetype of that particular format).

    $ ./symfony transforms:remove frontend sf_image_file --format=default --sf_format=jpg
    >> files-    Generated images removed.

Please also take a look at the chapter [Optimising the Invalidating process](#optimise-invalidation).

### <a name="auto-invalidation">Invalidating the cached images automatically</a>

When uploading new images to your models replacing previous ones the previously generated thumbnails still persist so the user of your websites never actually gets to see your new image.

Of course this is not the desired functionality but as there is no information stored anywhere about these thumbnails you can not know what files to delete.

sfImageTransformExtraPlugin provides a symfony event for you to notify when you need to automatically wipe existing thumbnails from the filesystem.

You can notify this event from anywhere like this.

    new sfEvent(null, 'sf_image_transform.changed_source', array('sf_route' => 'sf_image', ...));

The important thing is the parameters you pass. You are always required to provide a route name (`sf_route`) and as many of its route parameters as possible.

For the route parameters the same logic applies as in the previous chapter about the symfony task.

The deletion process will iterate over all files recursively and try to match them against the route. You can speed up this process by passing as much known route parameters as possible. The following best practice applies.

* __DON'T PASS WHOLE OBJECTS!__ As these can contain fields like slugs that might have changed themselves and could prevent matching of previously generated files. Do pass all route parameters separately.

For further info see also [this blogpost](http://test.ical.ly/2010/08/17/how-to-automatically-and-manually-delete-thumbnails-in-symfony-with-sfimagetransformextraplugin/ "How to automatically and manually delete thumbnails in symfony with sfImageTransformExtraPlugin").

Please also take a look at the next chapter [Optimising the Invalidating process](#optimise-invalidation).

### <a name="optimise-invalidation">Optimising the Invalidating process</a>

Since version 1.0.12 the invalidation process has greatly be improved and is now a lot faster which means more stability to content rich websites.

This is achieved by the plugin assuming a default depth for the caching folder. This depth defaults to 10 but can be set per route in your `routing.yml`.

    sf_image:
      class: sfImageTransformRoute
      url:   /thumbnails/:format/:filepath.:sf_format
      param: { module: sfImageTransformator, action: index }
      requirements:
        format:    '[\w_-]+'
        filepath:  '[\w/.]+'
        sf_format: 'gif|png|jpg'
        sf_method: [ get ]
      options:
        image_source: File
        image_location: %SF_ROOT_DIR%
        max_folder_depth: 10

The above route definition does not define a definite depth for the thumbnail file as the `:filepath` parameter can include many folders. By setting `max_folder_depth` to 10 or another number the invalisation process can now use this information to search for generated thumbnail files rather than doing a recursive directory scan.

As you know your application best this is a value that you can set yourself per route.

## <a name="demo">Demonstration</a>

Here are a few examples to see what is possible.

Consider the following source image.

![original](http://stat.ical.ly/thumbnails/original.jpg "No Transformation")

Here are just a few examples that were all transformed from the above image.

![resize](http://stat.ical.ly/thumbnails/resize.jpg "Resize Transformation")
![fit](http://stat.ical.ly/thumbnails/fit.jpg "Thumbnail Fit Transformation")
![crop](http://stat.ical.ly/thumbnails/crop.jpg "Crop Transformation")
![flip](http://stat.ical.ly/thumbnails/flip.jpg "Flip Transformation")
![rotate](http://stat.ical.ly/thumbnails/rotate.jpg "Rotate Transformation")
![mirror](http://stat.ical.ly/thumbnails/mirror.jpg "Mirror Transformation")
![border](http://stat.ical.ly/thumbnails/border.jpg "Border Transformation")
![line](http://stat.ical.ly/thumbnails/line.jpg "Line Transformation")
![rectangle](http://stat.ical.ly/thumbnails/rectangle.jpg "Rectangle Transformation")
![arc](http://stat.ical.ly/thumbnails/arc.jpg "Arc Transformation")
![ellipse](http://stat.ical.ly/thumbnails/ellipse.jpg "Ellipse Transformation")
![overlay](http://stat.ical.ly/thumbnails/overlay.jpg "Overlay Transformation")
![colorize](http://stat.ical.ly/thumbnails/colorize.jpg "Colorize Transformation")
![contrast](http://stat.ical.ly/thumbnails/contrast.jpg "Contrast Transformation")
![edgeDetect](http://stat.ical.ly/thumbnails/edgeDetect.jpg "Edge Detect Transformation")
![emboss](http://stat.ical.ly/thumbnails/emboss.jpg "Emboss Transformation")
![greyscale](http://stat.ical.ly/thumbnails/greyscale.jpg "Greyscale Transformation")
![negate](http://stat.ical.ly/thumbnails/negate.jpg "Negate Transformation")
![opacity](http://stat.ical.ly/thumbnails/opacity.jpg "Opacity Transformation")
![noise](http://stat.ical.ly/thumbnails/noise.jpg "Noise Transformation")
![blur](http://stat.ical.ly/thumbnails/blur.jpg "Blur Transformation")
![pixelize](http://stat.ical.ly/thumbnails/pixelize.jpg "Pixelize Transformation")
![scatter](http://stat.ical.ly/thumbnails/scatter.jpg "Scatter Transformation")
![sketchy](http://stat.ical.ly/thumbnails/sketchy.jpg "Sketchy Transformation")
![text](http://stat.ical.ly/thumbnails/text.jpg "Text Transformation")
![rounded_corners](http://stat.ical.ly/thumbnails/rounded_corners.gif "Rounded Corners Transformation")
![reflection](http://stat.ical.ly/thumbnails/reflection.jpg "Reflection Transformation")
![frame](http://stat.ical.ly/thumbnails/frame.png "Alpha Mask (Frame) Transformation")
![pattern](http://stat.ical.ly/thumbnails/pattern.png "Alpha Mask (Pattern) Transformation")
![just](http://stat.ical.ly/thumbnails/just.gif "Create & Text Transformation")

And of course a simple scaling:

![scale](http://stat.ical.ly/thumbnails/scale.jpg "Thumbnail Scale Transformation")

## <a name="internals">How does it work?</a>

The generation process that we designed so far works like this:

1. An HTTP Request is made to a thumbnail
2. All necessary parameters are parsed from the URL
3. The requested source image is found
4. The thumbnail gets generated according to the format specification
5. The thumbnail gets cached (saved to disk)
6. The thumbnail is send out to the user

![Thumbnail request lifecycle](http://yuml.me/54355ffc)

The thumbnail image is generated on the first request. All succeeding requests are coming from cache (per default the 
filesystem) and are served by Apache without spawning a PHP process.

Image generation is quite expansive in terms of CPU and memory usage. This is why sfsfImageTransformExtraPlugin by 
default stores generated images for the production environment on the filesystem.
For this the custom cache class ``sfRawFileCache`` is used which is basically a copy of sfFileCache but does not prepend 
the cached file with expire time information but instead saves only the generated image. It also maintains the real 
filename and does not add a ``.cache`` suffix.

You can see the typical lifecycle of a generated image in the following Firebug screenshots.

![firebug-1-generation](http://stat.ical.ly/thumbnails/firebug-1-generation.jpg "First request on a thumbnail triggering 
the generation and caching")

The image is generated, saved to the filesystem and sent to the requesting browser.

![firebug-2-static](http://stat.ical.ly/thumbnails/firebug-2-static.jpg "Second request on a thumbnail already directly 
served from filesystem")

The image is read directly from the filesystem without invoking a PHP process.

![firebug-3-notmodified](http://stat.ical.ly/thumbnails/firebug-3-notmodified.jpg "Third and succeeding requests on a 
thumbnail will be served from the browser cache")

Apache automatically informs the browser that the image has not been modified by sending a ``304`` status (depending on 
your Apache configuration, however the described behaviour is the default).

As you can see the time needed to deliver a generated image after the second request is drastically reduced.
(The times will vary on different installations.)

The deletion of generated images use the sfCache interface and can be triggered by a task of a symfony event.

- - -

sfImageTransformExtraPlugin is fully unit tested with PHPUnit. You can run the test suite like this.

    $ cd /path/to/sfImageTransformExtraPlugin
    $ phpunit --tap test/sfImageTransformExtraPluginsTests.php

sfImageTransformExtraPlugin has a (quite) complete API documentation using PHPdocumentor. You can generate the API documentation like this.

    $ cd /path/to/sfImageTransformExtraPlugin
    $ phpdoc -o  HTML:frames:DOM/phphtmllib -d . -t /path/to/where/you/want/the/apidocs/to/be/generated