repoze.bitblt 0.6

Image transforming WSGI middleware

This package provides a WSGI middleware component which automatically scales images according to the width and height property in the <img> tag.

To configure the middleware, pass in a string for secret; this may be any string internal to the system.

Usage

The middleware operates in two phases, on HTML documents and images respectively.

When processing HTML documents, it looks for image tags in the document soup:

<img src="some_image.png" width="640" height="480" />

In the case it finds such an image element, it rewrites the URL to include scaling information which the middleware will read when the image is served through it.

This effectively means that application developers needn’t worry about image scaling; simply put the desired size in the HTML document.

Note that this middleware is protected from DoS attacks (which is important for any middleware that does significant processing) by signing all URLs with an SHA digest signature.

Credits

Malthe Borch <[e-mail]> Stefan Eletzhofer <[e-mail]> Jeroen Vloothuis <[e-mail]>

Changelog

0.6 (released 2008-10-11)

• Require to pass in a secret parameter to configure middleware security. [malthe]

0.5 (released 2008-10-11)

• Rewritten URLs are now signed by the middleware to ensure that bitblt requests are only crafted by the middleware. This is required to shield against DoS attacks. [malthe]

0.4 (released 2008-10-11)

• Fixed path handling. [malthe]

• Added HTML document processing which scans document for image tags and rewrite image src attribute to include “bitblt” traversing directive. This makes it work as an actual middleware, since the application semantics are then unchanged. [malthe]

• No longer accept query parameters, but instead require traversing directive “/bitblt-<width>x<height>”. [malthe]

• Removed functionality to MIME-type convert. [malthe]

0.3 (released 2008-10-10)

• Made logic robust to unexpected parameters. [malthe]

• Fixed bug where parameters would be drawn from the WSGI environment. [malthe]

• Added mimetype conversion. [malthe]

0.2 (released 2008-10-08)

• Fixed entry point name.

0.1 (released 2008-10-03)

• Initial release.