Notes on the circle_gif module
---

To install, compile nginx with this ./configure option:

    --add-module=path/to/this/directory

To build the module dynamically, use this ./configure option:

    --add-dynamic-module=path/to/this/directory

You must have the ImageMagick development headers for it to work.

The circle_gif module generates simple circle images with the colors and size
specified in the URL. The images are served quickly, much faster than if they
had been read from disk. The module was made to help web designers change the
colors of their "round corners" without having to fire up PhotoShop.

To enable the circles, add a "circle_gif;" directive to the location where you
want them. My nginx.conf has this:

    location /circles {
        circle_gif;
    }

After that, the circles will be accessible like this:

    /circles/<background color>/<foreground color>/<size>.gif

Background and foreground color are 24-bit hex colors, e.g. "ffffff" is white
and "000000" is black. Size is the radius of the circle in pixels. This
generates a black on white circle of radius 20:

    /circles/ffffff/000000/20.gif

By default, only even-numbered radii between 10 and 20 are allowed. To change
this, you can use the directives "circle_min_radius" (default 10),
"circle_max_radius" (default 20), and "circle_step_radius" (default 2).
Note that an image for each radius is created at server startup and kept
in memory, so adding more circle sizes will slow server startup and use (a
very small amount of) RAM.

--Evan Miller
emmiller@gmail.com