Merlin's Hat

Merlin's Hat is some express middleware to quickly provide an image from a URL of an arbitrary resolution with caching. You must implement your own storage method.

There is an example at example/server.coffee.

Dependency

GraphicsMagick needs to be installed. You can do this on a Mac using homebrew very easily:

brew install graphicsmagick

On Ubuntu 14.04+ you can install it like this:

sudo apt-get install graphicsmagick

Implementation

The middleware expects 3 functions to be passed:

• 1 to handle storing a resized image
• 1 to fetch a stored image/test if a store image exists
• 1 to delete a stored image

See example/server.coffee.

HTTP API

You need to mount the middleware on a route. Once you have done that, Merlin's Hat can be used very simply.

In this example, Merlin's Hat is mounted at /api/v1/image. The following query paramaterys are available to you:

• width : The max width to resize to
• height : The max height to resize to
• quality : From 0 to 100, what should be the quality of the resulting JPG (default: 80)
• url : The URL of the upstream image to download and resize.

Note: one of width and height are required, but not both.