imagerl

Image renderer and cacher in Erlang. It supports:

• resizing based on the device size (using WURFL Cloud to perform lookups),
• image convertion using the convert utility provided by ImageMagick,
• serving of locally hosted images using the file://<path_to_file> scheme, and
• serving of Amazon S3 (privately) hosted images using the s3://<bucket>/<key> scheme, which builds the required signed URL.

Quick usage guide

Cache and serve an image

If the image is located at "http://www.google.co.za/images/srpr/logo3w.png", make the following call:

http://localhost:8000/render?url=http%3A%2F%2Fwww.google.co.za%2Fimages%2Fsrpr%2Flogo3w.png

The image will be retrieved, cached and served the first time it is request. Thereafter it will simply be served from the cache.

Note that:

• Local files can be served using the "file://" scheme.
• Files hosted on Amazon S3 can be served using the s3:// scheme.
• Source image caching can be disabled in the config file if necessary.

Restrict the width or height

If you require the image to have a restricted width or height, it can be specified:

http://localhost:8000/render?url=http%3A%2F%2Fwww.google.co.za%2Fimages%2Fsrpr%2Flogo3w.png&width=100

or

http://localhost:8000/render?url=http%3A%2F%2Fwww.google.co.za%2Fimages%2Fsrpr%2Flogo3w.png&height=100

The aspect ratio will be preserved in this case.

The width or height values may be set to wurfl, in which case a WURFL lookup will be performed using the specified ua argument, or the detected device. Opera Mini's custom user agent header is supported.

Resize an image to specific dimensions

If you need to resize the image to specific dimensions, specify BOTH the width and the height:

http://localhost:8000/render?url=http%3A%2F%2Fwww.google.co.za%2Fimages%2Fsrpr%2Flogo3w.png&width=100&height=100

Annotate the image with text

Text can be annotated diagonally across the image by adding "annotation=", e.g.

http://localhost:8000/render?url=http%3A%2F%2Fwww.google.co.za%2Fimages%2Fsrpr%2Flogo3w.png&annotation=SAMPLE

Debugging

For debugging purposes the following additional arguments have been exposed:

• nocache - Forces the imager to retrieve the specified image from the source and repopulate the cached copy, rather than use the cached copy.
• debug - Enables detailed debug logging for the request.

User interface

A graphical user interface is available at

http://localhost:8000/ui

Notes to self...

Check out

http://www.imagemagick.org/Usage/annotating/

Some notes from the Imagick website relating to geometry specifications...

size	General description (actual behavior can vary for different options and settings)
scale%	Height and width both scaled by specified percentage.
scale-x%xscale-y%	Height and width individually scaled by specified percentages. (Only one % symbol needed.)
width	Width given, height automagically selected to preserve aspect ratio.
xheight	Height given, width automagically selected to preserve aspect ratio.
widthxheight	Maximum values of height and width given, aspect ratio preserved.
widthxheight^	Minimum values of width and height given, aspect ratio preserved.
widthxheight!	Width and height emphatically given, original aspect ratio ignored.
widthxheight>	Shrinks an image with dimension(s) larger than the corresponding width and/or height argument(s).
widthxheight<	Enlarges an image with dimension(s) smaller than the corresponding width and/or height argument(s).
area@	Resize image to have specified area in pixels. Aspect ratio is preserved.