JavaScript: Bitmap Editing

Following on from my discovery of RFC 2397 I realised that we would be able to manipulate the “src” property of the “img” element in JavaScript and thereby change the image being displayed. The Base64 encoding is conveniently handled by JavaScript’s (non-standard but ubiquitous in the browser) btoa function (2008-05-10: ubiquitous apart from Opera, that is). I chose OS/2’s BMP image file format as being suitably simple to manipulate.

The result is BME (BitMap Editor). Note that all the work is done by client-side JavaScript, there’s no server side programming or communication at all (that would be madness!).

Bi-level any-colour-you-like-as-long-as-it’s-grey-and-blue at the moment. I suggest you right-click to save.

This use of RFC 2397 shows up some bugs and misfeatures of the OS X user interface. For example, dragging the image onto Mail.app opens a new mail message containing the contents of the URL as text rather than an image.