Indyvon [INteractive DYnamic VisualizatiON] is an experimental GUI
library for Clojure. Indyvon allows you to build and draw interactive
objects in immediate mode without maintaining a scene graph or a
hierarchy of widgets.

It is based around the idea of basically stateless UI elements defined
by the following simple protocol:

    (defprotocol View
      (render! [view]
        "Draws the view.")
      (geometry [view]
        "Returns preferred size for the view."))

View functions are called in the View context which is defined by
bindings to vars including:

-   `*graphics*` — an instance of java.awt.Graphics2D used for drawing;
-   `*width*` and `*height*` — size of the drawing bounds;
-   `*clip*` — clipping area (instance of java.awt.geom.Shape).

In the `render!` function View could draw using the provided Graphics2D
instance, display another Views at the specified locations relative to
it's own context, and register event handlers.

Event dispatching is done by remembering the clipping areas and affine
transforms of visible View contexts after every repaint for the time
until the rendering of the next frame is complete.

It is possible to draw Views asynchronously in parallel threads by
wrapping them in `async-view`, which uses two off-screen buffers (triple
buffering) to avoid locking.