Draw2d Overview
Draw2d is a lightweight toolkit of graphical components called figures. Lightweight means that a figure is simply a java object, with no corresponding resource in the operating system. Figures can be composed via a parent-child relationship. Every figure has a rectangular bounds inside which it, and its children, paint. A layout manager can be used to place children based on their index and/or constraint.
A LightweightSystem
associates a figure composition with an SWT
Canvas. The lightweight system hooks listeners for most SWT events, and
forwards most of them to an EventDispatcher
, which translates them
into events on the appropriate figure.
Paint events, however, are forwarded to the UpdateManager
, which
coordinates painting and layout. Figures can be updated in ways which
affect their appearance or size, and the update manager ensures that
only one layout occurs, followed by a repaint of only the region which
was updated.
Any type of diagram, document, or drawing can be easily constructed and efficiently updated by combining the provided figure and layout implementations along with the use of custom figures or layouts when needed.