Design Patterns Applied in VGLViewer

An index of Gang of Four patterns applied in VGLViewer

What's a design pattern?
Check out the Wikipedia definition and the canonical book Design Patterns: Elements of Reusable Object-Oriented Software (ISBN 0-201-63361-2).

Category	Pattern	VGLViewer Package	How applied
Creational	Builder	vglDocument.utils	Defines VGLDocumentBuilder, which implements a Builder.
	Factory Method	vglDocument	Users of package vglDocument are required to implement AbstractVGLFontFactory, which creates VGLFonts
	Factory Method	vglViewer	AWT_VGLFontFactory implements AbstractVGLFontFactory to create VGLFonts with VGLFontMetrics compatible with AWT.
Structural	Adapter	vglviewer	SDAZDocViewPanelSubject adapts a DocViewPanel to a SDAZSubject.
	Composite	boundaryMap	BoundaryMap implements a KD-tree for fast intersection tests and is the Composite, Leaf and Component particpant in the Composite design pattern.
	Decorator	vglViewer	MultiErrorHandler decorates an ErrorHandler to buffer multiple error messages.
	Flyweight	vglDocument	Multiple VGLElements can save memory by sharing the same VGLStyle instances.
Behavioural	Observer	docViewPanel	A RepaintObserver can be attached to a DocViewPanel, to be notified whenever the DocViewPanel has painted itself.
	Observer	vglViewer	A ViewPanel attaches a DocViewMouseListener to its DocViewPanel, to be notified of any mouse events on DocViewPanel
	State	vglDocument.utils	Package vglDocument.utils defines VGLDocumentBuilder which switches internally between different implementations of AbstractBuilderState as it builds different types of document element.
		sdaz	SDAZDriver switches between three implementations of SDAZState for its Dormant, Zooming and Restoring phases
		vglViewer	DocViewMouseListener has two states: it is either listening for SDAZ mouse events or for marquee-zoom mouse events.
	Strategy	vglDocument.utils	VGLDocumentLoader drives a user-supplied VGLDocumentBuilder to construct a VGLDocument as it parses XML.
		vglRenderer	VGLDocumentRenderer requires that a user supplies an implementation of VGLRenderingStrategy with whichit can render graphics primitives.
		docViewPanel	DocViewPanel supplies AWTRenderingStrategy, an implementation of VGLRenderingStrategy, to its aggregated VGLRenderer.
	Template Method	boundaryMap	Interface BoundaryMapElement, which requires that implementors define a method to bisect themselves to assist the algorithm within BoundaryMap.
	Template Method	docViewpanel	DoubleBufferedPanel defines paintBuffer, to be implemented by subclass DocViewPanel.
	Visitor	vglDocument	VGLElements within a VGLDocument can be visited with a VGLElementVisitor.

The patterns identified here are described in detail in the book Design Patterns: Elements of Reusable Object-Oriented Software (ISBN 0-201-63361-2).