# Package org.eclipse.jface.text.source.projection

package org.eclipse.jface.text.source.projection

This package provides the UI part for projection documents of which the most important part is the projection viewer. A projection viewer is a text viewer that allows to expand and collapse folded regions defined by a projection document. This package also introduces a projection annotation model, projection annotations. The projection viewer offers support to show a summary for a folded region.

## Package Specification

`ProjectionViewer` is a specialized `SourceViewer` that can display line-based folding based on a `ProjectionDocument`. To do this it uses supporting classes like `IProjectionListener`, `IProjectionPosition`, `ProjectionAnnotation` and others.

Related Packages
Package
Description
org.eclipse.jface.text.source
Provides a framework for connecting document regions with annotations and for displaying those.
org.eclipse.jface.text.source.inlined
Class
Description
AnnotationBag
A bag of annotations.
IProjectionListener
Implementers registered with a `ProjectionViewer` get informed when the projection mode of the viewer gets enabled and when it gets disabled.
IProjectionPosition
An `IProjectionPosition` is a position that is associated with a `ProjectionAnnotation` and that is able to compute its collapsed regions.
ProjectionAnnotation
Annotation used to represent the projection of a master document onto a `ProjectionDocument`.
ProjectionAnnotationModel
A projection annotation model.
ProjectionSupport
Supports the configuration of projection capabilities a `ProjectionViewer`.
ProjectionViewer
A projection source viewer is a source viewer which supports multiple visible regions which can dynamically be changed.