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| <TITLE>Content outliners</TITLE> |
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| <h2> |
| Content outliners</h2> |
| <P > |
| Editors often have corresponding <b>content outliners</b> that provide a |
| structured view of the editor contents and assist the user in navigating through |
| the contents of the editor.</P> |
| <P > |
| The workbench provides a standard <b>Outline</b> view for this purpose. |
| The workbench user controls when this view is visible using the <b>Window > Show |
| View</b> menu.</P> |
| <P >Since the generic |
| <a href="../reference/api/org/eclipse/ui/editors/text/TextEditor.html"><b> TextEditor</b></a> |
| doesn't know anything about the structure of its text, it cannot provide |
| behavior for an interesting outline view. Therefore, the default <b>Outline</b> view, |
| shown below, doesn't |
| do much.</P> |
| <P ><img src="images/genericoutliner.png" alt="Default content outliner" border="0"></P> |
| <P > </P> |
| <P >Editors in the text framework can supply their own content outliner page to the |
| outline view. The outliner for an editor is specified when the workbench requests an |
| adapter of type <b><a href="../reference/api/org/eclipse/ui/views/contentoutline/IContentOutlinePage.html">IContentOutlinePage</a></b>.</P> |
| <pre> |
| public Object getAdapter(Class required) { |
| if (IContentOutlinePage.class.equals(required)) { |
| if (fOutlinePage == null) { |
| fOutlinePage= new <b>JavaContentOutlinePage</b>(getDocumentProvider(), this); |
| if (getEditorInput() != null) |
| fOutlinePage.setInput(getEditorInput()); |
| } |
| return fOutlinePage; |
| } |
| return super.getAdapter(required); |
| } |
| </pre> |
| |
| |
| <P >A content outliner page must implement <b><a href="../reference/api/org/eclipse/ui/views/contentoutline/IContentOutlinePage.html">IContentOutlinePage</a></b>. |
| This interface combines the ability to notify selection change listeners (<a href="../reference/api/org/eclipse/jface/viewers/ISelectionProvider.html"><b>ISelectionProvider</b></a>) |
| with the behavior of being a page in a view (<a href="../reference/api/org/eclipse/ui/part/IPage.html"><b>IPage</b></a>). |
| Content outliners are typically implemented using JFace viewers. The |
| default implementation of a content outliner (<b><a href="../reference/api/org/eclipse/ui/views/contentoutline/ContentOutlinePage.html">ContentOutlinePage</a></b>) |
| uses a JFace tree viewer to display a hierarchical representation of the |
| outline. This representation is suitable for many structured outliners, including |
| <b>JavaContentOutlinePage</b>.</P> |
| |
| |
| <P >Let's take a look at the implementation of the page. When the outline page |
| is created by the editor in the snippet above, its input element is set to the |
| editor's input element. This input can often be passed directly to the |
| outline page's viewer, as is done below.</P> |
| |
| |
| <pre> |
| public void createControl(Composite parent) { |
| |
| super.createControl(parent); |
| |
| TreeViewer viewer= getTreeViewer(); |
| viewer.setContentProvider(new ContentProvider()); |
| viewer.setLabelProvider(new LabelProvider()); |
| viewer.addSelectionChangedListener(this); |
| |
| if (fInput != null) |
| viewer.setInput(fInput); |
| } |
| </pre> |
| |
| |
| <P >The tree viewer creation is inherited from <b><a href="../reference/api/org/eclipse/ui/views/contentoutline/ContentOutlinePage.html">ContentOutlinePage</a></b>. |
| The standard label provider is used. The content provider is provided inside |
| <b>JavaContentOutlinePage</b> and is responsible for parsing the editor input into |
| individual segments whenever it changes.</P> |
| |
| |
| <pre> |
| public void inputChanged(Viewer viewer, Object oldInput, Object newInput) { |
| ... |
| if (newInput != null) { |
| IDocument document= fDocumentProvider.getDocument(newInput); |
| if (document != null) { |
| document.addPositionCategory(SEGMENTS); |
| document.addPositionUpdater(fPositionUpdater); |
| parse(document); |
| } |
| } |
| } |
| </pre> |
| |
| |
| <P >The text is parsed into ranges, called segments, within the document. |
| These segments are displayed by name in the outline view.</P> |
| |
| |
| <P ><img src="images/javacontentoutline.png" alt="Java example outliner" border="0"></P> |
| |
| |
| <P >When the selection changes, the selected segment is |
| retrieved. Its offsets are used to set the highlight range in the editor.</P> |
| |
| |
| <pre> |
| public void selectionChanged(SelectionChangedEvent event) { |
| |
| super.selectionChanged(event); |
| |
| ISelection selection= event.getSelection(); |
| if (selection.isEmpty()) |
| fTextEditor.resetHighlightRange(); |
| else { |
| Segment segment= (Segment) ((IStructuredSelection) selection).getFirstElement(); |
| int start= segment.position.getOffset(); |
| int length= segment.position.getLength(); |
| try { |
| fTextEditor.setHighlightRange(start, length, true); |
| } catch (IllegalArgumentException x) { |
| fTextEditor.resetHighlightRange(); |
| } |
| } |
| } |
| </pre> |
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