【JfaceTextFramework学习笔记之三】大纲视图

本文探讨了文本编辑器如何提供大纲视图，包括如何获取适配器、实现大纲页面接口、创建视图和更新内容，以及如何响应选择变化。

摘要生成于 C知道，由 DeepSeek-R1 满血版支持，前往体验 >

1-通用的 TextEditor 由于不知道要编辑的文本结构，所以不能提供大纲视图

public Object getAdapter(Class required) {
	if (IContentOutlinePage.class.equals(required)) {
		if (fOutlinePage == null) {
			fOutlinePage= new JavaContentOutlinePage(getDocumentProvider(), this);
			if (getEditorInput() != null)
				fOutlinePage.setInput(getEditorInput());
		}
		return fOutlinePage;
	}
	return super.getAdapter(required);
}

3-A content outliner page must implement IContentOutlinePage.

This interface combines the ability to notify selection change

listeners (ISelectionProvider) with the behavior of being a page

in a view (IPage).  通常在该视图中使用JFace的 TreeViewer来显示文本结构

4- 编辑器的EditInput也要传入大概视图中的Viewer

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);
}
The tree viewer creation is inherited from ContentOutlinePage.  
The standard label provider is used. 
The content provider is provided inside JavaContentOutlinePage 
and is responsible for parsing the editor input into individual 
segments whenever it changes.
	
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);
				}
			}
		}
5-
When the selection changes, the selected segment is retrieved.  
 
Its offsets are used to set the highlight range in the editor.
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();
		}
	}
}