*
* The Document is a container for text that serves
* as the model for swing text components. The goal for this
* interface is to scale from very simple needs (a plain text textfield)
* to complex needs (an HTML or XML document, for example).
*
*
Content *
* At the simplest level, text can be * modeled as a linear sequence of characters. To support * internationalization, the Swing text model uses * unicode characters. * The sequence of characters displayed in a text component is * generally referred to as the component's content. *
* To refer to locations within the sequence, the coordinates * used are the location between two characters. As the diagram * below shows, a location in a text document can be referred to * as a position, or an offset. This position is zero-based. *
*
* In the example, if the content of a document is the * sequence "The quick brown fox," as shown in the preceding diagram, * the location just before the word "The" is 0, and the location after * the word "The" and before the whitespace that follows it is 3. * The entire sequence of characters in the sequence "The" is called a * range. *
The following methods give access to the character data * that makes up the content. *
Structure *
* Text is rarely represented simply as featureless content. Rather, * text typically has some sort of structure associated with it. * Exactly what structure is modeled is up to a particular Document * implementation. It might be as simple as no structure (i.e. a * simple text field), or it might be something like diagram below. *
*
* The unit of structure (i.e. a node of the tree) is referred to * by the Element interface. Each Element * can be tagged with a set of attributes. These attributes * (name/value pairs) are defined by the * AttributeSet interface. *
The following methods give access to the document structure. *
Mutations *
* All documents need to be able to add and remove simple text. * Typically, text is inserted and removed via gestures from * a keyboard or a mouse. What effect the insertion or removal * has upon the document structure is entirely up to the * implementation of the document. *
The following methods are related to mutation of the * document content: *
Notification *
* Mutations to the Document must be communicated to
* interested observers. The notification of change follows the event model
* guidelines that are specified for JavaBeans. In the JavaBeans
* event model, once an event notification is dispatched, all listeners
* must be notified before any further mutations occur to the source
* of the event. Further, order of delivery is not guaranteed.
*
* Notification is provided as two separate events,
* DocumentEvent, and
* UndoableEditEvent.
* If a mutation is made to a Document through its api,
* a DocumentEvent will be sent to all of the registered
* DocumentListeners. If the Document
* implementation supports undo/redo capabilities, an
* UndoableEditEvent will be sent
* to all of the registered UndoableEditListeners.
* If an undoable edit is undone, a DocumentEvent should be
* fired from the Document to indicate it has changed again.
* In this case however, there should be no UndoableEditEvent
* generated since that edit is actually the source of the change
* rather than a mutation to the Document made through its
* api.
*
*
* Referring to the above diagram, suppose that the component shown * on the left mutates the document object represented by the blue * rectangle. The document responds by dispatching a DocumentEvent to * both component views and sends an UndoableEditEvent to the listening * logic, which maintains a history buffer. *
* Now suppose that the component shown on the right mutates the same * document. Again, the document dispatches a DocumentEvent to both * component views and sends an UndoableEditEvent to the listening logic * that is maintaining the history buffer. *
* If the history buffer is then rolled back (i.e. the last UndoableEdit * undone), a DocumentEvent is sent to both views, causing both of them to * reflect the undone mutation to the document (that is, the * removal of the right component's mutation). If the history buffer again * rolls back another change, another DocumentEvent is sent to both views, * causing them to reflect the undone mutation to the document -- that is, * the removal of the left component's mutation. *
* The methods related to observing mutations to the document are: *
Properties *
* Document implementations will generally have some set of properties
* associated with them at runtime. Two well known properties are the
* StreamDescriptionProperty,
* which can be used to describe where the Document came from,
* and the TitleProperty, which can be used to
* name the Document. The methods related to the properties are:
*
For more information on the Document class, see
* The Swing Connection
* and most particularly the article,
*
* The Element Interface.
*
* @author Timothy Prinzing
*
* @see javax.swing.event.DocumentEvent
* @see javax.swing.event.DocumentListener
* @see javax.swing.event.UndoableEditEvent
* @see javax.swing.event.UndoableEditListener
* @see Element
* @see Position
* @see AttributeSet
*/
public interface Document {
/**
* Returns number of characters of content currently
* in the document.
*
* @return number of characters >= 0
*/
public int getLength();
/**
* Registers the given observer to begin receiving notifications
* when changes are made to the document.
*
* @param listener the observer to register
* @see Document#removeDocumentListener
*/
public void addDocumentListener(DocumentListener listener);
/**
* Unregisters the given observer from the notification list
* so it will no longer receive change updates.
*
* @param listener the observer to register
* @see Document#addDocumentListener
*/
public void removeDocumentListener(DocumentListener listener);
/**
* Registers the given observer to begin receiving notifications
* when undoable edits are made to the document.
*
* @param listener the observer to register
* @see javax.swing.event.UndoableEditEvent
*/
public void addUndoableEditListener(UndoableEditListener listener);
/**
* Unregisters the given observer from the notification list
* so it will no longer receive updates.
*
* @param listener the observer to register
* @see javax.swing.event.UndoableEditEvent
*/
public void removeUndoableEditListener(UndoableEditListener listener);
/**
* Gets the properties associated with the document.
*
* @param key a non-null property key
* @return the properties
* @see #putProperty(Object, Object)
*/
public Object getProperty(Object key);
/**
* Associates a property with the document. Two standard
* property keys provided are:
* StreamDescriptionProperty and
* TitleProperty.
* Other properties, such as author, may also be defined.
*
* @param key the non-null property key
* @param value the property value
* @see #getProperty(Object)
*/
public void putProperty(Object key, Object value);
/**
* Removes a portion of the content of the document.
* This will cause a DocumentEvent of type
* DocumentEvent.EventType.REMOVE to be sent to the
* registered DocumentListeners, unless an exception
* is thrown. The notification will be sent to the
* listeners by calling the removeUpdate method on the
* DocumentListeners.
*
* To ensure reasonable behavior in the face
* of concurrency, the event is dispatched after the
* mutation has occurred. This means that by the time a
* notification of removal is dispatched, the document
* has already been updated and any marks created by
* createPosition have already changed.
* For a removal, the end of the removal range is collapsed
* down to the start of the range, and any marks in the removal
* range are collapsed down to the start of the range.
*
*
* If the Document structure changed as result of the removal, * the details of what Elements were inserted and removed in * response to the change will also be contained in the generated * DocumentEvent. It is up to the implementation of a Document * to decide how the structure should change in response to a * remove. *
* If the Document supports undo/redo, an UndoableEditEvent will * also be generated. * * @param offs the offset from the beginning >= 0 * @param len the number of characters to remove >= 0 * @exception BadLocationException some portion of the removal range * was not a valid part of the document. The location in the exception * is the first bad position encountered. * @see javax.swing.event.DocumentEvent * @see javax.swing.event.DocumentListener * @see javax.swing.event.UndoableEditEvent * @see javax.swing.event.UndoableEditListener */ public void remove(int offs, int len) throws BadLocationException; /** * Inserts a string of content. This will cause a DocumentEvent * of type DocumentEvent.EventType.INSERT to be sent to the * registered DocumentListers, unless an exception is thrown. * The DocumentEvent will be delivered by calling the * insertUpdate method on the DocumentListener. * The offset and length of the generated DocumentEvent * will indicate what change was actually made to the Document. *
*
* If the Document structure changed as result of the insertion, * the details of what Elements were inserted and removed in * response to the change will also be contained in the generated * DocumentEvent. It is up to the implementation of a Document * to decide how the structure should change in response to an * insertion. *
* If the Document supports undo/redo, an UndoableEditEvent will * also be generated. * * @param offset the offset into the document to insert the content >= 0. * All positions that track change at or after the given location * will move. * @param str the string to insert * @param a the attributes to associate with the inserted * content. This may be null if there are no attributes. * @exception BadLocationException the given insert position is not a valid * position within the document * @see javax.swing.event.DocumentEvent * @see javax.swing.event.DocumentListener * @see javax.swing.event.UndoableEditEvent * @see javax.swing.event.UndoableEditListener */ public void insertString(int offset, String str, AttributeSet a) throws BadLocationException; /** * Fetches the text contained within the given portion * of the document. * * @param offset the offset into the document representing the desired * start of the text >= 0 * @param length the length of the desired string >= 0 * @return the text, in a String of length >= 0 * @exception BadLocationException some portion of the given range * was not a valid part of the document. The location in the exception * is the first bad position encountered. */ public String getText(int offset, int length) throws BadLocationException; /** * Fetches the text contained within the given portion * of the document. *
* If the partialReturn property on the txt parameter is false, the * data returned in the Segment will be the entire length requested and * may or may not be a copy depending upon how the data was stored. * If the partialReturn property is true, only the amount of text that * can be returned without creating a copy is returned. Using partial * returns will give better performance for situations where large * parts of the document are being scanned. The following is an example * of using the partial return to access the entire document: * *
*
* int nleft = doc.getDocumentLength();
* Segment text = new Segment();
* int offs = 0;
* text.setPartialReturn(true);
* while (nleft > 0) {
* doc.getText(offs, nleft, text);
* // do someting with text
* nleft -= text.count;
* offs += text.count;
* }
*
* * Typically there will be only one document structure, but the interface * supports building an arbitrary number of structural projections over the * text data. The document can have multiple root elements to support * multiple document structures. Some examples might be: *
*Runnable used to render the model
*/
public void render(Runnable r);
/**
* The property name for the description of the stream
* used to initialize the document. This should be used
* if the document was initialized from a stream and
* anything is known about the stream.
*/
public static final String StreamDescriptionProperty = "stream";
/**
* The property name for the title of the document, if
* there is one.
*/
public static final String TitleProperty = "title";
}