public interface

UndoManager

com.pspdfkit.undo.UndoManager

Class Overview

A generic manager for undoing/redoing edits on a PdfFragment. This can be retrieved using getUndoManager().

Summary

Public Methods
abstract void addOnUndoHistoryChangeListener(OnUndoHistoryChangeListener listener)
Adds an OnUndoHistoryChangeListener for being notified of changes to the undo manager's edit history (i.e.
abstract boolean canRedo()
Returns whether there are edits that can be redone or not.
abstract boolean canUndo()
Returns whether there are edits that can be undone or not.
abstract void clearHistory()
Clears the history of all currently recorded edits.
abstract void redo()
Redoes the next edit or throws an exception if a redo operation is not possible.
abstract void removeOnUndoHistoryChangeListener(OnUndoHistoryChangeListener listener)
Removes a previously added OnUndoHistoryChangeListener.
abstract void undo()
Undoes the last edit or throws an exception if an undo operation is not possible.

Public Methods

public abstract void addOnUndoHistoryChangeListener (OnUndoHistoryChangeListener listener)

Adds an OnUndoHistoryChangeListener for being notified of changes to the undo manager's edit history (i.e. its undo and redo stacks). If a listener has already been added previously, this method will be a no-op. Passing null is not allowed and will result in an exception.

Parameters
listener OnUndoHistoryChangeListener that should be notified. Must be non-null.
See Also

public abstract boolean canRedo ()

Returns whether there are edits that can be redone or not. If this returns false a call to redo() will throw an exception.

Returns
  • true if a redo operation is possible, false otherwise.

public abstract boolean canUndo ()

Returns whether there are edits that can be undone or not. If this returns false a call to undo() will throw an exception.

Returns
  • true if an undo operation is possible, false otherwise.

public abstract void clearHistory ()

Clears the history of all currently recorded edits. After calling this method, this UndoManager will have no edits that can be undone or redone.

public abstract void redo ()

Redoes the next edit or throws an exception if a redo operation is not possible. It's recommended that you check whether a redo operation is available using (canRedo()) before calling this method. Redoing may be unavailable if there are no edits on the redo stack or if the latest edit on the redo stack cannot be redone. When redoing an edit, the edit is moved to the internal undo stack.

Throws
RedoEditFailedException Thrown if redo operation was unsuccessful, if the redo stack was empty, or if the last edit is not redoable.

public abstract void removeOnUndoHistoryChangeListener (OnUndoHistoryChangeListener listener)

Removes a previously added OnUndoHistoryChangeListener. Upon calling this method, listener will no longer be notified of any changes. If listener has not been added previously, this method will be a no-op. Passing null is not allowed, and will result in an exception.

Parameters
listener OnUndoHistoryChangeListener that should be removed. Must be non-null.
See Also

public abstract void undo ()

Undoes the last edit or throws an exception if an undo operation is not possible. It's recommended that you check whether an undo operation is available using (canUndo()) before calling this method. Undoing may be unavailable if there are no edits on the undo stack or if the latest edit on the undo stack cannot be undone. When undoing an edit, the edit is moved to the internal redo stack.

Throws
UndoEditFailedException Thrown if an undo operation was unsuccessful, if the undo stack was empty, or if the last edit is not undoable.