com.pspdfkit.undo.UndoManager |
A generic manager for undoing/redoing edits on a PdfFragment
. This can be retrieved using getUndoManager()
.
Public Methods | |||||||||||
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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.
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abstract boolean |
canUndo()
Returns whether there are edits that can be undone or not.
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abstract void |
clearHistory()
Clears the history of all currently recorded edits.
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abstract void |
redo()
Redoes the next edit or throws an exception if a redo operation is not possible.
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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.
|
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.
listener | OnUndoHistoryChangeListener that should be notified. Must be non-null . |
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Returns whether there are edits that can be redone or not. If this returns false
a call to redo()
will throw an exception.
true
if a redo operation is possible, false
otherwise.
Returns whether there are edits that can be undone or not. If this returns false
a call to undo()
will throw an exception.
true
if an undo operation is possible, false
otherwise.
Clears the history of all currently recorded edits. After calling this method, this UndoManager
will have no edits that can be undone or redone.
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.
RedoEditFailedException | Thrown if redo operation was unsuccessful, if the redo stack was empty, or if the last edit is not redoable. |
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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.
listener | OnUndoHistoryChangeListener that should be removed. Must be non-null . |
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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.
UndoEditFailedException | Thrown if an undo operation was unsuccessful, if the undo stack was empty, or if the last edit is not undoable. |
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