class QUndoGroup

The QUndoGroup class is a group of QUndoStack objects. More…

Inheritance diagram of PySide6.QtGui.QUndoGroup

Synopsis

Methods

Slots

Signals

Note

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Detailed Description

For an overview of the Qt’s undo framework, see the overview.

An application often has multiple undo stacks, one for each opened document. At the same time, an application usually has one undo action and one redo action, which triggers undo or redo in the active document.

QUndoGroup is a group of QUndoStack objects, one of which may be active. It has an undo() and redo() slot, which calls undo() and redo() for the active stack. It also has the functions createUndoAction() and createRedoAction() . The actions returned by these functions behave in the same way as those returned by createUndoAction() and createRedoAction() of the active stack.

Stacks are added to a group with addStack() and removed with removeStack() . A stack is implicitly added to a group when it is created with the group as its parent QObject.

It is the programmer’s responsibility to specify which stack is active by calling setActive() , usually when the associated document window receives focus. The active stack may also be set with setActiveStack() , and is returned by activeStack() .

When a stack is added to a group using addStack() , the group does not take ownership of the stack. This means the stack has to be deleted separately from the group. When a stack is deleted, it is automatically removed from a group. A stack may belong to only one group. Adding it to another group will cause it to be removed from the previous group.

A QUndoGroup is also useful in conjunction with QUndoView. If a QUndoView is set to watch a group using QUndoView::setGroup(), it will update itself to display the active stack.

__init__([parent=None])
Parameters:

parent – QObject

Creates an empty QUndoGroup object with parent parent.

See also

addStack()

activeStack()
Return type:

QUndoStack

Returns the active stack of this group.

If none of the stacks are active, or if the group is empty, this function returns None.

activeStackChanged(stack)
Parameters:

stack – QUndoStack

This signal is emitted whenever the active stack of the group changes. This can happen when setActiveStack() or setActive() is called, or when the active stack is removed form the group. stack is the new active stack. If no stack is active, stack is 0.

addStack(stack)
Parameters:

stack – QUndoStack

Adds stack to this group. The group does not take ownership of the stack. Another way of adding a stack to a group is by specifying the group as the stack’s parent QObject in QUndoStack() . In this case, the stack is deleted when the group is deleted, in the usual manner of QObjects.

See also

removeStack() stacks() QUndoStack()

canRedo()
Return type:

bool

Returns the value of the active stack’s canRedo() .

If none of the stacks are active, or if the group is empty, this function returns false.

canRedoChanged(canRedo)
Parameters:

canRedo – bool

This signal is emitted whenever the active stack emits canRedoChanged() or the active stack changes.

canRedo is the new state, or false if the active stack is 0.

canUndo()
Return type:

bool

Returns the value of the active stack’s canUndo() .

If none of the stacks are active, or if the group is empty, this function returns false.

canUndoChanged(canUndo)
Parameters:

canUndo – bool

This signal is emitted whenever the active stack emits canUndoChanged() or the active stack changes.

canUndo is the new state, or false if the active stack is 0.

cleanChanged(clean)
Parameters:

clean – bool

This signal is emitted whenever the active stack emits cleanChanged() or the active stack changes.

clean is the new state, or true if the active stack is 0.

createRedoAction(parent[, prefix=""])
Parameters:

  • parent – QObject

  • prefix – str

Return type:

QAction

Creates an redo QAction object with parent parent.

Triggering this action will cause a call to redo() on the active stack. The text of this action will always be the text of the command which will be redone in the next call to redo() , prefixed by prefix. If there is no command available for redo, if the group is empty or if none of the stacks are active, this action will be disabled.

If prefix is empty, the default template “Redo %1” is used instead of prefix. Before Qt 4.8, the prefix “Redo” was used by default.

createUndoAction(parent[, prefix=""])
Parameters:

  • parent – QObject

  • prefix – str

Return type:

QAction

Creates an undo QAction object with parent parent.

Triggering this action will cause a call to undo() on the active stack. The text of this action will always be the text of the command which will be undone in the next call to undo() , prefixed by prefix. If there is no command available for undo, if the group is empty or if none of the stacks are active, this action will be disabled.

If prefix is empty, the default template “Undo %1” is used instead of prefix. Before Qt 4.8, the prefix “Undo” was used by default.

indexChanged(idx)
Parameters:

idx – int

This signal is emitted whenever the active stack emits indexChanged() or the active stack changes.

idx is the new current index, or 0 if the active stack is 0.

isClean()
Return type:

bool

Returns the value of the active stack’s isClean() .

If none of the stacks are active, or if the group is empty, this function returns true.

See also

setActiveStack()

redo()

Calls redo() on the active stack.

If none of the stacks are active, or if the group is empty, this function does nothing.

redoText()
Return type:

str

Returns the value of the active stack’s redoText() .

If none of the stacks are active, or if the group is empty, this function returns an empty string.

redoTextChanged(redoText)
Parameters:

redoText – str

This signal is emitted whenever the active stack emits redoTextChanged() or the active stack changes.

redoText is the new state, or an empty string if the active stack is 0.

removeStack(stack)
Parameters:

stack – QUndoStack

Removes stack from this group. If the stack was the active stack in the group, the active stack becomes 0.

See also

addStack() stacks() ~QUndoStack()

setActiveStack(stack)
Parameters:

stack – QUndoStack

Sets the active stack of this group to stack.

If the stack is not a member of this group, this function does nothing.

Synonymous with calling setActive() on stack.

The actions returned by createUndoAction() and createRedoAction() will now behave in the same way as those returned by stack's createUndoAction() and createRedoAction() .

stacks()
Return type:

.list of QUndoStack

Returns a list of stacks in this group.

undo()

Calls undo() on the active stack.

If none of the stacks are active, or if the group is empty, this function does nothing.

undoText()
Return type:

str

Returns the value of the active stack’s undoText() .

If none of the stacks are active, or if the group is empty, this function returns an empty string.

undoTextChanged(undoText)
Parameters:

undoText – str

This signal is emitted whenever the active stack emits undoTextChanged() or the active stack changes.

undoText is the new state, or an empty string if the active stack is 0.