Class: QgsLayoutUndoStack

An undo stack for QgsLayouts.

Class Hierarchy

Base classes

QObject

Methods

beginCommand	Begins a new undo command for the specified object.
beginMacro	Starts a macro command, with the given descriptive commandText.
blockCommands	Sets whether undo commands for the layout should be temporarily blocked.
cancelCommand	Cancels the active command, discarding it without pushing to the undo history.
endCommand	Saves final state of an object and pushes the active command to the undo history.
endMacro	Ends a macro command.
isBlocked	Returns True if undo commands are currently blocked.
notifyUndoRedoOccurred	Notifies the stack that an undo or redo action occurred for a specified item.
push	Manually pushes a command to the stack, and takes ownership of the command.
stack	Returns a pointer to the internal QUndoStack.

Signals

undoRedoOccurredForItems

Emitted when an undo or redo action has occurred, which affected a set of layout itemUuids.

class qgis.core.QgsLayoutUndoStack

Bases: QObject

__init__(layout: QgsLayout | None)

Constructor for QgsLayoutUndoStack, for the specified parent layout.

Parameters:

layout (Optional[QgsLayout])

beginCommand(self, object: QgsLayoutUndoObjectInterface | None, commandText: str | None, id: int = 0)

Begins a new undo command for the specified object.

This must be followed by a call to endCommand() or cancelCommand() after the desired changes have been made to object.

The id argument can be used to specify an id number for the source event - this is used to determine whether QUndoCommand command compression can apply to the command.

See also

endCommand()

See also

cancelCommand()

Parameters:

• object (Optional[QgsLayoutUndoObjectInterface])

• commandText (Optional[str])

• id (int = 0)

beginMacro(self, commandText: str | None)

Starts a macro command, with the given descriptive commandText.

Any commands added to the stack (either via direct manipulation of stack() or via beginCommand()/endCommand() calls) between a beginMacro() and endMacro() block are collapsed into a single undo command, which will be applied or rolled back in a single step.

See also

endMacro()

Parameters:

commandText (Optional[str])

blockCommands(self, blocked: bool)

Sets whether undo commands for the layout should be temporarily blocked.

If blocked is True, subsequent undo commands will be blocked until a follow-up call to blockCommands( False ) is made.

Note that calls to blockCommands are stacked, so two calls blocking the commands will take two calls unblocking commands in order to release the block.

See also

isBlocked()

Parameters:

blocked (bool)

cancelCommand(self)

Cancels the active command, discarding it without pushing to the undo history.

See also

endCommand()

See also

cancelCommand()

endCommand(self)

Saves final state of an object and pushes the active command to the undo history.

See also

beginCommand()

See also

cancelCommand()

endMacro(self)

Ends a macro command. This must be called after beginMacro(), when all child undo commands which form part of the macro have been completed.

Any commands added to the stack (either via direct manipulation of stack() or via beginCommand()/endCommand() calls) between a beginMacro() and endMacro() block are collapsed into a single undo command, which will be applied or rolled back in a single step.

See also

beginMacro()

isBlocked(self) → bool

Returns True if undo commands are currently blocked.

See also

blockCommands()

Return type:

bool

notifyUndoRedoOccurred(self, item: QgsLayoutItem | None)

Notifies the stack that an undo or redo action occurred for a specified item.

Parameters:

item (Optional[QgsLayoutItem])

push(self, command: QUndoCommand | None)

Manually pushes a command to the stack, and takes ownership of the command.

Parameters:

command (Optional[QUndoCommand])

stack(self) → QUndoStack | None

Returns a pointer to the internal QUndoStack.

Return type:

Optional[QUndoStack]

signal undoRedoOccurredForItems(itemUuids: Set[str])

Emitted when an undo or redo action has occurred, which affected a set of layout itemUuids.

Parameters:

itemUuids (Set[str])