QgsLayoutUndoStack class

An undo stack for QgsLayouts.

Reference

Constructors, destructors, conversion operators

QgsLayoutUndoStack(QgsLayout* layout): Constructor for QgsLayoutUndoStack, for the specified parent layout.

Public functions

void beginCommand(QgsLayoutUndoObjectInterface* object, const QString& commandText, int id = 0): Begins a new undo command for the specified object.
void beginMacro(const QString& commandText): Starts a macro command, with the given descriptive commandText.
void blockCommands(bool blocked): Sets whether undo commands for the layout should be temporarily blocked.
void cancelCommand(): Cancels the active command, discarding it without pushing to the undo history.
void endCommand(): Saves final state of an object and pushes the active command to the undo history.
void endMacro(): Ends a macro command.
auto isBlocked() const -> bool: Returns true if undo commands are currently blocked.
void notifyUndoRedoOccurred(QgsLayoutItem* item): Notifies the stack that an undo or redo action occurred for a specified item.
void push(QUndoCommand* command): Manually pushes a command to the stack, and takes ownership of the command.
auto stack() -> QUndoStack*: Returns a pointer to the internal QUndoStack.

Signals

void undoRedoOccurredForItems(QSet<QString> itemUuids): Emitted when an undo or redo action has occurred, which affected a set of layout itemUuids.

Function documentation

void QgsLayoutUndoStack::beginCommand(QgsLayoutUndoObjectInterface* object, const QString& commandText, int id = 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.

void QgsLayoutUndoStack::beginMacro(const QString& commandText)

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.

void QgsLayoutUndoStack::blockCommands(bool blocked)

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.

void QgsLayoutUndoStack::cancelCommand()

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

void QgsLayoutUndoStack::endCommand()

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

void QgsLayoutUndoStack::endMacro()

Ends a macro command.

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

bool QgsLayoutUndoStack::isBlocked() const

Returns true if undo commands are currently blocked.