QAction

QAction is a class in the Qt application framework that represents an abstract user interface action. It is designed to be attached to widgets such as menus, toolbars, or custom controls, enabling a single action to drive multiple UI elements and maintain consistent behavior across the interface.

Key features include a text label, an icon, and a shortcut (keyboard sequence). An action can also provide a status tip, a what’s this help text, and a data payload for application-specific information. It can be marked as checkable, with a checked state that can be controlled programmatically. Actions can be added to a QActionGroup to implement mutually exclusive selections, and enabling or disabling the action propagates to all widgets that reference it.

Signals associated with QAction include triggered(bool) and toggled(bool). The triggered signal is emitted when the user activates the action, with the boolean indicating the new checked state for checkable actions. The toggled signal notifies listeners when the check state changes. Additional signals such as hovered() and changed() may be emitted when the action is interacted with or its properties change.

Usage typically involves creating a QAction with a parent object, configuring its text, icon, and shortcut, and connecting its signals to application slots. The same QAction instance can be added to multiple menus and toolbars, ensuring a unified response to user input. This approach allows a single action to drive multiple UI elements and centralize behavior across the application.

Notes: QAction is part of the QtWidgets module; its exact namespace or module may vary across Qt versions. In PyQt/PySide bindings, the concept and API are mirrored.