QSplitter

QSplitter is a widget in the Qt framework that provides a resizable layout for its child widgets. It arranges its children along a single axis (horizontal or vertical) and places draggable handles between adjacent widgets to allow the user to resize them at runtime.

The orientation of the splitter is determined by the constructor or setOrientation and can be Qt.Horizontal or Qt.Vertical. The splitter exposes a handle between every pair of neighboring widgets; users can drag these handles to adjust the relative sizes of the panes. In addition, individual panes can be made collapsible so that dragging to zero size is possible, and the overall resizing behavior can be tuned.

Key operations include adding and inserting widgets with addWidget and insertWidget, retrieving widgets with widget and count, and moving splitter positions with moveSplitter. The sizes of the current panes can be queried or set via sizes() and setSizes(const QList<int>&). Stretch factors can be assigned with setStretchFactor(int index, int stretch) to influence how extra space is allocated during resizing.

QSplitter emits signals such as splitterMoved(int pos, int index) when a handle is moved, enabling the application to react to layout changes. For customization, the appearance and interaction of the handles can be altered by subclassing QSplitterHandle or by replacing the default handle.

QSplitter is commonly used to create multi-pane interfaces where users need control over pane sizes, such as development environments, graphics tools, or complex forms. It is part of the Qt Widgets module and is cross-platform.