QTreeView

QTreeView is a Qt widget that presents data in a hierarchical tree structure. It is part of the Qt Widgets module and implements the view side of Qt's Model/View architecture. A QTreeView renders items provided by a model that implements QAbstractItemModel, with data organized in a tree across one or more columns. The model supplies the data and the hierarchical relationships, while the view handles presentation, selection, and editing.

The view is designed to work with any suitable model, such as QStandardItemModel or a custom subclass of QAbstractItemModel. The root item is not shown by default, and items can be expanded or collapsed. The presence of the expansion indicators can be controlled with setRootIsDecorated(bool), and the indentation between levels is controlled with setIndentation(int). QTreeView supports multiple columns, allowing each item to have data in several columns.

Editing, rendering, and interaction are handled through item delegates and the model/view framework. Editing can be enabled to allow in-place modification of items. The view also supports drag and drop when both the view and model are configured for it, providing drag sources, drop targets, and drop indicators.

Sorting can be enabled with setSortingEnabled(bool); sorting is typically implemented by the model or with a proxy model. The view can be customized further with a header, via header() for multi-column trees, and other visual and interaction options such as uniform row heights.

Typical usage involves creating a model (for example, QStandardItemModel), populating hierarchical items, attaching it with setModel, and optionally enabling features like editing, drag-and-drop, sorting, and performance optimizations such as setUniformRowHeights(true).