View class

Bootstraps a render tree that is rendered into the provided FlutterView.

The content rendered into that view is determined by the provided child. Descendants within the same LookupBoundary can look up the view they are rendered into via View.of and View.maybeOf.

The provided child is wrapped in a MediaQuery constructed from the given view, a FocusScope, and a RawView widget.

For most use cases, using MediaQuery.of, or its associated "...Of" methods are a more appropriate way of obtaining the information that a FlutterView exposes. For example, using MediaQuery.sizeOf will expose the logical device size (MediaQueryData.size) rather than the physical size (FlutterView.physicalSize). Similarly, while FlutterView.padding conveys the information from the operating system, the MediaQueryData.padding attribute (obtained from MediaQuery.paddingOf) further adjusts this information to be aware of the context of the widget; e.g. the Scaffold widget adjusts the values for its various children.

Each FlutterView can be associated with at most one View or RawView widget in the widget tree. Two or more View or RawView widgets configured with the same FlutterView must never exist within the same widget tree at the same time. This limitation is enforced by a GlobalObjectKey that derives its identity from the view provided to this widget.

Since the View widget bootstraps its own independent render tree using its embedded RawView, neither it nor any of its descendants will insert a RenderObject into an existing render tree. Therefore, the View widget can only be used in those parts of the widget tree where it is not required to participate in the construction of the surrounding render tree. In other words, the widget may only be used in a non-rendering zone of the widget tree (see WidgetsBinding for a definition of rendering and non-rendering zones).

In practical terms, the widget is typically used at the root of the widget tree outside of any other View or RawView widget, as a child of a ViewCollection widget, or in the ViewAnchor.view slot of a ViewAnchor widget. It is not required to be a direct child, though, since other non-RenderObjectWidgets (e.g. InheritedWidgets, Builders, or StatefulWidgets/StatelessWidgets that only produce non-RenderObjectWidgets) are allowed to be present between those widgets and the View widget.

See also:

• RawView, the workhorse that View uses to create the render tree, but without the MediaQuery and FocusScope that View adds.
• Element.debugExpectsRenderObjectForSlot, which defines whether a View widget is allowed in a given child slot.