build abstract method
Describes the part of the user interface represented by this component.
The framework calls this method in a number of different situations. For example:
- After calling initState.
- After calling didUpdateComponent.
- After receiving a call to setState.
- After a dependency of this State object changes (e.g., an InheritedComponent referenced by the previous build changes).
- After calling deactivate and then reinserting the State object into the tree at another location.
This method can potentially be called in every frame and should not have any side effects beyond building a component.
The framework replaces the subtree below this component with the component returned by this method, either by updating the existing subtree or by removing the subtree and inflating a new subtree, depending on whether the component returned by this method can update the root of the existing subtree, as determined by calling Component.canUpdate.
Typically implementations return a newly created constellation of components that are configured with information from this component's constructor, the given BuildContext, and the internal state of this State object.
The given BuildContext contains information about the location in the
tree at which this component is being built. For example, the context
provides the set of inherited components for this location in the tree. The
BuildContext argument is always the same as the context property of
this State object and will remain the same for the lifetime of this
object. The BuildContext argument is provided redundantly here so that
this method matches the signature for a ComponentBuilder.
See also:
- StatefulComponent, which contains the discussion on performance considerations.
Implementation
@protected
Iterable<Component> build(BuildContext context);