Build owner
- Flutter course
- Expert
- Lesson 4/39
- 4 min
Learn how BuildOwner drives the build process.
Build owner
BuildOwner is the object that manages the build process. When a widget is marked dirty, scheduleBuild schedules a build for the next frame. BuildOwner tracks which elements need to be rebuilt.
final owner = BuildOwner();
owner.scheduleBuildFor(element);
owner.buildScope(element);Dirty element
When setState is called, an element is flagged as dirty. BuildOwner collects dirty elements and rebuilds them inside buildScope. This is Flutter's efficient update model.
Practice BuildOwner instance
In main, create a BuildOwner instance and print its runtimeType.
Starter code
import 'package:flutter/widgets.dart';
void main() {
// BuildOwner örneği oluştur ve runtimeType yazdır
}Sample solution
import 'package:flutter/widgets.dart';
void main() {
final owner = BuildOwner();
print(owner.runtimeType);
}Expected output
BuildOwner
Questions and answers
Review the lesson questions together with their answers. To test yourself, solve the lesson interactively.
1 What does scheduleBuild do?
- Creates a RenderObject
- Schedules a dirty element to be built in the next frame Correct answer
- Makes an HTTP call
- Deletes the element
Explanation: scheduleBuild enqueues a dirty-marked element to be built in the next frame by BuildOwner; it does not build immediately.
2 buildScope call
owner.____(element);owner.buildScope(element);Explanation: owner.buildScope(element) triggers building of dirty elements; scheduleBuildFor only schedules, mount is for first insertion, dispose for removal.
3 BuildOwner matches
| Term | Meaning |
|---|---|
BuildOwner |
Build manager |
scheduleBuild |
Schedules build |
dirty |
Needs rebuild |
buildScope |
Build scope |