Widget Tree
What are the three trees in Flutter's rendering architecture?
Flutter uses three synchronized trees: the Widget tree (immutable blueprints), the Element tree (mutable li...
20 XP3m
Widget Tree
25 questions
3-tree architecture, slivers, constraints, painting
Widget Tree
What is the difference between StatelessWidget and StatefulWidget?
StatelessWidget renders based solely on its constructor arguments and never changes. StatefulWidget maintai...
10 XP2m
Widget Tree
Explain Flutter's constraint-based layout protocol: 'constraints go down, sizes go up'.
Parent passes BoxConstraints (min/max width and height) down to each child. The child determines its own si...
30 XP4m
Widget Tree
When and why should you use Keys in Flutter?
Keys help Flutter's reconciliation algorithm match elements to widgets when the widget type stays the same ...
30 XP3m
Widget Tree
How does InheritedWidget work and what is it used for?
InheritedWidget provides a way to efficiently propagate data down the widget tree. Descendant widgets subsc...
30 XP4m
Widget Tree
What is BuildContext and why does it matter?
BuildContext is a handle to the location of a widget in the element tree. It's used for theme lookups, navi...
20 XP2m
Widget Tree
What are Slivers in Flutter and when should you use them?
Slivers are scrollable areas with a custom scroll effect protocol. They allow fine-grained control over scr...
50 XP5m
Widget Tree
What is RepaintBoundary and how does it help performance?
RepaintBoundary creates an isolated layer in the render tree. When content inside it changes, only that lay...
50 XP3m
Widget Tree
Describe the complete lifecycle of a StatefulWidget.
StatefulWidget lifecycle: createState → initState → didChangeDependencies → build → (didUpdateWidget / setS...
20 XP3m
Widget Tree
How do const constructors improve Flutter performance?
Const widgets are canonicalized at compile time — Flutter skips rebuilding them entirely because it knows t...
20 XP2m
Widget Tree
When would you create a custom RenderObject?
Create a custom RenderObject when you need layout or painting behavior that cannot be achieved by composing...
80 XP6m
Widget Tree
Should you prefer composition or inheritance when building Flutter widgets?
Flutter strongly favors composition over inheritance. Build complex widgets by combining smaller ones rathe...
20 XP2m
Widget Tree
How does Flutter's element reconciliation algorithm work?
Flutter reconciles by checking if the new widget's runtimeType and key match the existing element's. If yes...
50 XP4m
Widget Tree
Why does Flutter throw 'RenderFlex overflowed' and how do you fix it?
RenderFlex overflow occurs when the total intrinsic size of children exceeds the available space in a Row o...
20 XP3m
Widget Tree
What is the difference between GlobalKey and LocalKey?
LocalKey (ValueKey, ObjectKey, UniqueKey) identifies a widget among its siblings. GlobalKey uniquely identi...
30 XP3m
Widget Tree
When should you use LayoutBuilder vs MediaQuery for responsive layouts?
Use LayoutBuilder when you need the constraints available to your widget. Use MediaQuery when you need scre...
30 XP3m
Widget Tree
What is the difference between Opacity, Visibility, and Offstage?
Opacity paints transparently but still lays out and hit-tests. Visibility can remove the widget from layout...
30 XP3m
Widget Tree
When should you use GestureDetector vs InkWell?
Use InkWell for Material Design ripple feedback on tappable widgets. Use GestureDetector for custom gesture...
10 XP2m
Widget Tree
What is the difference between IndexedStack and PageView?
IndexedStack keeps all children in the tree (preserving their state) and shows only one at a time. PageView...
20 XP2m
Widget Tree
Describe Flutter's rendering pipeline from frame start to pixel output.
Flutter's rendering pipeline: vsync signal → build (widget tree diff) → layout (constraints/sizes) → paint ...
80 XP6m
Widget Tree
How does Flutter's box model compare to CSS box model?
Flutter doesn't have a traditional CSS box model. Padding is an explicit widget. 'Margin' is achieved with ...
30 XP3m
Widget Tree
How does CustomPainter work and what are its performance considerations?
CustomPainter provides a Canvas API for arbitrary 2D drawing. Override paint() for drawing logic and should...
50 XP4m
Widget Tree
What is the difference between a widget test and a golden file test?
Widget tests verify widget structure and behavior via finder/matcher APIs. Golden tests render a widget to ...
30 XP3m
Widget Tree
How does NestedScrollView work and when do you need it?
NestedScrollView coordinates scrolling between an outer scrollable (e.g., SliverAppBar) and inner scrollabl...
50 XP4m
Widget Tree
How does Flutter handle accessibility and the Semantics widget?
Flutter builds a semantic tree in parallel with the widget tree. The Semantics widget annotates nodes with ...
30 XP4m