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<topic_start>
Debugging
<topic_end>
<topic_start>
What tools can I use to debug my app in Flutter?
Use the DevTools suite for debugging Flutter or Dart apps.DevTools includes support for profiling, examining the heap,
inspecting the widget tree, logging diagnostics, debugging,
observing executed lines of code, debugging memory leaks and memory
fragmentation. For more information, see the
DevTools documentation.If you’re using an IDE,
you can debug your application using the IDE’s debugger.<topic_end>
<topic_start>
How do I perform a hot reload?
Flutter’s Stateful Hot Reload feature helps you quickly and easily experiment,
build UIs, add features, and fix bugs. Instead of recompiling your app
every time you make a change, you can hot reload your app instantly.
The app is updated to reflect your change,
and the current state of the app is preserved.In React Native,
the shortcut is ⌘R for the iOS Simulator and tapping R twice on
Android emulators.In Flutter, If you are using IntelliJ IDE or Android Studio,
you can select Save All (⌘s/ctrl-s), or you can click the
Hot Reload button on the toolbar. If you
are running the app at the command line using flutter run,
type r in the Terminal window.
You can also perform a full restart by typing R in the
Terminal window.<topic_end>
<topic_start>
How do I access the in-app developer menu?
In React Native, the developer menu can be accessed by shaking your device: ⌘D
for the iOS Simulator or ⌘M for Android emulator.In Flutter, if you are using an IDE, you can use the IDE tools. If you start
your application using flutter run you can also access the menu by typing h
in the terminal window, or type the following shortcuts:<topic_end>
<topic_start>
Animation
Well-designed animation makes a UI feel intuitive,
contributes to the look and feel of a polished app,
and improves the user experience.
Flutter’s animation support makes it easy
to implement simple and complex animations.
The Flutter SDK includes many Material Design widgets
that include standard motion effects,
and you can easily customize these effects
to personalize your app.In React Native, Animated APIs are used to create animations.In Flutter, use the Animation
class and the AnimationController class.
Animation is an abstract class that understands its
current value and its state (completed or dismissed).
The AnimationController class lets you
play an animation forward or in reverse,
or stop animation and set the animation
to a specific value to customize the motion.<topic_end>
<topic_start>
How do I add a simple fade-in animation?
In the React Native example below, an animated component,
FadeInView is created using the Animated API.
The initial opacity state, final state, and the
duration over which the transition occurs are defined.
The animation component is added inside the Animated component,
the opacity state fadeAnim is mapped
to the opacity of the Text component that we want to animate,
and then, start() is called to start the animation.To create the same animation in Flutter, create an
AnimationController object named controller
and specify the duration. By default, an AnimationController
linearly produces values that range from 0.0 to 1.0,
during a given duration. The animation controller generates a new value
whenever the device running your app is ready to display a new frame.
Typically, this rate is around 60 values per second.When defining an AnimationController,
you must pass in a vsync object.
The presence of vsync prevents offscreen
animations from consuming unnecessary resources.
You can use your stateful object as the vsync by adding
TickerProviderStateMixin to the class definition.
An AnimationController needs a TickerProvider,
which is configured using the vsync argument on the constructor.A Tween describes the interpolation between a
beginning and ending value or the mapping from an input
range to an output range. To use a Tween object
with an animation, call the Tween object’s animate()
method and pass it the Animation object that you want to modify.For this example, a FadeTransition
widget is used and the opacity property is
mapped to the animation object.To start the animation, use controller.forward().
Other operations can also be performed using the
controller such as fling() or repeat().
For this example, the FlutterLogo
widget is used inside the FadeTransition widget.
<code_start>import 'package:flutter/material.dart';
void main() {
runApp(const Center(child: LogoFade()));
}
class LogoFade extends StatefulWidget {
const LogoFade({super.key});
@override
State<LogoFade> createState() => _LogoFadeState();
}
class _LogoFadeState extends State<LogoFade>
with SingleTickerProviderStateMixin {
late Animation<double> animation;
late AnimationController controller;
@override
void initState() {
super.initState();
controller = AnimationController(