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<topic_start>
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Debugging
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<topic_end>
|
<topic_start>
|
What tools can I use to debug my app in Flutter?
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Use the DevTools suite for debugging Flutter or Dart apps.DevTools includes support for profiling, examining the heap,
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inspecting the widget tree, logging diagnostics, debugging,
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observing executed lines of code, debugging memory leaks and memory
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fragmentation. For more information, see the
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DevTools documentation.If you’re using an IDE,
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you can debug your application using the IDE’s debugger.<topic_end>
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<topic_start>
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How do I perform a hot reload?
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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.
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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,
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type r in the Terminal window.
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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?
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In React Native, the developer menu can be accessed by shaking your device: ⌘D
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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
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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
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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
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play an animation forward or in reverse,
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or stop animation and set the animation
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to a specific value to customize the motion.<topic_end>
|
<topic_start>
|
How do I add a simple fade-in animation?
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In the React Native example below, an animated component,
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FadeInView is created using the Animated API.
|
The initial opacity state, final state, and the
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duration over which the transition occurs are defined.
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The animation component is added inside the Animated component,
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the opacity state fadeAnim is mapped
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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
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linearly produces values that range from 0.0 to 1.0,
|
during a given duration. The animation controller generates a new value
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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.
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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() {
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runApp(const Center(child: LogoFade()));
|
}
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class LogoFade extends StatefulWidget {
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const LogoFade({super.key});
|
@override
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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(
|
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