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770dd48484f7-1 | Flutter is different from other frameworks because its UI
is built in code, not (for example) in an XML file or similar.
Widgets are the basic building blocks of a Flutter UI.
As you progress through this codelab,
you’ll learn that almost everything in Flutter is a widget.
A widget is an immutable object that describes... | https://docs.flutter.dev/codelabs/layout-basics/index.html |
770dd48484f7-2 | 1. Click the Run button.
2. In the code, change the Row to a Column, and run again.
Axis size and alignment
So far, the BlueBox widgets have been squished together
(either to the left or at the top of the UI Output).
You can change how the BlueBox widgets are spaced
out using the axis size and alignment properties.
... | https://docs.flutter.dev/codelabs/layout-basics/index.html |
770dd48484f7-3 | Tip:
MainAxisSize.max is the mainAxisSize property’s default value.
If you don’t specify another value,
the default value is used,
as shown in the previous example.
Example: Modifying axis size
The following example explicitly sets mainAxisSize
to its default value, MainAxisSize.max.
1. Click the Run butto... | https://docs.flutter.dev/codelabs/layout-basics/index.html |
770dd48484f7-4 | Divides the extra space evenly between children
and before and after the children.
Similar to MainAxisAlignment.spaceEvenly,
but reduces half of the space before the first
child and after the last child
to half of the width between the children.
Example: Modifying main axis alignment
The following example explicitly... | https://docs.flutter.dev/codelabs/layout-basics/index.html |
770dd48484f7-5 | Positions children at the middle of the cross axis. (Middle for Row, Center for Column)
Stretches children across the cross axis.
(Top-to-bottom for Row, left-to-right for Column)
Aligns children by their character baselines.
(Text class only, and requires that the
textBaseline property is set to
TextBaseline.alphabe... | https://docs.flutter.dev/codelabs/layout-basics/index.html |
770dd48484f7-6 | Tip:
Before moving to the next section,
change CrossAxisAlignment.start to another value.
Flexible widget
Compares itself against other flex
properties before determining what fraction of the
total remaining space each Flexible widget receives.
Determines whether a Flexible widget
fills all of its extra space.
... | https://docs.flutter.dev/codelabs/layout-basics/index.html |
770dd48484f7-7 | Example: Testing flex values
When flex properties are compared against one another,
the ratio between their flex values determines
what fraction of the total remaining space each
Flexible widget receives.
remainingSpace
flex
totalOfAllFlexValues
In this example, the sum of the flex values (2),
determines t... | https://docs.flutter.dev/codelabs/layout-basics/index.html |
770dd48484f7-8 | 1. Click the Run button.
2. Wrap the second BlueBox widget in an Expanded widget.
For example:
Expanded
child:
BlueBox
(),),
3. Select the Format button to properly format the code,
and run again.
SizedBox widget
Example: Resizing a widget
The following example wraps the middle BlueBox widget inside ... | https://docs.flutter.dev/codelabs/layout-basics/index.html |
770dd48484f7-9 | Example: Creating space
The following example contains three BlueBox widgets
and one SizedBox widget that separates the first
and second BlueBox widgets. The SizedBox widget
contains a width property equal to 50 logical pixels.
1. Click the Run button.
2. Create more space by adding another
SizedBox w... | https://docs.flutter.dev/codelabs/layout-basics/index.html |
770dd48484f7-10 | Text widget
The Text widget displays text and can be configured
for different fonts, sizes, and colors.
Example: Aligning text
The following example displays “Hey!” three times,
but at different font sizes and in different colors.
Row specifies the crossAxisAlignment
and textBaseline properties.
1. Click the ... | https://docs.flutter.dev/codelabs/layout-basics/index.html |
770dd48484f7-11 | 3. Give the Icon a color of Colors.amber from the
Material Color palette, and run again.
Image widget
The Image widget displays an image.
You either can reference images using a URL,
or you can include images inside your app package.
Since DartPad can’t package an image,
the following example uses an image f... | https://docs.flutter.dev/codelabs/layout-basics/index.html |
770dd48484f7-12 | 3. Then change pic1.jpg to pic2.jpg or pic3.jpg,
and run again.
Putting it all together
You’re almost at the end of this codelab.
If you’d like to test your knowledge of the
techniques that you’ve learned, why not apply
those skills into building a Flutter UI that
displays a business card!
You’ll break down... | https://docs.flutter.dev/codelabs/layout-basics/index.html |
770dd48484f7-13 | Part 1
Exercise: Create the name and title
Implement a Column that contains two text widgets:
The first Text widget has the name Flutter McFlutter and
the style property set to Theme.of(context).textTheme.headlineSmall.
The second Text widget contains the title Experienced App Developer.
For the Column,
set ma... | https://docs.flutter.dev/codelabs/layout-basics/index.html |
770dd48484f7-14 | The Row should look like this:
Row
children:
Padding
padding:
const
EdgeInsets
all
8.0
),
child:
Icon
Icons
account_circle
size:
50
),
),
Column
...
),
// <--- The Column you first implemented
],
);
Part 2
Exercise: Tweak the layout
A SizedBox widget with a height of 8.
An empty Row where you... | https://docs.flutter.dev/codelabs/layout-basics/index.html |
770dd48484f7-15 | A second SizedBox widget with a height of 16.
A second empty Row where you’ll add
four icons (Part 3).
The Column’s list of widgets should be formatted as follows,
so the contact information and icons are displayed below the
name and title:
],
),
// <--- Closing parenthesis for the Row
SizedBox
(),
Row
(),... | https://docs.flutter.dev/codelabs/layout-basics/index.html |
770dd48484f7-16 | Enter two Text widgets inside the first empty Row :
The first Text widget contains the address 123 Main Street.
The second Text widget contains the phone number (415) 555-0198.
For the first empty Row,
set the mainAxisAlignment property to
MainAxisAlignment.spaceBetween.
Part 3
Exercise: Add four icons
Enter ... | https://docs.flutter.dev/codelabs/layout-basics/index.html |
770dd48484f7-17 | What’s next?
Congratulations, you’ve finished this codelab!
If you’d like to know more about Flutter,
here are a few suggestions for resources worth exploring:
Learn more about layouts in Flutter by
visiting the Building layouts page.
Check out the sample apps.
Visit Flutter’s YouTube channel,
where you can watch a... | https://docs.flutter.dev/codelabs/layout-basics/index.html |
e3783a92f014-0 | Using Flutter in China
Configuring Flutter to use a mirror site
Community-run mirror sites
The Flutter community has made a Simplified Chinese version of the
Flutter website available at
https://flutter.cn.
If you’d like to install Flutter using an
installation bundle,
you can replace the domain of the original UR... | https://docs.flutter.dev/community/china/index.html |
e3783a92f014-1 | Important:
Use mirror sites only if you trust the provider.
The Flutter team cannot verify their reliability or security.
Configuring Flutter to use a mirror site
If you’re installing or using Flutter in China, it may be helpful to use
a trustworthy local mirror site that hosts Flutter’s dependencies.
To instruct... | https://docs.flutter.dev/community/china/index.html |
e3783a92f014-2 | export
FLUTTER_STORAGE_BASE_URL
=https://storage.flutter-io.cn
git clone
b dev https://github.com/flutter/flutter.git
export
PATH
$PWD
/flutter/bin:
$PATH
cd ./flutter
flutter doctor
After these steps, you should be able to continue
setting up Flutter normally.
From here on, packages fetched by flutter pub ... | https://docs.flutter.dev/community/china/index.html |
e3783a92f014-3 | The flutter-io.cn server is a provisional mirror for Flutter
dependencies and packages maintained by GDG China.
The Flutter team cannot guarantee long-term availability of this service.
You’re free to use other mirrors if they become available. If you’re
interested in setting up your own mirror in China, contact
flutte... | https://docs.flutter.dev/community/china/index.html |
59721f97162f-0 | Animate a widget using a physics simulation
Fade a widget in and out
Animate the properties of a container
Cookbook
Animation
Animate the properties of a container
1. Create a StatefulWidget with default properties
2. Build an AnimatedContainer using the properties
3. Start the animation by rebuilding with new ... | https://docs.flutter.dev/cookbook/animation/animated-container/index.html |
59721f97162f-1 | To animate these properties,
Flutter provides the AnimatedContainer widget.
Like the Container widget, AnimatedContainer allows you to define
the width, height, background colors, and more. However, when the
AnimatedContainer is rebuilt with new properties, it automatically
animates between the old and new values. In F... | https://docs.flutter.dev/cookbook/animation/animated-container/index.html |
59721f97162f-2 | These properties belong to a custom State class so they
can be updated when the user taps a button.
2. Build an AnimatedContainer using the properties
Next, build the AnimatedContainer using the properties defined in the
previous step. Furthermore, provide a duration that defines how long
the animation should run.
3... | https://docs.flutter.dev/cookbook/animation/animated-container/index.html |
59721f97162f-3 | Interactive example
Animate a widget using a physics simulation
Fade a widget in and out | https://docs.flutter.dev/cookbook/animation/animated-container/index.html |
1295cc44d657-0 | Animation
Cookbook
Animation
Animate a page route transition
Animate a widget using a physics simulation
Animate the properties of a container
Fade a widget in and out | https://docs.flutter.dev/cookbook/animation/index.html |
5d3b34bf6dd4-0 | Animate the properties of a container
Add a drawer to a screen
Fade a widget in and out
Cookbook
Animation
Fade a widget in and out
1. Create a box to fade in and out
2. Define a StatefulWidget
3. Display a button that toggles the visibility
4. Fade the box in and out
Interactive example
UI developers often ... | https://docs.flutter.dev/cookbook/animation/opacity-animation/index.html |
5d3b34bf6dd4-1 | Define a StatefulWidget.
Display a button that toggles the visibility.
Fade the box in and out.
1. Create a box to fade in and out
First, create something to fade in and out. For this example,
draw a green box on screen.
2. Define a StatefulWidget
Now that you have a green box to animate,
you need a way to know w... | https://docs.flutter.dev/cookbook/animation/opacity-animation/index.html |
5d3b34bf6dd4-2 | To construct a StatefulWidget, create two classes: A
StatefulWidget and a corresponding State class.
Pro tip: The Flutter plugins for Android Studio and VSCode include
the stful snippet to quickly generate this code.
3. Display a button that toggles the visibility
Now that you have some data to determine whether the ... | https://docs.flutter.dev/cookbook/animation/opacity-animation/index.html |
5d3b34bf6dd4-3 | 4. Fade the box in and out
You have a green box on screen and a button to toggle the visibility
to true or false. How to fade the box in and out? With an
AnimatedOpacity widget.
The AnimatedOpacity widget requires three arguments:
opacity: A value from 0.0 (invisible) to 1.0 (fully visible).
duration: How long the ... | https://docs.flutter.dev/cookbook/animation/opacity-animation/index.html |
edd81e24fde3-0 | Animate a widget using a physics simulation
Animate a page route transition
Cookbook
Animation
Animate a page route transition
1. Set up a PageRouteBuilder
2. Create a Tween
3. Use an AnimatedWidget
4. Use a CurveTween
5. Combine the two Tweens
Interactive example
A design language, such as Material, defines... | https://docs.flutter.dev/cookbook/animation/page-route-animation/index.html |
edd81e24fde3-1 | To create a custom page route transition, this recipe uses the following steps:
Set up a PageRouteBuilder
Create a Tween
Add an AnimatedWidget
Use a CurveTween
Combine the two Tweens
1. Set up a PageRouteBuilder
To start, use a PageRouteBuilder to create a Route.
PageRouteBuilder has two callbacks, one to build ... | https://docs.flutter.dev/cookbook/animation/page-route-animation/index.html |
edd81e24fde3-2 | 2. Create a Tween
To make the new page animate in from the bottom, it should animate from
Offset(0,1) to Offset(0, 0) (usually defined using the Offset.zero
constructor). In this case, the Offset is a 2D vector for the
‘FractionalTranslation’ widget.
Setting the dy argument to 1 represents a vertical translation one
f... | https://docs.flutter.dev/cookbook/animation/page-route-animation/index.html |
edd81e24fde3-3 | AnimatedWidget Return a SlideTransition
with the Animation<Offset> and the child widget:
4. Use a CurveTween
Flutter provides a selection of easing curves that
adjust the rate of the animation over time.
The Curves class
provides a predefined set of commonly used curves.
For example, Curves.easeOut
makes the animatio... | https://docs.flutter.dev/cookbook/animation/page-route-animation/index.html |
edd81e24fde3-4 | This new Tween (or Animatable) produces Offset values by first evaluating the
CurveTween, then evaluating the Tween<Offset>. When the animation runs, the
values are computed in this order:
The animation (provided to the transitionsBuilder callback) produces values
from 0 to 1.
The CurveTween maps those values to new ... | https://docs.flutter.dev/cookbook/animation/page-route-animation/index.html |
d50b441773ec-0 | Animate a page route transition
Animate the properties of a container
Animate a widget using a physics simulation
Cookbook
Animation
Animate a widget using a physics simulation
Step 1: Set up an animation controller
Step 2: Move the widget using gestures
Step 3: Animate the widget
Step 4: Calculate the velocit... | https://docs.flutter.dev/cookbook/animation/physics-simulation/index.html |
d50b441773ec-1 | Move the widget using gestures
Animate the widget
Calculate the velocity to simulate a springing motion
Step 1: Set up an animation controller
Start with a stateful widget called DraggableCard:
SingleTickerProviderStateMixin.
Then construct an
AnimationController in
TickerProvider.
lib/{starter.dart → step1.dar... | https://docs.flutter.dev/cookbook/animation/physics-simulation/index.html |
d50b441773ec-2 | 32
+
with SingleTickerProviderStateMixin {
33
+
late AnimationController _controller;
34
32
35
@override
33
36
void initState() {
34
37
super.initState();
38
+
_controller =
39
+
AnimationController(vsync: this, duration: const Duration(sec... | https://docs.flutter.dev/cookbook/animation/physics-simulation/index.html |
d50b441773ec-3 | 43
+
_controller.dispose();
38
44
super.dispose();
39
45
Step 2: Move the widget using gestures
Make the widget move when it’s dragged, and add an Alignment field to the
_DraggableCardState class:
lib/{step1.dart (alignment) → step2.dart (alignment)}
@@ -1,3 +1,4 @@
1
1
class _DraggableCardSta... | https://docs.flutter.dev/cookbook/animation/physics-simulation/index.html |
d50b441773ec-4 | GestureDetector that handles the
MediaQuery to get the
size of the widget, and divide by 2. (This converts units of “pixels dragged” to
coordinates that
Align uses.) Then, set the
lib/{step1.dart (build) → step2.dart (build)}
@@ -1,8 +1,22 @@
1
1
@override
2
2
Widget build(BuildContext context) {
return Align(... | https://docs.flutter.dev/cookbook/animation/physics-simulation/index.html |
d50b441773ec-5 | +
setState(() {
+
_dragAlignment += Alignment(
+
details.delta.dx / (size.width / 2),
10
+
details.delta.dy / (size.height / 2),
11
+
);
12
+
});
13
+
},
14
+
... | https://docs.flutter.dev/cookbook/animation/physics-simulation/index.html |
d50b441773ec-6 | 18
+
child: widget.child,
19
+
),
6
20
),
7
21
);
8
22
Step 3: Animate the widget
When the widget is released, it should spring back to the center.
Add an Animation<Alignment> field and an _runAnimation method. This
method defines a Tween that interpolates between the po... | https://docs.flutter.dev/cookbook/animation/physics-simulation/index.html |
d50b441773ec-7 | 2
2
with SingleTickerProviderStateMixin {
3
3
late AnimationController _controller;
+
late Animation<Alignment> _animation;
4
5
Alignment _dragAlignment = Alignment.center;
Next, update _dragAlignment when the AnimationController produces a
value:
lib/{step2.dart (initState) → step3.dart (initStat... | https://docs.flutter.dev/cookbook/animation/physics-simulation/index.html |
d50b441773ec-8 | +
setState(() {
+
_dragAlignment = _animation.value;
+
});
10
+
});
6
11
Next, make the Align widget use the _dragAlignment field:
Finally, update the GestureDetector to manage the animation controller:
lib/{step2.dart (gesture) → step3.dart (gestu... | https://docs.flutter.dev/cookbook/animation/physics-simulation/index.html |
d50b441773ec-9 | onPanUpdate: (details) {
4
6
setState(() {
5
7
_dragAlignment += Alignment(
@@ -8,7 +10,9 @@
8
10
);
9
11
});
10
12
},
11
onPanEnd: (details) {},
13
+
onPanEnd: (details) {
14
+
_runAnimation();
15
+
},
12
16
child: Align(
13
17
alignment: _dragAlignmen... | https://docs.flutter.dev/cookbook/animation/physics-simulation/index.html |
d50b441773ec-10 | 13
17
alignment: _dragAlignment,
14
18
child: Card(
Step 4: Calculate the velocity to simulate a springing motion
The last step is to do a little math, to calculate the velocity of the widget
after it’s finished being dragged. This is so that the widget realistically
continues at that speed before being snapped ba... | https://docs.flutter.dev/cookbook/animation/physics-simulation/index.html |
d50b441773ec-11 | First, import the physics package:
The onPanEnd callback provides a DragEndDetails object. This object
provides the velocity of the pointer when it stopped contacting the screen. The
velocity is in pixels per second, but the Align widget doesn’t use pixels. It
uses coordinate values between [-1.0, -1.0] and [1.0, 1.0]... | https://docs.flutter.dev/cookbook/animation/physics-simulation/index.html |
3dd6cf292a00-0 | Fade a widget in and out
Display a snackbar
Add a drawer to a screen
Cookbook
Design
Add a drawer to a screen
1. Create a Scaffold
2. Add a drawer
3. Populate the drawer with items
4. Close the drawer programmatically
Interactive example
In apps that use Material Design,
there are two primary options for nav... | https://docs.flutter.dev/cookbook/design/drawer/index.html |
3dd6cf292a00-1 | Add a drawer.
Populate the drawer with items.
Close the drawer programmatically.
1. Create a Scaffold
To add a drawer to the app, wrap it in a Scaffold widget.
The Scaffold widget provides a consistent visual structure to apps that
follow the Material Design Guidelines.
It also supports special Material Design
comp... | https://docs.flutter.dev/cookbook/design/drawer/index.html |
3dd6cf292a00-2 | 3. Populate the drawer with items
Now that you have a Drawer in place, add content to it.
For this example, use a ListView.
While you could use a Column widget,
ListView is handy because it allows users to scroll
through the drawer if the
content takes more space than the screen supports.
Populate the ListView with a... | https://docs.flutter.dev/cookbook/design/drawer/index.html |
b0995cd6c3a2-0 | Update the UI based on orientation
Use themes to share colors and font styles
Use a custom font
Cookbook
Design
Use a custom font
1. Import the font files
Supported font formats
2. Declare the font in the pubspec
pubspec.yaml option definitions
3. Set a font as the default
4. Use the font in a specific widge... | https://docs.flutter.dev/cookbook/design/fonts/index.html |
b0995cd6c3a2-1 | Note:
Check out the google_fonts package for direct access
to over 1,000 open-sourced font families.
Note:
For another approach to using custom fonts,
especially if you want to re-use one font over multiple projects,
see Export fonts from a package.
Flutter works with custom fonts and you can apply a cust... | https://docs.flutter.dev/cookbook/design/fonts/index.html |
b0995cd6c3a2-2 | For example, to import the Raleway and Roboto Mono font
files into a project, the folder structure might look like this:
Supported font formats
Flutter supports the following font formats:
.ttc
.ttf
.otf
Flutter does not support .woff and .woff2 fonts for all platforms.
2. Declare the font in the pubspec
Once y... | https://docs.flutter.dev/cookbook/design/fonts/index.html |
b0995cd6c3a2-3 | style
italic
family
RobotoMono
fonts
asset
fonts/RobotoMono-Regular.ttf
asset
fonts/RobotoMono-Bold.ttf
weight
700
pubspec.yaml option definitions
The family determines the name of the font, which you use in the
fontFamily property of a TextStyle object.
The asset is a path to the font file,
relative to th... | https://docs.flutter.dev/cookbook/design/fonts/index.html |
b0995cd6c3a2-4 | A single font can reference many different files with different
outline weights and styles:
The weight property specifies the weight of the outlines in
the file as an integer multiple of 100, between 100 and 900.
These values correspond to the FontWeight and can be used in the
fontWeight property of a TextStyle object... | https://docs.flutter.dev/cookbook/design/fonts/index.html |
b0995cd6c3a2-5 | The style property specifies whether the outlines in the file are
italic or normal.
These values correspond to the FontStyle and can be used in the
fontStyle property of a TextStyle object.
For example, if you want to use the Raleway-Italic font defined above,
you would set fontStyle to FontStyle.italic in your Text... | https://docs.flutter.dev/cookbook/design/fonts/index.html |
b0995cd6c3a2-6 | For more information on themes,
see the Using Themes to share colors and font styles recipe.
4. Use the font in a specific widget
If you want to apply the font to a specific widget,
such as a Text widget,
provide a TextStyle to the widget.
In this example, apply the RobotoMono font to a single Text widget.
Once agai... | https://docs.flutter.dev/cookbook/design/fonts/index.html |
b0995cd6c3a2-7 | name
custom_fonts
description
An example of how to use custom fonts with Flutter
dependencies
flutter
sdk
flutter
dev_dependencies
flutter_test
sdk
flutter
flutter
fonts
family
Raleway
fonts
asset
fonts/Raleway-Regular.ttf
asset
fonts/Raleway-Italic.ttf
style
italic
family
RobotoMono
fonts
ass... | https://docs.flutter.dev/cookbook/design/fonts/index.html |
b0995cd6c3a2-8 | fonts/RobotoMono-Bold.ttf
weight
700
uses-material-design
true
main.dart
Update the UI based on orientation
Use themes to share colors and font styles | https://docs.flutter.dev/cookbook/design/fonts/index.html |
e160c5218499-0 | Design
Cookbook
Design
Add a drawer to a screen
Display a snackbar
Export fonts from a package
Update the UI based on orientation
Use a custom font
Use themes to share colors and font styles
Work with tabs | https://docs.flutter.dev/cookbook/design/index.html |
e20ae02519c9-0 | Export fonts from a package
Use a custom font
Update the UI based on orientation
Cookbook
Design
Update the UI based on orientation
1. Build a GridView with two columns
2. Use an OrientationBuilder to change the number of columns
Interactive example
In some situations,
you want to update the display of an app ... | https://docs.flutter.dev/cookbook/design/orientation/index.html |
e20ae02519c9-1 | Use an OrientationBuilder to change the number of columns.
1. Build a GridView with two columns
First, create a list of items to work with.
Rather than using a normal list,
create a list that displays items in a grid.
For now, create a grid with two columns.
To learn more about working with GridViews,
see the Creati... | https://docs.flutter.dev/cookbook/design/orientation/index.html |
e20ae02519c9-2 | Note:
If you’re interested in the orientation of the screen,
rather than the amount of space available to the parent,
use MediaQuery.of(context).orientation instead of an
OrientationBuilder widget.
Interactive example
Export fonts from a package
Use a custom font | https://docs.flutter.dev/cookbook/design/orientation/index.html |
1b44b7ec3972-0 | Display a snackbar
Update the UI based on orientation
Export fonts from a package
Cookbook
Design
Export fonts from a package
1. Add a font to a package
2. Add the package and fonts to the app
Add the package to the app
Declare the font assets
3. Use the font
Complete example
Fonts
pubspec.yaml
main.dart
Ra... | https://docs.flutter.dev/cookbook/design/package-fonts/index.html |
1b44b7ec3972-1 | Add the package and font to the app.
Use the font.
Note:
Check out the google_fonts package for direct access
to almost 1000 open-sourced font families.
1. Add a font to a package
To export a font from a package, you need to import the font files into the
lib folder of the package project. You can place font fi... | https://docs.flutter.dev/cookbook/design/package-fonts/index.html |
1b44b7ec3972-2 | <latest_version>
Declare the font assets
Now that you’ve imported the package, tell Flutter where to
find the fonts from the awesome_package.
To declare package fonts, prefix the path to the font with
packages/awesome_package.
This tells Flutter to look in the lib folder
of the package for the font.
flutter
fonts
... | https://docs.flutter.dev/cookbook/design/package-fonts/index.html |
1b44b7ec3972-3 | Complete example
Fonts
The Raleway and RobotoMono fonts were downloaded from
Google Fonts.
pubspec.yaml
name
package_fonts
description
An example of how to use package fonts with Flutter
dependencies
awesome_package
flutter
sdk
flutter
dev_dependencies
flutter_test
sdk
flutter
flutter
fonts
family
R... | https://docs.flutter.dev/cookbook/design/package-fonts/index.html |
1b44b7ec3972-4 | style
italic
uses-material-design
true
main.dart
Display a snackbar
Update the UI based on orientation | https://docs.flutter.dev/cookbook/design/package-fonts/index.html |
aa5b1b9aeab9-0 | Add a drawer to a screen
Export fonts from a package
Display a snackbar
Cookbook
Design
Display a snackbar
1. Create a Scaffold
2. Display a SnackBar
3. Provide an optional action
Interactive example
It can be useful to briefly inform your users when certain actions
take place. For example, when a user swipes... | https://docs.flutter.dev/cookbook/design/snackbars/index.html |
aa5b1b9aeab9-1 | 1. Create a Scaffold
When creating apps that follow the Material Design guidelines,
give your apps a consistent visual structure.
In this example, display the SnackBar at the bottom of the screen,
without overlapping other important
widgets, such as the FloatingActionButton.
The Scaffold widget, from the material lib... | https://docs.flutter.dev/cookbook/design/snackbars/index.html |
aa5b1b9aeab9-2 | 3. Provide an optional action
You might want to provide an action to the user when
the SnackBar is displayed.
For example, if the user accidentally deletes a message,
they might use an optional action in the SnackBar to recover
the message.
Here’s an example of providing
an additional action to the SnackBar widget:
... | https://docs.flutter.dev/cookbook/design/snackbars/index.html |
61deba6fea6d-0 | Use themes to share colors and font styles
Create a download button
Work with tabs
Cookbook
Design
Work with tabs
1. Create a TabController
2. Create the tabs
3. Create content for each tab
Interactive example
Working with tabs is a common pattern in apps that follow the
Material Design guidelines.
Flutter in... | https://docs.flutter.dev/cookbook/design/tabs/index.html |
61deba6fea6d-1 | Create content for each tab.
1. Create a TabController
For tabs to work, you need to keep the selected tab and content
sections in sync.
This is the job of the TabController.
Either create a TabController manually,
or automatically by using a DefaultTabController widget.
Using DefaultTabController is the simplest o... | https://docs.flutter.dev/cookbook/design/tabs/index.html |
61deba6fea6d-2 | 3. Create content for each tab
Now that you have tabs, display content when a tab is selected.
For this purpose, use the TabBarView widget.
Note:
Order is important and must correspond to the order of the tabs in the
TabBar.
Interactive example
Use themes to share colors and font styles
Create a download butto... | https://docs.flutter.dev/cookbook/design/tabs/index.html |
b0159abcb281-0 | Use a custom font
Work with tabs
Use themes to share colors and font styles
Cookbook
Design
Themes
Creating an app theme
Themes for part of an application
Creating unique ThemeData
Extending the parent theme
Using a Theme
Interactive example
To share colors and font styles throughout an app, use themes.
You ... | https://docs.flutter.dev/cookbook/design/themes/index.html |
b0159abcb281-1 | Creating an app theme
To share a Theme across an entire app, provide a
ThemeData to the MaterialApp constructor.
If no theme is provided, Flutter creates a default theme for you.
See the ThemeData documentation to see all of
the colors and fonts you can define.
Themes for part of an application
To override the app... | https://docs.flutter.dev/cookbook/design/themes/index.html |
b0159abcb281-2 | Extending the parent theme
Rather than overriding everything, it often makes sense to extend the parent
theme. You can handle this by using the copyWith() method.
Using a Theme
Now that you’ve defined a theme, use it within the widgets’ build()
methods by using the Theme.of(context) method.
The Theme.of(context) me... | https://docs.flutter.dev/cookbook/design/themes/index.html |
f957251ff109-0 | Work with tabs
Create a nested navigation flow
Create a download button
Cookbook
Effects
Create a download button
Define a new stateless widget
Define the button’s possible visual states
Display the button shape
Display the button text
Display a spinner while fetching download
Display the progress and a stop... | https://docs.flutter.dev/cookbook/effects/download-button/index.html |
f957251ff109-1 | The following animation shows the app’s behavior:
Define a new stateless widget
Your button widget needs to change its appearance over time.
Therefore, you need to implement your button with a custom
stateless widget.
Define a new stateless widget called DownloadButton.
Define the button’s possible visual states
T... | https://docs.flutter.dev/cookbook/effects/download-button/index.html |
f957251ff109-2 | documentation
or in a dedicated video in the Flutter
YouTube channel.
For now, the AnimatedContainer child is just a SizedBox because we will come back at it in another step.
You might wonder why you need a ShapeDecoration
widget for a transparent circle, given that it’s invisible.
The purpose of the invisible circl... | https://docs.flutter.dev/cookbook/effects/download-button/index.html |
f957251ff109-3 | Add widgets to display text during each download phase,
and animate the text’s opacity in between. Add the text
widget tree as a child of the AnimatedContainer in the
button wrapper widget.
Display a spinner while fetching download
During the fetchingDownload phase, the DownloadButton
displays a radial spinner. This ... | https://docs.flutter.dev/cookbook/effects/download-button/index.html |
f957251ff109-4 | Display the progress and a stop button while downloading
After the fetchingDownload phase is the downloading phase.
During the downloading phase, the DownloadButton
replaces the radial progress spinner with a growing
radial progress bar. The DownloadButton also displays a stop
button icon so that the user can cancel ... | https://docs.flutter.dev/cookbook/effects/download-button/index.html |
f957251ff109-5 | Congratulations! You have a button that changes its display
depending on which phase the button is in: not downloaded,
fetching download, downloading, and downloaded.
Now, the user can tap to start a download, tap to cancel an
in-progress download, and tap to open a completed download.
Interactive example
Run the ap... | https://docs.flutter.dev/cookbook/effects/download-button/index.html |
d8b85c53c7c2-0 | Create gradient chat bubbles
Build a form with validation
Drag a UI element
Cookbook
Effects
Drag a UI element
Press and drag
Drop the draggable
Add a menu item to a cart
Interactive example
Drag and drop is a common mobile app interaction.
As the user long presses (sometimes called touch & hold)
on a widget,... | https://docs.flutter.dev/cookbook/effects/drag-a-widget/index.html |
d8b85c53c7c2-1 | The following animation shows the app’s behavior:
This recipe begins with a prebuilt list of menu items and
a row of customers.
The first step is to recognize a long press
and display a draggable photo of a menu item.
Press and drag
Flutter provides a widget called LongPressDraggable
that provides the exact behavior... | https://docs.flutter.dev/cookbook/effects/drag-a-widget/index.html |
d8b85c53c7c2-2 | Wrap the MenuListItem widget with a LongPressDraggable widget.
In this case, when the user long presses on the
MenuListItem widget, the LongPressDraggable
widget displays a DraggingListItem.
This DraggingListItem displays a photo of the
selected food item, centered beneath
the user’s finger.
The dragAnchorStrategy p... | https://docs.flutter.dev/cookbook/effects/drag-a-widget/index.html |
d8b85c53c7c2-3 | The data associated with a LongPressDraggable
is sent to a special widget called DragTarget,
where the user releases the drag gesture.
You’ll implement the drop behavior next.
Drop the draggable
The user can drop a LongPressDraggable wherever they choose,
but dropping the draggable has no effect unless it’s dropped
o... | https://docs.flutter.dev/cookbook/effects/drag-a-widget/index.html |
d8b85c53c7c2-4 | When the user drops a draggable on the DragTarget widget,
the onAccept callback is invoked. This is when you get
to decide whether or not to accept the data that was dropped.
In this case, the item is always accepted and processed.
You might choose to inspect the incoming item to make a
different decision.
Notice tha... | https://docs.flutter.dev/cookbook/effects/drag-a-widget/index.html |
d8b85c53c7c2-5 | The CustomerCart widget displays the customer’s photo,
name, total, and item count based on a Customer instance.
To update a customer’s cart when a menu item is dropped,
add the dropped item to the associated Customer object.
The _itemDroppedOnCustomerCart method is invoked in
onAccept() when the user drops a menu it... | https://docs.flutter.dev/cookbook/effects/drag-a-widget/index.html |
d8b85c53c7c2-6 | While holding, the food item’s image
will appear above the list.
Drag the image and drop it on one of the
people at the bottom of the screen.
The text under the image updates to
reflect the charge for that person.
You can continue to add food items
and watch the charges accumulate.
Create gradient chat bubbles
Build... | https://docs.flutter.dev/cookbook/effects/drag-a-widget/index.html |
a9e96c33aff5-0 | Create a typing indicator
Create gradient chat bubbles
Create an expandable FAB
Cookbook
Effects
Create an expandable FAB
Create an ExpandableFab widget
FAB cross-fade
Create an ActionButton widget
Expand and collapse the action buttons
Interactive example
A Floating Action Button (FAB) is a round button tha... | https://docs.flutter.dev/cookbook/effects/expandable-fab/index.html |
a9e96c33aff5-1 | The following animation shows the app’s behavior:
Create an ExpandableFab widget
Start by creating a new stateful widget called ExpandableFab.
This widget displays the primary FAB and coordinates the expansion
and collapse of the other action buttons. The widget takes
in parameters for whether or not the ExpandedFab ... | https://docs.flutter.dev/cookbook/effects/expandable-fab/index.html |
a9e96c33aff5-2 | To achieve the cross-fade animation, the open button uses an
AnimatedContainer with a scale transform and an AnimatedOpacity.
The open button scales down and fades out when the ExpandableFab
goes from collapsed to expanded. Then, the open button scales up
and fades in when the ExpandableFab goes from expanded to collap... | https://docs.flutter.dev/cookbook/effects/expandable-fab/index.html |
a9e96c33aff5-3 | Define a new stateless widget called ActionButton to display
these round buttons.
Pass a few instances of this new ActionButton widget into your
ExpandableFab.
Expand and collapse the action buttons
The child ActionButtons should fly out from under the open
FAB when expanded. Then, the child ActionButtons should
fly... | https://docs.flutter.dev/cookbook/effects/expandable-fab/index.html |
a9e96c33aff5-4 | Congratulations! You now have an expandable FAB.
Interactive example
Run the app:
Click the FAB in the lower-right corner,
represented with an Edit icon.
It fans out to 3 buttons and is itself replaced by
a close button, represented by an X.
Click the close button to see the expanded
buttons fly back to the origina... | https://docs.flutter.dev/cookbook/effects/expandable-fab/index.html |
046373897162-0 | Create an expandable FAB
Drag a UI element
Create gradient chat bubbles
Cookbook
Effects
Create gradient chat bubbles
Understand the challenge
Replace original background widget
Create a custom painter
Provide access to scrolling information
Paint a full-screen bubble gradient
Recap
Traditional chat apps di... | https://docs.flutter.dev/cookbook/effects/gradient-bubbles/index.html |
046373897162-1 | The following animation shows the app’s behavior:
Understand the challenge
The traditional chat bubble solution probably uses a
DecoratedBox or a similar widget to paint a rounded
rectangle behind each chat message. That approach is
great for a solid color or even for a gradient that
repeats in every chat bubble. Ho... | https://docs.flutter.dev/cookbook/effects/gradient-bubbles/index.html |
046373897162-2 | Each bubble’s gradient requires knowledge of the
bubble’s location on the screen. This means that
the painting behavior requires access to layout information.
Such painting behavior isn’t possible with typical widgets
because widgets like Container and DecoratedBox
make decisions about background colors before layout ... | https://docs.flutter.dev/cookbook/effects/gradient-bubbles/index.html |
046373897162-3 | Replace original background widget
Replace the widget responsible for drawing the
background with a new stateless widget called
BubbleBackground. Include a colors property to
represent the full-screen gradient that should be
applied to the bubble.
Create a custom painter
Provide access to scrolling information
Pai... | https://docs.flutter.dev/cookbook/effects/gradient-bubbles/index.html |
046373897162-4 | Recap
The fundamental challenge when painting based on the
scroll position, or the screen position in general,
is that the painting behavior must occur after the
layout phase is complete. CustomPaint is a unique
widget that allows you to execute custom painting
behaviors after the layout phase is complete.
If you exec... | https://docs.flutter.dev/cookbook/effects/gradient-bubbles/index.html |
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