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569481dcb67d-0 | Effects
Cookbook
Effects
Create a download button
Create a nested navigation flow
Create a photo filter carousel
Create a scrolling parallax effect
Create a shimmer loading effect
Create a staggered menu animation
Create a typing indicator
Create an expandable FAB
Create gradient chat bubbles
Drag a UI elem... | https://docs.flutter.dev/cookbook/effects/index.html |
5edcbedc41f9-0 | Create a download button
Create a photo filter carousel
Create a nested navigation flow
Cookbook
Effects
Create a nested navigation flow
Prepare for navigation
Display an app bar for the setup flow
Generate nested routes
Interactive example
Apps accumulate dozens and then hundreds of routes over time.
Some of... | https://docs.flutter.dev/cookbook/effects/nested-nav/index.html |
5edcbedc41f9-1 | Consider an Internet of Things (IoT) setup flow for a wireless
light bulb that you control with your app.
This setup flow consists of 4 pages:
find nearby bulbs, select the bulb that you want to add,
add the bulb, and then complete the setup.
You could orchestrate this behavior from your top-level
Navigator widget. H... | https://docs.flutter.dev/cookbook/effects/nested-nav/index.html |
5edcbedc41f9-2 | Prepare for navigation
This IoT app has two top-level screens,
along with the setup flow. Define these
route names as constants so that they can
be referenced within code.
The home and settings screens are referenced with
static names. The setup flow pages, however,
use two paths to create their route names:
a /set... | https://docs.flutter.dev/cookbook/effects/nested-nav/index.html |
5edcbedc41f9-3 | Implement onGenerateRoute to return the appropriate widget
for each of the three top-level paths.
Notice that the home and settings routes are matched with exact
route names. However, the setup flow route condition only
checks for a prefix. If the route name contains the setup
flow prefix, then the rest of the route ... | https://docs.flutter.dev/cookbook/effects/nested-nav/index.html |
5edcbedc41f9-4 | The app bar displays a back arrow and exits the setup
flow when the back arrow is pressed. However,
exiting the flow causes the user to lose all progress.
Therefore, the user is prompted to confirm whether they
want to exit the setup flow.
Prompt the user to confirm exiting the setup flow,
and ensure that the prompt ... | https://docs.flutter.dev/cookbook/effects/nested-nav/index.html |
5edcbedc41f9-5 | Generate nested routes
The setup flow’s job is to display the appropriate
page within the flow.
Add a Navigator widget to SetupFlow,
and implement the onGenerateRoute property.
The _onGenerateRoute function works the same as
for a top-level Navigator. A RouteSettings
object is passed into the function,
which include... | https://docs.flutter.dev/cookbook/effects/nested-nav/index.html |
5edcbedc41f9-6 | Interactive example
Run the app:
On the Add your first bulb screen,
click the FAB, shown with a plus sign, +.
This brings you to the Select a nearby device
screen. A single bulb is listed.
Click the listed bulb. A Finished! screen appears.
Click the Finished button to return to the
first screen.
Create a download ... | https://docs.flutter.dev/cookbook/effects/nested-nav/index.html |
77a6d5fd7e8a-0 | Create a photo filter carousel
Create a shimmer loading effect
Create a scrolling parallax effect
Cookbook
Effects
Create a scrolling parallax effect
Create a list to hold the parallax items
Display items with text and a static image
Implement the parallax effect
Interactive example
When you scroll a list of ... | https://docs.flutter.dev/cookbook/effects/parallax-scrolling/index.html |
77a6d5fd7e8a-1 | The following animation shows the app’s behavior:
Create a list to hold the parallax items
To display a list of parallax scrolling images,
you must first display a list.
Create a new stateless widget called ParallaxRecipe.
Within ParallaxRecipe, build a widget tree with a
SingleChildScrollView and a Column, which fo... | https://docs.flutter.dev/cookbook/effects/parallax-scrolling/index.html |
77a6d5fd7e8a-2 | Implement a stateless widget called LocationListItem
that consists of the previously mentioned visuals.
For now, use a static Image widget for the background.
Later, you’ll replace that widget with a parallax version.
Next, add the list items to your ParallaxRecipe widget.
You now have a typical, scrollable list of c... | https://docs.flutter.dev/cookbook/effects/parallax-scrolling/index.html |
77a6d5fd7e8a-3 | The parallax effect depends on the list item’s
current position within its ancestor Scrollable.
As the list item’s scroll position changes, the position
of the list item’s background image must also change.
This is an interesting problem to solve. The position
of a list item within the Scrollable isn’t
available until... | https://docs.flutter.dev/cookbook/effects/parallax-scrolling/index.html |
77a6d5fd7e8a-4 | In cases where you need control over the layout,
painting, and hit testing, consider defining a
custom RenderBox.
Wrap your background Image widget with a
Flow widget.
Introduce a new FlowDelegate called ParallaxFlowDelegate.
A FlowDelegate controls how its children are sized
and where those children are painted... | https://docs.flutter.dev/cookbook/effects/parallax-scrolling/index.html |
77a6d5fd7e8a-5 | The bounds of the individual list item
The size of the image after it’s scaled down
to fit in the list item
To look up the bounds of the Scrollable,
you pass a ScrollableState into your FlowDelegate.
To look up the bounds of your individual list item,
you pass your list item’s BuildContext into your FlowDelegate.
T... | https://docs.flutter.dev/cookbook/effects/parallax-scrolling/index.html |
77a6d5fd7e8a-6 | First, calculate the pixel position of a list
item within its ancestor Scrollable.
Use the pixel position of the list item to calculate its
percentage from the top of the Scrollable.
A list item at the top of the scrollable area should
produce 0%, and a list item at the bottom of the
scrollable area should produce 10... | https://docs.flutter.dev/cookbook/effects/parallax-scrolling/index.html |
77a6d5fd7e8a-7 | You need one final detail to achieve the parallax effect.
The ParallaxFlowDelegate repaints when the inputs change,
but the ParallaxFlowDelegate doesn’t repaint every time
the scroll position changes.
Pass the ScrollableState’s ScrollPosition to
the FlowDelegate superclass so that the FlowDelegate
repaints every time ... | https://docs.flutter.dev/cookbook/effects/parallax-scrolling/index.html |
35525a794e24-0 | Create a nested navigation flow
Create a scrolling parallax effect
Create a photo filter carousel
Cookbook
Effects
Create a photo filter carousel
Add a selector ring and dark gradient
Create a filter carousel item
Implement the filter carousel
Interactive example
Everybody knows that a photo looks better with... | https://docs.flutter.dev/cookbook/effects/photo-filter-carousel/index.html |
35525a794e24-1 | Create a new stateful widget called
FilterSelector that you’ll use to
implement the selector.
Add the FilterSelector widget to the existing
widget tree. Position the FilterSelector widget
on top of the photo, at the bottom and centered.
Within the FilterSelector widget,
display a selector ring on top of a
dark grad... | https://docs.flutter.dev/cookbook/effects/photo-filter-carousel/index.html |
35525a794e24-2 | Create a filter carousel item
Each filter item in the carousel displays a
circular image with a color applied to the image
that corresponds to the associated filter color.
Define a new stateless widget called FilterItem
that displays a single list item.
Implement the filter carousel
Filter items scroll to the left ... | https://docs.flutter.dev/cookbook/effects/photo-filter-carousel/index.html |
35525a794e24-3 | Scrollable widget with a
viewportBuilder, and place a
Flow widget inside the
delegate property
that allows you to position child widgets wherever
you want, based on the current
Configure your widget tree to make space for the PageView.
Build each FilterItem widget within the
PageView widget based on the given ... | https://docs.flutter.dev/cookbook/effects/photo-filter-carousel/index.html |
35525a794e24-4 | Calculate an appropriate scale and opacity for each
FilterItem widget within the AnimatedBuilder and
apply those values.
Each FilterItem widget now shrinks and fades
away as it moves farther from the center of the screen.
Add a method to change the selected filter when a
FilterItem widget is tapped.
Configure each F... | https://docs.flutter.dev/cookbook/effects/photo-filter-carousel/index.html |
8ee8a55b05b5-0 | Create a scrolling parallax effect
Create a staggered menu animation
Create a shimmer loading effect
Cookbook
Effects
Create a shimmer loading effect
Draw the shimmer shapes
Paint the shimmer gradient
Paint one big shimmer
Animate the shimmer
Loading times are unavoidable in application development.
From a us... | https://docs.flutter.dev/cookbook/effects/shimmer-loading/index.html |
8ee8a55b05b5-1 | The following animation shows the app’s behavior:
This recipe begins with the content widgets defined and positioned.
There is also a Floating Action Button (FAB) in the bottom-right
corner that toggles between a loading mode and a loaded mode
so that you can easily validate your implementation.
Draw the shimmer shap... | https://docs.flutter.dev/cookbook/effects/shimmer-loading/index.html |
8ee8a55b05b5-2 | On the other hand, consider the text that appears beneath the
rounded rectangle images. You won’t know how many lines of
text exist until the text loads.
Therefore, there is no point in trying to draw a rectangle
for every line of text. Instead, while the data is loading,
you draw a couple of very thin rounded rectang... | https://docs.flutter.dev/cookbook/effects/shimmer-loading/index.html |
8ee8a55b05b5-3 | Your UI now renders itself differently depending on
whether it’s loading or loaded.
By temporarily commenting out the image URLs,
you can see the two ways your UI renders.
The next goal is to paint all of the colored areas
with a single gradient that looks like a shimmer.
Paint the shimmer gradient
The key to the ef... | https://docs.flutter.dev/cookbook/effects/shimmer-loading/index.html |
8ee8a55b05b5-4 | Wrap your CardListItem widgets with a ShimmerLoading widget.
When your shapes are loading, they now display
the shimmer gradient that is
returned from the shaderCallback.
This is a big step in the right direction,
but there’s a problem with this gradient display.
Each CircleListItem widget and each CardListItem widg... | https://docs.flutter.dev/cookbook/effects/shimmer-loading/index.html |
8ee8a55b05b5-5 | To be more precise, rather than assume that the shimmer
should take up the entire screen,
there should be some area that shares the shimmer.
Maybe that area takes up the entire screen,
or maybe it doesn’t. The way to solve this
kind of problem in Flutter is to define another widget
that sits above all of the ShimmerLo... | https://docs.flutter.dev/cookbook/effects/shimmer-loading/index.html |
8ee8a55b05b5-6 | Animate the shimmer
The shimmer gradient needs to move in order to
give the appearance of a shimmering shine.
The LinearGradient has a property called transform
that can be used to transform the appearance of the gradient,
for example, to move it horizontally.
The transform property accepts a GradientTransform insta... | https://docs.flutter.dev/cookbook/effects/shimmer-loading/index.html |
8ee8a55b05b5-7 | Expose the _shimmerController from ShimmerState
as a Listenable.
In ShimmerLoading, listen for changes to the ancestor
ShimmerState’s shimmerChanges property,
and repaint the shimmer gradient.
Congratulations!
You now have a full-screen,
animated shimmer effect that turns
on and off as the content loads.
Note:
Th... | https://docs.flutter.dev/cookbook/effects/shimmer-loading/index.html |
3ca106db67a6-0 | Create a shimmer loading effect
Create a typing indicator
Create a staggered menu animation
Cookbook
Effects
Create a staggered menu animation
Create the menu without animations
Prepare for animations
Animate the list items and button
Interactive example
A single app screen might contain multiple animations.
... | https://docs.flutter.dev/cookbook/effects/staggered-menu-animation/index.html |
3ca106db67a6-1 | Create the menu without animations
The drawer menu displays a list of titles,
followed by a Get started button at
the bottom of the menu.
Define a stateful widget called Menu
that displays the list and button
in static locations.
Prepare for animations
Control of the animation timing requires an
AnimationControll... | https://docs.flutter.dev/cookbook/effects/staggered-menu-animation/index.html |
3ca106db67a6-2 | In this case, all the animations are delayed by 50 ms.
After that, list items begin to appear.
Each list item’s appearance is delayed by 50 ms after the
previous list item begins to slide in.
Each list item takes 250 ms to slide from right to left.
After the last list item begins to slide in,
the button at the bottom ... | https://docs.flutter.dev/cookbook/effects/staggered-menu-animation/index.html |
3ca106db67a6-3 | The desired animation times are shown in the following diagram:
To animate a value during a subsection of a larger animation,
Flutter provides the Interval class.
An Interval takes a start time percentage and an end
time percentage. That Interval can then be used to
animate a value between those start and end times,
... | https://docs.flutter.dev/cookbook/effects/staggered-menu-animation/index.html |
3ca106db67a6-4 | Each list item slides from right to left and
fades in at the same time.
Use the list item’s Interval and an easeOut
curve to animate the opacity and translation
values for each list item.
Use the same approach to animate the opacity and
scale of the bottom button. This time, use an
elasticOut curve to give the button... | https://docs.flutter.dev/cookbook/effects/staggered-menu-animation/index.html |
3af7c9f2c09b-0 | Create a staggered menu animation
Create an expandable FAB
Create a typing indicator
Cookbook
Effects
Create a typing indicator
Define the typing indicator widget
Make room for the typing indicator
Animate the speech bubbles
Animate the flashing circles
Interactive example
Modern chat apps display indicators... | https://docs.flutter.dev/cookbook/effects/typing-indicator/index.html |
3af7c9f2c09b-1 | Define the typing indicator widget
The typing indicator exists within its own widget so that
it can be used anywhere in your app. As with any widget
that controls animations, the typing indicator needs to
be a stateful widget. The widget accepts a boolean value
that determines whether the indicator is visible.
This s... | https://docs.flutter.dev/cookbook/effects/typing-indicator/index.html |
3af7c9f2c09b-2 | The height of the typing indicator could be the natural
height of the speech bubbles within the typing indicator.
However, the speech bubbles expand with an elastic curve.
This elasticity would be too visually jarring if it quickly
pushed all the conversation messages up or down. Instead,
the height of the typing indi... | https://docs.flutter.dev/cookbook/effects/typing-indicator/index.html |
3af7c9f2c09b-3 | The animation that controls the height uses different
animation curves depending on its direction.
When the animation moves forward, it needs to quickly make
space for the speech bubbles. For this reason,
the forward curve runs the entire height animation within
the first 40% of the overall appearance animation.
When ... | https://docs.flutter.dev/cookbook/effects/typing-indicator/index.html |
3af7c9f2c09b-4 | Each bubble appears by animating its scale from 0% to 100%,
and each bubble does this at slightly different times so
that it looks like each bubble appears after the one before it.
This is called a staggered animation.
Paint the three bubbles in the desired positions from the
lower left. Then, animate the scale of the... | https://docs.flutter.dev/cookbook/effects/typing-indicator/index.html |
3af7c9f2c09b-5 | Each circle calculates its color using a sine (sin)
function so that the color changes gradually at the
minimum and maximum points. Additionally,
each circle animates its color within a specified interval
that takes up a portion of the overall animation time.
The position of these intervals generates the visual
effect ... | https://docs.flutter.dev/cookbook/effects/typing-indicator/index.html |
c3f7df168026-0 | Retrieve the value of a text field
Add Material touch ripples
Focus and text fields
Cookbook
Forms
Focus and text fields
Focus a text field as soon as it’s visible
Focus a text field when a button is tapped
1. Create a FocusNode
2. Pass the FocusNode to a TextField
3. Give focus to the TextField when a button i... | https://docs.flutter.dev/cookbook/forms/focus/index.html |
c3f7df168026-1 | Managing focus is a fundamental tool for creating forms with an intuitive
flow. For example, say you have a search screen with a text field.
When the user navigates to the search screen,
you can set the focus to the text field for the search term.
This allows the user to start typing as soon as the screen
is visible, w... | https://docs.flutter.dev/cookbook/forms/focus/index.html |
c3f7df168026-2 | Focus a text field when a button is tapped
Rather than immediately shifting focus to a specific text field,
you might need to give focus to a text field at a later point in time.
In the real world, you might also need to give focus to a specific
text field in response to an API call or a validation error.
In this exam... | https://docs.flutter.dev/cookbook/forms/focus/index.html |
c3f7df168026-3 | Since focus nodes are long-lived objects, manage the lifecycle
using a State object. Use the following instructions to create
a FocusNode instance inside the initState() method of a
State class, and clean it up in the dispose() method:
2. Pass the FocusNode to a TextField
Now that you have a FocusNode,
pass it to a s... | https://docs.flutter.dev/cookbook/forms/focus/index.html |
9819f966f5a4-0 | Forms
Cookbook
Forms
Build a form with validation
Create and style a text field
Focus and text fields
Handle changes to a text field
Retrieve the value of a text field | https://docs.flutter.dev/cookbook/forms/index.html |
851a93473d17-0 | Create an expandable FAB
Focus and text fields
Retrieve the value of a text field
Cookbook
Forms
Retrieve the value of a text field
1. Create a TextEditingController
2. Supply the TextEditingController to a TextField
3. Display the current value of the text field
Interactive example
In this recipe,
learn how ... | https://docs.flutter.dev/cookbook/forms/retrieve-input/index.html |
851a93473d17-1 | Important: Call dispose of the TextEditingController when
you’ve finished using it. This ensures that you discard any resources
used by the object.
2. Supply the TextEditingController to a TextField
Now that you have a TextEditingController, wire it up
to a text field using the controller property:
3. Display th... | https://docs.flutter.dev/cookbook/forms/retrieve-input/index.html |
e14db9e7fb96-0 | Create and style a text field
Retrieve the value of a text field
Handle changes to a text field
Cookbook
Forms
Handle changes to a text field
1. Supply an onChanged() callback to a TextField or a TextFormField
2. Use a TextEditingController
Create a TextEditingController
Connect the TextEditingController to a t... | https://docs.flutter.dev/cookbook/forms/text-field-changes/index.html |
e14db9e7fb96-1 | Supply an onChanged() callback to a TextField or a TextFormField.
Use a TextEditingController.
1. Supply an onChanged() callback to a TextField or a TextFormField
The simplest approach is to supply an onChanged() callback to a
TextField or a TextFormField.
Whenever the text changes, the callback is invoked.
In this... | https://docs.flutter.dev/cookbook/forms/text-field-changes/index.html |
e14db9e7fb96-2 | Create a function to print the latest value.
Listen to the controller for changes.
Create a TextEditingController
Create a TextEditingController:
Note:
Remember to dispose of the TextEditingController when it’s no
longer needed. This ensures that you discard any resources used
by the object.
Connect the Text... | https://docs.flutter.dev/cookbook/forms/text-field-changes/index.html |
e14db9e7fb96-3 | Listen to the controller for changes
Finally, listen to the TextEditingController and call the
_printLatestValue() method when the text changes. Use the
addListener() method for this purpose.
Begin listening for changes when the
_MyCustomFormState class is initialized,
and stop listening when the _MyCustomFormState i... | https://docs.flutter.dev/cookbook/forms/text-field-changes/index.html |
14f96c16047e-0 | Build a form with validation
Handle changes to a text field
Create and style a text field
Cookbook
Forms
Create and style a text field
TextField
TextFormField
Interactive example
Text fields allow users to type text into an app.
They are used to build forms,
send messages, create search experiences, and more.
... | https://docs.flutter.dev/cookbook/forms/text-input/index.html |
14f96c16047e-1 | To retrieve the value when it changes,
see the Handle changes to a text field recipe.
TextFormField
TextFormField wraps a TextField and integrates it
with the enclosing Form.
This provides additional functionality,
such as validation and integration with other
FormField widgets.
Interactive example
For more informa... | https://docs.flutter.dev/cookbook/forms/text-input/index.html |
e728004b0c49-0 | Drag a UI element
Create and style a text field
Build a form with validation
Cookbook
Forms
Build a form with validation
1. Create a Form with a GlobalKey
2. Add a TextFormField with validation logic
3. Create a button to validate and submit the form
How does this work?
Interactive example
Apps often require... | https://docs.flutter.dev/cookbook/forms/validation/index.html |
e728004b0c49-1 | Create a Form with a GlobalKey.
Add a TextFormField with validation logic.
Create a button to validate and submit the form.
1. Create a Form with a GlobalKey
First, create a Form.
The Form widget acts as a container for grouping
and validating multiple form fields.
When creating the form, provide a GlobalKey.
This... | https://docs.flutter.dev/cookbook/forms/validation/index.html |
e728004b0c49-2 | 2. Add a TextFormField with validation logic
Although the Form is in place,
it doesn’t have a way for users to enter text.
That’s the job of a TextFormField.
The TextFormField widget renders a material design text field
and can display validation errors when they occur.
Validate the input by providing a validator() f... | https://docs.flutter.dev/cookbook/forms/validation/index.html |
e728004b0c49-3 | When the user attempts to submit the form, check if the form is valid.
If it is, display a success message.
If it isn’t (the text field has no content) display the error message.
How does this work?
To validate the form, use the _formKey created in
step 1. You can use the _formKey.currentState()
method to access the ... | https://docs.flutter.dev/cookbook/forms/validation/index.html |
7af096deb78c-0 | Handle taps
Display images from the internet
Implement swipe to dismiss
Cookbook
Gestures
Implement swipe to dismiss
1. Create a list of items
Create a data source
Convert the data source into a list
2. Wrap each item in a Dismissible widget
3. Provide “leave behind” indicators
Interactive example
The “swipe... | https://docs.flutter.dev/cookbook/gestures/dismissible/index.html |
7af096deb78c-1 | Wrap each item in a Dismissible widget.
Provide “leave behind” indicators.
1. Create a list of items
First, create a list of items. For detailed
instructions on how to create a list,
follow the Working with long lists recipe.
Create a data source
In this example,
you want 20 sample items to work with.
To keep it s... | https://docs.flutter.dev/cookbook/gestures/dismissible/index.html |
7af096deb78c-2 | After the user has swiped away the item,
remove the item from the list and display a snackbar.
In a real app, you might need to perform more complex logic,
such as removing the item from a web service or database.
Update the itemBuilder() function to return a Dismissible widget:
3. Provide “leave behind” indicators
... | https://docs.flutter.dev/cookbook/gestures/dismissible/index.html |
7af096deb78c-3 | @@ -16,6 +16,8 @@
16
16
ScaffoldMessenger.of(context)
17
17
.showSnackBar(SnackBar(content: Text('$item dismissed')));
18
18
},
19
+
// Show a red background as the item is swiped away.
20
+
background: Container(color: Colors.red),
19
21
child: ListTile(
20
22
title: Text(... | https://docs.flutter.dev/cookbook/gestures/dismissible/index.html |
1a26ce5e03ad-0 | Add Material touch ripples
Implement swipe to dismiss
Handle taps
Cookbook
Gestures
Handle taps
Notes
Interactive example
You not only want to display information to users,
you want users to interact with your app.
Use the GestureDetector widget to respond
to fundamental actions, such as tapping and dragging.
... | https://docs.flutter.dev/cookbook/gestures/handling-taps/index.html |
1a26ce5e03ad-1 | Although this example creates a custom button,
Flutter includes a handful of button implementations, such as:
ElevatedButton, TextButton, and
CupertinoButton.
Interactive example
Add Material touch ripples
Implement swipe to dismiss | https://docs.flutter.dev/cookbook/gestures/handling-taps/index.html |
e61a53daea2d-0 | Gestures
Cookbook
Gestures
Add Material touch ripples
Handle taps
Implement swipe to dismiss | https://docs.flutter.dev/cookbook/gestures/index.html |
13230da44f69-0 | Retrieve the value of a text field
Handle taps
Add Material touch ripples
Cookbook
Gestures
Add Material touch ripples
Interactive example
Widgets that follow the Material Design guidelines display
a ripple animation when tapped.
Flutter provides the InkWell
widget to perform this effect.
Create a ripple effect... | https://docs.flutter.dev/cookbook/gestures/ripples/index.html |
05ef46d0bafe-0 | Fade in images with a placeholder
Use lists
Work with cached images
Cookbook
Images
Work with cached images
Adding a placeholder
Complete example
In some cases, it’s handy to cache images as they’re downloaded from the
web, so they can be used offline. For this purpose,
use the cached_network_image package.
No... | https://docs.flutter.dev/cookbook/images/cached-images/index.html |
836ed7deb43d-0 | Display images from the internet
Work with cached images
Fade in images with a placeholder
Cookbook
Images
Fade in images with a placeholder
In-Memory
Complete example
From asset bundle
Complete example
When displaying images using the default Image widget,
you might notice they simply pop onto the screen as ... | https://docs.flutter.dev/cookbook/images/fading-in-images/index.html |
836ed7deb43d-1 | Complete example
From asset bundle
You can also consider using local assets for placeholders.
First, add the asset to the project’s pubspec.yaml file
(for more details, see Adding assets and images):
+ - assets/loading.gif
Then, use the FadeInImage.assetNetwork() constructor:
Complete example
Display images fr... | https://docs.flutter.dev/cookbook/images/fading-in-images/index.html |
e9bbcf82964e-0 | Images
Cookbook
Images
Display images from the internet
Fade in images with a placeholder
Work with cached images | https://docs.flutter.dev/cookbook/images/index.html |
2fd7977db626-0 | Implement swipe to dismiss
Fade in images with a placeholder
Display images from the internet
Cookbook
Images
Display images from the internet
Bonus: animated gifs
Placeholders and caching
Interactive example
Displaying images is fundamental for most mobile apps.
Flutter provides the Image widget to
display di... | https://docs.flutter.dev/cookbook/images/network-image/index.html |
2fd7977db626-1 | Fade in images with a placeholder
Work with cached images
Interactive example
Implement swipe to dismiss
Fade in images with a placeholder | https://docs.flutter.dev/cookbook/images/network-image/index.html |
bc3a44873072-0 | Cookbook
Animation
Design
Effects
Forms
Gestures
Images
Lists
Maintenance
Navigation
Networking
Persistence
Plugins
Testing
Integration
Unit
Widget
This cookbook contains recipes that demonstrate how to solve common problems
while writing Flutter apps. Each recipe is self-contained and can be used as a
... | https://docs.flutter.dev/cookbook/index.html |
bc3a44873072-1 | 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
Effects
Create a download button
Create a nested navigation flow
Create a photo filter carousel
Create a scrolling parallax effect
Create a shimmer loa... | https://docs.flutter.dev/cookbook/index.html |
bc3a44873072-2 | Retrieve the value of a text field
Gestures
Add Material touch ripples
Handle taps
Implement swipe to dismiss
Images
Display images from the internet
Fade in images with a placeholder
Work with cached images
Lists
Create a grid list
Create a horizontal list
Create lists with different types of items
Place ... | https://docs.flutter.dev/cookbook/index.html |
bc3a44873072-3 | Set up app links for Android
Set up universal links for iOS
Return data from a screen
Send data to a new screen
Networking
Fetch data from the internet
Make authenticated requests
Parse JSON in the background
Send data to the internet
Update data over the internet
Delete data on the internet
Work with WebSoc... | https://docs.flutter.dev/cookbook/index.html |
bc3a44873072-4 | Mock dependencies using Mockito
Widget
An introduction to widget testing
Find widgets
Handle scrolling
Tap, drag, and enter text | https://docs.flutter.dev/cookbook/index.html |
50010c6b7544-0 | Work with cached images
Create a horizontal list
Use lists
Cookbook
Lists
Use lists
Create a ListView
Interactive example
Displaying lists of data is a fundamental pattern for mobile apps.
Flutter includes the ListView
widget to make working with lists a breeze.
Create a ListView
Using the standard ListView c... | https://docs.flutter.dev/cookbook/lists/basic-list/index.html |
5c117b2fe6d0-0 | Create lists with different types of items
Work with long lists
Place a floating app bar above a list
Cookbook
Lists
Place a floating app bar above a list
1. Create a CustomScrollView
2. Use SliverAppBar to add a floating app bar
3. Add a list of items using a SliverList
Interactive example
To make it easier f... | https://docs.flutter.dev/cookbook/lists/floating-app-bar/index.html |
5c117b2fe6d0-1 | Moving the app bar from a Scaffold widget into a
CustomScrollView allows you to create an app bar
that scrolls offscreen as you scroll through a
list of items contained inside the CustomScrollView.
This recipe demonstrates how to use a CustomScrollView to display a list of
items with an app bar on top that scrolls off... | https://docs.flutter.dev/cookbook/lists/floating-app-bar/index.html |
5c117b2fe6d0-2 | For this example, create a CustomScrollView that contains a
SliverAppBar and a SliverList. In addition, remove any app bars
that you provide to the Scaffold widget.
2. Use SliverAppBar to add a floating app bar
Next, add an app bar to the CustomScrollView.
Flutter provides the SliverAppBar widget which,
much like the... | https://docs.flutter.dev/cookbook/lists/floating-app-bar/index.html |
5c117b2fe6d0-3 | Add a flexibleSpace widget that fills the available
expandedHeight.
Tip:
Play around with the
various properties you can pass to the SliverAppBar widget,
and use hot reload to see the results. For example, use an Image
widget for the flexibleSpace property to create a background image that
shrinks in size as... | https://docs.flutter.dev/cookbook/lists/floating-app-bar/index.html |
5c117b2fe6d0-4 | Interactive example
Create lists with different types of items
Work with long lists | https://docs.flutter.dev/cookbook/lists/floating-app-bar/index.html |
8f2674c9ac1b-0 | Create a horizontal list
Create lists with different types of items
Create a grid list
Cookbook
Lists
Create a grid list
Interactive example
In some cases, you might want to display your items as a grid rather than
a normal list of items that come one after the next.
For this task, use the GridView widget.
The ... | https://docs.flutter.dev/cookbook/lists/grid-lists/index.html |
6db9d15dbd28-0 | Use lists
Create a grid list
Create a horizontal list
Cookbook
Lists
Create a horizontal list
Interactive example
You might want to create a list that scrolls
horizontally rather than vertically.
The ListView widget supports horizontal lists.
Use the standard ListView constructor, passing in a horizontal
scroll... | https://docs.flutter.dev/cookbook/lists/horizontal-list/index.html |
b72eaba32151-0 | Lists
Cookbook
Lists
Create a grid list
Create a horizontal list
Create lists with different types of items
Place a floating app bar above a list
Use lists
Work with long lists | https://docs.flutter.dev/cookbook/lists/index.html |
cebb648bb1da-0 | Place a floating app bar above a list
Report errors to a service
Work with long lists
Cookbook
Lists
Work with long lists
1. Create a data source
2. Convert the data source into widgets
Interactive example
Children’s extent
The standard ListView constructor works well
for small lists. To work with lists that ... | https://docs.flutter.dev/cookbook/lists/long-lists/index.html |
cebb648bb1da-1 | For this example, generate a list of 10,000 Strings using the
List.generate constructor.
2. Convert the data source into widgets
To display the list of strings, render each String as a widget
using ListView.builder().
In this example, display each String on its own line.
Interactive example
Children’s extent
To sp... | https://docs.flutter.dev/cookbook/lists/long-lists/index.html |
ba32ebc3231f-0 | Create a grid list
Place a floating app bar above a list
Create lists with different types of items
Cookbook
Lists
Create lists with different types of items
1. Create a data source with different types of items
Types of items
Create a list of items
2. Convert the data source into a list of widgets
Interactive... | https://docs.flutter.dev/cookbook/lists/mixed-list/index.html |
ba32ebc3231f-1 | Types of items
To represent different types of items in a list, define
a class for each type of item.
In this example, create an app that shows a header followed by five
messages. Therefore, create three classes: ListItem, HeadingItem,
and MessageItem.
Create a list of items
Most of the time, you would fetch data f... | https://docs.flutter.dev/cookbook/lists/mixed-list/index.html |
ba32ebc3231f-2 | Interactive example
Create a grid list
Place a floating app bar above a list | https://docs.flutter.dev/cookbook/lists/mixed-list/index.html |
86d7fc6a8769-0 | Work with long lists
Animate a widget across screens
Report errors to a service
Cookbook
Maintenance
Report errors to a service
1. Get a DSN from Sentry
2. Import the Sentry package
3. Initialize the Sentry SDK
What does that give me?
4. Capture errors programatically
Learn more
Complete example
While one ... | https://docs.flutter.dev/cookbook/maintenance/error-reporting/index.html |
86d7fc6a8769-1 | How can you determine how often your users experiences bugs?
Whenever an error occurs, create a report containing the
error that occurred and the associated stacktrace.
You can then send the report to an error tracking
service, such as Bugsnag, Fabric, Firebase Crashlytics, Rollbar, or Sentry.
The error tracking servi... | https://docs.flutter.dev/cookbook/maintenance/error-reporting/index.html |
86d7fc6a8769-2 | To get a DSN, use the following steps:
Create an account with Sentry.
Log in to the account.
Create a new Flutter project.
Copy the code snippet that includes the DSN.
2. Import the Sentry package
Import the sentry_flutter package into the app.
The sentry package makes it easier to send
error reports to the Sentr... | https://docs.flutter.dev/cookbook/maintenance/error-reporting/index.html |
86d7fc6a8769-3 | What does that give me?
This is all you need for Sentry to capture unhandled errors in Dart and native layers.
This includes Swift, Objective-C, C, and C++ on iOS, and Java, Kotlin, C, and C++ on Android.
4. Capture errors programatically
Besides the automatic error reporting that Sentry generates by
importing and i... | https://docs.flutter.dev/cookbook/maintenance/error-reporting/index.html |
63688096c27b-0 | Maintenance
Cookbook
Maintenance
Report errors to a service | https://docs.flutter.dev/cookbook/maintenance/index.html |
c092d5894025-0 | Report errors to a service
Navigate to a new screen and back
Animate a widget across screens
Cookbook
Navigation
Animate a widget across screens
1. Create two screens showing the same image
2. Add a Hero widget to the first screen
3. Add a Hero widget to the second screen
Interactive example
It’s often helpfu... | https://docs.flutter.dev/cookbook/navigation/hero-animations/index.html |
c092d5894025-1 | Add a Hero widget to the second screen.
1. Create two screens showing the same image
In this example, display the same image on both screens.
Animate the image from the first screen to the second screen when
the user taps the image. For now, create the visual structure;
handle animations in the next steps.
Note:
T... | https://docs.flutter.dev/cookbook/navigation/hero-animations/index.html |
c092d5894025-2 | 3. Add a Hero widget to the second screen
To complete the connection with the first screen,
wrap the Image on the second screen with a Hero
widget that has the same tag as the Hero in the first screen.
After applying the Hero widget to the second screen,
the animation between screens just works.
Note:
This code is... | https://docs.flutter.dev/cookbook/navigation/hero-animations/index.html |
f669fabee511-0 | Navigation
Cookbook
Navigation
Animate a widget across screens
Navigate to a new screen and back
Navigate with named routes
Pass arguments to a named route
Return data from a screen
Send data to a new screen
Set up app links for Android
Set up universal links for iOS | https://docs.flutter.dev/cookbook/navigation/index.html |
98f6e20a03d5-0 | Navigate to a new screen and back
Pass arguments to a named route
Navigate with named routes
Cookbook
Navigation
Navigate with named routes
1. Create two screens
2. Define the routes
3. Navigate to the second screen
4. Return to the first screen
Interactive example
Note:
Named routes are no longer recommen... | https://docs.flutter.dev/cookbook/navigation/named-routes/index.html |
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