* Adds support for `flutter test --wasm`.
* The test compilation flow is a bit different now, so that it supports compilers other than DDC. Specifically, when we run a set of unit tests, we generate a "switchboard" main function that imports each unit test and runs the main function for a specific one based off of a value set by the JS bootstrapping code. This way, there is one compile step and the same compile output is invoked for each unit test file.
* Also, removes all references to `dart:html` from flutter/flutter.
* Adds CI steps for running the framework unit tests with dart2wasm+skwasm
* These steps are marked as `bringup: true`, so we don't know what kind of failures they will result in. Any failures they have will not block the tree at all yet while we're still in `bringup: true`. Once this PR is merged, I plan on looking at any failures and either fixing them or disabling them so we can get these CI steps running on presubmit.
This fixes https://github.com/flutter/flutter/issues/126692
This pull request introduces a new field named `helper` to the InputDecoration class. This field allows for specifying a widget containing contextual information about the InputDecorator.child's value. Unlike `helperText`, which accepts a plain string, `helper` supports widgets, enabling functionalities like tappable links for further explanation. This change aligns with the established pattern of `error`, `label`, `prefix`, and `suffix`.
fixes [#145163](https://github.com/flutter/flutter/issues/145163)
Fixes#138270.
Moves the majority of the logic of MaterialStateProperties down to the widgets layer, then has the existing Material classes pull from the widgets versions.
This pull request is part of the effort to solve issue #144903.
In the past, my efforts to reduce line length involved refactoring away from switch statements, but unlike [yesterday's PR](https://github.com/flutter/flutter/pull/144905), this one is full of switch statements that make things more concise!
Improved the smiley image TextButton example a little. Handling the case where the `Future.delayed` object that represents the button's one second long action is superseded by a second button press that triggers a new one-second action. This does complicate the example - just a little - but it's a little more robust. In case someone copy-and-pastes the code.
The TextButton example was recently updated: https://github.com/flutter/flutter/pull/144583
## Description
This PR simplifies one external link in a commented section of the Android manifest template.
## Related Issue
Fixes https://github.com/flutter/flutter/issues/144249
## Tests
Documentation only PR.
Reverts flutter/flutter#144001
Initiated by: Piinks
Reason for reverting: Failing goldens at the tip of tree
Original PR Author: QuncCccccc
Reviewed By: {HansMuller}
This change reverts the following previous change:
Original Description:
Reverts flutter/flutter#143973
This is a reland for #138521 with an updated g3fix(cl/605555997). Local test: cl/609608958.
The original PR was reverted because the new caret positioning callpath triggered a skparagraph assert. The assert has been removed. Relanding the PR with no changes applied.
Reverts flutter/flutter#143281
Initiated by: LongCatIsLooong
Reason for reverting: https://github.com/flutter/flutter/issues/143797
Original PR Author: LongCatIsLooong
Reviewed By: {justinmc, jason-simmons}
This change reverts the following previous change:
Original Description:
The behavior largely remains the same, except:
1. The EOT cursor `(textLength, downstream)` for text ending in the opposite writing direction as the paragraph is now placed at the visual end of the last line.
For example, in a LTR paragraph, the EOT cursor for `aA` (lowercase for LTR and uppercase for RTL) is placed to the right of the line: `aA|` (it was `a|A` before).
This matches the behavior of most applications that do logical order arrow key navigation instead of visual order navigation.
And it makes the navigation order consistent for `aA\naA`:
```
|aA => aA| => aA| => aA => aA => aA
aA aA aA |aA aA| aA|
(1) (2) (3) (4) (5) (6)
```
This is indeed still pretty confusing as (2) and (3), as well as (5) and (6) are hard to distinguish (when the I beam has a large width they are actually visually distinguishable -- they use the same anchor but one gets painted to the left and the other to the right. I noticed that emacs does the same).
But logical order navigation will always be confusing in bidi text, in one way or another.
Interestingly there are 3 different behaviors I've observed in chrome:
- the chrome download dialog (which I think uses GTK text widgets but not sure which version) gives me 2 cursors when navigating bidi text, and
- its HTML fields only show one, and presumably they place the I beam at the **trailing edge** of the character (which makes more sense for backspacing I guess).
- On the other hand, its (new) omnibar seems to use visual order arrow navigation
Side note: we may need to update the "tap to place the caret here" logic to handle the case where the tap lands outside of the text and the text ends in the opposite writing direction.
2. Removed the logarithmic search. The same could be done using the characters package but when glyphInfo tells you about the baseline location in the future we probably don't need the `getBoxesForRange` call. This should fix https://github.com/flutter/flutter/issues/123424.
## Internal Tests
This is going to change the image output of some internal golden tests. I'm planning to merge https://github.com/flutter/flutter/pull/143281 before this to avoid updating the same golden files twice for invalid selections.
The behavior largely remains the same, except:
1. The EOT cursor `(textLength, downstream)` for text ending in the opposite writing direction as the paragraph is now placed at the visual end of the last line.
For example, in a LTR paragraph, the EOT cursor for `aA` (lowercase for LTR and uppercase for RTL) is placed to the right of the line: `aA|` (it was `a|A` before).
This matches the behavior of most applications that do logical order arrow key navigation instead of visual order navigation.
And it makes the navigation order consistent for `aA\naA`:
```
|aA => aA| => aA| => aA => aA => aA
aA aA aA |aA aA| aA|
(1) (2) (3) (4) (5) (6)
```
This is indeed still pretty confusing as (2) and (3), as well as (5) and (6) are hard to distinguish (when the I beam has a large width they are actually visually distinguishable -- they use the same anchor but one gets painted to the left and the other to the right. I noticed that emacs does the same).
But logical order navigation will always be confusing in bidi text, in one way or another.
Interestingly there are 3 different behaviors I've observed in chrome:
- the chrome download dialog (which I think uses GTK text widgets but not sure which version) gives me 2 cursors when navigating bidi text, and
- its HTML fields only show one, and presumably they place the I beam at the **trailing edge** of the character (which makes more sense for backspacing I guess).
- On the other hand, its (new) omnibar seems to use visual order arrow navigation
Side note: we may need to update the "tap to place the caret here" logic to handle the case where the tap lands outside of the text and the text ends in the opposite writing direction.
2. Removed the logarithmic search. The same could be done using the characters package but when glyphInfo tells you about the baseline location in the future we probably don't need the `getBoxesForRange` call. This should fix https://github.com/flutter/flutter/issues/123424.
## Internal Tests
This is going to change the image output of some internal golden tests. I'm planning to merge https://github.com/flutter/flutter/pull/143281 before this to avoid updating the same golden files twice for invalid selections.
## Description
This PR adds more documentation for `TextEditingController(String text)` constructor and it adds one example.
https://github.com/flutter/flutter/pull/96245 was a first improvement to the documentation.
https://github.com/flutter/flutter/issues/79495 tried to hide the cursor when an invalid selection is set but it was reverted.
https://github.com/flutter/flutter/pull/123777 mitigated the issue of having a default invalid selection: it takes care of setting a proper selection when a text field is focused and its controller selection is not initialized.
I will try changing the initial selection in another PR, but It will probably break several existing tests.
## Related Issue
Fixes https://github.com/flutter/flutter/issues/95978
## Tests
Adds 1 test for the new example.
Entire pr generated with [ktlint](https://github.com/pinterest/ktlint) --format. First step before enabling linting as part of presubmit for kotlin changes.
Re-sets two jvmargs that were getting cleared because we set a value for `-Xmx`. Could help with https://github.com/flutter/flutter/issues/142957. Copied from comment here https://github.com/flutter/flutter/issues/142957:
>Two random things I ran into while looking into this that might help:
>
>1. Gradle has defaults for a couple of the jvmargs, and setting any one of them clears those defaults for the others (bug here https://github.com/gradle/gradle/issues/19750). This can cause the "Gradle daemon to consume more and more native memory until it crashes", though the bug typically has a different associated error. It seems worth it to re-set those defaults.
>2. There is a property we can set that will give us a heap dump on OOM ([-XX:HeapDumpOnOutOfMemoryError](https://docs.oracle.com/javase/8/docs/technotes/guides/troubleshoot/clopts001.html))
Mostly just a find and replace from `find . -name gradle.properties -exec sed -i '' 's/\-Xmx4G/-Xmx4G\ \-XX:MaxMetaspaceSize=2G\ \-XX:+HeapDumpOnOutOfMemoryError/g' {} \;`, with the templates and the one test that writes from a string replaced by hand. I didn't set a value for `MaxMetaspaceSize` in the template files because I want to make sure this value doesn't cause problems in ci first (changes to the templates are essentially un-revertable for those who `flutter create` while the changes exist).
Previously, we were comparing the signed int `target_length` (returned by WideCharToMultiByte) to a size_t string length, resulting in a signed/unsigned comparison warning as follows:
```
windows\runner\utils.cpp(54,43): warning C4018: '>': signed/unsigned mismatch
```
WideCharToMultiByte returns:
* 0 on error
* the number of bytes written to the buffer pointed to by its fifth parameter, lpMultiByteStr, on success.
As a result it's safe to store the return value in an unsigned int, which eliminates the warning.
No changes to tests since this is dependent on end-user project settings/modifications and does not trigger a warning with default project settings.
Fixes: https://github.com/flutter/flutter/issues/134227
This PR updates almost* all Gradle buildscripts in the Flutter repo the `example` and `dev` (in particular, in `dev/integration_tests` and in `dev/benchmarks`) directories to apply Flutter's Gradle plugins using the declarative `plugins {}` block.
*almost, because:
- add-to-app (aka hybrid) apps are not migrated (related https://github.com/flutter/flutter/issues/138756)
- apps that purposefully use build files to ensure backward compatibility (e.g. [`gradle_deprecated_settings`](https://github.com/flutter/flutter/tree/3.16.0/dev/integration_tests/gradle_deprecated_settings))
Reland https://github.com/flutter/flutter/pull/141818 with a fix for a special case: If only `background` is specified for `TextButton.styleFrom` or `OutlinedButton.styleFrom` it applies the button's disabled state, i.e. as if the same value had been specified for disabledBackgroundColor.
The change relative to #141818 is the indicated line below:
```dart
final MaterialStateProperty<Color?>? backgroundColorProp = switch ((backgroundColor, disabledBackgroundColor)) {
(null, null) => null,
(_, null) => MaterialStatePropertyAll<Color?>(backgroundColor), // ADDED THIS LINE
(_, _) => _TextButtonDefaultColor(backgroundColor, disabledBackgroundColor),
};
```
This backwards incompatibility cropped up in an internal test, see internal Google issue b/323399158.
Reverts flutter/flutter#141818
Initiated by: XilaiZhang
This change reverts the following previous change:
Original Description:
Fixes https://github.com/flutter/flutter/issues/139456, https://github.com/flutter/flutter/issues/130335, https://github.com/flutter/flutter/issues/89563.
Two new properties have been added to ButtonStyle to make it possible to insert arbitrary state-dependent widgets in a button's background or foreground. These properties can be specified for an individual button, using the style parameter, or for all buttons using a button theme's style parameter.
The new ButtonStyle properties are `backgroundBuilder` and `foregroundBuilder` and their (function) types are:
```dart
typedef ButtonLayerBuilder = Widget Function(
BuildContext context,
Set<MaterialState> states,
Widget? child
);
```
The new builder functions are called whenever the button is built and the `states` parameter communicates the pressed/hovered/etc state fo the button.
## `backgroundBuilder`
Creates a widget that becomes the child of the button's Material and whose child is the rest of the button, including the button's `child` parameter. By default the returned widget is clipped to the Material's ButtonStyle.shape.
The `backgroundBuilder` can be used to add a gradient to the button's background. Here's an example that creates a yellow/orange gradient background:
```dart
TextButton(
onPressed: () {},
style: TextButton.styleFrom(
backgroundBuilder: (BuildContext context, Set<MaterialState> states, Widget? child) {
return DecoratedBox(
decoration: BoxDecoration(
gradient: LinearGradient(colors: [Colors.orange, Colors.yellow]),
),
child: child,
);
},
),
child: Text('Text Button'),
)
```
Because the background widget becomes the child of the button's Material, if it's opaque (as it is in this case) then it obscures the overlay highlights which are painted on the button's Material. To ensure that the highlights show through one can decorate the background with an `Ink` widget. This version also overrides the overlay color to be (shades of) red, because that makes the highlights look a little nicer with the yellow/orange background.
```dart
TextButton(
onPressed: () {},
style: TextButton.styleFrom(
overlayColor: Colors.red,
backgroundBuilder: (BuildContext context, Set<MaterialState> states, Widget? child) {
return Ink(
decoration: BoxDecoration(
gradient: LinearGradient(colors: [Colors.orange, Colors.yellow]),
),
child: child,
);
},
),
child: Text('Text Button'),
)
```
Now the button's overlay highlights are painted on the Ink widget. An Ink widget isn't needed if the background is sufficiently translucent. This version of the example creates a translucent backround widget.
```dart
TextButton(
onPressed: () {},
style: TextButton.styleFrom(
overlayColor: Colors.red,
backgroundBuilder: (BuildContext context, Set<MaterialState> states, Widget? child) {
return DecoratedBox(
decoration: BoxDecoration(
gradient: LinearGradient(colors: [
Colors.orange.withOpacity(0.5),
Colors.yellow.withOpacity(0.5),
]),
),
child: child,
);
},
),
child: Text('Text Button'),
)
```
One can also decorate the background with an image. In this example, the button's background is an burlap texture image. The foreground color has been changed to black to make the button's text a little clearer relative to the mottled brown backround.
```dart
TextButton(
onPressed: () {},
style: TextButton.styleFrom(
foregroundColor: Colors.black,
backgroundBuilder: (BuildContext context, Set<MaterialState> states, Widget? child) {
return Ink(
decoration: BoxDecoration(
image: DecorationImage(
image: NetworkImage(burlapUrl),
fit: BoxFit.cover,
),
),
child: child,
);
},
),
child: Text('Text Button'),
)
```
The background widget can depend on the `states` parameter. In this example the blue/orange gradient flips horizontally when the button is hovered/pressed.
```dart
TextButton(
onPressed: () {},
style: TextButton.styleFrom(
backgroundBuilder: (BuildContext context, Set<MaterialState> states, Widget? child) {
final Color color1 = Colors.blue.withOpacity(0.5);
final Color color2 = Colors.orange.withOpacity(0.5);
return DecoratedBox(
decoration: BoxDecoration(
gradient: LinearGradient(
colors: switch (states.contains(MaterialState.hovered)) {
true => <Color>[color1, color2],
false => <Color>[color2, color1],
},
),
),
child: child,
);
},
),
child: Text('Text Button'),
)
```
The preceeding examples have not included a BoxDecoration border because ButtonStyle already supports `ButtonStyle.shape` and `ButtonStyle.side` parameters that can be uesd to define state-dependent borders. Borders defined with the ButtonStyle side parameter match the button's shape. To add a border that changes color when the button is hovered or pressed, one must specify the side property using `copyWith`, since there's no `styleFrom` shorthand for this case.
```dart
TextButton(
onPressed: () {},
style: TextButton.styleFrom(
foregroundColor: Colors.indigo,
backgroundBuilder: (BuildContext context, Set<MaterialState> states, Widget? child) {
final Color color1 = Colors.blue.withOpacity(0.5);
final Color color2 = Colors.orange.withOpacity(0.5);
return DecoratedBox(
decoration: BoxDecoration(
gradient: LinearGradient(
colors: switch (states.contains(MaterialState.hovered)) {
true => <Color>[color1, color2],
false => <Color>[color2, color1],
},
),
),
child: child,
);
},
).copyWith(
side: MaterialStateProperty.resolveWith<BorderSide?>((Set<MaterialState> states) {
if (states.contains(MaterialState.hovered)) {
return BorderSide(width: 3, color: Colors.yellow);
}
return null; // defer to the default
}),
),
child: Text('Text Button'),
)
```
Although all of the examples have created a ButtonStyle locally and only applied it to one button, they could have configured the `ThemeData.textButtonTheme` instead and applied the style to all TextButtons. And, of course, all of this works for all of the ButtonStyleButton classes, not just TextButton.
## `foregroundBuilder`
Creates a Widget that contains the button's child parameter. The returned widget is clipped by the button's [ButtonStyle.shape] inset by the button's [ButtonStyle.padding] and aligned by the button's [ButtonStyle.alignment].
The `foregroundBuilder` can be used to wrap the button's child, e.g. with a border or a `ShaderMask` or as a state-dependent substitute for the child.
This example adds a border that's just applied to the child. The border only appears when the button is hovered/pressed.
```dart
ElevatedButton(
onPressed: () {},
style: ElevatedButton.styleFrom(
foregroundBuilder: (BuildContext context, Set<MaterialState> states, Widget? child) {
final ColorScheme colorScheme = Theme.of(context).colorScheme;
return DecoratedBox(
decoration: BoxDecoration(
border: states.contains(MaterialState.hovered)
? Border(bottom: BorderSide(color: colorScheme.primary))
: Border(), // essentially "no border"
),
child: child,
);
},
),
child: Text('Text Button'),
)
```
The foregroundBuilder can be used with `ShaderMask` to change the way the button's child is rendered. In this example the ShaderMask's gradient causes the button's child to fade out on top.
```dart
ElevatedButton(
onPressed: () { },
style: ElevatedButton.styleFrom(
foregroundBuilder: (BuildContext context, Set<MaterialState> states, Widget? child) {
final ColorScheme colorScheme = Theme.of(context).colorScheme;
return ShaderMask(
shaderCallback: (Rect bounds) {
return LinearGradient(
begin: Alignment.bottomCenter,
end: Alignment.topCenter,
colors: <Color>[
colorScheme.primary,
colorScheme.primaryContainer,
],
).createShader(bounds);
},
blendMode: BlendMode.srcATop,
child: child,
);
},
),
child: const Text('Elevated Button'),
)
```
A commonly requested configuration for butttons has the developer provide images, one for pressed/hovered/normal state. You can use the foregroundBuilder to create a button that fades between a normal image and another image when the button is pressed. In this case the foregroundBuilder doesn't use the child it's passed, even though we've provided the required TextButton child parameter.
```dart
TextButton(
onPressed: () {},
style: TextButton.styleFrom(
foregroundBuilder: (BuildContext context, Set<MaterialState> states, Widget? child) {
final String url = states.contains(MaterialState.pressed) ? smiley2Url : smiley1Url;
return AnimatedContainer(
width: 100,
height: 100,
duration: Duration(milliseconds: 300),
decoration: BoxDecoration(
image: DecorationImage(
image: NetworkImage(url),
fit: BoxFit.contain,
),
),
);
},
),
child: Text('No Child'),
)
```
In this example the button's default overlay appears when the button is hovered and pressed. Another image can be used to indicate the hovered state and the default overlay can be defeated by specifying `Colors.transparent` for the `overlayColor`:
```dart
TextButton(
onPressed: () {},
style: TextButton.styleFrom(
overlayColor: Colors.transparent,
foregroundBuilder: (BuildContext context, Set<MaterialState> states, Widget? child) {
String url = states.contains(MaterialState.hovered) ? smiley3Url : smiley1Url;
if (states.contains(MaterialState.pressed)) {
url = smiley2Url;
}
return AnimatedContainer(
width: 100,
height: 100,
duration: Duration(milliseconds: 300),
decoration: BoxDecoration(
image: DecorationImage(
image: NetworkImage(url),
fit: BoxFit.contain,
),
),
);
},
),
child: Text('No Child'),
)
```
Fixes https://github.com/flutter/flutter/issues/139456, https://github.com/flutter/flutter/issues/130335, https://github.com/flutter/flutter/issues/89563.
Two new properties have been added to ButtonStyle to make it possible to insert arbitrary state-dependent widgets in a button's background or foreground. These properties can be specified for an individual button, using the style parameter, or for all buttons using a button theme's style parameter.
The new ButtonStyle properties are `backgroundBuilder` and `foregroundBuilder` and their (function) types are:
```dart
typedef ButtonLayerBuilder = Widget Function(
BuildContext context,
Set<MaterialState> states,
Widget? child
);
```
The new builder functions are called whenever the button is built and the `states` parameter communicates the pressed/hovered/etc state fo the button.
## `backgroundBuilder`
Creates a widget that becomes the child of the button's Material and whose child is the rest of the button, including the button's `child` parameter. By default the returned widget is clipped to the Material's ButtonStyle.shape.
The `backgroundBuilder` can be used to add a gradient to the button's background. Here's an example that creates a yellow/orange gradient background:
```dart
TextButton(
onPressed: () {},
style: TextButton.styleFrom(
backgroundBuilder: (BuildContext context, Set<MaterialState> states, Widget? child) {
return DecoratedBox(
decoration: BoxDecoration(
gradient: LinearGradient(colors: [Colors.orange, Colors.yellow]),
),
child: child,
);
},
),
child: Text('Text Button'),
)
```
Because the background widget becomes the child of the button's Material, if it's opaque (as it is in this case) then it obscures the overlay highlights which are painted on the button's Material. To ensure that the highlights show through one can decorate the background with an `Ink` widget. This version also overrides the overlay color to be (shades of) red, because that makes the highlights look a little nicer with the yellow/orange background.
```dart
TextButton(
onPressed: () {},
style: TextButton.styleFrom(
overlayColor: Colors.red,
backgroundBuilder: (BuildContext context, Set<MaterialState> states, Widget? child) {
return Ink(
decoration: BoxDecoration(
gradient: LinearGradient(colors: [Colors.orange, Colors.yellow]),
),
child: child,
);
},
),
child: Text('Text Button'),
)
```
Now the button's overlay highlights are painted on the Ink widget. An Ink widget isn't needed if the background is sufficiently translucent. This version of the example creates a translucent backround widget.
```dart
TextButton(
onPressed: () {},
style: TextButton.styleFrom(
overlayColor: Colors.red,
backgroundBuilder: (BuildContext context, Set<MaterialState> states, Widget? child) {
return DecoratedBox(
decoration: BoxDecoration(
gradient: LinearGradient(colors: [
Colors.orange.withOpacity(0.5),
Colors.yellow.withOpacity(0.5),
]),
),
child: child,
);
},
),
child: Text('Text Button'),
)
```
One can also decorate the background with an image. In this example, the button's background is an burlap texture image. The foreground color has been changed to black to make the button's text a little clearer relative to the mottled brown backround.
```dart
TextButton(
onPressed: () {},
style: TextButton.styleFrom(
foregroundColor: Colors.black,
backgroundBuilder: (BuildContext context, Set<MaterialState> states, Widget? child) {
return Ink(
decoration: BoxDecoration(
image: DecorationImage(
image: NetworkImage(burlapUrl),
fit: BoxFit.cover,
),
),
child: child,
);
},
),
child: Text('Text Button'),
)
```
The background widget can depend on the `states` parameter. In this example the blue/orange gradient flips horizontally when the button is hovered/pressed.
```dart
TextButton(
onPressed: () {},
style: TextButton.styleFrom(
backgroundBuilder: (BuildContext context, Set<MaterialState> states, Widget? child) {
final Color color1 = Colors.blue.withOpacity(0.5);
final Color color2 = Colors.orange.withOpacity(0.5);
return DecoratedBox(
decoration: BoxDecoration(
gradient: LinearGradient(
colors: switch (states.contains(MaterialState.hovered)) {
true => <Color>[color1, color2],
false => <Color>[color2, color1],
},
),
),
child: child,
);
},
),
child: Text('Text Button'),
)
```
The preceeding examples have not included a BoxDecoration border because ButtonStyle already supports `ButtonStyle.shape` and `ButtonStyle.side` parameters that can be uesd to define state-dependent borders. Borders defined with the ButtonStyle side parameter match the button's shape. To add a border that changes color when the button is hovered or pressed, one must specify the side property using `copyWith`, since there's no `styleFrom` shorthand for this case.
```dart
TextButton(
onPressed: () {},
style: TextButton.styleFrom(
foregroundColor: Colors.indigo,
backgroundBuilder: (BuildContext context, Set<MaterialState> states, Widget? child) {
final Color color1 = Colors.blue.withOpacity(0.5);
final Color color2 = Colors.orange.withOpacity(0.5);
return DecoratedBox(
decoration: BoxDecoration(
gradient: LinearGradient(
colors: switch (states.contains(MaterialState.hovered)) {
true => <Color>[color1, color2],
false => <Color>[color2, color1],
},
),
),
child: child,
);
},
).copyWith(
side: MaterialStateProperty.resolveWith<BorderSide?>((Set<MaterialState> states) {
if (states.contains(MaterialState.hovered)) {
return BorderSide(width: 3, color: Colors.yellow);
}
return null; // defer to the default
}),
),
child: Text('Text Button'),
)
```
Although all of the examples have created a ButtonStyle locally and only applied it to one button, they could have configured the `ThemeData.textButtonTheme` instead and applied the style to all TextButtons. And, of course, all of this works for all of the ButtonStyleButton classes, not just TextButton.
## `foregroundBuilder`
Creates a Widget that contains the button's child parameter. The returned widget is clipped by the button's [ButtonStyle.shape] inset by the button's [ButtonStyle.padding] and aligned by the button's [ButtonStyle.alignment].
The `foregroundBuilder` can be used to wrap the button's child, e.g. with a border or a `ShaderMask` or as a state-dependent substitute for the child.
This example adds a border that's just applied to the child. The border only appears when the button is hovered/pressed.
```dart
ElevatedButton(
onPressed: () {},
style: ElevatedButton.styleFrom(
foregroundBuilder: (BuildContext context, Set<MaterialState> states, Widget? child) {
final ColorScheme colorScheme = Theme.of(context).colorScheme;
return DecoratedBox(
decoration: BoxDecoration(
border: states.contains(MaterialState.hovered)
? Border(bottom: BorderSide(color: colorScheme.primary))
: Border(), // essentially "no border"
),
child: child,
);
},
),
child: Text('Text Button'),
)
```
The foregroundBuilder can be used with `ShaderMask` to change the way the button's child is rendered. In this example the ShaderMask's gradient causes the button's child to fade out on top.
```dart
ElevatedButton(
onPressed: () { },
style: ElevatedButton.styleFrom(
foregroundBuilder: (BuildContext context, Set<MaterialState> states, Widget? child) {
final ColorScheme colorScheme = Theme.of(context).colorScheme;
return ShaderMask(
shaderCallback: (Rect bounds) {
return LinearGradient(
begin: Alignment.bottomCenter,
end: Alignment.topCenter,
colors: <Color>[
colorScheme.primary,
colorScheme.primaryContainer,
],
).createShader(bounds);
},
blendMode: BlendMode.srcATop,
child: child,
);
},
),
child: const Text('Elevated Button'),
)
```
A commonly requested configuration for butttons has the developer provide images, one for pressed/hovered/normal state. You can use the foregroundBuilder to create a button that fades between a normal image and another image when the button is pressed. In this case the foregroundBuilder doesn't use the child it's passed, even though we've provided the required TextButton child parameter.
```dart
TextButton(
onPressed: () {},
style: TextButton.styleFrom(
foregroundBuilder: (BuildContext context, Set<MaterialState> states, Widget? child) {
final String url = states.contains(MaterialState.pressed) ? smiley2Url : smiley1Url;
return AnimatedContainer(
width: 100,
height: 100,
duration: Duration(milliseconds: 300),
decoration: BoxDecoration(
image: DecorationImage(
image: NetworkImage(url),
fit: BoxFit.contain,
),
),
);
},
),
child: Text('No Child'),
)
```
In this example the button's default overlay appears when the button is hovered and pressed. Another image can be used to indicate the hovered state and the default overlay can be defeated by specifying `Colors.transparent` for the `overlayColor`:
```dart
TextButton(
onPressed: () {},
style: TextButton.styleFrom(
overlayColor: Colors.transparent,
foregroundBuilder: (BuildContext context, Set<MaterialState> states, Widget? child) {
String url = states.contains(MaterialState.hovered) ? smiley3Url : smiley1Url;
if (states.contains(MaterialState.pressed)) {
url = smiley2Url;
}
return AnimatedContainer(
width: 100,
height: 100,
duration: Duration(milliseconds: 300),
decoration: BoxDecoration(
image: DecorationImage(
image: NetworkImage(url),
fit: BoxFit.contain,
),
),
);
},
),
child: Text('No Child'),
)
```
This PR increases Android's `minSdkVersion` to 21.
There are two changes in this PR aside from simply increasing the number
from 19 to 21 everywhere.
First, tests using `flutter_gallery` fail without updating the
lockfiles. The changes in the PR are the results of running
`dev/tools/bin/generate_gradle_lockfiles.dart` on that app.
Second, from
[here](https://developer.android.com/build/multidex#mdex-pre-l):
> if your minSdkVersion is 21 or higher, multidex is enabled by default
and you don't need the multidex library.
As a result, the `multidex` option everywhere is obsolete. This PR
removes all logic and tests related to that option that I could find.
`Google testing` and `customer_tests` pass on this PR, so it seems like
this won't be too breaking if it is at all. If needed I'll give this
some time to bake in the framework before landing the flutter/engine
PRs.
Context: https://github.com/flutter/flutter/issues/138117,
https://github.com/flutter/flutter/issues/141277, b/319373605
