I am working on a Flutter app where I am using a drawer. The drawer consists of various menu options using the ListTile class. The documentation specifies that when the 'selected' property of a ListTile is true then 'By default the selected color is the theme's primary color.' but it makes no mention of the text color. Whenever a ListTile is selected the corresponding text changes to blue, which goes against my theme. How do I set the text color for a selected ListTile?
Thanks.
You can apply theme to ListTile by wrapping it with ListTileTheme.
ListTileTheme(
selectedColor: Colors.red, // text & icon color
selectedTileColor: Colors.green, // background color
child: ListTile(
title: Text('cats')
)
)
What is MaterialStateProperty in ButtonStyle?
ThemeData(
textButtonTheme: TextButtonThemeData(
style: ButtonStyle(
backgroundColor: , //?
),
),
),
The purpose of MaterialStateProperty is to make it possible to specify different styles for different states.
For example, if we want a button that's usually blue, but turns green when it's pressed, and enlarges its texts at the same time, we can use MaterialStateProperty.resolveWith to do exactly that.
ElevatedButton(
style: ButtonStyle(
backgroundColor: MaterialStateProperty.resolveWith((states) {
// If the button is pressed, return green, otherwise blue
if (states.contains(MaterialState.pressed)) {
return Colors.green;
}
return Colors.blue;
}),
textStyle: MaterialStateProperty.resolveWith((states) {
// If the button is pressed, return size 40, otherwise 20
if (states.contains(MaterialState.pressed)) {
return TextStyle(fontSize: 40);
}
return TextStyle(fontSize: 20);
}),
),
child: Text("Changing Button"),
onPressed: () {},
)
In addition to checking whether the button is being "pressed", MaterialStateProperty also supports: disabled, dragged, error, focused, hovered, pressed, scrolledUnder, selected. Note that it's possible to have multiple states at once. For example, a button can be both "disabled" & "hovered" at the same time. With MaterialStateProperty you can customize its appearance when that happens.
"Is there a clean way to resolve multiple states at once?"
The Flutter API documentation provides a nice clean pattern for resolving any of multiple states at one time. For example, if you want to respond the same way to all interactive states you could define a method like this:
Color getColor(Set<MaterialState> states) {
const Set<MaterialState> interactiveStates = <MaterialState>{
MaterialState.pressed, // Any states you want to affect here
MaterialState.hovered,
MaterialState.focused,
};
if (states.any(interactiveStates.contains)) {
// if any of the input states are found in our list
return Colors.blue;
}
return Colors.red; // default color
}
Then later in the button widget, simply assign that method as the resolver for the backgroundColor:
TextButton(
style: ButtonStyle(
backgroundColor: MaterialStateProperty.resolveWith(getColor),
),
onPressed: () {},
child: const Text('Changing Button'),
);
Play with the full example in Dart Pad.
"Okay, but I just want a red button."
Sure, it seems like you can use: MaterialStateProperty.all(Colors.red) to make it red in all cases. But that's probably NOT what you want. For example, when the button is disabled, do you still want it to be red?
See, "all" means "all". This is not good.
So what, are we stuck dealing with MaterialStateProperty and checking for disabled states all day?
Thankfully, no. There's a better way:
If you are using ElevatedButton, you can use ElevatedButton.styleFrom as a base style. Similarly, if you are using TextButton, you can use TextButton.styleFrom. From there, you can easily modify some of the styles.
Code:
ElevatedButton(
style: ElevatedButton.styleFrom(backgroundColor: Colors.red),
child: Text("Red Button"),
onPressed: () {},
)
That's it, you just pass in a Color class. Super easy, no MaterialStateProperty involved. And it automatically handles edge cases for you.
I am assuming that you want to know how to assign a color to the backgroundColor parameter of the ButtonStyle widget. If that is the case then just type something like this:
backgroundColor: MaterialStateProperty.all(Colors.green),
OR
backgroundColor: MaterialStateProperty.all(Color(0xFF5D5F6E)),
Interface for classes that resolve to a value of type T based on a widget's interactive "state", which is defined as a set of MaterialStates.
Material state properties represent values that depend on a widget's material "state". The state is encoded as a set of MaterialState values, like MaterialState.focused, MaterialState.hovered, MaterialState.pressed. For example, the InkWell.overlayColor defines the color that fills the ink well when it's pressed (the "splash color"), focused, or hovered. The InkWell uses the overlay color's resolve method to compute the color for the ink well's current state.
ButtonStyle, which is used to configure the appearance of buttons like TextButton, ElevatedButton, and OutlinedButton, has many material state properties. The button widgets keep track of their current material state and resolve the button style's material state properties when their value is needed.
Code Example:
Widget build(BuildContext context) {
Color getColor(Set<MaterialState> states) {
const Set<MaterialState> interactiveStates = <MaterialState>{
MaterialState.pressed,
MaterialState.hovered,
MaterialState.focused,
};
if (states.any(interactiveStates.contains)) {
return Colors.blue;
}
return Colors.red;
}
return TextButton(
style: ButtonStyle(
foregroundColor: MaterialStateProperty.resolveWith(getColor),
),
onPressed: () {},
child: Text('TextButton'),
);
}
A simple way to use it:
MaterialStateProperty.all(Colors.green) // Whatever value you want
To get more you can check official documentation of Material state properties made by the flutter team.
It is used to calculate the value depending on the current interactive state of the button, which can be hovered, pressed, focused,... (full list here).
If you want a fixed value, you can use MaterialStateProperty.all(YOUR_VALUE), this value will be applied to all button states.
You can find more information here: https://api.flutter.dev/flutter/material/MaterialStateProperty-class.html
I add this package to my project.
This works but I want to change the color of a container, for example, depending on which theme is selected. How can I do that?
Create a helper method getThemeColor as follows:
Color getThemeColor({#required Color darkThemeColor,#required Color lightThemeColor}) {
return Theme.of(context).brightness == Brightness.dark ? darkThemeColor : lightThemeColor;
}
And then use this wherever you want to set your color:
Container(
color: getThemeColor(darkThemeColor: Colors.red, lightThemeColor: Colors.green),
),
The goal is to verify the color of a RaisedButton.icon
During my widget tests, I have the ability to look for text with find.text as well as icons with find.byIcon. There is no built in method for finding color.
How does one do the equivalent of find.color?
And example of my code is
RaisedButton.icon(
color: Color(_isAttendingEvent ? 0xFFD9FFB3 : 0xFFE3FFC7),
icon: Icon(_isAttendingEvent ? Icons.star : Icons.star_border),
label: Text(
_isAttendingEvent ? 'Attending' : 'Attend',
),
),
I'm trying to determine whether there is color: Color(0xFFD9FFB3) or color: Color(0xFFE3FFC7)
And I'm not sure if this is possible
I am not sure with RaisedButton.icon, but if it is just an icon you can try using:
expect((tester.firstWidget(find.byType(Icon)) as Icon).color, Color(0xFFE3FFC7));
If it not the first icon widget that appears on your screen, you can specific an index of it by:
expect((tester.widget(find.byType(Icon).at(/*index*/)) as Icon).color, Color(0xFFE3FFC7));
Note: To find a widget colour, you need to cast that widget to be something that contain a color property
For example:
To find Material color you can use:
expect((tester.firstWidget(find.byType(Material)) as Material).color, Colors.black);
To find Container with BoxDecoration color:
expect(((tester.firstWidget(find.byType(Container)) as Container).decoration
as BoxDecoration).color, Colors.black);
To find Text color:
expect(((tester.firstWidget(find.text('text')) as Text).style).color, Colors.black);
To find Appbar Material. color
final appbar = tester.widget<AppBar>(find.byKey(Key("appbar")));
expect(appbar.backgroundColor,Colors.white);
To find Text color Material
final text = tester.widget<Text>(find.text("text"));
expect(text.style.color, Colors.grey);
expect(text.style.fontSize, 15);
Update you flutter version. It's working now, i am able to access color in widget test. My current flutter version is "Flutter 1.15.18 • channel dev".
Earlier it was not working with version "Flutter v1.12.13+hotfix.5"
Hope this will help. More details here
If you're using a TextButton, ElevatedButton, or Outlined button, the background color will be a MaterialStateProperty. You can verify the color in almost the same way as mentioned above:
expect(
tester.widget(textButton.first),
isA<TextButton>().having(
(w) => w.style?.backgroundColor?.resolve({}),
'button color',
Colors.grey,
));
In flutter, Raisedbutton has disabledColor option in its constructor but not any option to disable it? So how can someone apply the disabledColor when there is no information about whether RaisedButton is disabled or not.
If don't set onPressed callback, the button will be disabled.
RaisedButton(
child:Text("Disabled)
)
You need to pass onPressed otherwise IDE will show error/warning.
Use this,
RaisedButton(
onPressed: null, // disables the button
disabledColor: Colors.orange,
child: Text("Disabled"),
)
Output: