Style BottomNavigationBar in Flutter

问题:

I am trying out Flutter and I am trying to change the colour of the BottomNavigationBar on the app but all I could achieve was change the colour of the BottomNavigationItem (icon and text).

Here is where i declare my BottomNavigationBar:

class _BottomNavigationState extends State<BottomNavigationHolder>{

  @override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: null,
      body: pages(),
      bottomNavigationBar:new BottomNavigationBar(
        items: <BottomNavigationBarItem>[
          new BottomNavigationBarItem(
              icon: const Icon(Icons.home),
              title: new Text("Home")
          ),
          new BottomNavigationBarItem(
              icon: const Icon(Icons.work),
              title: new Text("Self Help")
          ),
          new BottomNavigationBarItem(
              icon: const Icon(Icons.face),
              title: new Text("Profile")
          )
        ],
        currentIndex: index,
        onTap: (int i){setState((){index = i;});},
        fixedColor: Colors.white,
      ),
    );
  }

Earlier I thought I had it figured out by editing canvasColor to green on my main app theme but it messed up the entire app colour scheme:

class MyApp extends StatelessWidget {
  // This widget is the root of your application.
  @override
  Widget build(BuildContext context) {
    return new MaterialApp(
      title: 'Flutter Demo',
      theme: new ThemeData(
        primarySwatch: Colors.blue,
        canvasColor: Colors.green
      ),
      home: new FirstScreen(),
    );
  }
}

回答1:

There is no option to specify the background color of BottomNavigationBar but to change the canvasColor. One way you can achieve it without messing up the whole app would be by wrapping BottomNavigationBar in a Theme with desired canvasColor.

Example:

  bottomNavigationBar: new Theme(
    data: Theme.of(context).copyWith(
        // sets the background color of the `BottomNavigationBar`
        canvasColor: Colors.green,
        // sets the active color of the `BottomNavigationBar` if `Brightness` is light
        primaryColor: Colors.red,
        textTheme: Theme
            .of(context)
            .textTheme
            .copyWith(caption: new TextStyle(color: Colors.yellow))), // sets the inactive color of the `BottomNavigationBar`
    child: new BottomNavigationBar(
      type: BottomNavigationBarType.fixed,
      currentIndex: 0,
      items: [
        new BottomNavigationBarItem(
          icon: new Icon(Icons.add),
          title: new Text("Add"),
        ),
        new BottomNavigationBarItem(
          icon: new Icon(Icons.delete),
          title: new Text("Delete"),
        )
      ],
    ),
  ),

Hope that helps!

回答2:

Earlier there was no direct way to set the colors, but now you can use.

BottomNavigationBar(
  backgroundColor: Colors.red,
  selectedItemColor: Colors.black,
  unselectedItemColor: Colors.white,
  ...
)  

回答3:

The accepted answer isn't entirely wrong. However, BottomNavigationBar does in-fact have a property of backgroundColor. As per the documentation

If type is BottomNavigationBarType.shifting and the itemss, have BottomNavigationBarItem.backgroundColor set, the item's backgroundColor will splash and overwrite this color.

What this means is that the BottomNavigation's backgroundColor will be overriden by the individual items backgroundColor because the default type is BottomNavigationBarType.shifting.

To fix this, simply add the following property to the declared BottomNavigationbar widget.

type: BottomNavigationBarTyle.fixed,

Note: If you do, however, want the shifting effect you'll have to declare colors for each item, or wrap the widget that allows the overriding of the child widget(s) background color.

i.e Somethign like Container widget.

回答4:

Try wrapping your BottomNavigationBar in a Container then set its color.

Example:

@override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: null,
      body: pages(),
      bottomNavigationBar:new Container(
        color: Colors.green,
        child: BottomNavigationBar(
          items: <BottomNavigationBarItem>[
            new BottomNavigationBarItem(
                icon: const Icon(Icons.home),
                title: new Text("Home")
            ),
            new BottomNavigationBarItem(
                icon: const Icon(Icons.work),
                title: new Text("Self Help")
            ),
            new BottomNavigationBarItem(
                icon: const Icon(Icons.face),
                title: new Text("Profile")
            )
          ],
        currentIndex: index,
        onTap: (int i){setState((){index = i;});},
        fixedColor: Colors.white,
        ),
      );
    );
  };

回答5:

Simply add the backgroundColor property to BottomNavigationBarwidget.

@override
  Widget build(BuildContext context) {
    return new Scaffold(
      appBar: null,
      body: pages(),
      bottomNavigationBar:new BottomNavigationBar(
        items: <BottomNavigationBarItem>[
          new BottomNavigationBarItem(
              icon: const Icon(Icons.home),
              title: new Text("Home")
          ),
          new BottomNavigationBarItem(
              icon: const Icon(Icons.work),
              title: new Text("Self Help")
          ),
          new BottomNavigationBarItem(
              icon: const Icon(Icons.face),
              title: new Text("Profile")
          )
        ],
        currentIndex: index,
        onTap: (int i){setState((){index = i;});},
        fixedColor: Colors.white,
        backgroundColor: Colors.black45,
      ),
    );
  }

回答6:

can change by setting colors to backgroundColor property if type is fixed.

BottomNavigationBar(
          backgroundColor: Colors.red,
          type: BottomNavigationBarType.fixed,
          items: [
            BottomNavigationBarItem(
                icon:Icon(Icons.home, color: Color.fromARGB(255, 255, 255, 255)),
                title: new Text('Home'),),
            BottomNavigationBarItem(
                icon: Icon(Icons.work,color: Color.fromARGB(255, 255, 255, 255)),
                title: new Text('Self Help'),),
            BottomNavigationBarItem(
                icon:Icon(Icons.face, color: Color.fromARGB(255, 255, 255, 255)),
                title: new Text('Profile'),),
          ]
        )

If the type is shifting it will use color inside bottomNavigationBarItem.

BottomNavigationBar(
          backgroundColor: Colors.red,
          type: BottomNavigationBarType.shifting,
          items: [
            BottomNavigationBarItem(
                icon:Icon(Icons.home, color: Color.fromARGB(255, 255, 255, 255)),
                title: new Text('Home'),
                backgroundColor: Colors.red),
            BottomNavigationBarItem(
                icon: Icon(Icons.work,color: Color.fromARGB(255, 255, 255, 255)),
                title: new Text('Self Help'),
                backgroundColor: Colors.blue),
            BottomNavigationBarItem(
                icon:Icon(Icons.face, color: Color.fromARGB(255, 255, 255, 255)),
                title: new Text('Profile'),
                backgroundColor: Colors.amber),
          ]

        )

You can see even though I have set backgroundColor property it does not apply that colors and the background color inside BottomNavigationBarItem widget will override that.

Found from here