選擇時如何更改 BottomNavigationBarItem 圖標，Flutter

Question

我是顫振的新手。 我有一個包含 4 個項目的BottomNavigationBar 。 我想在按下時更改項目的圖標。 請幫忙。

這是我到目前為止所做的。

bottomNavigationBar : new BottomNavigationBar(
        currentIndex: index,
        onTap: (int index) {
          setState(() {
            this.index = index;
          }
          );
          _navigateToScreens(index);
        },
        type: BottomNavigationBarType.fixed,
        items: [
          new BottomNavigationBarItem(
              backgroundColor: Colors.white,
              icon: new Image.asset('images/1.0x/icon1.png'),
              title: new Text("Route1", style: new TextStyle(
                  color: const Color(0xFF06244e), fontSize: 14.0))),
          new BottomNavigationBarItem(
              icon: new Image.asset('images/1.0x/icon2.png'),
              title: new Text("Route2", style: new TextStyle(
                  color: const Color(0xFF06244e), fontSize: 14.0))),
          new BottomNavigationBarItem(
              icon: new Image.asset('images/1.0x/icon3.png'),
              title: new Text("Route3", style: new TextStyle(
                  color: const Color(0xFF06244e), fontSize: 14.0),)),
          new BottomNavigationBarItem(
              icon: new Image.asset('images/1.0x/icon4.png'),
              title: new Text("Route4", style: new TextStyle(
                  color: const Color(0xFF06244e), fontSize: 14.0),))
        ]);

Answer 1

在 BottomNavigationBarItem 的 flutter 中添加了一個新功能，即active icon 。 we can use it to tell what should be the icon when a tab is active

bottomNavigationBar : new BottomNavigationBar(
    currentIndex: index,
    onTap: (int index) {
      setState(() {
        this.index = index;
      }
      );
      _navigateToScreens(index);
    },
    type: BottomNavigationBarType.fixed,
    items: [
      new BottomNavigationBarItem(
          backgroundColor: Colors.white,
          icon: new Image.asset('images/1.0x/icon1.png'),
          activeIcon:new Image.asset('images/1.0x/newIcon.png'),
          title: new Text("Route1", style: new TextStyle(
              color: const Color(0xFF06244e), fontSize: 14.0))),
      new BottomNavigationBarItem(
          icon: new Image.asset('images/1.0x/icon2.png'),
          activeIcon:new Image.asset('images/1.0x/newIcon.png'),
          title: new Text("Route2", style: new TextStyle(
              color: const Color(0xFF06244e), fontSize: 14.0))),
      new BottomNavigationBarItem(
          icon: new Image.asset('images/1.0x/icon3.png'),
          activeIcon: new Image.asset('images/1.0x/newIcon.png'),
          title: new Text("Route3", style: new TextStyle(
              color: const Color(0xFF06244e), fontSize: 14.0),)),
      new BottomNavigationBarItem(
          icon: new Image.asset('images/1.0x/icon4.png'),
          activeIcon: new Image.asset('images/1.0x/newIcon.png'),
          title: new Text("Route4", style: new TextStyle(
              color: const Color(0xFF06244e), fontSize: 14.0),))
    ]),

希望有人會發現這很有用。

Answer 2

您可以通過檢查當前索引是否等於BottomNavigationBarItem索引的索引來更改圖標。

具有靜態索引值的簡單示例：

bottomNavigationBar : new BottomNavigationBar(
        currentIndex: index,
        onTap: (int index) {
          setState(() {
            this.index = index;
          }
          );
          _navigateToScreens(index);
        },
        type: BottomNavigationBarType.fixed,
        items: [
          new BottomNavigationBarItem(
              backgroundColor: Colors.white,
              icon: index==0?new Image.asset('images/1.0x/icon1.png'):new Image.asset('images/1.0x/newIcon.png'),
              title: new Text("Route1", style: new TextStyle(
                  color: const Color(0xFF06244e), fontSize: 14.0))),
          new BottomNavigationBarItem(
              icon: index==1?new Image.asset('images/1.0x/icon2.png'):new Image.asset('images/1.0x/newIcon.png'),
              title: new Text("Route2", style: new TextStyle(
                  color: const Color(0xFF06244e), fontSize: 14.0))),
          new BottomNavigationBarItem(
              icon: index==2?new Image.asset('images/1.0x/icon3.png'):new Image.asset('images/1.0x/newIcon.png'),
              title: new Text("Route3", style: new TextStyle(
                  color: const Color(0xFF06244e), fontSize: 14.0),)),
          new BottomNavigationBarItem(
              icon: index==3?new Image.asset('images/1.0x/icon4.png'):new Image.asset('images/1.0x/newIcon.png'),
              title: new Text("Route4", style: new TextStyle(
                  color: const Color(0xFF06244e), fontSize: 14.0),))
        ])

希望有幫助！

Answer 3

如果有人正在尋找更改底部導航欄項目顏色的解決方案，當“type”設置為“shifting”時，請嘗試一下：

type: BottomNavigationBarType.shifting,
  items: [
    BottomNavigationBarItem(
      activeIcon: Icon(
          Icons.home,
          color: Colors.grey[700],
        ),
      icon: Icon(
          Icons.home,
          color: Colors.grey,
        ),
      title: Text(
        'Home',
        style: TextStyle(
          color: Colors.grey[600]
          ),
        ),
    ),

Answer 4

如果您只想更改 BottomNavigationBarItem 圖標的顏色，則不需要為一個圖標設置兩個不同顏色的圖像。 一個就夠了。

您可以使用 ImageIcon 從自定義圖像創建圖標，並使用它的顏色屬性更改圖標顏色，使用 currentIndex 的值，如下所示：

bottomNavigationBar: BottomNavigationBar(
    type: BottomNavigationBarType.fixed,
    currentIndex: currentTab,
    onTap: (int index) {
      setState(() {
        currentTab = index;
        currentPage = pages[index];
      });
    },
    items: <BottomNavigationBarItem>[
      BottomNavigationBarItem(
          icon: ImageIcon(
            AssetImage("assets/img/tab1.png"),
            color: currentTab == 0
                ? Colors.orange
                : Colors.black,
          ),
          title: Text('Title 1',
            style: TextStyle(
                fontSize: 10.0,
                color: currentTab == 0
                    ? Colors.orange
                    : Colors.black),
          )
      ),
      BottomNavigationBarItem(
          icon: ImageIcon(
            AssetImage("assets/img/tab2.png"),
            color: currentTab == 1
                ? Colors.orange
                : Colors.black,
          ),
          title: Text('Title 2',
            style: TextStyle(
                fontSize: 10.0,
                color: currentTab == 1
                    ? Colors.orange
                    : Colors.black),)
      ),
      BottomNavigationBarItem(
          icon: ImageIcon(
            AssetImage("assets/img/tab3.png"),
            color: currentTab == 2
                ? Colors.orange
                : Colors.black,
          ),
          title: Text('Title 3',
            style: TextStyle(
                fontSize: 10.0,
                color: currentTab == 2
                    ? Colors.orange
                    : Colors.black),)
      ),
      BottomNavigationBarItem(
          icon: ImageIcon(
            AssetImage("assets/img/tab4.png"),
            color: currentTab == 3
                ? Colors.orange
                : Colors.black,
          ),
          title: Text('Title 4',
            style: TextStyle(
                fontSize: 10.0,
                color: currentTab == 3
                    ? Colors.orange
                    : Colors.black),)
      )
    ],
  ),

希望有人會發現這很有用。

Answer 5

2020

圖片

2種方法

目前比較好的方法是：

    selectedItemColor: Colors.white,
    unselectedItemColor: Color(0xFFF434A50),
    items: <BottomNavigationBarItem>[
        BottomNavigationBarItem(
            icon: ImageIcon(AssetImage("assets/tab1.png"),),
            title: Text('Agents'),
        ),
    ]

替代方式：

BottomNavigationBarItem(
   activeIcon: Image.asset("assets/tab1.png",width: 15,color: Colors.white,),
   icon: Image.asset("assets/tab1.png",width: 15,color: Color(0xFFF434A50),),
   title: Text('Agents'),
 ),

activeIcon - 選定的選項卡

圖標 - 取消選擇的選項卡

Answer 6

如果您只想更改顏色而不是圖標本身， fixedColor確定圖標被選中時的顏色：

BottomNavigationBar(
        ...
        fixedColor: Colors.red,
        ...
)

Answer 7

如果您顯示來自圖像資產的圖標，則以這種方式更改底部導航欄的活動圖標：

BottomNavigationBarItem(
              activeIcon: Image.asset(
                'assets/images/useractive.png',
                height: 25,
                width: 25,
              ),
              icon: Image.asset(
                'assets/images/user.png',
                height: 25,
                width: 25,
              ),
              title: Text('My Time Out')
),

Answer 8

我是這樣解決的。 在BottomNavigationBar ，有兩個屬性selectedItemColor和unselectedItemColor

bottomNavigationBar: BottomNavigationBar(
    ...
    selectedItemColor: Theme.of(context).primaryColor,
    unselectedItemColor: Theme.of(context).secondaryHeaderColor,
    ...
    items: [
      BottomNavigationBarItem(
        icon: Icon(Icons.search),
        title: Text('Search'),
      ),
      BottomNavigationBarItem(
        icon: Icon(Icons.star),
        title: Text('Featured'),
      ),
   ],
  ),

Answer 9

color: _selectedIndex == ThisIndex?SelectedColor:normalColor,

Answer 10

只是想添加到現有的答案：雖然fixedColor ， (un)selectedItemColor是可行的方法，但有一個陷阱：

它們將被BottomNavigationBarItem.icon.color覆蓋！

因此，請確保首先擺脫硬編碼的圖標顏色。

Answer 11

BottomNavigationBarItem(
          activeIcon: Image.asset(
            'lib/assets/images/homeActive.png',
            height: 25,
            width: 25,
          ),
          icon: Image.asset(
            'lib/assets/images/homePassive.png',
            height: 25,
            width: 25,
          ),
          label: 'Home'
      )

更新 2022