How to create unselected indicator for tab bar in Flutter

Question

I created a custom indicator for tab bar using Decorator. I want to create a unselected indicator for not selected tabs in tab bar.

I did a container with custom decoration but current selected indicator draws behind container decoration.

new TabBar( 
labelColor: Colors.black,
unselectedLabelColor: Colors.grey,
indicator: new CustomTabIndicator(),
tabs: [
new Container(decoration: new CustomTabInactive(),child: Tab(icon: Icon(Icons.person )))])

tab bar with unselected indicator

Answer 1

Instead of using container in tabs, try this (wrapping the TabBar with DecoratedBox and providing bottom border

DecoratedBox(
  //This is responsible for the background of the tabbar, does the magic
  decoration: BoxDecoration(
    //This is for background color
    color: Colors.white.withOpacity(0.0),
    //This is for bottom border that is needed
    border: Border(bottom: BorderSide(color: Colors.grey, width: 0.8)),
  ),
  child: TabBar(
    controller: _controller,
    tabs: [
      ...
    ],
  ),
)

Will not look exactly as you want, but will give underlined indication to unselected tabs.

Answer 2

You can use Stack/Container and TabBar together to make the underline

Stack(
            fit: StackFit.passthrough,
            alignment: Alignment.bottomCenter,
            children: <Widget>[
              Container(
                decoration: BoxDecoration(
                  border: Border(
                    bottom: BorderSide(color: colorSecondary, width: 2.0),
                  ),
                ),
              ),
              TabBar(
                isScrollable: true,
                onTap: (index) => tabsModel.value = listTabsModel[index],
                tabs: listTabsModel
                    .map(
                      (value) => Tab(
                        child: value.tabComponent,
                      ),
                    )
                    .toList(),
              ),
            ],
          );

TabBar with an underline for unselected

Not exactly what you are looking for but it can give the underline for un-selected tab.