How can the subpages of pageview monitor page switching in flutter?

Question

PageView.builder(
      itemBuilder: (ctx, index) => pages[index],
      itemCount: pages.length,
      controller: _pageController,
      physics: NeverScrollableScrollPhysics(),
      onPageChanged: (index) {
        setState(() {
          _selectedIndex = index;
        });
      },
    )

when pageChanged,i wish item can know it was been disPlayed or hidden,so I can do something maybe i need a listener? but I don't know how to code,some one help me!

use `AnimatedBuilder` and pass `animation: _pageController` in the constructor — pskink, Dec 31 '20 at 06:17
i forgot to add that you should use that `AnimatedBuilder` inside `itemBuilder` — pskink, Dec 31 '20 at 06:49
@zerongjiang Can you exactly describe what you want to do with the code ? — Mukul, Dec 31 '20 at 07:23

score 1 · Answer 1 · answered Dec 31 '20 at 09:53

That is nothing but a standard state-passing problem. In your widget building this PageView (say, MyHomePage), you hold your _selectedIndex as your state. On the other hand, you want to pass this state down into some widgets inside page[index]. Thus, you want to pass down a state to a child.

There are really a lot of ways to do so. Try to search state management. You can use a heavy (but beautiful) lib like Mobx. You can also use lightweight things like InheritedWidget.

@zerongjiang You are welcome :) If my answer helps you, you can click the "accept this answer" at the left of this answer — ch271828n, Jan 01 '21 at 06:20

How can the subpages of pageview monitor page switching in flutter?

1 Answers1