ScrollController doesn't scroll ListView to bottom + AnimatedContainer doesn't work

Question

I have a list of report items.

I initialised a scrollController here:

 class ReportList extends StatelessWidget {

  ReportList({Key? key}) : super(key: key);

  final ScrollController scrollController = ScrollController();

  scrollDown() {
    scrollController.animateTo(scrollController.position.maxScrollExtent,
        duration: const Duration(seconds: 1), curve: Curves.bounceOut);
  }

I also have a list view with the controller, and I want the list view to stroll to bottom when the last item is selected:

ListView.separated(
        controller: scrollController,
        itemCount: 13,
        itemBuilder: (_, index) {
          return Column(
            children: [
              ReportItem(
                onClick: () {
                  viewModel.setCommentReportStat(index);
                  if (index == 12 && viewModel.commentReportStat[12]) {
                    scrollDown();
                  }
                  debugPrint(viewModel.commentReportStat.toString());
                },
                isSelected: viewModel.commentReportStat[index],
                title: CommentReport.items[index],
              ),
              //show additional message field to the user
              if (index == 12 && viewModel.commentReportStat[12])
                AnimatedContainer(
                  duration: const Duration(seconds: 1),
                  child: MessageField(commentId: commentId),
                )
            ],
          );
        },
        separatorBuilder: (_, index) => const SizedBox(
          height: 16,
        ),
      )

Everything about the state management works since the message field appears as the user clicks on the last item.

My problem in general is that neither does message field appear with the animated container which is wrapped around it, nor does it scroll down!

How it is right now:

What I want to happen:

(If I scroll manually, I can see the entire message field, but I want this to be automated using the scroll controller)

when last item showed, the list already is at the bottom. why do you want to scroll? — eamirho3ein
– eamirho3ein, Commented Oct 4, 2022 at 7:25

rasityilmaz · Accepted Answer · 2022-10-16 08:52:38Z

1

instead of this

 if (index == 12 && viewModel.commentReportStat[12])
                AnimatedContainer(
                  duration: const Duration(seconds: 1),
                  child: MessageField(commentId: commentId),
                )

use this

AnimatedCrossFade(
  duration: const Duration(seconds: 1),
  firstChild: const SizedBox(),
  secondChild: MessageField(commentId: commentId),
  crossFadeState: (index == 12 && viewModel.commentReportStat[12]) ? CrossFadeState.showSecond : CrossFadeState.showFirst,
)

You can also use this function if you want to scroll to the end of the page when an event occurs.

toMaxScroll() {
       _scrollController.animateTo(_scrollController.position.maxScrollExtent,duration:const Duration(milliseconds:300),curve:Curves.easeIn);
    }

edited Oct 16, 2022 at 8:52

answered Oct 4, 2022 at 9:26

rasityilmaz

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1 Comment

Kamand Shayegan Over a year ago

Thank you. This helped me with the animation of my MessageField; however, It still doesn't scroll down as I want it to.

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