How do I use PanelBuilder for multiple lists?

[pengboboer]

Describe the bug I have a local route in the sliding panel, and I can jump from a main list to a detail page, which also has a list. When I use PanelBuilder, it will call back a ScrollController to me, but because I have created a local route, there are now two lists in my sliding panel. How can I handle this situation? Can multiple ScrollControllers be provided externally?

zone onError 'package:flutter/src/widgets/scroll_controller.dart': Failed assertion: line 108 pos 12: '_positions.length == 1': ScrollController attached to multiple scroll views. #0

To Reproduce Steps to reproduce the behavior: There is a local route in the sliding panel that jumps from one page to another. Both pages have a listview and use the panelBuilder's ScrollController, which then throws an exception

Expected behavior Both lists can correctly respond to sliding events. Can PanelBuilder provide multiple ScrollControllers?

[pengboboer]

I found a solution and it works fine.

I see that the ScrollController in the source code is created like this：

    // prevent the panel content from being scrolled only if the widget is
    // draggable and panel scrolling is enabled
    _sc = new ScrollController();
    _sc.addListener(() {
      if (widget.isDraggable && !_scrollingEnabled) _sc.jumpTo(0);
    });

Then we can extend the PanelController of sliding_up_panel to have the ability to set ScrollController. Add a setScrollController method to PanelController:

  void setScrollController(ScrollController sc) {
    _panelState!.sc = sc;
  }

Then change the ScrollController of the Panel when jumping to another page and returning to the page，like this:

double offset = listController?.offset ?? 0;
panelController.setScrollController(listScrollController);

Navigator.push(...).then((value) {
  panelController.setScrollController(detailScrollController);
  listController?.jumpTo(offset);
});

[pengboboer]

This is my demo, if you need it, I hope it can help you.

https://github.com/pengboboer/flutter_comment_panel_example