scroll_to_index_sample

A new Flutter project.

Getting Started

Demonstrate IndexedScrollController, which leverages the scroll_to_index package from the Quire team - located at https://pub.dev/packages/scroll_to_index

• copes with variable-height-rows (vertical) / variable-width-columns (horizontal)
• can be used with StatelessWidgets only, if you prefer (as I do).

To use IndexedScrollController:

• create an IndexedScrollController, e.g. in the builder of a Provider (as-in this example app)
  • optionally include "currentIndexCallBack" to allow the value of the currently "1st-visible-on-screen" item to be passed up the tree
• create your data-source iterable
• create your List items from your data-source
• pass these items into IndexedScrollController.setItems
  • where they will be "wrapped" with AutoScrollTag
• create your ListView, with:
  • controller: indexedController.controller,
  • children: indexedController.items,

Scrolling can be performed:

• programmatically via these methods of IndexedScrollController:
  • scrollToBeginning()
  • scrollToEnd()
  • scrollForwardBy(...)
  • scrollBackBy(...)
  • scrollToIndex(...)
• manually via the user's finger, and the model will always track the currently visible-at-the-beginning row
  • so "scroll back/forward by X rows" works any time

The item-list can be edited also. e.g. see the sample app, for how to support deleting items. Let your data-source drive the change, and then trigger a rebuild on the widget (e.g. using StatefulWidget + setState, or StatelessWidget + ChangeNotifierProvider (as in the sample))

Richard Shepherd 2019