https://github.com/pieces-app/scrollable_positioned_list

https://github.com/pieces-app/scrollable_positioned_list

Last synced: about 2 months ago
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• Host: GitHub
• URL: https://github.com/pieces-app/scrollable_positioned_list
• Owner: pieces-app
• License: bsd-3-clause
• Created: 2024-09-10T16:46:32.000Z (5 months ago)
• Default Branch: main
• Last Pushed: 2024-09-17T20:27:21.000Z (4 months ago)
• Last Synced: 2024-09-18T01:24:01.777Z (4 months ago)
• Language: Dart
• Size: 45.9 KB
• Stars: 0
• Watchers: 0
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • Changelog: CHANGELOG.md
  • License: LICENSE

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README

        
# scrollable_positioned_list

A flutter list that allows scrolling to a specific item in the list.

Also allows determining what items are currently visible.

## Usage

A `ScrollablePositionedList` works much like the builder version of `ListView`

except that the list can be scrolled or jumped to a specific item.

### Example

A `ScrollablePositionedList` can be created with:

```dart

final ItemScrollController itemScrollController = ItemScrollController();

final ScrollOffsetController scrollOffsetController = ScrollOffsetController();

final ItemPositionsListener itemPositionsListener = ItemPositionsListener.create();

final ScrollOffsetListener scrollOffsetListener = ScrollOffsetListener.create()

ScrollablePositionedList.builder(

  itemCount: 500,

  itemBuilder: (context, index) => Text('Item $index'),

  itemScrollController: itemScrollController,

  scrollOffsetController: scrollOffsetController,

  itemPositionsListener: itemPositionsListener,

  scrollOffsetListener: scrollOffsetListener,

);

```

One then can scroll to a particular item with:

```dart

itemScrollController.scrollTo(

  index: 150,

  duration: Duration(seconds: 2),

  curve: Curves.easeInOutCubic);

```

or jump to a particular item with:

```dart

itemScrollController.jumpTo(index: 150);

```

One can monitor what items are visible on screen with:

```dart

itemPositionsListener.itemPositions.addListener(() => ...);

```

### Experimental APIs (subject to bugs and changes)

Changes in scroll position can be monitored with:

```dart

scrollOffsetListener.changes.listen((event) => ...)

```

see `ScrollSum` in [this test](test/scroll_offset_listener_test.dart) for an example of how the current offset can be 

calculated from the stream of scroll change deltas.  This feature is new and experimental.

Changes in scroll position in pixels, relative to the current scroll position, can be made with:

```dart

scrollOffsetController.animateScroll(offset: 100, duration: Duration(seconds: 1));

```

A full example can be found in the example folder.

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This is not an officially supported Google product.