Deprecated cacheExtent and cacheExtentStyle

Two properties, cacheExtent and cacheExtentStyle, are deprecated in scrolling related widgets (like ListView, GridView, CustomScrollView, Viewport) and their corresponding RenderObjects (like RenderViewport). A new property, scrollCacheExtent, has been introduced that encapsulates both the value and the caching strategy (pixels or viewport).

Previously, cacheExtent was a double and cacheExtentStyle determined how that double was interpreted (either as pixels or as a fraction of the viewport). It also separated the value from its unit, which could be confusing.

The new scrollCacheExtent property uses a ScrollCacheExtent object that explicitly encapsulates both the value and the caching strategy (pixels or viewport), ensuring type safety and clearer intent.

If you were using cacheExtent (which defaults to pixels), use scrollCacheExtent with ScrollCacheExtent.pixels.

Before:

ListView(
  cacheExtent: 500.0,
  children: // ...
)

After:

ListView(
  scrollCacheExtent: const ScrollCacheExtent.pixels(500.0),
  children: // ...
)

If you were using cacheExtent with CacheExtentStyle.viewport (commonly used in Viewport), use scrollCacheExtent with ScrollCacheExtent.viewport.

Before:

Viewport(
  cacheExtent: 0.5,
  cacheExtentStyle: CacheExtentStyle.viewport,
  slivers: // ...
)

After:

Viewport(
  scrollCacheExtent: const ScrollCacheExtent.viewport(0.5),
  slivers: // ...
)

If you were manually setting properties on RenderViewport or similar, update to use scrollCacheExtent.

Before:

renderViewport.cacheExtent = 500.0;
renderViewport.cacheExtentStyle = CacheExtentStyle.pixel;

After:

renderViewport.scrollCacheExtent = const ScrollCacheExtent.pixels(500.0);

Landed in version: 3.41.0-0.0.pre In stable release: TBD

API documentation:

• ScrollCacheExtent
• ScrollView.scrollCacheExtent
• RenderViewportBase.scrollCacheExtent

Relevant PRs:

• Introduce ScrollCacheExtent