Summary:
After a fair bit of use, we have concluded that the `ItemComponent` mechanism is not worth the
hassle. Flow has trouble type checking it thoroughly, requiring an 'item' prop is annoying, and it
is very common to need to capture `this` anyway, e.g. for an `onPress` handler. A common pattern was
something like:
_renderItem = ({item}) => <MyItem foo={item.foo} onPress={() => this._onPress(item)} />};
...
ItemComponent={this._renderItem}
which wouldn't flow check the props and doesn't benefit from reusing components.
If we find some specific patterns that would benefit from the `ItemComponent` pattern, we can create
a new component that provides that API and wraps `FlatList` under the hood.
I'm going to do `SectionList` in a stacked diff.
Reviewed By: bvaughn
Differential Revision: D4625338
fbshipit-source-id: a4901f1c9d77e0115b0b8032b8c210f624e97ea3
Summary:
- Properly inherit flow types from base components, including `defaultProps`
- template-ify the `Item` type as it flows from the `data` prop into `ItemComponent`
Note that for `SectionList` is is harder to do the `Item` typing because each section in the
`sections` array can have a different `Item` type, plus all the optional overrides...not sure how to
tackle that.
Reviewed By: yungsters
Differential Revision: D4557523
fbshipit-source-id: a0c5279fcdaabe6aab5fe11743a99c3715a44032
Summary:
We really need a better list view - so here it is!
Main changes from existing `ListView`:
* Items are "virtualized" to limit memory - that is, items outside of the render window are unmounted and their memory is reclaimed. This means that instance state is not preserved when items scroll out of the render window.
* No `DataSource` - just a simple `data` prop of shape `Array<any>`. By default, they are expected to be of the shape `{key: string}` but a custom `rowExtractor` function can be provided for different shapes, e.g. graphql data where you want to map `id` to `key`. Note the underlying `VirtualizedList` is much more flexible.
* Fancy `scrollTo` functionality: `scrollToEnd`, `scrollToIndex`, and `scrollToItem` in addition to the normal `scrollToOffset`.
* Built-in pull to refresh support - set set the `onRefresh` and `refreshing` props.
* Rendering additional rows is usually done with low priority, after any interactions/animations complete, unless we're about to run out of rendered content. This should help apps feel more responsive.
* Component props replace render functions, e.g. `ItemComponent: ReactClass<{item: Item, index: number}>` replaces `renderRow: (...) => React.Element<*>`
* Supports dynamic items automatically by using `onLayout`, or `getItemLayout` can be provided for a perf boost and smoother `scrollToIndex` and scroll bar behavior.
* Visibility callback replaced with more powerful viewability callback and works in vertical and horizontal mode on at least Android and iOS, but probably other platforms as well. Extra power comes from the `viewablePercentThreshold` that lets the client decide when an item should be considered viewable.
Demo:
https://www.facebook.com/groups/576288835853049/permalink/753923058089625/
Reviewed By: yungsters
Differential Revision: D4412469
fbshipit-source-id: e2d891490bf76fe14df49294ecddf78a58adcf23
Spencer Ahrens