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cleanup and open source WindowedListView 

Summary:`WindowedListView` is designed for memory efficient scrolling of
huge/infinite lists of variable height rows. It works by measuring row heights
with `onLayout` and caching the results, then unmounting rows that scroll
offscreen, replacing them with an equivalent offset in the spacer view. Care is
taken to render a constant number of rows, and to only render one new row per
tick to improve framerate and app responsiveness. WLV is also compatible with
<Incremental> used within the rows themselves.

`WindowedListView` is not a drop-in replacement for `ListView` - it doesn't
support many of the features of `ListView`, such as section headers, only
accepts a simple array of data instead of a datasource, and doesn't support
horizontal scrolling. This may change in the future.

This is still experimental - we haven't deployed this for any production apps
yet.

Differential Revision: D2791402

fb-gh-sync-id: 5f104e0903f6ba586d2d651bdf82863a231279d8
fbshipit-source-id: 5f104e0903f6ba586d2d651bdf82863a231279d8
This commit is contained in:
Spencer Ahrens 2016-04-01 13:53:54 -07:00 committed by Facebook Github Bot 2
parent cb5d37713f
commit cd79e269dc
3 changed files with 731 additions and 2 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

7
Libraries/Experimental/Incremental.js
View File

@ -88,7 +88,6 @@ export type Props = {
*/ */
name: string; name: string;
children: any; children: any;
disabled: boolean;
}; };
class Incremental extends React.Component { class Incremental extends React.Component {
props: Props; props: Props;
@ -98,6 +97,7 @@ class Incremental extends React.Component {
context: Context; context: Context;
_incrementId: number; _incrementId: number;
_mounted: boolean; _mounted: boolean;
_rendered: boolean;
constructor(props: Props, context: Context) { constructor(props: Props, context: Context) {
super(props, context); super(props, context);
@ -135,8 +135,11 @@ class Incremental extends React.Component {
} }
render(): ?ReactElement { render(): ?ReactElement {
if (this.props.disabled || !this.context.incrementalGroupEnabled || this.state.doIncrementalRender) { if (this._rendered || // Make sure that once we render once, we stay rendered even if incrementalGroupEnabled gets flipped.
!this.context.incrementalGroupEnabled ||
this.state.doIncrementalRender) {
DEBUG && console.log('render ' + this.getName()); DEBUG && console.log('render ' + this.getName());
this._rendered = true;
return this.props.children; return this.props.children;
} }
return null; return null;

83
Libraries/Experimental/ViewabilityHelper.js Normal file
View File

@ -0,0 +1,83 @@
/**
* Copyright (c) 2013-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*
* @providesModule ViewabilityHelper
* @flow
*/
'use strict';
/**
* A row is said to be in a "viewable" state when either of the following
* is true:
* - Occupying >= viewablePercentThreshold of the viewport
* - Entirely visible on screen
*/
const ViewabilityHelper = {
computeViewableRows(
viewablePercentThreshold: number,
rowFrames: Array<Object>,
scrollOffsetY: number,
viewportHeight: number
): Array<number> {
var viewableRows = [];
var firstVisible = -1;
for (var idx = 0; idx < rowFrames.length; idx++) {
var frame = rowFrames[idx];
if (!frame) {
continue;
}
var top = frame.y - scrollOffsetY;
var bottom = top + frame.height;
if ((top < viewportHeight) && (bottom > 0)) {
firstVisible = idx;
if (_isViewable(
viewablePercentThreshold,
top,
bottom,
viewportHeight
)) {
viewableRows.push(idx);
}
} else if (firstVisible >= 0) {
break;
}
}
return viewableRows;
},
};
function _isViewable(
viewablePercentThreshold: number,
top: number,
bottom: number,
viewportHeight: number
): bool {
return _isEntirelyVisible(top, bottom, viewportHeight) ||
_getPercentOccupied(top, bottom, viewportHeight) >=
viewablePercentThreshold;
}
function _getPercentOccupied(
top: number,
bottom: number,
viewportHeight: number
): number {
var visibleHeight = Math.min(bottom, viewportHeight) - Math.max(top, 0);
visibleHeight = Math.max(0, visibleHeight);
return Math.max(0, visibleHeight * 100 / viewportHeight);
}
function _isEntirelyVisible(
top: number,
bottom: number,
viewportHeight: number
): bool {
return top >= 0 && bottom <= viewportHeight && bottom > top;
}
module.exports = ViewabilityHelper;

643
Libraries/Experimental/WindowedListView.js Normal file
View File

@ -0,0 +1,643 @@
/**
* Copyright (c) 2013-present, Facebook, Inc.
* All rights reserved.
*
* This source code is licensed under the BSD-style license found in the
* LICENSE file in the root directory of this source tree. An additional grant
* of patent rights can be found in the PATENTS file in the same directory.
*
* Facebook, Inc. ("Facebook") owns all right, title and interest, including
* all intellectual property and other proprietary rights, in and to the React
* Native CustomComponents software (the "Software"). Subject to your
* compliance with these terms, you are hereby granted a non-exclusive,
* worldwide, royalty-free copyright license to (1) use and copy the Software;
* and (2) reproduce and distribute the Software as part of your own software
* ("Your Software"). Facebook reserves all rights not expressly granted to
* you in this license agreement.
*
* THE SOFTWARE AND DOCUMENTATION, IF ANY, ARE PROVIDED "AS IS" AND ANY EXPRESS
* OR IMPLIED WARRANTIES (INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE) ARE DISCLAIMED.
* IN NO EVENT SHALL FACEBOOK OR ITS AFFILIATES, OFFICERS, DIRECTORS OR
* EMPLOYEES BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
* EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
* PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
* OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
* WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR
* OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THE SOFTWARE, EVEN IF
* ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* @providesModule WindowedListView
* @flow
*/
'use strict';
const IncrementalGroup = require('IncrementalGroup');
const React = require('React');
const ScrollView = require('ScrollView');
const Set = require('Set');
const StyleSheet = require('StyleSheet');
const Systrace = require('Systrace');
const View = require('View');
const ViewabilityHelper = require('ViewabilityHelper');
const clamp = require('clamp');
const deepDiffer = require('deepDiffer');
const invariant = require('invariant');
const nullthrows = require('nullthrows');
import type ReactComponent from 'ReactComponent';
const DEBUG = false;
/**
* An experimental ListView implementation designed for efficient memory usage
* when rendering huge/infinite lists. It works by rendering a subset of rows
* and replacing offscreen rows with an empty spacer, which means that it has to
* re-render rows when scrolling back up.
*
* Note that rows must be the same height when they are re-mounted as when they
* are unmounted otherwise the content will jump around. This means that any
* state that affects the height, such as tap to expand, should be stored
* outside the row component to maintain continuity.
*
* This is not a drop-in replacement for `ListView` - many features are not
* supported, including section headers, dataSources, horizontal layout, etc.
*
* Row data should be provided as a simple array corresponding to rows. `===`
* is used to determine if a row has changed and should be re-rendered.
*
* Rendering is done incrementally one row at a time to minimize the amount of
* work done per JS event tick. Individual rows can also use <Incremental>
* to further break up the work and keep the app responsive and improve scroll
* perf if rows get exceedingly complex.
*
* Note that it's possible to scroll faster than rows can be rendered. Instead
* of showing the user a bunch of un-mounted blank space, WLV sets contentInset
* to prevent scrolling into unrendered areas. Supply the
* `renderWindowBoundaryIndicator` prop to indicate the boundary to the user,
* e.g. with a row placeholder.
*/
type Props = {
/**
* A simple array of data blobs that are passed to the renderRow function in
* order. Note there is no dataSource like in the standard `ListView`.
*/
data: Array<mixed>;
/**
* Takes a data blob from the `data` array prop plus some meta info and should
* return a row.
*/
renderRow: (
data: mixed, sectionIdx: number, rowIdx: number, key: string
) => ?ReactElement;
/**
* Rendered when the list is scrolled faster than rows can be rendered.
*/
renderWindowBoundaryIndicator?: () => ?ReactElement;
/**
* Always rendered at the bottom of all the rows.
*/
renderFooter?: () => ?ReactElement;
/**
* Pipes through normal onScroll events from the underlying `ScrollView`.
*/
onScroll?: (event: Object) => void;
/**
* Called when the rows that are visible in the viewport change.
*/
onVisibleRowsChanged?: (firstIdx: number, count: number) => void;
/**
* Called when the viewability of rows changes, as defined by the
* `viewablePercentThreshold` prop.
*/
onViewableRowsChanged?: (viewableRows: Array<number>) => void;
/**
* The percent of a row that must be visible to consider it "viewable".
*/
viewablePercentThreshold: number;
/**
* Number of rows to render on first mount.
*/
initialNumToRender: number;
/**
* Maximum number of rows to render while scrolling, i.e. the window size.
*/
maxNumToRender: number;
/**
* Number of rows to render beyond the viewport. Note that this combined with
* `maxNumToRender` and the number of rows that can fit in one screen will
* determine how many rows to render above the viewport.
*/
numToRenderAhead: number;
/**
* Super dangerous and experimental - rows and all their decendents must be
* fully stateless otherwise recycling their instances may introduce nasty
* bugs. Some apps may see an improvement in perf, but sometimes perf and
* memory usage can actually get worse with this.
*/
enableDangerousRecycling: boolean;
/**
* Used to log perf events for async row rendering.
*/
asyncRowPerfEventName: ?string;
/**
* A function that returns the scrollable component in which the list rows
* are rendered. Defaults to returning a ScrollView with the given props.
*/
renderScrollComponent: (props: ?Object) => ReactElement;
/**
* Use to disable incremental rendering when not wanted, e.g. to speed up initial render.
*/
disableIncrementalRendering: boolean;
/**
* This determines how frequently events such as scroll and layout can trigger a re-render.
*/
recomputeRowsBatchingPeriod: number;
};
const defaultProps = {
enableDangerousRecycling: false,
initialNumToRender: 10,
maxNumToRender: 30,
numToRenderAhead: 10,
viewablePercentThreshold: 50,
renderScrollComponent: (props) => <ScrollView {...props} />,
disableIncrementalRendering: false,
recomputeRowsBatchingPeriod: 100,
};
class WindowedListView extends React.Component {
props: Props;
state: {
boundaryIndicatorHeight?: number;
firstRow: number;
lastRow: number;
firstVisible: number;
lastVisible: number;
};
_scrollOffsetY: number = 0;
_frameHeight: number = 0;
_rowFrames: Array<Object> = [];
_hasCalledOnEndReached: bool = false;
_willComputeRowsToRender: bool = false;
_timeoutHandle: number = 0;
_incrementPending: bool = false;
_viewableRows: Array<number> = [];
_cellsInProgress: Set<number> = new Set();
_scrollRef: ?Object;
constructor(props: Props) {
super(props);
invariant(
this.props.numToRenderAhead < this.props.maxNumToRender,
'WindowedListView: numToRenderAhead must be less than maxNumToRender'
);
this.state = {
firstRow: 0,
lastRow:
Math.min(this.props.data.length, this.props.initialNumToRender) - 1,
firstVisible: -1,
lastVisible: -1,
};
}
getScrollResponder(): ?ReactComponent {
return this._scrollRef &&
this._scrollRef.getScrollResponder &&
this._scrollRef.getScrollResponder();
}
componentWillReceiveProps(newProps: Object) {
// This has to happen immediately otherwise we could crash, e.g. if the data
// array has gotten shorter.
if (newProps.data.length < this._rowFrames.length) {
this._rowFrames = this._rowFrames.splice(0, newProps.data.length);
}
this._computeRowsToRender(newProps);
}
_onScroll = (e: Object) => {
this._scrollOffsetY = e.nativeEvent.contentOffset.y;
this._frameHeight = e.nativeEvent.layoutMeasurement.height;
// We don't want to enqueue any updates if any cells are in the middle of an incremental render,
// because it would just be wasted work.
if (this._cellsInProgress.size === 0) {
this._enqueueComputeRowsToRender();
}
if (this.props.onViewableRowsChanged && this._rowFrames.length) {
const viewableRows = ViewabilityHelper.computeViewableRows(
this.props.viewablePercentThreshold,
this._rowFrames,
e.nativeEvent.contentOffset.y,
e.nativeEvent.layoutMeasurement.height
);
if (deepDiffer(viewableRows, this._viewableRows)) {
this._viewableRows = viewableRows;
nullthrows(this.props.onViewableRowsChanged)(this._viewableRows);
}
}
this.props.onScroll && this.props.onScroll(e);
};
// Caller does the diffing so we don't have to.
_onNewLayout = (params: {rowIndex: number, layout: Object}) => {
const {rowIndex, layout} = params;
if (DEBUG) {
const layoutPrev = this._rowFrames[rowIndex] || {};
console.log(
'record layout for row: ',
{i: rowIndex, h: layout.height, y: layout.y, hp: layoutPrev.height, yp: layoutPrev.y}
);
}
this._rowFrames[rowIndex] = {...layout, offscreenLayoutDone: true};
if (this._cellsInProgress.size === 0) {
this._enqueueComputeRowsToRender();
}
};
_onWillUnmountCell = (rowIndex: number) => {
if (this._rowFrames[rowIndex]) {
this._rowFrames[rowIndex].offscreenLayoutDone = false;
}
};
/**
* This is used to keep track of cells that are in the process of rendering. If any cells are in progress, then
* other updates are skipped because they will just be wasted work.
*/
_onProgressChange = ({rowIndex, inProgress}: {rowIndex: number, inProgress: boolean}) => {
if (inProgress) {
this._cellsInProgress.add(rowIndex);
} else {
this._cellsInProgress.delete(rowIndex);
}
};
/**
* Recomputing which rows to render is batched up and run asynchronously to avoid wastful updates, e.g. from multiple
* layout updates in rapid succession.
*/
_enqueueComputeRowsToRender(): void {
if (!this._willComputeRowsToRender) {
this._willComputeRowsToRender = true; // batch up computations
clearTimeout(this._timeoutHandle);
this._timeoutHandle = setTimeout(
() => {
this._willComputeRowsToRender = false;
this._incrementPending = false;
this._computeRowsToRender(this.props);
},
this.props.recomputeRowsBatchingPeriod
);
}
}
componentWillUnmount() {
clearTimeout(this._timeoutHandle);
}
_computeRowsToRender(props: Object): void {
const totalRows = props.data.length;
if (totalRows === 0) {
this.setState({
firstRow: 0,
lastRow: -1,
firstVisible: -1,
lastVisible: -1,
});
return;
}
const rowFrames = this._rowFrames;
let firstVisible = -1;
let lastVisible = 0;
const top = this._scrollOffsetY;
const bottom = top + this._frameHeight;
for (let idx = 0; idx < rowFrames.length; idx++) {
const frame = rowFrames[idx];
if (!frame) {
// No frame - sometimes happens when they come out of order, so just wait for the rest.
return;
}
if (((frame.y + frame.height) > top) && (firstVisible < 0)) {
firstVisible = idx;
}
if (frame.y < bottom) {
lastVisible = idx;
} else {
break;
}
}
if (firstVisible === -1) {
firstVisible = 0;
}
this._updateVisibleRows(firstVisible, lastVisible);
// Unfortuantely, we can't use <Incremental> to simplify our increment logic in this function because we need to
// make sure that cells are rendered in the right order one at a time when scrolling back up.
const numRendered = this.state.lastRow - this.state.firstRow + 1;
// Our last row target that we will approach incrementally
const targetLastRow = clamp(
numRendered - 1, // Don't reduce numRendered when scrolling back up
lastVisible + props.numToRenderAhead, // Primary goal
totalRows - 1, // Don't render past the end
);
let lastRow = this.state.lastRow;
// Increment the last row one at a time per JS event loop
if (!this._incrementPending) {
if (targetLastRow > this.state.lastRow) {
lastRow++;
this._incrementPending = true;
} else if (targetLastRow < this.state.lastRow) {
lastRow--;
this._incrementPending = true;
}
}
// Once last row is set, figure out the first row
const firstRow = Math.max(
0, // Don't render past the top
lastRow - props.maxNumToRender + 1, // Don't exceed max to render
lastRow - numRendered, // Don't render more than 1 additional row
);
if (lastRow >= totalRows) {
// It's possible that the number of rows decreased by more than one
// increment could compensate for. Need to make sure we don't render more
// than one new row at a time, but don't want to render past the end of
// the data.
lastRow = totalRows - 1;
}
if (props.onEndReached) {
// Make sure we call onEndReached exactly once every time we reach the
// end. Resets if scoll back up and down again.
const willBeAtTheEnd = lastRow === (totalRows - 1);
if (willBeAtTheEnd && !this._hasCalledOnEndReached) {
props.onEndReached();
this._hasCalledOnEndReached = true;
} else {
// If lastRow is changing, reset so we can call onEndReached again
this._hasCalledOnEndReached = this.state.lastRow === lastRow;
}
}
if (this.state.firstRow !== firstRow || this.state.lastRow !== lastRow) {
console.log('WLV: row render range changed:', {firstRow, lastRow});
}
this.setState({firstRow, lastRow});
}
_updateVisibleRows(newFirstVisible: number, newLastVisible: number) {
if (this.state.firstVisible !== newFirstVisible ||
this.state.lastVisible !== newLastVisible) {
if (this.props.onVisibleRowsChanged) {
this.props.onVisibleRowsChanged(
newFirstVisible,
newLastVisible - newFirstVisible + 1);
}
this.setState({
firstVisible: newFirstVisible,
lastVisible: newLastVisible,
});
}
}
render(): ReactElement {
const firstRow = this.state.firstRow;
const lastRow = this.state.lastRow;
const rowFrames = this._rowFrames;
const rows = [];
let spacerHeight = 0;
for (let ii = firstRow; ii <= lastRow; ii++) {
if (!rowFrames[ii]) {
break; // if rowFrame missing, no following ones will exist so quit early
}
// Look for the first row where offscreen layout is done (only true for mounted rows) and set the spacer height
// such that it will offset all the unmounted rows before that one using the saved frame data.
if (rowFrames[ii].offscreenLayoutDone) {
const frame = rowFrames[ii - 1];
spacerHeight = frame ? frame.y + frame.height : 0;
break;
}
}
let showIndicator = false;
if (spacerHeight > (this.state.boundaryIndicatorHeight || 0) && this.props.renderWindowBoundaryIndicator) {
showIndicator = true;
spacerHeight -= this.state.boundaryIndicatorHeight || 0;
}
DEBUG && console.log('render top spacer with height ', spacerHeight);
rows.push(<View key="sp-top" style={{height: spacerHeight}} />);
if (this.props.renderWindowBoundaryIndicator) {
// Always render it, even if removed, so that we can get the height right away and don't waste time creating/
// destroying it. Should see if there is a better spinner option that is not as expensive.
rows.push(
<View
style={!showIndicator && styles.remove}
key="ind-top"
onLayout={(e) => {
const layout = e.nativeEvent.layout;
if (layout.height !== this.state.boundaryIndicatorHeight) {
this.setState({boundaryIndicatorHeight: layout.height});
}
}}>
{this.props.renderWindowBoundaryIndicator()}
</View>
);
}
for (let idx = firstRow; idx <= lastRow; idx++) {
const key = '' + (this.props.enableDangerousRecycling ? (idx % this.props.maxNumToRender) : idx);
rows.push(
<CellRenderer
key={key}
recyclingKey={key}
rowIndex={idx}
onNewLayout={this._onNewLayout}
onWillUnmount={this._onWillUnmountCell}
includeInLayout={this.props.disableIncrementalRendering ||
(this._rowFrames[idx] && this._rowFrames[idx].offscreenLayoutDone)}
onProgressChange={this._onProgressChange}
asyncRowPerfEventName={this.props.asyncRowPerfEventName}
data={this.props.data[idx]}
renderRow={this.props.renderRow}
/>
);
}
const showFooter = this._rowFrames[lastRow] &&
this._rowFrames[lastRow].offscreenLayoutDone &&
lastRow === this.props.data.length - 1;
if (this.props.renderFooter) {
rows.push(
<View style={showFooter ? styles.include : styles.remove}>
{this.props.renderFooter()}
</View>
);
}
if (this.props.renderWindowBoundaryIndicator) {
rows.push(
<View
key="ind-bot"
style={showFooter ? styles.remove : styles.include}
onLayout={(e) => {
const layout = e.nativeEvent.layout;
if (layout.height !== this.state.boundaryIndicatorHeight) {
this.setState({boundaryIndicatorHeight: layout.height});
}
}}>
{this.props.renderWindowBoundaryIndicator()}
</View>
);
}
// Prevent user from scrolling into empty space of unmounted rows.
const contentInset = {top: firstRow === 0 ? 0 : -spacerHeight};
return (
<IncrementalGroup name="WLV" disabled={this.props.disableIncrementalRendering}>
{this.props.renderScrollComponent({
scrollEventThrottle: 50,
removeClippedSubviews: true,
...this.props,
contentInset,
ref: (ref) => { this._scrollRef = ref; },
onScroll: this._onScroll,
children: rows,
})}
</IncrementalGroup>
);
}
}
WindowedListView.defaultProps = defaultProps;
// performance testing id, unique for each component mount cycle
let g_perf_update_id = 0;
type CellProps = {
/**
* Row-specific data passed to renderRow and used in shouldComponentUpdate with ===
*/
data: mixed;
/**
* Renders the actual row contents.
*/
renderRow: (data: mixed, sectionIdx: number, rowIdx: number) => ?ReactElement;
/**
* Index of the row, passed through to other callbacks.
*/
rowIndex: number;
/**
* Used for marking async begin/end events for row rendering.
*/
asyncRowPerfEventName: ?string;
/**
* Initially false to indicate the cell should be rendered "offscreen" with position: absolute so that incremental
* rendering doesn't cause things to jump around. Once onNewLayout is called after offscreen rendering has completed,
* includeInLayout will be set true and the finished cell can be dropped into place.
*
* This is coordinated outside this component so the parent can syncronize this re-render with managing the
* placeholder sizing.
*/
includeInLayout: boolean;
/**
* Updates the parent with the latest layout. Only called when incremental rendering is done and triggers the parent
* to re-render this row with includeInLayout true.
*/
onNewLayout: (params: {rowIndex: number, layout: ?Object}) => void;
/**
* Used to track when rendering is in progress so the parent can avoid wastedful re-renders that are just going to be
* invalidated once the cell finishes.
*/
onProgressChange: (progress: {rowIndex: number; inProgress: boolean}) => void;
/**
* Used to invalidate the layout so the parent knows it needs to compensate for the height in the placeholder size.
*/
onWillUnmount: (rowIndex: number) => void;
};
class CellRenderer extends React.Component {
props: CellProps;
_offscreenRenderDone = false;
_timer = 0;
_lastLayout: ?Object = null;
_perfUpdateID: number = 0;
_asyncCookie: any;
componentWillMount() {
if (this.props.asyncRowPerfEventName) {
this._perfUpdateID = g_perf_update_id++;
this._asyncCookie = Systrace.beginAsyncEvent(this.props.asyncRowPerfEventName + this._perfUpdateID);
console.log(`perf_asynctest_${this.props.asyncRowPerfEventName}_start ${this._perfUpdateID} ${Date.now()}`);
}
this.props.onProgressChange({rowIndex: this.props.rowIndex, inProgress: true});
}
_onLayout = (e) => {
const layout = e.nativeEvent.layout;
const layoutChanged = deepDiffer(this._lastLayout, layout);
this._lastLayout = layout;
if (!this._offscreenRenderDone || !layoutChanged) {
return; // Don't send premature or duplicate updates
}
this.props.onNewLayout({
rowIndex: this.props.rowIndex,
layout,
});
};
_onOffscreenRenderDone = () => {
DEBUG && console.log('_onOffscreenRenderDone for row ' + this.props.rowIndex);
this._timer = setTimeout(() => { // Flush any pending layout events.
invariant(!this._offscreenRenderDone, 'should only finish rendering once');
this._offscreenRenderDone = true;
// If this is not called before calling onNewLayout, the number of inProgress cells will remain non-zero,
// and thus the onNewLayout call will not fire the needed state change update.
this.props.onProgressChange({rowIndex: this.props.rowIndex, inProgress: false});
// If an onLayout event hasn't come in yet, then we skip here and assume it will come in later. This happens
// when Incremental is disabled and _onOffscreenRenderDone is called faster than layout can happen.
this._lastLayout && this.props.onNewLayout({rowIndex: this.props.rowIndex, layout: this._lastLayout});
DEBUG && console.log('\n >>>>> display row ' + this.props.rowIndex + '\n\n\n');
if (this.props.asyncRowPerfEventName) {
Systrace.endAsyncEvent(this.props.asyncRowPerfEventName + this._perfUpdateID, this._asyncCookie);
console.log(`perf_asynctest_${this.props.asyncRowPerfEventName}_end ${this._perfUpdateID} ${Date.now()}`);
}
}, 1);
};
componentWillUnmount() {
clearTimeout(this._timer);
this.props.onProgressChange({rowIndex: this.props.rowIndex, inProgress: false});
this.props.onWillUnmount(this.props.rowIndex);
}
componentWillReceiveProps(newProps) {
if (newProps.includeInLayout && !this.props.includeInLayout) {
invariant(this._offscreenRenderDone, 'Should never try to add to layout before render done');
this.refs.container.setNativeProps({style: styles.include});
} else {
invariant(!(this.props.includeInLayout && !newProps.includeInLayout), 'Should never unset includeInLayout');
}
}
shouldComponentUpdate(newProps) {
return newProps.data !== this.props.data;
}
render() {
let debug;
if (DEBUG) {
console.log('render cell ' + this.props.rowIndex);
const Text = require('Text');
debug = <Text style={{backgroundColor: 'lightblue'}}>
Row: {this.props.rowIndex}
</Text>;
}
const style = this.props.includeInLayout ? styles.include : styles.remove;
return (
<IncrementalGroup onDone={this._onOffscreenRenderDone} name={`CellRenderer_${this.props.rowIndex}`}>
<View
ref="container"
style={style}
onLayout={this._onLayout}>
{debug}
{this.props.renderRow(this.props.data, 0, this.props.rowIndex)}
{debug}
</View>
</IncrementalGroup>
);
}
}
const removedXOffset = DEBUG ? 123 : 0;
const styles = StyleSheet.create({
include: {
position: 'relative',
left: 0,
right: 0,
opacity: 1,
},
remove: {
position: 'absolute',
left: removedXOffset,
right: -removedXOffset,
opacity: DEBUG ? 0.1 : 0,
},
});
module.exports = WindowedListView;