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Perf optimization: dont render offscreen items #117

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119 changes: 105 additions & 14 deletions lib/AutoDragSortableView.js
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Original file line number Diff line number Diff line change
Expand Up @@ -7,6 +7,10 @@ const {width,height} = Dimensions.get('window')
const defaultZIndex = 8
const touchZIndex = 99

function determineInitialItemRenderCountForOptimization(itemHeight, columnCount) {
return Math.max(Math.ceil(Dimensions.get("window").height / itemHeight) * columnCount, 15);
}

export default class AutoDragSortableView extends Component{

constructor(props) {
Expand All @@ -20,6 +24,9 @@ export default class AutoDragSortableView extends Component{
// this.reComplexDataSource(true,props) // react < 16.3
// react > 16.3 Fiber
const rowNum = parseInt(props.parentWidth / itemWidth);

const forLoadOptimizationInitialRenderCount = determineInitialItemRenderCountForOptimization(itemHeight, rowNum);

const dataSource = props.dataSource.map((item, index) => {
const newData = {}
const left = (index % rowNum) * itemWidth
Expand All @@ -34,16 +41,25 @@ export default class AutoDragSortableView extends Component{
y: parseInt(top + 0.5),
})
newData.scaleValue = new Animated.Value(1)
newData.shouldRender = props.enableInitialLoadOptimization ? index < forLoadOptimizationInitialRenderCount : true;
return newData
});
this.state = {
dataSource: dataSource,
curPropsDataSource: props.dataSource,
height: Math.ceil(dataSource.length / rowNum) * itemHeight,
columnCount: rowNum,
rowCount: Math.ceil(dataSource.length / rowNum),
itemWidth,
itemHeight,
};

this.viewableItemsData = {
layoutDimensions: undefined,
mostRecentStartItemIndex: undefined,
mostRecentEndItemIndex: undefined,
};

this._panResponder = PanResponder.create({
onStartShouldSetPanResponder: (evt, gestureState) => true,
onStartShouldSetPanResponderCapture: (evt, gestureState) => {
Expand Down Expand Up @@ -76,6 +92,7 @@ export default class AutoDragSortableView extends Component{
if (nextprops.dataSource != prevState.curPropsDataSource || itemWidth !== prevState.itemWidth || itemHeight !== prevState.itemHeight) {

const rowNum = parseInt(nextprops.parentWidth / itemWidth);
const forLoadOptimizationInitialRenderCount = determineInitialItemRenderCountForOptimization(itemHeight, rowNum);
const dataSource = nextprops.dataSource.map((item, index) => {
const newData = {};
const left = index % rowNum * itemWidth;
Expand All @@ -90,12 +107,17 @@ export default class AutoDragSortableView extends Component{
y: parseInt(top + 0.5),
});
newData.scaleValue = new Animated.Value(1);
newData.shouldRender = nextprops.enableInitialLoadOptimization ?
(prevState.dataSource[index] !== undefined ? prevState.dataSource[index].shouldRender : index < forLoadOptimizationInitialRenderCount) :
true;
return newData;
});
return {
dataSource: dataSource,
curPropsDataSource: nextprops.dataSource,
height: Math.ceil(dataSource.length / rowNum) * itemHeight,
columnCount: rowNum,
rowCount: Math.ceil(dataSource.length / rowNum),
itemWidth,
itemHeight,
}
Expand All @@ -110,6 +132,11 @@ export default class AutoDragSortableView extends Component{

componentDidUpdate() {
this.autoMeasureHeight()
if (this.state.columnCount !== prevState.columnCount || this.state.rowCount !== prevState.rowCount || this.state.dataSource !== prevState.dataSource) {
this.viewableItemsData.mostRecentStartItemIndex = undefined;
this.viewableItemsData.mostRecentEndItemIndex = undefined;
}
this.updateViewableItems();
}

// Compatible with different systems and paging loading
Expand Down Expand Up @@ -582,10 +609,68 @@ export default class AutoDragSortableView extends Component{
offsetY: nativeEvent.contentOffset.y,
hasScroll: true,
}
this.updateViewableItems();
if (nativeEvent.contentOffset.y !== 0) this.isHasMeasure = true;
if (this.props.onScrollListener) this.props.onScrollListener(event)
}

handleLayout = ({ nativeEvent}) => {
this.viewableItemsData.layoutDimensions = nativeEvent.layout;
this.updateViewableItems();
}

updateViewableItems = () => {
if (!this.props.enableInitialLoadOptimization) {
return;
}
const windowHeight = this.curScrollData !== undefined ? this.curScrollData.windowHeight : (this.viewableItemsData.layoutDimensions !== undefined ? this.viewableItemsData.layoutDimensions.height : 0);
const rowHeight = this.state.itemHeight;
const maxRowsVisibleOnScreen = (1 + Math.ceil(windowHeight / rowHeight));

const offsetY = this.curScrollData !== undefined ? this.curScrollData.offsetY : 0;

// In the following two calculations, think of maxRowsVisibleOnScreen as
// like "page size" or "batch size" (where a batch or page is measured in #
// of rows, not items)
const topRowIndex = Math.floor(Math.floor(offsetY / rowHeight) / maxRowsVisibleOnScreen) * maxRowsVisibleOnScreen;
// The `+ (maxRowsVisibleOnScreen*2)` means we render EVEN MORE than what
// is visible (like an additional "batch")
const bottomRowIndex = Math.ceil(Math.ceil((offsetY + windowHeight) / rowHeight) / maxRowsVisibleOnScreen) * maxRowsVisibleOnScreen + (maxRowsVisibleOnScreen*2);

const startItemIndex = Math.max(topRowIndex, 0) * this.state.columnCount;
const endItemIndex = Math.min(bottomRowIndex * this.state.columnCount + this.state.columnCount - 1, this.state.dataSource.length - 1);

// This is a small perf optimization to avoid going through the loop if we just did these rows
if (startItemIndex === this.viewableItemsData.mostRecentStartItemIndex && endItemIndex === this.viewableItemsData.mostRecentEndItemIndex) {
// No need to do any updates
return;
}

this.viewableItemsData.mostRecentStartItemIndex = startItemIndex;
this.viewableItemsData.mostRecentEndItemIndex = endItemIndex;

let changed = false;

for (let i = startItemIndex; i <= endItemIndex; i++) {
const item = this.state.dataSource[i];
if (item.shouldRender) {
continue;
}
item.shouldRender = true;
changed = true;
}

if (changed) {
// This looks like it doesn't do anything but actually it triggers a
// re-render since this component isn't a PureComponent. The reason we
// do this is because the update to `shouldRender` above won't by
// itself trigger a re-render because React has no idea that some
// object nested within another object that is part of state has
// changed.
this.setState({ dataSource: this.state.dataSource })
}
}

render() {
return (
<ScrollView
Expand All @@ -599,7 +684,9 @@ export default class AutoDragSortableView extends Component{
}}
scrollEnabled = {this.state.scrollEnabled}
onScroll={this.onScrollListener}
style={styles.container}>
style={styles.container}
onLayout={this.handleLayout}
>
{this.props.renderHeaderView ? this.props.renderHeaderView : null}
<View
//ref={(ref)=>this.sortParentRef=ref}
Expand Down Expand Up @@ -644,19 +731,21 @@ export default class AutoDragSortableView extends Component{
opacity: item.scaleValue.interpolate({inputRange,outputRange}),
transform: [transformObj]
}]}>
<TouchableOpacity
activeOpacity = {1}
delayLongPress={this.props.delayLongPress}
onPressOut={()=> this.onPressOut()}
onLongPress={()=>this.startTouch(index)}
onPress={()=>{
if (this.props.onClickItem) {
this.isHasMeasure = true
this.props.onClickItem(this.getOriginalData(),item.data,index)
}
}}>
{this.props.renderItem(item.data,index)}
</TouchableOpacity>
{(!this.props.enableInitialLoadOptimization || item.shouldRender) &&
<TouchableOpacity
activeOpacity = {1}
delayLongPress={this.props.delayLongPress}
onPressOut={()=> this.onPressOut()}
onLongPress={()=>this.startTouch(index)}
onPress={()=>{
if (this.props.onClickItem) {
this.isHasMeasure = true
this.props.onClickItem(this.getOriginalData(),item.data,index)
}
}}>
{this.props.renderItem(item.data,index)}
</TouchableOpacity>
}
</Animated.View>
)
})
Expand All @@ -682,6 +771,8 @@ AutoDragSortableView.propTypes = {

sortable: PropTypes.bool,

enableInitialLoadOptimization: PropTypes.bool,

onClickItem: PropTypes.func,
onDragStart: PropTypes.func,
onDragEnd: PropTypes.func,
Expand Down
2 changes: 2 additions & 0 deletions lib/index.d.ts
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Original file line number Diff line number Diff line change
Expand Up @@ -14,6 +14,8 @@ interface IProps{

sortable?: boolean;

enableInitialLoadOptimization?: boolean;

onClickItem?: (data: any[],item: any,index: number) => void;
onDragStart?: (fromIndex: number) => void;
onDragEnd?: (fromIndex: number,toIndex: number) => void;
Expand Down