ভিন্নজাতীয় আইটেম হাইটের সাথে একক-দিকের অসীম স্ক্রোলিংয়ের মডেলিংয়ের জন্য আমি একই ধরণের চ্যালেঞ্জের মুখোমুখি হয়েছি এবং তাই আমার সমাধান থেকে একটি এনপিএম প্যাকেজ তৈরি করেছে:
https://www.npmjs.com/package/react-variable-height-infinite-scroller
এবং একটি ডেমো: http://tnrich.github.io/react-variable-height-infinite-scroller/
আপনি লজিকের জন্য সোর্স কোডটি পরীক্ষা করে দেখতে পারেন, তবে আমি মূলত উপরের উত্তরে বর্ণিত রেজিস্ট্রেশন @ ভিজেউক্সটি অনুসরণ করেছি। আমি এখনও কোনও নির্দিষ্ট আইটেমটিতে ঝাঁপিয়ে পড়ার বিষয়টি মোকাবেলা করি নি, তবে আমি শীঘ্রই এটি বাস্তবায়নের আশা করছি।
কোডটি বর্তমানে কেমন দেখাচ্ছে তার মূর্খতা এখানে রয়েছে:
var React = require('react');
var areNonNegativeIntegers = require('validate.io-nonnegative-integer-array');
var InfiniteScoller = React.createClass({
propTypes: {
averageElementHeight: React.PropTypes.number.isRequired,
containerHeight: React.PropTypes.number.isRequired,
preloadRowStart: React.PropTypes.number.isRequired,
renderRow: React.PropTypes.func.isRequired,
rowData: React.PropTypes.array.isRequired,
},
onEditorScroll: function(event) {
var infiniteContainer = event.currentTarget;
var visibleRowsContainer = React.findDOMNode(this.refs.visibleRowsContainer);
var currentAverageElementHeight = (visibleRowsContainer.getBoundingClientRect().height / this.state.visibleRows.length);
this.oldRowStart = this.rowStart;
var newRowStart;
var distanceFromTopOfVisibleRows = infiniteContainer.getBoundingClientRect().top - visibleRowsContainer.getBoundingClientRect().top;
var distanceFromBottomOfVisibleRows = visibleRowsContainer.getBoundingClientRect().bottom - infiniteContainer.getBoundingClientRect().bottom;
var rowsToAdd;
if (distanceFromTopOfVisibleRows < 0) {
if (this.rowStart > 0) {
rowsToAdd = Math.ceil(-1 * distanceFromTopOfVisibleRows / currentAverageElementHeight);
newRowStart = this.rowStart - rowsToAdd;
if (newRowStart < 0) {
newRowStart = 0;
}
this.prepareVisibleRows(newRowStart, this.state.visibleRows.length);
}
} else if (distanceFromBottomOfVisibleRows < 0) {
//scrolling down, so add a row below
var rowsToGiveOnBottom = this.props.rowData.length - 1 - this.rowEnd;
if (rowsToGiveOnBottom > 0) {
rowsToAdd = Math.ceil(-1 * distanceFromBottomOfVisibleRows / currentAverageElementHeight);
newRowStart = this.rowStart + rowsToAdd;
if (newRowStart + this.state.visibleRows.length >= this.props.rowData.length) {
//the new row start is too high, so we instead just append the max rowsToGiveOnBottom to our current preloadRowStart
newRowStart = this.rowStart + rowsToGiveOnBottom;
}
this.prepareVisibleRows(newRowStart, this.state.visibleRows.length);
}
} else {
//we haven't scrolled enough, so do nothing
}
this.updateTriggeredByScroll = true;
//set the averageElementHeight to the currentAverageElementHeight
// setAverageRowHeight(currentAverageElementHeight);
},
componentWillReceiveProps: function(nextProps) {
var rowStart = this.rowStart;
var newNumberOfRowsToDisplay = this.state.visibleRows.length;
this.props.rowData = nextProps.rowData;
this.prepareVisibleRows(rowStart, newNumberOfRowsToDisplay);
},
componentWillUpdate: function() {
var visibleRowsContainer = React.findDOMNode(this.refs.visibleRowsContainer);
this.soonToBeRemovedRowElementHeights = 0;
this.numberOfRowsAddedToTop = 0;
if (this.updateTriggeredByScroll === true) {
this.updateTriggeredByScroll = false;
var rowStartDifference = this.oldRowStart - this.rowStart;
if (rowStartDifference < 0) {
// scrolling down
for (var i = 0; i < -rowStartDifference; i++) {
var soonToBeRemovedRowElement = visibleRowsContainer.children[i];
if (soonToBeRemovedRowElement) {
var height = soonToBeRemovedRowElement.getBoundingClientRect().height;
this.soonToBeRemovedRowElementHeights += this.props.averageElementHeight - height;
// this.soonToBeRemovedRowElementHeights.push(soonToBeRemovedRowElement.getBoundingClientRect().height);
}
}
} else if (rowStartDifference > 0) {
this.numberOfRowsAddedToTop = rowStartDifference;
}
}
},
componentDidUpdate: function() {
//strategy: as we scroll, we're losing or gaining rows from the top and replacing them with rows of the "averageRowHeight"
//thus we need to adjust the scrollTop positioning of the infinite container so that the UI doesn't jump as we
//make the replacements
var infiniteContainer = React.findDOMNode(this.refs.infiniteContainer);
var visibleRowsContainer = React.findDOMNode(this.refs.visibleRowsContainer);
var self = this;
if (this.soonToBeRemovedRowElementHeights) {
infiniteContainer.scrollTop = infiniteContainer.scrollTop + this.soonToBeRemovedRowElementHeights;
}
if (this.numberOfRowsAddedToTop) {
//we're adding rows to the top, so we're going from 100's to random heights, so we'll calculate the differenece
//and adjust the infiniteContainer.scrollTop by it
var adjustmentScroll = 0;
for (var i = 0; i < this.numberOfRowsAddedToTop; i++) {
var justAddedElement = visibleRowsContainer.children[i];
if (justAddedElement) {
adjustmentScroll += this.props.averageElementHeight - justAddedElement.getBoundingClientRect().height;
var height = justAddedElement.getBoundingClientRect().height;
}
}
infiniteContainer.scrollTop = infiniteContainer.scrollTop - adjustmentScroll;
}
var visibleRowsContainer = React.findDOMNode(this.refs.visibleRowsContainer);
if (!visibleRowsContainer.childNodes[0]) {
if (this.props.rowData.length) {
//we've probably made it here because a bunch of rows have been removed all at once
//and the visible rows isn't mapping to the row data, so we need to shift the visible rows
var numberOfRowsToDisplay = this.numberOfRowsToDisplay || 4;
var newRowStart = this.props.rowData.length - numberOfRowsToDisplay;
if (!areNonNegativeIntegers([newRowStart])) {
newRowStart = 0;
}
this.prepareVisibleRows(newRowStart , numberOfRowsToDisplay);
return; //return early because we need to recompute the visible rows
} else {
throw new Error('no visible rows!!');
}
}
var adjustInfiniteContainerByThisAmount;
//check if the visible rows fill up the viewport
//tnrtodo: maybe put logic in here to reshrink the number of rows to display... maybe...
if (visibleRowsContainer.getBoundingClientRect().height / 2 <= this.props.containerHeight) {
//visible rows don't yet fill up the viewport, so we need to add rows
if (this.rowStart + this.state.visibleRows.length < this.props.rowData.length) {
//load another row to the bottom
this.prepareVisibleRows(this.rowStart, this.state.visibleRows.length + 1);
} else {
//there aren't more rows that we can load at the bottom so we load more at the top
if (this.rowStart - 1 > 0) {
this.prepareVisibleRows(this.rowStart - 1, this.state.visibleRows.length + 1); //don't want to just shift view
} else if (this.state.visibleRows.length < this.props.rowData.length) {
this.prepareVisibleRows(0, this.state.visibleRows.length + 1);
}
}
} else if (visibleRowsContainer.getBoundingClientRect().top > infiniteContainer.getBoundingClientRect().top) {
//scroll to align the tops of the boxes
adjustInfiniteContainerByThisAmount = visibleRowsContainer.getBoundingClientRect().top - infiniteContainer.getBoundingClientRect().top;
// this.adjustmentScroll = true;
infiniteContainer.scrollTop = infiniteContainer.scrollTop + adjustInfiniteContainerByThisAmount;
} else if (visibleRowsContainer.getBoundingClientRect().bottom < infiniteContainer.getBoundingClientRect().bottom) {
//scroll to align the bottoms of the boxes
adjustInfiniteContainerByThisAmount = visibleRowsContainer.getBoundingClientRect().bottom - infiniteContainer.getBoundingClientRect().bottom;
// this.adjustmentScroll = true;
infiniteContainer.scrollTop = infiniteContainer.scrollTop + adjustInfiniteContainerByThisAmount;
}
},
componentWillMount: function(argument) {
//this is the only place where we use preloadRowStart
var newRowStart = 0;
if (this.props.preloadRowStart < this.props.rowData.length) {
newRowStart = this.props.preloadRowStart;
}
this.prepareVisibleRows(newRowStart, 4);
},
componentDidMount: function(argument) {
//call componentDidUpdate so that the scroll position will be adjusted properly
//(we may load a random row in the middle of the sequence and not have the infinte container scrolled properly initially, so we scroll to the show the rowContainer)
this.componentDidUpdate();
},
prepareVisibleRows: function(rowStart, newNumberOfRowsToDisplay) { //note, rowEnd is optional
//setting this property here, but we should try not to use it if possible, it is better to use
//this.state.visibleRowData.length
this.numberOfRowsToDisplay = newNumberOfRowsToDisplay;
var rowData = this.props.rowData;
if (rowStart + newNumberOfRowsToDisplay > this.props.rowData.length) {
this.rowEnd = rowData.length - 1;
} else {
this.rowEnd = rowStart + newNumberOfRowsToDisplay - 1;
}
// var visibleRows = this.state.visibleRowsDataData.slice(rowStart, this.rowEnd + 1);
// rowData.slice(rowStart, this.rowEnd + 1);
// setPreloadRowStart(rowStart);
this.rowStart = rowStart;
if (!areNonNegativeIntegers([this.rowStart, this.rowEnd])) {
var e = new Error('Error: row start or end invalid!');
console.warn('e.trace', e.trace);
throw e;
}
var newVisibleRows = rowData.slice(this.rowStart, this.rowEnd + 1);
this.setState({
visibleRows: newVisibleRows
});
},
getVisibleRowsContainerDomNode: function() {
return this.refs.visibleRowsContainer.getDOMNode();
},
render: function() {
var self = this;
var rowItems = this.state.visibleRows.map(function(row) {
return self.props.renderRow(row);
});
var rowHeight = this.currentAverageElementHeight ? this.currentAverageElementHeight : this.props.averageElementHeight;
this.topSpacerHeight = this.rowStart * rowHeight;
this.bottomSpacerHeight = (this.props.rowData.length - 1 - this.rowEnd) * rowHeight;
var infiniteContainerStyle = {
height: this.props.containerHeight,
overflowY: "scroll",
};
return (
<div
ref="infiniteContainer"
className="infiniteContainer"
style={infiniteContainerStyle}
onScroll={this.onEditorScroll}
>
<div ref="topSpacer" className="topSpacer" style={{height: this.topSpacerHeight}}/>
<div ref="visibleRowsContainer" className="visibleRowsContainer">
{rowItems}
</div>
<div ref="bottomSpacer" className="bottomSpacer" style={{height: this.bottomSpacerHeight}}/>
</div>
);
}
});
module.exports = InfiniteScoller;