114 lines
4.2 KiB
JavaScript
114 lines
4.2 KiB
JavaScript
/*
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Copyright 2020 Bruno Windels <bruno@windels.cloud>
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Copyright 2020 The Matrix.org Foundation C.I.C.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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/*
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need better naming, but
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entry = event or gap from matrix layer
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tile = item on visual timeline like event, date separator?, group of joined events
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shall we put date separators as marker in EventViewItem or separate item? binary search will be complicated ...
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pagination ...
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on the timeline viewmodel (containing the TilesCollection?) we'll have a method to (un)load a tail or head of
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the timeline (counted in tiles), which results to a range in sortKeys we want on the screen. We pass that range
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to the room timeline, which unload entries from memory.
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when loading, it just reads events from a sortkey backwards or forwards...
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*/
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import {TilesCollection} from "./TilesCollection.js";
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import {ViewModel} from "../../../ViewModel";
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export class TimelineViewModel extends ViewModel {
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constructor(options) {
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super(options);
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const {timeline, tileOptions} = options;
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this._timeline = this.track(timeline);
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this._tiles = new TilesCollection(timeline.entries, tileOptions);
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this._startTile = null;
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this._endTile = null;
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this._topLoadingPromise = null;
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this._requestedStartTile = null;
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this._requestedEndTile = null;
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this._requestScheduled = false;
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this._showJumpDown = false;
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}
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/** if this._tiles is empty, call this with undefined for both startTile and endTile */
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setVisibleTileRange(startTile, endTile) {
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// don't clear these once done as they are used to check
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// for more tiles once loadAtTop finishes
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this._requestedStartTile = startTile;
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this._requestedEndTile = endTile;
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if (!this._requestScheduled) {
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Promise.resolve().then(() => {
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this._setVisibleTileRange(this._requestedStartTile, this._requestedEndTile);
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this._requestScheduled = false;
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});
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this._requestScheduled = true;
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}
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}
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_setVisibleTileRange(startTile, endTile) {
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let loadTop;
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if (startTile && endTile) {
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// old tiles could have been removed from tilescollection once we support unloading
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this._startTile = startTile;
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this._endTile = endTile;
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const startIndex = this._tiles.getTileIndex(this._startTile);
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const endIndex = this._tiles.getTileIndex(this._endTile);
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for (const tile of this._tiles.sliceIterator(startIndex, endIndex + 1)) {
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tile.notifyVisible();
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}
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loadTop = startIndex < 10;
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this._setShowJumpDown(endIndex < (this._tiles.length - 1));
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} else {
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// tiles collection is empty, load more at top
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loadTop = true;
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this._setShowJumpDown(false);
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}
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if (loadTop && !this._topLoadingPromise) {
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this._topLoadingPromise = this._timeline.loadAtTop(10).then(hasReachedEnd => {
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this._topLoadingPromise = null;
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if (!hasReachedEnd) {
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// check if more items need to be loaded by recursing
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// use the requested start / end tile,
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// so we don't end up overwriting a newly requested visible range here
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this.setVisibleTileRange(this._requestedStartTile, this._requestedEndTile);
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}
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});
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}
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}
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get tiles() {
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return this._tiles;
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}
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_setShowJumpDown(show) {
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if (this._showJumpDown !== show) {
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this._showJumpDown = show;
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this.emitChange("showJumpDown");
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}
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}
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get showJumpDown() {
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return this._showJumpDown;
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}
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}
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