json-joy/esm/json-crdt-peritext-ui/plugins/cursor/state.js

Collection of libraries for building collaborative editing apps.

import { ValueSyncStore } from '../../../util/events/sync-store';
export class CursorState {
    ctx;
    /** Current score. */
    score = new ValueSyncStore(0);
    /** By how much the score changed. */
    scoreDelta = new ValueSyncStore(0);
    /** The last score that was shown to the user. */
    lastVisScore = new ValueSyncStore(0);
    constructor(ctx) {
        this.ctx = ctx;
    }
    /** -------------------------------------------------- {@link UiLifeCycles} */
    start() {
        const dom = this.ctx.dom;
        let lastNow = 0;
        const onChange = (event) => {
            const now = Date.now();
            const timeDiff = now - lastNow;
            let delta = 0;
            switch (event.detail.ev?.type) {
                case 'delete':
                case 'insert':
                case 'format':
                case 'marker': {
                    delta = timeDiff < 30 ? 10 : timeDiff < 70 ? 5 : timeDiff < 150 ? 2 : timeDiff <= 1000 ? 1 : -1;
                    break;
                }
                default: {
                    delta = timeDiff <= 1000 ? 0 : -1;
                    break;
                }
            }
            if (delta)
                this.score.next(delta >= 0 ? this.score.value + delta : 0);
            this.scoreDelta.next(delta);
            lastNow = now;
        };
        dom.et.addEventListener('change', onChange);
        return () => {
            dom.et.removeEventListener('change', onChange);
        };
    }
}