@aurigma/design-atoms/History/History.js

Design Atoms is a part of Customer's Canvas SDK which allows for manipulating individual design elements through your code.

import { EventObject } from "@aurigma/design-atoms-model/EventObject";
export class History {
    constructor(handler, historySize = 10) {
        this._snapshots = [];
        this._current = -1;
        this._enabled = true;
        this._locked = false;
        this._pauseCount = 0;
        this._addSnapshotOnResume = false;
        this._overflowMaxUndoStepCount = false;
        this._changed = new EventObject();
        this._undoPerformed = new EventObject();
        this._redoPerformed = new EventObject();
        this._snapshotHandler = handler;
        this.historySize = historySize;
    }
    set historySize(historySize) {
        if (historySize >= 0)
            this._maxUndoStepCount = historySize;
        else {
            console.warn("History: historySize value isn't correct, reset to 10");
            this._maxUndoStepCount = 10;
        }
    }
    get canRedo() {
        return (this._current < this._snapshots.length - 1);
    }
    get canUndo() {
        return (this._current >= 1);
    }
    get overflowMaxUndoStepCount() {
        return this._overflowMaxUndoStepCount;
    }
    enable() {
        if (!this._enabled)
            this._enabled = true;
    }
    disable() {
        if (this._enabled) {
            this._enabled = false;
            this.clear();
        }
    }
    isPaused() {
        return this._pauseCount > 0;
    }
    pause() {
        this._pauseCount++;
        if (this._pauseCount === 1)
            this._addSnapshotOnResume = false;
    }
    resume(addSnapshot = true, forceAddSnapshot = false, replaceLastSnapshot = false) {
        if (this._pauseCount <= 0)
            return;
        this._pauseCount--;
        if (this._pauseCount === 0) {
            if (addSnapshot && this._addSnapshotOnResume || forceAddSnapshot)
                this.addSnapshot(false, replaceLastSnapshot);
        }
    }
    raiseChanged() {
        this._changed.notify();
    }
    _clearRedo() {
        this._snapshots.splice(this._current + 1);
    }
    _clearUndo() {
        this._snapshots.splice(0, this._current + 1);
        this._current = -1;
        this._overflowMaxUndoStepCount = false;
    }
    clear(suppressOnChanged = false) {
        this._snapshots = [];
        this._current = -1;
        this.addSnapshot(true);
        if (!suppressOnChanged)
            this.raiseChanged();
    }
    addSnapshot(suppressOnChanged = false, replaceLastSnapshot = false) {
        if (!this._enabled || this._locked)
            return;
        if (this._pauseCount > 0) {
            this._addSnapshotOnResume = true;
            return;
        }
        const snapshot = this._snapshotHandler.createSnapshot();
        if (snapshot == null)
            throw "Snapshot can not be null";
        this._locked = true;
        if (this.canRedo)
            this._clearRedo();
        if (replaceLastSnapshot && this._snapshots.length > 0) {
            this._snapshots.pop();
            this._current--;
        }
        this._snapshots.push(snapshot);
        this._current++;
        this._locked = false;
        if (this._current > this._maxUndoStepCount) {
            this._snapshots.splice(0, 1);
            this._current--;
            this._overflowMaxUndoStepCount = true;
        }
        if (!suppressOnChanged)
            this.raiseChanged();
    }
    redo() {
        if (!this._enabled || !this.canRedo)
            return;
        this._locked = true;
        this._current++;
        const snapshot = this._snapshots[this._current];
        this._snapshotHandler.loadSnapshot(snapshot);
        this._locked = false;
        this.raiseChanged();
        this._redoPerformed.notify();
    }
    undo() {
        if (!this._enabled || !this.canUndo)
            return;
        this._locked = true;
        this._current--;
        const snapshot = this._snapshots[this._current];
        this._snapshotHandler.loadSnapshot(snapshot);
        this._locked = false;
        this.raiseChanged();
        this._undoPerformed.notify();
    }
    addChanged(listener) {
        this._changed.add(listener);
    }
    removeChanged(listener) {
        this._changed.remove(listener);
    }
    addUndoPerformed(listener) {
        this._undoPerformed.add(listener);
    }
    removeUndoPerformed(listener) {
        this._undoPerformed.remove(listener);
    }
    addRedoPerformed(listener) {
        this._redoPerformed.add(listener);
    }
    removeRedoPerformed(listener) {
        this._redoPerformed.remove(listener);
    }
}
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