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joplin/packages/lib/services/UndoRedoService.ts

104 lines
2.2 KiB
TypeScript

import AsyncActionQueue from '../AsyncActionQueue';
const EventEmitter = require('events');
class UndoQueue {
private inner_: any[] = [];
private size_: number = 20;
pop() {
return this.inner_.pop();
}
push(e: any) {
this.inner_.push(e);
while (this.length > this.size_) {
this.inner_.splice(0,1);
}
}
get length(): number {
return this.inner_.length;
}
at(index: number): any {
return this.inner_[index];
}
}
export default class UndoRedoService {
private pushAsyncQueue: AsyncActionQueue = new AsyncActionQueue(700);
private undoStates: UndoQueue = new UndoQueue();
private redoStates: UndoQueue = new UndoQueue();
private eventEmitter: any = new EventEmitter();
private isUndoing: boolean = false;
constructor() {
this.push = this.push.bind(this);
}
on(eventName: string, callback: Function) {
return this.eventEmitter.on(eventName, callback);
}
off(eventName: string, callback: Function) {
return this.eventEmitter.removeListener(eventName, callback);
}
push(state: any) {
this.undoStates.push(state);
this.redoStates = new UndoQueue();
this.eventEmitter.emit('stackChange');
}
schedulePush(state: any) {
this.pushAsyncQueue.push(async () => {
this.push(state);
});
}
async undo(redoState: any) {
if (this.isUndoing) return;
if (!this.canUndo) throw new Error('Nothing to undo');
this.isUndoing = true;
await this.pushAsyncQueue.processAllNow();
const state = this.undoStates.pop();
this.redoStates.push(redoState);
this.eventEmitter.emit('stackChange');
this.isUndoing = false;
return state;
}
async redo(undoState: any) {
if (this.isUndoing) return;
if (!this.canRedo) throw new Error('Nothing to redo');
this.isUndoing = true;
await this.pushAsyncQueue.processAllNow();
const state = this.redoStates.pop();
this.undoStates.push(undoState);
this.eventEmitter.emit('stackChange');
this.isUndoing = false;
return state;
}
async reset() {
this.undoStates = new UndoQueue();
this.redoStates = new UndoQueue();
this.isUndoing = false;
const output = this.pushAsyncQueue.reset();
this.eventEmitter.emit('stackChange');
return output;
}
get canUndo(): boolean {
return !!this.undoStates.length;
}
get canRedo(): boolean {
return !!this.redoStates.length;
}
}