zoom.ts

import assert from "assert";
import Fraction from "fraction.js";

import { RootStore } from "../../store";
import { Action } from "../action";

/**
 * Arguments for the ZoomAction.
 */
export interface ZoomArgs {
    to: Fraction;
}

/**
 * Action for setting the notefield zoom.
 */
export class ZoomAction implements Action {
    args: ZoomArgs;
    oldZoom!: Fraction;

    store: RootStore;

    /**
     * The default scalar for zooming.
     */
    static readonly SCALAR = 1.5;

    constructor(store: RootStore, args: ZoomArgs) {
        assert(args.to.compare(0) === 1, "zoom must be greater than zero");

        this.args = args;
        this.store = store;
    }

    run(): void {
        const { notefield } = this.store;

        this.oldZoom = notefield.data.zoom;
        notefield.setZoom(this.args.to);
    }

    undo(): void {
        this.store.notefield.setZoom(this.oldZoom);
    }
}