src/component/keyboard/KeyZoomHandler.ts

import { withLatestFrom } from "rxjs/operators";
import { Subscription } from "rxjs";

import { Transform } from "../../geo/Transform";
import { ViewportCoords } from "../../geo/ViewportCoords";
import { RenderCamera } from "../../render/RenderCamera";
import { Container } from "../../viewer/Container";
import { Navigator } from "../../viewer/Navigator";
import { Component } from "../Component";
import { KeyboardConfiguration } from "../interfaces/KeyboardConfiguration";
import { HandlerBase } from "../util/HandlerBase";

/**
 * The `KeyZoomHandler` allows the user to zoom in and out using the
 * following key commands:
 *
 * `+`: Zoom in.
 * `-`: Zoom out.
 *
 * @example
 * ```js
 * var keyboardComponent = viewer.getComponent("keyboard");
 *
 * keyboardComponent.keyZoom.disable();
 * keyboardComponent.keyZoom.enable();
 *
 * var isEnabled = keyboardComponent.keyZoom.isEnabled;
 * ```
 */
export class KeyZoomHandler extends HandlerBase<KeyboardConfiguration> {
    private _keyDownSubscription: Subscription;

    private _viewportCoords: ViewportCoords;

    /** @ignore */
    constructor(
        component: Component<KeyboardConfiguration>,
        container: Container,
        navigator: Navigator,
        viewportCoords: ViewportCoords) {
        super(component, container, navigator);

        this._viewportCoords = viewportCoords;
    }

    protected _enable(): void {
        this._keyDownSubscription = this._container.keyboardService.keyDown$.pipe(
            withLatestFrom(
                this._container.renderService.renderCamera$,
                this._navigator.stateService.currentTransform$))
            .subscribe(
                ([event, render, transform]: [KeyboardEvent, RenderCamera, Transform]): void => {
                    if (event.altKey || event.ctrlKey || event.metaKey) {
                        return;
                    }

                    let delta: number = 0;
                    switch (event.key) {
                        case "+":
                            delta = 1;
                            break;
                        case "-":
                            delta = -1;
                            break;
                        default:
                            return;
                    }

                    event.preventDefault();

                    const unprojected: THREE.Vector3 = this._viewportCoords.unprojectFromViewport(0, 0, render.perspective);
                    const reference: number[] = transform.projectBasic(unprojected.toArray());

                    this._navigator.stateService.zoomIn(delta, reference);
                });
    }

    protected _disable(): void {
        this._keyDownSubscription.unsubscribe();
    }

    protected _getConfiguration(enable: boolean): KeyboardConfiguration {
        return { keyZoom: enable };
    }
}