@woosh/meep-engine/src/engine/animation/curve/editor/OperationRouter.js

Pure JavaScript game engine. Fully featured and production ready.

/**
 *  Decide and execute the operation based on pointer device events
 */
export class OperationRouter {
    /**
     *
     * @param {PointerDevice} pointerDevice
     * @param {function} resolveOperation
     */
    constructor(pointerDevice, resolveOperation) {
        this.pointer = pointerDevice;
        this.resolveOperation = resolveOperation;
        this.activeOperation = null;

        this.pointer.on.down.add(this.start, this);
        this.pointer.on.drag.add(this.run, this);
        this.pointer.on.up.add(this.stop, this);
        this.pointer.on.dragEnd.add(this.stop, this);
    }

    start(position, event) {
        if (this.activeOperation) return;

        const operation = this.resolveOperation(event);
        if (!operation) return;

        this.activeOperation = operation;
        this.activeOperation.start(position, event);
    }

    run(position, origin, last, event) {
        if (!this.activeOperation) return;

        const delta = position.clone().sub(last);
        this.activeOperation.drag(position, delta, event);
    }

    stop(position, event) {
        if (!this.activeOperation) return;

        this.activeOperation.end(position, event);
        this.activeOperation = null;
    }
}