src/js/handler.js

export class Handler {
    constructor() {
        this.enabled = true;
        this.boundLayer = null;
    }

    enable() {
        this.enabled = true;
    }

    disable() {
        this.enabled = false;
    }

    bind(layer) {
        this.boundLayer = layer;
    }

    canHandle() {
        return this.enabled && this.boundLayer && this.boundLayer.inputEnabled;
    }
}

export class LayerHandler extends Handler {
    constructor(eventType, handler) {
        super();
        this.eventType = eventType;
        this.baseHandler = handler;
    }

    handle(event) {
        if (this.canHandle()) {
            this.baseHandler(event, this.boundLayer);
        }
    }
}

export class InputHandler extends Handler {
    constructor(canvas) {
        super();
        this.canvas = canvas;
        this.handlers = new Map();
    }

    addHandler(eventType, handler) {
        if (!this.handlers.has(eventType)) {
            this.handlers.set(eventType, []);
        }
        this.handlers.get(eventType).push(handler);
    }

    removeHandler(eventType, handler) {
        if (this.handlers.has(eventType)) {
            const handlers = this.handlers.get(eventType);
            const index = handlers.indexOf(handler);
            if (index !== -1) {
                handlers.splice(index, 1);
            }
        }
    }

    getMousePosition(event) {
        const rect = this.canvas.getBoundingClientRect();
        return {
            x: event.clientX - rect.left,
            y: event.clientY - rect.top
        };
    }
}