Movement Detector

move.js

class MovementDetector {
  constructor(options = {}) {
    // Configuration with defaults
    this.threshold = options.threshold || 5;
    this.debug = options.debug || false;
    this.onMovementChange = options.onMovementChange || null;
    
    // State tracking
    this.lastRotation = { x: 0, y: 0, z: 0 };
    this.isMoving = false;
    
    // Bind the handler to preserve 'this' context
    this.handleDeviceMotion = this.handleDeviceMotion.bind(this);
  }
  
  start() {
    window.addEventListener("devicemotion", this.handleDeviceMotion);
    if (this.debug) console.log("Movement detector started");
  }
  
  stop() {
    window.removeEventListener("devicemotion", this.handleDeviceMotion);
    if (this.debug) console.log("Movement detector stopped");
  }
  
  handleDeviceMotion(event) {
    const rotation = {
      x: event.rotationRate.alpha,
      y: event.rotationRate.beta,
      z: event.rotationRate.gamma
    };
    
    // Calculate differences on all axes
    const diffs = {
      x: Math.abs(rotation.x - this.lastRotation.x),
      y: Math.abs(rotation.y - this.lastRotation.y),
      z: Math.abs(rotation.z - this.lastRotation.z)
    };
    
    // Check if any axis exceeds the threshold
    const movementDetected = 
      diffs.x > this.threshold || 
      diffs.y > this.threshold || 
      diffs.z > this.threshold;
    
    // Only report changes in movement state
    if (movementDetected !== this.isMoving) {
      this.isMoving = movementDetected;
      
      if (this.debug) {
        console.log(this.isMoving ? "Movement detected!" : "Movement stopped");
      }
      
      // Call the callback if provided
      if (typeof this.onMovementChange === 'function') {
        this.onMovementChange(this.isMoving);
      }
    }
    
    // Update last rotation values
    this.lastRotation = rotation;
  }
}