Android Compass(나침반)

불현득 생각이 나서 코틀린 연습 겸 샘플용으로 만들었습니다~

 

 

센서처리는 다음 블로그를 참고했어요.

http://swlock.blogspot.com/2017/10/android-compass.html

Android Compass (나침반)

 

 

MainActivity는 다음과 같이 되어있어요.

Listener를 별도로 빼고 interface로 연결해주면 좀 더 깔끔하게 작성할 수 있습니다.

class MainActivity : AppCompatActivity(), SeekBarToView, SensorToView{

    private val sensorImpl = SensorEventListenerImpl(this)
    private lateinit var sm: SensorManager

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(R.layout.activity_main)
        sm = getSystemService(Context.SENSOR_SERVICE) as SensorManager
    }

    override fun onResume() {
        super.onResume()
        sm.registerListener(sensorImpl, sm.getDefaultSensor(Sensor.TYPE_ACCELEROMETER), SensorManager.SENSOR_DELAY_NORMAL)
        sm.registerListener(sensorImpl, sm.getDefaultSensor(Sensor.TYPE_MAGNETIC_FIELD), SensorManager.SENSOR_DELAY_NORMAL)
    }

    override fun onPause() {
        super.onPause()
        sm.unregisterListener(sensorImpl)
    }

    // from Listener
    override fun onDegreeChanged(degree: Float) {
        mainCanvas.degree = degree
    }
}

 

 

나침반 역할을 하는 View는 다음과 같이 CustomView로 만들어줬습니다.

간단한 삼각함수로 절대좌표를 구했어요. Canvas의 상대 사이즈로 만들어졌기 때문에 여기에서 더 코드 보완이 필요하겠네요.

private const val FIRST_RING_WIDTH = 10f

class Compass(ctx: Context, attr: AttributeSet?) : View(ctx, attr) {

    var degree: Float = 0.0f
        set(value) {
            // 90˚ offset
            field = value + 90f
            invalidate()
        }

    constructor(ctx: Context) : this(ctx, null)

    private val blackCirclePaint: Paint = Paint(Paint.ANTI_ALIAS_FLAG)
    private val whiteCirclePaint: Paint = Paint(Paint.ANTI_ALIAS_FLAG)
    private val indicatorPaint: Paint = Paint(Paint.ANTI_ALIAS_FLAG)


    init {
        // Paint for black outer circle
        blackCirclePaint.color = Color.BLACK

        // Paint for white inner circle
        whiteCirclePaint.color = Color.WHITE

        // line indicator
        indicatorPaint.strokeWidth = 5f
        indicatorPaint.strokeCap = Paint.Cap.ROUND
    }

    override fun onDraw(canvas: Canvas?) {
        canvas?.let {
            myDraw(it)
        }
    }

    private fun myDraw(canvas: Canvas) {

        val halfHeight = canvas.height / 2f
        val radius = canvas.width / 2f
        canvas.drawCircle(radius, halfHeight, radius, blackCirclePaint)
        canvas.drawCircle(radius, halfHeight, radius - FIRST_RING_WIDTH, whiteCirclePaint)

        canvas.drawLine(radius, halfHeight, radius + calculateXWithDegree(radius, degree), halfHeight + calculateYWithDegree(radius, degree), indicatorPaint)
    }

    private fun calculateXWithDegree(r: Float, degree: Float): Float {
        // a/r = cosθ
        return r * Math.cos(Math.toRadians(degree.toDouble())).toFloat()
    }

    private fun calculateYWithDegree(r: Float, degree: Float): Float {
        // b/r = sinθ
        return r * Math.sin(Math.toRadians(degree.toDouble())).toFloat()
    }
}

 

 

샘플실행예제

 

 

전체 소스는 아래를 참고해주세요!

https://gitlab.com/iroiroys/basiccompass