Android TouchSlopDelegate

TouchSlopDelegate.kt

import android.content.Context
import android.view.MotionEvent
import android.view.MotionEvent.*
import android.view.ViewConfiguration

class TouchSlopDelegate(context: Context) {
    private val targetTouchSlop = ViewConfiguration.get(context).scaledTouchSlop
    private var touchSlop: Int = 0
    private var lastTouchX: Float = 0f
    private var lastTouchY: Float = 0f

    val pastThreshold: Boolean
        get() = touchSlop > targetTouchSlop

    fun trackTouchEvent(event: MotionEvent) {
        when (event.action) {
            ACTION_DOWN -> {
                lastTouchX = event.x
                lastTouchY = event.y
            }
            ACTION_MOVE -> {
                val deltaX = Math.abs(event.x - lastTouchX)
                val deltaY = Math.abs(event.y - lastTouchY)
                touchSlop = Math.max(deltaX, deltaY).toInt()
            }
            ACTION_UP -> {
                touchSlop = 0
            }
        }
    }
}