Android Swipe Left / Right

AndroidSwipe.kt

import android.annotation.SuppressLint
import android.content.Context
import android.view.GestureDetector
import android.view.GestureDetector.SimpleOnGestureListener
import android.view.MotionEvent
import android.view.View
import android.view.View.OnTouchListener
import timber.log.Timber
import kotlin.math.abs

interface OnSwipeDelegate {
  fun onSwipeRight(): Boolean = false
  fun onSwipeLeft(): Boolean = false
  fun onSwipeUp(): Boolean = false
  fun onSwipeDown(): Boolean = false
}

fun View.setOnSwipe(delegate: OnSwipeDelegate) {
  setOnTouchListener(OnSwipeTouchListener(context, delegate))
}

private class OnSwipeTouchListener(
  context: Context,
  private val delegate: OnSwipeDelegate,
) : SimpleOnGestureListener(), OnTouchListener {
  companion object {
    private const val SwipeThreshold = 100
    private const val SwipeVelocityThreshold = 100
  }

  private val gestureDetector = GestureDetector(context, this)

  @SuppressLint("ClickableViewAccessibility")
  override fun onTouch(v: View, event: MotionEvent): Boolean = gestureDetector.onTouchEvent(event)

  override fun onDown(e: MotionEvent) = true

  override fun onFling(
    e1: MotionEvent,
    e2: MotionEvent,
    velocityX: Float,
    velocityY: Float,
  ): Boolean {
    try {
      val diffY = e2.y - e1.y
      val diffX = e2.x - e1.x

      if (abs(diffX) > abs(diffY)) {
        if (abs(diffX) > SwipeThreshold && abs(velocityX) > SwipeVelocityThreshold) {
          return when {
            diffX > 0 -> delegate.onSwipeRight()
            else -> delegate.onSwipeLeft()
          }
        }
      } else if (abs(diffY) > SwipeThreshold && abs(velocityY) > SwipeVelocityThreshold) {
        return when {
          diffY > 0 -> delegate.onSwipeDown()
          else -> delegate.onSwipeUp()
        }
      }
    } catch (exception: Exception) {
      Timber.w(exception)
    }

    return false
  }
}