ChildrenSwipeHandlingMotionLayout

ChildrenSwipeHandlingMotionLayout.kt

import android.content.Context
import android.os.SystemClock
import android.util.AttributeSet
import android.view.MotionEvent
import android.view.View
import androidx.constraintlayout.motion.widget.MotionLayout
import androidx.core.content.PackageManagerCompat.LOG_TAG
import kotlin.math.abs


/**
 * Issue: In MotionLayout, swipes over a clickable view doesn't work.
 */

class ChildrenSwipeHandlingMotionLayout @JvmOverloads constructor(
    context: Context,
    attrs: AttributeSet? = null,
    defStyle: Int = 0
) : MotionLayout(context, attrs, defStyle) {
    /*
    * we don't want to intercept for viewPager because in viewPager we have recycler that automatic
    * handle touches/swipes gracefully with MotionLayout, we are just concerned about clickable views in headers
    */
    var viewPagerArea: View? =
        null
    private var onActionDownYValue = 0f
    private var doNotAllowIntercept = false

    private fun isInViewPagerArea(event: MotionEvent): Boolean {
        return viewPagerArea?.let {
            val point = IntArray(2)
            it.getLocationOnScreen(point)
            val (_, y) = point
            if(y == 0) // if viewPager not shown on the screen.
                return false
            event.y >= y
        } ?: true
    }

    override fun onInterceptTouchEvent(event: MotionEvent): Boolean {
        return when {
            event.actionMasked != MotionEvent.ACTION_DOWN && doNotAllowIntercept -> super.onInterceptTouchEvent(
                event
            ) // when the user swipe from viewPagerArea, just return from here because it automatically handles the motion layout.

            else -> when (event.actionMasked) {
                MotionEvent.ACTION_DOWN -> {
                    onActionDownYValue = event.y
                    doNotAllowIntercept = isInViewPagerArea(event)
                    super.onInterceptTouchEvent(event)
                }

                MotionEvent.ACTION_MOVE -> {
                    abs(onActionDownYValue - event.y).takeIf { it > 50 }?.run {
                        onTouchEvent(
                            MotionEvent.obtain(
                                SystemClock.uptimeMillis(),
                                SystemClock.uptimeMillis() + 100,
                                MotionEvent.ACTION_DOWN,
                                event.rawX,
                                event.rawY,
                                0
                            )
                        )
                        true
                    } ?: super.onInterceptTouchEvent(event)
                }

                else ->
                    super.onInterceptTouchEvent(event)
            }
        }
    }

}