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package com.pitchedapps.frost.web
import android.annotation.SuppressLint
import android.content.Context
import android.support.v4.view.NestedScrollingChild
import android.support.v4.view.NestedScrollingChildHelper
import android.support.v4.view.ViewCompat
import android.util.AttributeSet
import android.view.MotionEvent
import android.webkit.WebView
/**
* Created by Allan Wang on 20/12/17.
*
* Webview extension that handles nested scrolls
*/
open class NestedWebView @JvmOverloads constructor(
context: Context, attrs: AttributeSet? = null, defStyleAttr: Int = 0
) : WebView(context, attrs, defStyleAttr), NestedScrollingChild {
private lateinit var childHelper: NestedScrollingChildHelper
private var lastY: Int = 0
private val scrollOffset = IntArray(2)
private val scrollConsumed = IntArray(2)
private var nestedOffsetY: Int = 0
init {
init()
}
fun init() {
// To avoid leaking constructor
childHelper = NestedScrollingChildHelper(this)
}
/**
* Handle nested scrolling against SwipeRecyclerView
* Courtesy of takahirom
*
* https://github.com/takahirom/webview-in-coordinatorlayout/blob/master/app/src/main/java/com/github/takahirom/webview_in_coodinator_layout/NestedWebView.java
*/
@SuppressLint("ClickableViewAccessibility")
override final fun onTouchEvent(ev: MotionEvent): Boolean {
val event = MotionEvent.obtain(ev)
val action = event.action
if (action == MotionEvent.ACTION_DOWN)
nestedOffsetY = 0
val eventY = event.y.toInt()
event.offsetLocation(0f, nestedOffsetY.toFloat())
val returnValue: Boolean
when (action) {
MotionEvent.ACTION_MOVE -> {
var deltaY = lastY - eventY
// NestedPreScroll
if (dispatchNestedPreScroll(0, deltaY, scrollConsumed, scrollOffset)) {
deltaY -= scrollConsumed[1]
event.offsetLocation(0f, -scrollOffset[1].toFloat())
nestedOffsetY += scrollOffset[1]
}
lastY = eventY - scrollOffset[1]
returnValue = super.onTouchEvent(event)
// NestedScroll
if (dispatchNestedScroll(0, scrollOffset[1], 0, deltaY, scrollOffset)) {
event.offsetLocation(0f, scrollOffset[1].toFloat())
nestedOffsetY += scrollOffset[1]
lastY -= scrollOffset[1]
}
}
MotionEvent.ACTION_DOWN -> {
returnValue = super.onTouchEvent(event)
lastY = eventY
startNestedScroll(ViewCompat.SCROLL_AXIS_VERTICAL)
}
MotionEvent.ACTION_UP, MotionEvent.ACTION_CANCEL -> {
returnValue = super.onTouchEvent(event)
stopNestedScroll()
}
else -> return false
}
return returnValue
}
/*
* ---------------------------------------------
* Nested Scrolling Content
* ---------------------------------------------
*/
override final fun setNestedScrollingEnabled(enabled: Boolean) {
childHelper.isNestedScrollingEnabled = enabled
}
override final fun isNestedScrollingEnabled() = childHelper.isNestedScrollingEnabled
override final fun startNestedScroll(axes: Int) = childHelper.startNestedScroll(axes)
override final fun stopNestedScroll() = childHelper.stopNestedScroll()
override final fun hasNestedScrollingParent() = childHelper.hasNestedScrollingParent()
override final fun dispatchNestedScroll(dxConsumed: Int, dyConsumed: Int, dxUnconsumed: Int, dyUnconsumed: Int, offsetInWindow: IntArray?)
= childHelper.dispatchNestedScroll(dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed, offsetInWindow)
override final fun dispatchNestedPreScroll(dx: Int, dy: Int, consumed: IntArray?, offsetInWindow: IntArray?)
= childHelper.dispatchNestedPreScroll(dx, dy, consumed, offsetInWindow)
override final fun dispatchNestedFling(velocityX: Float, velocityY: Float, consumed: Boolean)
= childHelper.dispatchNestedFling(velocityX, velocityY, consumed)
override final fun dispatchNestedPreFling(velocityX: Float, velocityY: Float)
= childHelper.dispatchNestedPreFling(velocityX, velocityY)
}
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