1 files changed, 113 insertions, 0 deletions
diff --git a/app/src/main/kotlin/com/pitchedapps/frost/web/NestedWebView.kt b/app/src/main/kotlin/com/pitchedapps/frost/web/NestedWebView.kt
new file mode 100644
index 00000000..f0bb6137
--- /dev/null
+++ b/app/src/main/kotlin/com/pitchedapps/frost/web/NestedWebView.kt
@@ -0,0 +1,113 @@
+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)
+}
+\ No newline at end of file