From ba3a37d33dfd8e1db3451f8c63844c373bce823e Mon Sep 17 00:00:00 2001
From: Marcos Holgado <marcosh@duckduckgo.com>
Date: Thu, 18 Feb 2021 12:55:40 +0000
Subject: [PATCH 1/2] Change swipe to refresh to only be triggered when a
 gesture begins

---
 .../app/browser/DuckDuckGoWebView.kt          | 29 ++++++++++++++-----
 1 file changed, 22 insertions(+), 7 deletions(-)

diff --git a/app/src/main/java/com/duckduckgo/app/browser/DuckDuckGoWebView.kt b/app/src/main/java/com/duckduckgo/app/browser/DuckDuckGoWebView.kt
index 5b9789d0efd0..d449d2962794 100644
--- a/app/src/main/java/com/duckduckgo/app/browser/DuckDuckGoWebView.kt
+++ b/app/src/main/java/com/duckduckgo/app/browser/DuckDuckGoWebView.kt
@@ -35,9 +35,11 @@ import androidx.core.view.ViewCompat
  * Originally based on https://github.com/takahirom/webview-in-coordinatorlayout for scrolling behaviour
  */
 class DuckDuckGoWebView : WebView, NestedScrollingChild {
-    private var lastClampedTopY: Boolean = false
+    private var lastClampedTopY: Boolean = true // when created we are always at the top
     private var contentAllowsSwipeToRefresh: Boolean = true
     private var enableSwipeRefreshCallback: ((Boolean) -> Unit)? = null
+    private var hasGestureFinished = true
+    private var canSwipeToRefresh = true
 
     private var lastY: Int = 0
     private var lastDeltaY: Int = 0
@@ -76,12 +78,15 @@ class DuckDuckGoWebView : WebView, NestedScrollingChild {
         event.offsetLocation(0f, nestedOffsetY.toFloat())
 
         when (action) {
+            MotionEvent.ACTION_UP -> {
+                hasGestureFinished = true
+                returnValue = super.onTouchEvent(event)
+                stopNestedScroll()
+            }
             MotionEvent.ACTION_MOVE -> {
                 var deltaY = lastY - eventY
 
-                if (deltaY > 0) {
-                    lastClampedTopY = false
-                }
+                lastClampedTopY = deltaY <= 0
 
                 if (dispatchNestedPreScroll(0, deltaY, scrollConsumed, scrollOffset)) {
                     deltaY -= scrollConsumed[1]
@@ -98,8 +103,8 @@ class DuckDuckGoWebView : WebView, NestedScrollingChild {
                     lastY -= scrollOffset[1]
                 }
 
-                if (scrollY == 0 && lastClampedTopY && nestedOffsetY == 0) {
-                    // we have reached the top, are clamped vertically and nestedScrollY is done too -> enable swipeRefresh (by default always disabled)
+                if (canSwipeToRefresh && scrollY == 0 && lastClampedTopY && nestedOffsetY == 0) {
+                    // we are on a new gesture, have reached the top, are clamped vertically and nestedScrollY is done too -> enable swipeRefresh (by default always disabled)
                     enableSwipeRefresh(true)
                 }
 
@@ -107,6 +112,7 @@ class DuckDuckGoWebView : WebView, NestedScrollingChild {
             }
 
             MotionEvent.ACTION_DOWN -> {
+                hasGestureFinished = false
                 // disable swipeRefresh until we can be sure it should be enabled
                 enableSwipeRefresh(false)
 
@@ -153,7 +159,16 @@ class DuckDuckGoWebView : WebView, NestedScrollingChild {
     override fun onOverScrolled(scrollX: Int, scrollY: Int, clampedX: Boolean, clampedY: Boolean) {
         // taking into account lastDeltaY since we are only interested whether we clamped at the top
         lastClampedTopY = clampedY && lastDeltaY <= 0
-        enableSwipeRefresh(clampedY && scrollY == 0 && (lastDeltaY <= 0 || nestedOffsetY == 0))
+
+        if (!lastClampedTopY) {
+            canSwipeToRefresh = false // disable because user scrolled down so we need a new gesture
+        }
+
+        if (lastClampedTopY && hasGestureFinished) {
+            canSwipeToRefresh = true // only enable if at the top and gestured finished
+        }
+
+        enableSwipeRefresh(canSwipeToRefresh && clampedY && scrollY == 0 && (lastDeltaY <= 0 || nestedOffsetY == 0))
         super.onOverScrolled(scrollX, scrollY, clampedX, clampedY)
     }
 

From 680bd964fdd8d112f4ae57069ceea1f988b490f2 Mon Sep 17 00:00:00 2001
From: Marcos Holgado <marcosh@duckduckgo.com>
Date: Mon, 22 Feb 2021 08:47:16 +0000
Subject: [PATCH 2/2] Change distance to trigger swipe to refresh

---
 .../java/com/duckduckgo/app/browser/BrowserTabFragment.kt    | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/app/src/main/java/com/duckduckgo/app/browser/BrowserTabFragment.kt b/app/src/main/java/com/duckduckgo/app/browser/BrowserTabFragment.kt
index de701ebb767c..81ca8694398d 100644
--- a/app/src/main/java/com/duckduckgo/app/browser/BrowserTabFragment.kt
+++ b/app/src/main/java/com/duckduckgo/app/browser/BrowserTabFragment.kt
@@ -991,6 +991,9 @@ class BrowserTabFragment :
     }
 
     private fun configureSwipeRefresh() {
+        val metrics = resources.displayMetrics
+        val distanceToTrigger = (DEFAULT_CIRCLE_TARGET_TIMES_1_5 * metrics.density).toInt()
+        swipeRefreshContainer.setDistanceToTriggerSync(distanceToTrigger)
         swipeRefreshContainer.setColorSchemeColors(ContextCompat.getColor(requireContext(), R.color.cornflowerBlue))
 
         swipeRefreshContainer.setOnRefreshListener {
@@ -1396,6 +1399,8 @@ class BrowserTabFragment :
         private const val TRACKERS_INI_DELAY = 500L
         private const val TRACKERS_SECONDARY_DELAY = 200L
 
+        private const val DEFAULT_CIRCLE_TARGET_TIMES_1_5 = 96
+
         fun newInstance(tabId: String, query: String? = null, skipHome: Boolean): BrowserTabFragment {
             val fragment = BrowserTabFragment()
             val args = Bundle()