commit fc60a78760589b76087e2973add98d0aa35d50ab
author Chris Banes <chrisbanes@google.com> Fri Oct 23 13:42:06 2015 +0100
committer Chris Banes <chrisbanes@google.com> Fri Oct 23 14:00:59 2015 +0100
tree 1727addf8839c32860bb3d629aa1505436884f79
parent 2e659d2367fc800cad5075c380d13df65ff36254

Make SwipeRefreshLayout play nice with AppBarLayout

Currently SwipeRefreshLayout has support for nested scrolling,
but still relies on it's own touch handling, which conflicts.
This CL fixes it by disabling the touch handling when a nested
scroll is happening.

BUG: 25209946
Change-Id: I812f67e35753d243937a34a212cb1112065bff10

v4/java/android/support/v4/widget/SwipeRefreshLayout.java

diff --git a/v4/java/android/support/v4/widget/SwipeRefreshLayout.java b/v4/java/android/support/v4/widget/SwipeRefreshLayout.java
index a5365e3..e1386ab 100644
--- a/v4/java/android/support/v4/widget/SwipeRefreshLayout.java
+++ b/v4/java/android/support/v4/widget/SwipeRefreshLayout.java
@@ -102,6 +102,7 @@
     private boolean mRefreshing = false;
     private int mTouchSlop;
     private float mTotalDragDistance = -1;
+
     // If nested scrolling is enabled, the total amount that needed to be
     // consumed by this as the nested scrolling parent is used in place of the
     // overscroll determined by MOVE events in the onTouch handler
@@ -109,6 +110,8 @@
     private final NestedScrollingParentHelper mNestedScrollingParentHelper;
     private final NestedScrollingChildHelper mNestedScrollingChildHelper;
     private final int[] mParentScrollConsumed = new int[2];
+    private final int[] mParentOffsetInWindow = new int[2];
+    private boolean mNestedScrollInProgress;
 
     private int mMediumAnimationDuration;
     private int mCurrentTargetOffsetTop;
@@ -654,7 +657,8 @@
             mReturningToStart = false;
         }
 
-        if (!isEnabled() || mReturningToStart || canChildScrollUp() || mRefreshing) {
+        if (!isEnabled() || mReturningToStart || canChildScrollUp()
+                || mRefreshing || mNestedScrollInProgress) {
             // Fail fast if we're not in a state where a swipe is possible
             return false;
         }
@@ -728,20 +732,18 @@
 
     @Override
     public boolean onStartNestedScroll(View child, View target, int nestedScrollAxes) {
-        if (isEnabled() && !mReturningToStart && !canChildScrollUp() && !mRefreshing
-                && (nestedScrollAxes & ViewCompat.SCROLL_AXIS_VERTICAL) != 0) {
-            // Dispatch up to the nested parent
-            startNestedScroll(nestedScrollAxes & ViewCompat.SCROLL_AXIS_VERTICAL);
-            return true;
-        }
-        return false;
+        return isEnabled() && !mReturningToStart && !mRefreshing
+                && (nestedScrollAxes & ViewCompat.SCROLL_AXIS_VERTICAL) != 0;
     }
 
     @Override
     public void onNestedScrollAccepted(View child, View target, int axes) {
         // Reset the counter of how much leftover scroll needs to be consumed.
         mNestedScrollingParentHelper.onNestedScrollAccepted(child, target, axes);
+        // Dispatch up to the nested parent
+        startNestedScroll(axes & ViewCompat.SCROLL_AXIS_VERTICAL);
         mTotalUnconsumed = 0;
+        mNestedScrollInProgress = true;
     }
 
     @Override
@@ -785,6 +787,7 @@
     @Override
     public void onStopNestedScroll(View target) {
         mNestedScrollingParentHelper.onStopNestedScroll(target);
+        mNestedScrollInProgress = false;
         // Finish the spinner for nested scrolling if we ever consumed any
         // unconsumed nested scroll
         if (mTotalUnconsumed > 0) {
@@ -796,15 +799,22 @@
     }
 
     @Override
-    public void onNestedScroll(View target, int dxConsumed, int dyConsumed, int dxUnconsumed,
-            int dyUnconsumed) {
-        if (dyUnconsumed < 0) {
-            dyUnconsumed = Math.abs(dyUnconsumed);
-            mTotalUnconsumed += dyUnconsumed;
+    public void onNestedScroll(final View target, final int dxConsumed, final int dyConsumed,
+            final int dxUnconsumed, final int dyUnconsumed) {
+        // Dispatch up to the nested parent first
+        dispatchNestedScroll(dxConsumed, dyConsumed, dxUnconsumed, dyUnconsumed,
+                mParentOffsetInWindow);
+
+        // This is a bit of a hack. Nested scrolling works from the bottom up, and as we are
+        // sometimes between two nested scrolling views, we need a way to be able to know when any
+        // nested scrolling parent has stopped handling events. We do that by using the
+        // 'offset in window 'functionality to see if we have been moved from the event.
+        // This is a decent indication of whether we should take over the event stream or not.
+        final int dy = dyUnconsumed + mParentOffsetInWindow[1];
+        if (dy < 0) {
+            mTotalUnconsumed += Math.abs(dy);
             moveSpinner(mTotalUnconsumed);
         }
-        // Dispatch up to the nested parent
-        dispatchNestedScroll(dxConsumed, dyConsumed, dxUnconsumed, dxConsumed, null);
     }
 
     // NestedScrollingChild
@@ -961,7 +971,7 @@
             mReturningToStart = false;
         }
 
-        if (!isEnabled() || mReturningToStart || canChildScrollUp()) {
+        if (!isEnabled() || mReturningToStart || canChildScrollUp() || mNestedScrollInProgress) {
             // Fail fast if we're not in a state where a swipe is possible
             return false;
         }