From 5229200dd36f803ed11c8d10d776c5c0cdeb0d14 Mon Sep 17 00:00:00 2001
From: shepshapard <shepshapard@google.com>
Date: Mon, 25 Jun 2018 13:42:11 -0700
Subject: [PATCH] Fix invisible scroll thumb blocks clicks.

The current issue is that Views that have either the horizontal or
vertical scroll bars enabled will intercept mouse interactions that
entire the region where the scrolling thumb would be even if the View
cannot actually scroll because it's content isn't larger than it.

This is fixed by only intercepting mouse interactions in the scroll
thumb region if there is something to scroll.

Bug: 110375792
Test: None yet

Change-Id: Ib638b4ac88375f55bc80ba2a66d945a16ecd6d22
---
 core/java/android/view/View.java | 25 +++++++++++++++----------
 1 file changed, 15 insertions(+), 10 deletions(-)

diff --git a/core/java/android/view/View.java b/core/java/android/view/View.java
index 0e5527dfe39e..546ea87e23a2 100644
--- a/core/java/android/view/View.java
+++ b/core/java/android/view/View.java
@@ -6119,14 +6119,18 @@ public class View implements Drawable.Callback, KeyEvent.Callback,
         }
         x += getScrollX();
         y += getScrollY();
-        if (isVerticalScrollBarEnabled() && !isVerticalScrollBarHidden()) {
+        final boolean canScrollVertically =
+                computeVerticalScrollRange() > computeVerticalScrollExtent();
+        if (isVerticalScrollBarEnabled() && !isVerticalScrollBarHidden() && canScrollVertically) {
             final Rect touchBounds = mScrollCache.mScrollBarTouchBounds;
             getVerticalScrollBarBounds(null, touchBounds);
             if (touchBounds.contains((int) x, (int) y)) {
                 return true;
             }
         }
-        if (isHorizontalScrollBarEnabled()) {
+        final boolean canScrollHorizontally =
+                computeHorizontalScrollRange() > computeHorizontalScrollExtent();
+        if (isHorizontalScrollBarEnabled() && canScrollHorizontally) {
             final Rect touchBounds = mScrollCache.mScrollBarTouchBounds;
             getHorizontalScrollBarBounds(null, touchBounds);
             if (touchBounds.contains((int) x, (int) y)) {
@@ -6141,18 +6145,18 @@ public class View implements Drawable.Callback, KeyEvent.Callback,
     }
 
     private boolean isOnVerticalScrollbarThumb(float x, float y) {
-        if (mScrollCache == null) {
+        if (mScrollCache == null || !isVerticalScrollBarEnabled() || isVerticalScrollBarHidden()) {
             return false;
         }
-        if (isVerticalScrollBarEnabled() && !isVerticalScrollBarHidden()) {
+        final int range = computeVerticalScrollRange();
+        final int extent = computeVerticalScrollExtent();
+        if (range > extent) {
             x += getScrollX();
             y += getScrollY();
             final Rect bounds = mScrollCache.mScrollBarBounds;
             final Rect touchBounds = mScrollCache.mScrollBarTouchBounds;
             getVerticalScrollBarBounds(bounds, touchBounds);
-            final int range = computeVerticalScrollRange();
             final int offset = computeVerticalScrollOffset();
-            final int extent = computeVerticalScrollExtent();
             final int thumbLength = ScrollBarUtils.getThumbLength(bounds.height(), bounds.width(),
                     extent, range);
             final int thumbOffset = ScrollBarUtils.getThumbOffset(bounds.height(), thumbLength,
@@ -6168,18 +6172,19 @@ public class View implements Drawable.Callback, KeyEvent.Callback,
     }
 
     private boolean isOnHorizontalScrollbarThumb(float x, float y) {
-        if (mScrollCache == null) {
+        if (mScrollCache == null || !isHorizontalScrollBarEnabled()) {
             return false;
         }
-        if (isHorizontalScrollBarEnabled()) {
+        final int range = computeHorizontalScrollRange();
+        final int extent = computeHorizontalScrollExtent();
+        if (range > extent) {
             x += getScrollX();
             y += getScrollY();
             final Rect bounds = mScrollCache.mScrollBarBounds;
             final Rect touchBounds = mScrollCache.mScrollBarTouchBounds;
             getHorizontalScrollBarBounds(bounds, touchBounds);
-            final int range = computeHorizontalScrollRange();
             final int offset = computeHorizontalScrollOffset();
-            final int extent = computeHorizontalScrollExtent();
+
             final int thumbLength = ScrollBarUtils.getThumbLength(bounds.width(), bounds.height(),
                     extent, range);
             final int thumbOffset = ScrollBarUtils.getThumbOffset(bounds.width(), thumbLength,
-- 
2.11.0