commit fb75738ee28839c67bef4abc15d6c7a407c34f55
author Jeff Brown <jeffbrown@google.com> Tue Jan 18 18:42:33 2011 -0800
committer Jeff Brown <jeffbrown@google.com> Tue Jan 18 18:42:33 2011 -0800
tree ec0e5fbad94b92b3e2958391dd9cce0c4263cb07
parent 36c84403ec07439d11ed284ac5f9a9db807fbf92

Never drag scroll views with no children.

Fixes a regression from Froyo.  Previously, when a scroll view
had no children, its onTouchEvent would return because the scroll
view would only start dragging if the user touched one of its children.
In Gingerbread, the user can drag from anywhere within the scroll
view, not just by touching a child.  However, it makes no sense
to drag a scroll view that has no children so an empty scroll view
should just ignore touches like any other empty view group would.

This change fixes applications that for some reason or other happen
to have empty scroll views in strange places.

Bug: 3246230
Change-Id: Iada6e886e8363e6778f42fc4861de228512d8bed

core/java/android/widget/HorizontalScrollView.java

diff --git a/core/java/android/widget/HorizontalScrollView.java b/core/java/android/widget/HorizontalScrollView.java
index f6b1dbc..db22a0c 100644
--- a/core/java/android/widget/HorizontalScrollView.java
+++ b/core/java/android/widget/HorizontalScrollView.java
@@ -511,8 +511,10 @@
 
         switch (action & MotionEvent.ACTION_MASK) {
             case MotionEvent.ACTION_DOWN: {
-                final float x = ev.getX();
-                mIsBeingDragged = true;
+                mIsBeingDragged = getChildCount() != 0;
+                if (!mIsBeingDragged) {
+                    return false;
+                }
 
                 /*
                  * If being flinged and user touches, stop the fling. isFinished
@@ -523,7 +525,7 @@
                 }
 
                 // Remember where the motion event started
-                mLastMotionX = x;
+                mLastMotionX = ev.getX();
                 mActivePointerId = ev.getPointerId(0);
                 break;
             }

core/java/android/widget/ScrollView.java

diff --git a/core/java/android/widget/ScrollView.java b/core/java/android/widget/ScrollView.java
index 8558c70..ce6da72 100644
--- a/core/java/android/widget/ScrollView.java
+++ b/core/java/android/widget/ScrollView.java
@@ -521,8 +521,10 @@
 
         switch (action & MotionEvent.ACTION_MASK) {
             case MotionEvent.ACTION_DOWN: {
-                final float y = ev.getY();
-                mIsBeingDragged = true;
+                mIsBeingDragged = getChildCount() != 0;
+                if (!mIsBeingDragged) {
+                    return false;
+                }
 
                 /*
                  * If being flinged and user touches, stop the fling. isFinished
@@ -537,7 +539,7 @@
                 }
 
                 // Remember where the motion event started
-                mLastMotionY = y;
+                mLastMotionY = ev.getY();
                 mActivePointerId = ev.getPointerId(0);
                 break;
             }