Fixes #1444844. Set a maximum fling velocity in scrollable views.

7 files changed, 76 insertions, 24 deletions

diff --git a/core/java/android/view/GestureDetector.java b/core/java/android/view/GestureDetector.java
index 23f3e3c..1e558be 100644
--- a/core/java/android/view/GestureDetector.java
+++ b/core/java/android/view/GestureDetector.java
@@ -198,6 +198,7 @@ public class GestureDetector {
     private int mTouchSlopSquare;
     private int mDoubleTapSlopSquare;
     private int mMinimumFlingVelocity;
+    private int mMaximumFlingVelocity;
 
     private static final int LONGPRESS_TIMEOUT = ViewConfiguration.getLongPressTimeout();
     private static final int TAP_TIMEOUT = ViewConfiguration.getTapTimeout();
@@ -361,11 +362,13 @@ public class GestureDetector {
             doubleTapSlop = ViewConfiguration.getDoubleTapSlop();
             //noinspection deprecation
             mMinimumFlingVelocity = ViewConfiguration.getMinimumFlingVelocity();
+            mMaximumFlingVelocity = ViewConfiguration.getMaximumFlingVelocity();
         } else {
             final ViewConfiguration configuration = ViewConfiguration.get(context);
             touchSlop = configuration.getScaledTouchSlop();
             doubleTapSlop = configuration.getScaledDoubleTapSlop();
             mMinimumFlingVelocity = configuration.getScaledMinimumFlingVelocity();
+            mMaximumFlingVelocity = configuration.getScaledMaximumFlingVelocity();
         }
         mTouchSlopSquare = touchSlop * touchSlop;
         mDoubleTapSlopSquare = doubleTapSlop * doubleTapSlop;
@@ -505,7 +508,7 @@ public class GestureDetector {
 
                 // A fling must travel the minimum tap distance
                 final VelocityTracker velocityTracker = mVelocityTracker;
-                velocityTracker.computeCurrentVelocity(1000);
+                velocityTracker.computeCurrentVelocity(1000, mMaximumFlingVelocity);
                 final float velocityY = velocityTracker.getYVelocity();
                 final float velocityX = velocityTracker.getXVelocity();
 
diff --git a/core/java/android/view/VelocityTracker.java b/core/java/android/view/VelocityTracker.java
index c708f54..5d89c46 100644
--- a/core/java/android/view/VelocityTracker.java
+++ b/core/java/android/view/VelocityTracker.java
@@ -165,7 +165,17 @@ public final class VelocityTracker implements Poolable<VelocityTracker> {
             pastTime[i] = 0;
         }
     }
-    
+
+    /**
+     * Equivalent to invoking {@link #computeCurrentVelocity(int, float)} with a maximum
+     * velocity of Float.MAX_VALUE.
+     * 
+     * @see #computeCurrentVelocity(int, float) 
+     */
+    public void computeCurrentVelocity(int units) {
+        computeCurrentVelocity(units, Float.MAX_VALUE);
+    }
+
     /**
      * Compute the current velocity based on the points that have been
      * collected.  Only call this when you actually want to retrieve velocity
@@ -175,8 +185,11 @@ public final class VelocityTracker implements Poolable<VelocityTracker> {
      * 
      * @param units The units you would like the velocity in.  A value of 1
      * provides pixels per millisecond, 1000 provides pixels per second, etc.
+     * @param maxVelocity The maximum velocity that can be computed by this method.
+     * This value must be declared in the same unit as the units parameter. This value
+     * must be positive.
      */
-    public void computeCurrentVelocity(int units) {
+    public void computeCurrentVelocity(int units, float maxVelocity) {
         final float[] pastX = mPastX;
         final float[] pastY = mPastY;
         final long[] pastTime = mPastTime;
@@ -210,8 +223,8 @@ public final class VelocityTracker implements Poolable<VelocityTracker> {
             if (accumY == 0) accumY = vel;
             else accumY = (accumY + vel) * .5f;
         }
-        mXVelocity = accumX;
-        mYVelocity = accumY;
+        mXVelocity = accumX < 0.0f ? Math.max(accumX, -maxVelocity) : Math.min(accumX, maxVelocity);
+        mYVelocity = accumY < 0.0f ? Math.max(accumY, -maxVelocity) : Math.min(accumY, maxVelocity);
         
         if (localLOGV) Log.v(TAG, "Y velocity=" + mYVelocity +" X velocity="
                 + mXVelocity + " N=" + N);
diff --git a/core/java/android/view/ViewConfiguration.java b/core/java/android/view/ViewConfiguration.java
index 8e1524b..0e36ec2 100644
--- a/core/java/android/view/ViewConfiguration.java
+++ b/core/java/android/view/ViewConfiguration.java
@@ -106,6 +106,11 @@ public class ViewConfiguration {
      * Minimum velocity to initiate a fling, as measured in pixels per second
      */
     private static final int MINIMUM_FLING_VELOCITY = 50;
+    
+    /**
+     * Maximum velocity to initiate a fling, as measured in pixels per second
+     */
+    private static final int MAXIMUM_FLING_VELOCITY = 4000;
 
     /**
      * The maximum size of View's drawing cache, expressed in bytes. This size
@@ -122,6 +127,7 @@ public class ViewConfiguration {
     private final int mEdgeSlop;
     private final int mFadingEdgeLength;
     private final int mMinimumFlingVelocity;
+    private final int mMaximumFlingVelocity;
     private final int mScrollbarSize;
     private final int mTouchSlop;
     private final int mDoubleTapSlop;
@@ -139,6 +145,7 @@ public class ViewConfiguration {
         mEdgeSlop = EDGE_SLOP;
         mFadingEdgeLength = FADING_EDGE_LENGTH;
         mMinimumFlingVelocity = MINIMUM_FLING_VELOCITY;
+        mMaximumFlingVelocity = MAXIMUM_FLING_VELOCITY;
         mScrollbarSize = SCROLL_BAR_SIZE;
         mTouchSlop = TOUCH_SLOP;
         mDoubleTapSlop = DOUBLE_TAP_SLOP;
@@ -164,6 +171,7 @@ public class ViewConfiguration {
         mEdgeSlop = (int) (density * EDGE_SLOP + 0.5f);
         mFadingEdgeLength = (int) (density * FADING_EDGE_LENGTH + 0.5f);
         mMinimumFlingVelocity = (int) (density * MINIMUM_FLING_VELOCITY + 0.5f);
+        mMaximumFlingVelocity = (int) (density * MAXIMUM_FLING_VELOCITY + 0.5f);
         mScrollbarSize = (int) (density * SCROLL_BAR_SIZE + 0.5f);
         mTouchSlop = (int) (density * TOUCH_SLOP + 0.5f);
         mDoubleTapSlop = (int) (density * DOUBLE_TAP_SLOP + 0.5f);
@@ -367,6 +375,23 @@ public class ViewConfiguration {
     }
 
     /**
+     * @return Maximum velocity to initiate a fling, as measured in pixels per second.
+     *
+     * @deprecated Use {@link #getScaledMaximumFlingVelocity()} instead.
+     */
+    @Deprecated
+    public static int getMaximumFlingVelocity() {
+        return MAXIMUM_FLING_VELOCITY;
+    }
+
+    /**
+     * @return Maximum velocity to initiate a fling, as measured in pixels per second.
+     */
+    public int getScaledMaximumFlingVelocity() {
+        return mMaximumFlingVelocity;
+    }
+    
+    /**
      * The maximum drawing cache size expressed in bytes.
      *
      * @return the maximum size of View's drawing cache expressed in bytes
diff --git a/core/java/android/webkit/WebView.java b/core/java/android/webkit/WebView.java
index 429f0f9..fcf946f 100644
--- a/core/java/android/webkit/WebView.java
+++ b/core/java/android/webkit/WebView.java
@@ -237,6 +237,7 @@ public class WebView extends AbsoluteLayout
      * Helper class to get velocity for fling
      */
     VelocityTracker mVelocityTracker;
+    private int mMaximumFling;
 
     /**
      * Touch mode
@@ -676,7 +677,8 @@ public class WebView extends AbsoluteLayout
         setClickable(true);
         setLongClickable(true);
 
-        final int slop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
+        final ViewConfiguration configuration = ViewConfiguration.get(getContext());
+        final int slop = configuration.getScaledTouchSlop();
         mTouchSlopSquare = slop * slop;
         mMinLockSnapReverseDistance = slop;
         final float density = getContext().getResources().getDisplayMetrics().density;
@@ -692,6 +694,7 @@ public class WebView extends AbsoluteLayout
         DEFAULT_MIN_ZOOM_SCALE = 0.25f * density;
         mMaxZoomScale = DEFAULT_MAX_ZOOM_SCALE;
         mMinZoomScale = DEFAULT_MIN_ZOOM_SCALE;
+        mMaximumFling = configuration.getScaledMaximumFlingVelocity();
     }
 
     /* package */void updateDefaultZoomDensity(int zoomDensity) {
@@ -4157,7 +4160,7 @@ public class WebView extends AbsoluteLayout
         int maxX = Math.max(computeHorizontalScrollRange() - getViewWidth(), 0);
         int maxY = Math.max(computeVerticalScrollRange() - getViewHeight(), 0);
 
-        mVelocityTracker.computeCurrentVelocity(1000);
+        mVelocityTracker.computeCurrentVelocity(1000, mMaximumFling);
         int vx = (int) mVelocityTracker.getXVelocity();
         int vy = (int) mVelocityTracker.getYVelocity();
 
diff --git a/core/java/android/widget/AbsListView.java b/core/java/android/widget/AbsListView.java
index 23a38db..f9ca8cb 100644
--- a/core/java/android/widget/AbsListView.java
+++ b/core/java/android/widget/AbsListView.java
@@ -438,6 +438,8 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
     private InputConnectionWrapper mPublicInputConnection;
 
     private Runnable mClearScrollingCache;
+    private int mMinimumVelocity;
+    private int mMaximumVelocity;
 
     /**
      * Interface definition for a callback to be invoked when the list or grid
@@ -549,7 +551,10 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
         setAlwaysDrawnWithCacheEnabled(false);
         setScrollingCacheEnabled(true);
 
-        mTouchSlop = ViewConfiguration.get(mContext).getScaledTouchSlop();
+        final ViewConfiguration configuration = ViewConfiguration.get(mContext);
+        mTouchSlop = configuration.getScaledTouchSlop();
+        mMinimumVelocity = configuration.getScaledMinimumFlingVelocity();
+        mMaximumVelocity = configuration.getScaledMaximumFlingVelocity();
         mDensityScale = getContext().getResources().getDisplayMetrics().density;
     }
 
@@ -2058,12 +2063,9 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
                 break;
             case TOUCH_MODE_SCROLL:
                 final VelocityTracker velocityTracker = mVelocityTracker;
-                velocityTracker.computeCurrentVelocity(1000);
-                int initialVelocity = (int)velocityTracker.getYVelocity();
-
-                if ((Math.abs(initialVelocity) >
-                        ViewConfiguration.get(mContext).getScaledMinimumFlingVelocity()) &&
-                        (getChildCount() > 0)) {
+                velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
+                final int initialVelocity = (int) velocityTracker.getYVelocity();
+                if (Math.abs(initialVelocity) > mMinimumVelocity && (getChildCount() > 0)) {
                     if (mFlingRunnable == null) {
                         mFlingRunnable = new FlingRunnable();
                     }
diff --git a/core/java/android/widget/HorizontalScrollView.java b/core/java/android/widget/HorizontalScrollView.java
index 02fc7c6..f86b37c 100644
--- a/core/java/android/widget/HorizontalScrollView.java
+++ b/core/java/android/widget/HorizontalScrollView.java
@@ -114,6 +114,8 @@ public class HorizontalScrollView extends FrameLayout {
     private boolean mSmoothScrollingEnabled = true;
 
     private int mTouchSlop;
+    private int mMinimumVelocity;
+    private int mMaximumVelocity;
 
     public HorizontalScrollView(Context context) {
         this(context, null);
@@ -179,7 +181,10 @@ public class HorizontalScrollView extends FrameLayout {
         setFocusable(true);
         setDescendantFocusability(FOCUS_AFTER_DESCENDANTS);
         setWillNotDraw(false);
-        mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
+        final ViewConfiguration configuration = ViewConfiguration.get(mContext);
+        mTouchSlop = configuration.getScaledTouchSlop();
+        mMinimumVelocity = configuration.getScaledMinimumFlingVelocity();
+        mMaximumVelocity = configuration.getScaledMaximumFlingVelocity();
     }
 
     @Override
@@ -477,12 +482,10 @@ public class HorizontalScrollView extends FrameLayout {
                 break;
             case MotionEvent.ACTION_UP:
                 final VelocityTracker velocityTracker = mVelocityTracker;
-                velocityTracker.computeCurrentVelocity(1000);
+                velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
                 int initialVelocity = (int) velocityTracker.getXVelocity();
 
-                if ((Math.abs(initialVelocity) >
-                        ViewConfiguration.get(mContext).getScaledMinimumFlingVelocity()) &&
-                        getChildCount() > 0) {
+                if ((Math.abs(initialVelocity) > mMinimumVelocity) && getChildCount() > 0) {
                     fling(-initialVelocity);
                 }
 
diff --git a/core/java/android/widget/ScrollView.java b/core/java/android/widget/ScrollView.java
index c9b3751..90e1242 100644
--- a/core/java/android/widget/ScrollView.java
+++ b/core/java/android/widget/ScrollView.java
@@ -115,6 +115,8 @@ public class ScrollView extends FrameLayout {
     private boolean mSmoothScrollingEnabled = true;
 
     private int mTouchSlop;
+    private int mMinimumVelocity;
+    private int mMaximumVelocity;
 
     public ScrollView(Context context) {
         this(context, null);
@@ -180,7 +182,10 @@ public class ScrollView extends FrameLayout {
         setFocusable(true);
         setDescendantFocusability(FOCUS_AFTER_DESCENDANTS);
         setWillNotDraw(false);
-        mTouchSlop = ViewConfiguration.get(getContext()).getScaledTouchSlop();
+        final ViewConfiguration configuration = ViewConfiguration.get(mContext);
+        mTouchSlop = configuration.getScaledTouchSlop();
+        mMinimumVelocity = configuration.getScaledMinimumFlingVelocity();
+        mMaximumVelocity = configuration.getScaledMaximumFlingVelocity();
     }
 
     @Override
@@ -478,12 +483,10 @@ public class ScrollView extends FrameLayout {
                 break;
             case MotionEvent.ACTION_UP:
                 final VelocityTracker velocityTracker = mVelocityTracker;
-                velocityTracker.computeCurrentVelocity(1000);
+                velocityTracker.computeCurrentVelocity(1000, mMaximumVelocity);
                 int initialVelocity = (int) velocityTracker.getYVelocity();
 
-                if ((Math.abs(initialVelocity) >
-                        ViewConfiguration.get(mContext).getScaledMinimumFlingVelocity()) &&
-                        getChildCount() > 0) {
+                if ((Math.abs(initialVelocity) > mMinimumVelocity) && getChildCount() > 0) {
                     fling(-initialVelocity);
                 }