Add an API to control AbsListView's friction.

Change-Id: Iafb08cd28703d282c369c472a5d85a22cc5dacb7

2 files changed, 39 insertions, 25 deletions

diff --git a/core/java/android/widget/AbsListView.java b/core/java/android/widget/AbsListView.java
index c694ff1..2af59f9 100644
--- a/core/java/android/widget/AbsListView.java
+++ b/core/java/android/widget/AbsListView.java
@@ -2965,7 +2965,7 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
             final int firstPos = mFirstPosition;
             final int lastPos = firstPos + getChildCount() - 1;
             
-            int viewTravelCount = 0;
+            int viewTravelCount;
             if (position <= firstPos) {                
                 viewTravelCount = firstPos - position + 1;
                 mMode = MOVE_UP_POS;
@@ -2998,7 +2998,7 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
             final int firstPos = mFirstPosition;
             final int lastPos = firstPos + getChildCount() - 1;
             
-            int viewTravelCount = 0;
+            int viewTravelCount;
             if (position <= firstPos) {
                 final int boundPosFromLast = lastPos - boundPosition;
                 if (boundPosFromLast < 1) {
@@ -3059,7 +3059,7 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
             final int childCount = getChildCount();
             final int lastPos = firstPos + childCount - 1;
 
-            int viewTravelCount = 0;
+            int viewTravelCount;
             if (position < firstPos) {
                 viewTravelCount = firstPos - position;
             } else if (position > lastPos) {
@@ -3249,6 +3249,20 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
     }
     
     /**
+     * The amount of friction applied to flings. The default value
+     * is {@link ViewConfiguration#getScrollFriction}.
+     * 
+     * @return A scalar dimensionless value representing the coefficient of
+     *         friction.
+     */
+    public void setFriction(float friction) {
+        if (mFlingRunnable == null) {
+            mFlingRunnable = new FlingRunnable();
+        }
+        mFlingRunnable.mScroller.setFriction(friction);        
+    }
+    
+    /**
      * Smoothly scroll to the specified adapter position. The view will
      * scroll such that the indicated position is displayed.
      * @param position Scroll to this adapter position.
@@ -3581,22 +3595,6 @@ public abstract class AbsListView extends AdapterView<ListAdapter> implements Te
      * @return The position of the first (or only) item in the row containing y
      */
     abstract int findMotionRow(int y);
-    
-    /**
-     * Find the row closest to y. This row will be used as the motion row when scrolling.
-     * 
-     * @param y Where the user touched
-     * @return The position of the first (or only) item in the row closest to y
-     */
-    int findClosestMotionRow(int y) {
-        final int childCount = getChildCount();
-        if (childCount == 0) {
-            return INVALID_POSITION;
-        }
-        
-        final int motionRow = findMotionRow(y);
-        return motionRow != INVALID_POSITION ? motionRow : mFirstPosition + childCount - 1;
-    }
 
     /**
      * Causes all the views to be rebuilt and redrawn.
diff --git a/core/java/android/widget/Scroller.java b/core/java/android/widget/Scroller.java
index 4cb0839..d2e6688 100644
--- a/core/java/android/widget/Scroller.java
+++ b/core/java/android/widget/Scroller.java
@@ -63,7 +63,8 @@ public class Scroller  {
     private static final int SCROLL_MODE = 0;
     private static final int FLING_MODE = 1;
 
-    private final float mDeceleration;
+    private float mDeceleration;
+    private final float mPpi;
 
     /**
      * Create a Scroller with the default duration and interpolator.
@@ -79,13 +80,28 @@ public class Scroller  {
     public Scroller(Context context, Interpolator interpolator) {
         mFinished = true;
         mInterpolator = interpolator;
-        float ppi = context.getResources().getDisplayMetrics().density * 160.0f;
-        mDeceleration = SensorManager.GRAVITY_EARTH   // g (m/s^2)
-                      * 39.37f                        // inch/meter
-                      * ppi                           // pixels per inch
-                      * ViewConfiguration.getScrollFriction();
+        mPpi = context.getResources().getDisplayMetrics().density * 160.0f;
+        mDeceleration = computeDeceleration(ViewConfiguration.getScrollFriction());
+    }
+
+    /**
+     * The amount of friction applied to flings. The default value
+     * is {@link ViewConfiguration#getScrollFriction}.
+     * 
+     * @return A scalar dimensionless value representing the coefficient of
+     *         friction.
+     */
+    public final void setFriction(float friction) {
+        computeDeceleration(friction);
     }
     
+    private float computeDeceleration(float friction) {
+        return SensorManager.GRAVITY_EARTH   // g (m/s^2)
+                      * 39.37f               // inch/meter
+                      * mPpi                 // pixels per inch
+                      * friction;
+    }
+
     /**
      * 
      * Returns whether the scroller has finished scrolling.