Adjust mBiggerTouchSlopSquare to the suitable value

If the scaling factor is larger than 1.0 (i.e. 1.5),
then mTouchSlopSquare(576) is bigger than mBiggerTouchSlopSquare(400).
The double tap condition should be bigger than a single tap's one.
This causes the fail of the following CTS test cases in the device has
over 240 density.
- android.view.cts.GestureDetectorTest
  * testOnTouchEvent
- android.view.cts.GestureDetector_SimpleOnGestureListenerTest
  * testSimpleOnGestureListener
To fix this issue, I'll add a new public method
ViewConfiguration#getScaledLargeTouchSlop() then the value returned
from that method is used as a slop area of mLargeTouchSlop.

Change-Id: I0e61c13670e1300be1ccf45a89ef89410496fb48

api/current.xml

@@ -190704,6 +190704,17 @@
  visibility="public"
 >
 </method>
+<method name="getScaledLargeTouchSlop"
+ return="int"
+ abstract="false"
+ native="false"
+ synchronized="false"
+ static="false"
+ final="false"
+ deprecated="not deprecated"
+ visibility="public"
+>
+</method>
 <method name="getScaledMaximumDrawingCacheSize"
  return="int"
  abstract="false"

core/java/android/view/GestureDetector.java

@@ -193,10 +193,8 @@ public class GestureDetector {
         }
     }
 
-    // TODO: ViewConfiguration
-    private int mBiggerTouchSlopSquare = 20 * 20;
-
     private int mTouchSlopSquare;
+    private int mLargeTouchSlopSquare;
     private int mDoubleTapSlopSquare;
     private int mMinimumFlingVelocity;
     private int mMaximumFlingVelocity;
@@ -384,10 +382,11 @@ public class GestureDetector {
         mIgnoreMultitouch = ignoreMultitouch;
 
         // Fallback to support pre-donuts releases
-        int touchSlop, doubleTapSlop;
+        int touchSlop, largeTouchSlop, doubleTapSlop;
         if (context == null) {
             //noinspection deprecation
             touchSlop = ViewConfiguration.getTouchSlop();
+            largeTouchSlop = touchSlop + 2;
             doubleTapSlop = ViewConfiguration.getDoubleTapSlop();
             //noinspection deprecation
             mMinimumFlingVelocity = ViewConfiguration.getMinimumFlingVelocity();
@@ -395,11 +394,13 @@ public class GestureDetector {
         } else {
             final ViewConfiguration configuration = ViewConfiguration.get(context);
             touchSlop = configuration.getScaledTouchSlop();
+            largeTouchSlop = configuration.getScaledLargeTouchSlop();
             doubleTapSlop = configuration.getScaledDoubleTapSlop();
             mMinimumFlingVelocity = configuration.getScaledMinimumFlingVelocity();
             mMaximumFlingVelocity = configuration.getScaledMaximumFlingVelocity();
         }
         mTouchSlopSquare = touchSlop * touchSlop;
+        mLargeTouchSlopSquare = largeTouchSlop * largeTouchSlop;
         mDoubleTapSlopSquare = doubleTapSlop * doubleTapSlop;
     }
 
@@ -534,7 +535,7 @@ public class GestureDetector {
                     mHandler.removeMessages(SHOW_PRESS);
                     mHandler.removeMessages(LONG_PRESS);
                 }
-                if (distance > mBiggerTouchSlopSquare) {
+                if (distance > mLargeTouchSlopSquare) {
                     mAlwaysInBiggerTapRegion = false;
                 }
             } else if ((Math.abs(scrollX) >= 1) || (Math.abs(scrollY) >= 1)) {

core/java/android/view/ViewConfiguration.java

@@ -101,6 +101,12 @@ public class ViewConfiguration {
      */
     private static final int TOUCH_SLOP = 16;
     
+    /**
+     * Distance a touch can wander before we think the user is the first touch
+     * in a sequence of double tap
+     */
+    private static final int LARGE_TOUCH_SLOP = 18;
+
     /**
      * Distance a touch can wander before we think the user is attempting a paged scroll
      * (in dips)
@@ -156,6 +162,7 @@ public class ViewConfiguration {
     private final int mMaximumFlingVelocity;
     private final int mScrollbarSize;
     private final int mTouchSlop;
+    private final int mLargeTouchSlop;
     private final int mPagingTouchSlop;
     private final int mDoubleTapSlop;
     private final int mWindowTouchSlop;
@@ -177,6 +184,7 @@ public class ViewConfiguration {
         mMaximumFlingVelocity = MAXIMUM_FLING_VELOCITY;
         mScrollbarSize = SCROLL_BAR_SIZE;
         mTouchSlop = TOUCH_SLOP;
+        mLargeTouchSlop = LARGE_TOUCH_SLOP;
         mPagingTouchSlop = PAGING_TOUCH_SLOP;
         mDoubleTapSlop = DOUBLE_TAP_SLOP;
         mWindowTouchSlop = WINDOW_TOUCH_SLOP;
@@ -206,6 +214,7 @@ public class ViewConfiguration {
         mMaximumFlingVelocity = (int) (density * MAXIMUM_FLING_VELOCITY + 0.5f);
         mScrollbarSize = (int) (density * SCROLL_BAR_SIZE + 0.5f);
         mTouchSlop = (int) (density * TOUCH_SLOP + 0.5f);
+        mLargeTouchSlop =  (int) (density * LARGE_TOUCH_SLOP + 0.5f);
         mPagingTouchSlop = (int) (density * PAGING_TOUCH_SLOP + 0.5f);
         mDoubleTapSlop = (int) (density * DOUBLE_TAP_SLOP + 0.5f);
         mWindowTouchSlop = (int) (density * WINDOW_TOUCH_SLOP + 0.5f);
@@ -366,6 +375,14 @@ public class ViewConfiguration {
         return mTouchSlop;
     }
     
+    /**
+     * @return Distance a touch can wander before we think the user is the first touch
+     *         in a sequence of double tap
+     */
+    public int getScaledLargeTouchSlop() {
+        return mLargeTouchSlop;
+    }
+
     /**
      * @return Distance a touch can wander before we think the user is scrolling a full page
      *         in dips