Touch slop added to double tap detection

Similar to what is done in GestureDetector

Removed all gesture constants. Only one one them is used on MOVE
(added an early exit test), the 2 others on UP or DOWN where
performance is not such an issue.

Change-Id: Icd58ead5078f94f86786f934ddf81aa5ec9bf549

Author: Gilles Debunne

core/java/android/widget/TextView.java

@@ -357,7 +357,6 @@ static class InputMethodState {
     private float mLastDownPositionX, mLastDownPositionY;
     private Callback mCustomSelectionActionModeCallback;
 
-    private final int mSquaredTouchSlopDistance;
     // Set when this TextView gained focus with some text selected. Will start selection mode.
     private boolean mCreatedWithASelection = false;
 
@@ -443,15 +442,12 @@ public TextView(Context context) {
         this(context, null);
     }
 
-    public TextView(Context context,
-                    AttributeSet attrs) {
+    public TextView(Context context, AttributeSet attrs) {
         this(context, attrs, com.android.internal.R.attr.textViewStyle);
     }
 
     @SuppressWarnings("deprecation")
-    public TextView(Context context,
-                    AttributeSet attrs,
-                    int defStyle) {
+    public TextView(Context context, AttributeSet attrs, int defStyle) {
         super(context, attrs, defStyle);
         mText = "";
 
@@ -1134,10 +1130,6 @@ public TextView(Context context,
         setLongClickable(longClickable);
 
         prepareCursorControllers();
-
-        final ViewConfiguration viewConfiguration = ViewConfiguration.get(context);
-        final int touchSlop = viewConfiguration.getScaledTouchSlop();
-        mSquaredTouchSlopDistance = touchSlop * touchSlop;
     }
 
     private void setTypefaceByIndex(int typefaceIndex, int styleIndex) {
@@ -3202,8 +3194,7 @@ private void setText(CharSequence text, BufferType type,
 
         int n = mFilters.length;
         for (int i = 0; i < n; i++) {
-            CharSequence out = mFilters[i].filter(text, 0, text.length(),
-                                                  EMPTY_SPANNED, 0, 0);
+            CharSequence out = mFilters[i].filter(text, 0, text.length(), EMPTY_SPANNED, 0, 0);
             if (out != null) {
                 text = out;
             }
@@ -5621,11 +5612,13 @@ public boolean onKeyUp(int keyCode, KeyEvent event) {
         return super.onKeyUp(keyCode, event);
     }
 
-    @Override public boolean onCheckIsTextEditor() {
+    @Override
+    public boolean onCheckIsTextEditor() {
         return mInputType != EditorInfo.TYPE_NULL;
     }
 
-    @Override public InputConnection onCreateInputConnection(EditorInfo outAttrs) {
+    @Override
+    public InputConnection onCreateInputConnection(EditorInfo outAttrs) {
         if (onCheckIsTextEditor() && isEnabled()) {
             if (mInputMethodState == null) {
                 mInputMethodState = new InputMethodState();
@@ -9248,7 +9241,6 @@ public boolean performLongClick() {
         boolean vibrate = true;
 
         if (super.performLongClick()) {
-            mDiscardNextActionUp = true;
             handled = true;
         }
 
@@ -10798,7 +10790,12 @@ public boolean onTouchEvent(MotionEvent ev) {
                         final float deltaX = mDownPositionX - ev.getRawX();
                         final float deltaY = mDownPositionY - ev.getRawY();
                         final float distanceSquared = deltaX * deltaX + deltaY * deltaY;
-                        if (distanceSquared < mSquaredTouchSlopDistance) {
+
+                        final ViewConfiguration viewConfiguration = ViewConfiguration.get(
+                                TextView.this.getContext());
+                        final int touchSlop = viewConfiguration.getScaledTouchSlop();
+
+                        if (distanceSquared < touchSlop * touchSlop) {
                             if (mActionPopupWindow != null && mActionPopupWindow.isShowing()) {
                                 // Tapping on the handle dismisses the displayed action popup
                                 mActionPopupWindow.hide();
@@ -11012,7 +11009,8 @@ private class SelectionModifierCursorController implements CursorController {
 
         // Double tap detection
         private long mPreviousTapUpTime = 0;
-        private float mPreviousTapPositionX, mPreviousTapPositionY;
+        private float mDownPositionX, mDownPositionY;
+        private boolean mGestureStayedInTapRegion;
 
         SelectionModifierCursorController() {
             resetTouchOffsets();
@@ -11075,20 +11073,28 @@ public void onTouchEvent(MotionEvent event) {
                     mMinTouchOffset = mMaxTouchOffset = getOffsetForPosition(x, y);
 
                     // Double tap detection
-                    long duration = SystemClock.uptimeMillis() - mPreviousTapUpTime;
-                    if (duration <= ViewConfiguration.getDoubleTapTimeout() &&
-                            isPositionOnText(x, y)) {
-                        final float deltaX = x - mPreviousTapPositionX;
-                        final float deltaY = y - mPreviousTapPositionY;
-                        final float distanceSquared = deltaX * deltaX + deltaY * deltaY;
-                        if (distanceSquared < mSquaredTouchSlopDistance) {
-                            startSelectionActionMode();
-                            mDiscardNextActionUp = true;
+                    if (mGestureStayedInTapRegion) {
+                        long duration = SystemClock.uptimeMillis() - mPreviousTapUpTime;
+                        if (duration <= ViewConfiguration.getDoubleTapTimeout()) {
+                            final float deltaX = x - mDownPositionX;
+                            final float deltaY = y - mDownPositionY;
+                            final float distanceSquared = deltaX * deltaX + deltaY * deltaY;
+
+                            ViewConfiguration viewConfiguration = ViewConfiguration.get(
+                                    TextView.this.getContext());
+                            int doubleTapSlop = viewConfiguration.getScaledDoubleTapSlop();
+                            boolean stayedInArea = distanceSquared < doubleTapSlop * doubleTapSlop;
+
+                            if (stayedInArea && isPositionOnText(x, y)) {
+                                startSelectionActionMode();
+                                mDiscardNextActionUp = true;
+                            }
                         }
                     }
 
-                    mPreviousTapPositionX = x;
-                    mPreviousTapPositionY = y;
+                    mDownPositionX = x;
+                    mDownPositionY = y;
+                    mGestureStayedInTapRegion = true;
                     break;
 
                 case MotionEvent.ACTION_POINTER_DOWN:
@@ -11101,6 +11107,22 @@ public void onTouchEvent(MotionEvent event) {
                     }
                     break;
 
+                case MotionEvent.ACTION_MOVE:
+                    if (mGestureStayedInTapRegion) {
+                        final float deltaX = event.getX() - mDownPositionX;
+                        final float deltaY = event.getY() - mDownPositionY;
+                        final float distanceSquared = deltaX * deltaX + deltaY * deltaY;
+
+                        final ViewConfiguration viewConfiguration = ViewConfiguration.get(
+                                TextView.this.getContext());
+                        int doubleTapTouchSlop = viewConfiguration.getScaledDoubleTapTouchSlop();
+
+                        if (distanceSquared > doubleTapTouchSlop * doubleTapTouchSlop) {
+                            mGestureStayedInTapRegion = false;
+                        }
+                    }
+                    break;
+
                 case MotionEvent.ACTION_UP:
                     mPreviousTapUpTime = SystemClock.uptimeMillis();
                     break;