Bug 716673 - Completely encapsulate Axis variable firstTouchPos. r=pcwalton

mobile/android/base/ui/PanZoomController.java

@@ -50,6 +50,7 @@ import org.mozilla.gecko.GeckoEvent;
 import org.mozilla.gecko.GeckoEventListener;
 import android.graphics.PointF;
 import android.graphics.RectF;
+import android.util.FloatMath;
 import android.util.Log;
 import android.view.GestureDetector;
 import android.view.MotionEvent;
@@ -293,8 +294,9 @@ public class PanZoomController
             Log.e(LOGTAG, "Received impossible touch move while in " + mState);
             return false;
         case TOUCHING:
-            if (panDistance(event) < PAN_THRESHOLD * GeckoAppShell.getDpi())
+            if (panDistance(event) < PAN_THRESHOLD * GeckoAppShell.getDpi()) {
                 return false;
+            }
             cancelTouch();
             // fall through
         case PANNING_HOLD_LOCKED:
@@ -370,9 +372,9 @@ public class PanZoomController
     }
 
     private float panDistance(MotionEvent move) {
-        float dx = mX.firstTouchPos - move.getX(0);
-        float dy = mY.firstTouchPos - move.getY(0);
-        return (float)Math.sqrt(dx * dx + dy * dy);
+        float dx = mX.panDistance(move.getX(0));
+        float dy = mY.panDistance(move.getY(0));
+        return FloatMath.sqrt(dx * dx + dy * dy);
     }
 
     private void track(float x, float y, long time) {
@@ -386,7 +388,7 @@ public class PanZoomController
 
         if (mState == PanZoomState.PANNING_LOCKED) {
             // check to see if we should break the axis lock
-            double angle = Math.atan2(y - mY.firstTouchPos, x - mX.firstTouchPos); // range [-pi, pi]
+            double angle = Math.atan2(mY.panDistance(y), mX.panDistance(x)); // range [-pi, pi]
             angle = Math.abs(angle); // range [0, pi]
             if (angle < AXIS_LOCK_ANGLE || angle > (Math.PI - AXIS_LOCK_ANGLE)) {
                 // lock to x-axis
@@ -699,7 +701,7 @@ public class PanZoomController
             BOTH,       // Overscrolled in both directions (page is zoomed to smaller than screen)
         }
 
-        public float firstTouchPos;             /* Position of the first touch event on the current drag. */
+        private float firstTouchPos;            /* Position of the first touch event on the current drag. */
         public float touchPos;                  /* Position of the most recent touch event on the current drag. */
         public float lastTouchPos;              /* Position of the touch event before touchPos. */
         public float velocity;                  /* Velocity in this direction. */
@@ -733,6 +735,10 @@ public class PanZoomController
             firstTouchPos = touchPos = lastTouchPos = pos;
         }
 
+        float panDistance(float currentPos) {
+            return currentPos - firstTouchPos;
+        }
+
         void updateWithTouchAt(float pos, float timeDelta) {
             float newVelocity = (touchPos - pos) / timeDelta * MS_PER_FRAME;