Bug 783553 - Disable overscroll in webapps. r=kats

mobile/android/base/GeckoApp.java

@@ -2494,7 +2494,7 @@ abstract public class GeckoApp
         GeckoAppShell.sendEventToGecko(GeckoEvent.createBroadcastEvent("Update:CheckResult", result ? "true" : "false"));
     }
 
-    private void connectGeckoLayerClient() {
+    protected void connectGeckoLayerClient() {
         mLayerView.getLayerClient().notifyGeckoReady();
 
         mLayerView.getTouchEventHandler().setOnTouchListener(new ContentTouchListener() {

mobile/android/base/WebApp.java.in

@@ -146,5 +146,10 @@ public class WebApp extends GeckoApp {
         }
         super.onTabChanged(tab, msg, data);
     }
+
+    protected void connectGeckoLayerClient() {
+        super.connectGeckoLayerClient();
+        getLayerView().setOverScrollMode(View.OVER_SCROLL_NEVER);
+    }
 };
 

mobile/android/base/gfx/LayerView.java

@@ -382,4 +382,18 @@ public class LayerView extends FrameLayout {
 
         }
     }
+
+    @Override
+    public void setOverScrollMode(int overscrollMode) {
+        super.setOverScrollMode(overscrollMode);
+        if (mLayerClient != null)
+            mLayerClient.getPanZoomController().setOverScrollMode(overscrollMode);
+    }
+
+    @Override
+    public int getOverScrollMode() {
+        if (mLayerClient != null)
+            return mLayerClient.getPanZoomController().getOverScrollMode();
+        return super.getOverScrollMode();
+    }
 }

mobile/android/base/ui/Axis.java

@@ -10,6 +10,7 @@ import org.mozilla.gecko.util.FloatUtils;
 import org.json.JSONArray;
 
 import android.util.Log;
+import android.view.View;
 
 import java.util.Map;
 
@@ -105,6 +106,7 @@ abstract class Axis {
 
     private final SubdocumentScrollHelper mSubscroller;
 
+    private int mOverscrollMode; /* Default to only overscrolling if we're allowed to scroll in a direction */
     private float mFirstTouchPos;           /* Position of the first touch event on the current drag. */
     private float mTouchPos;                /* Position of the most recent touch event on the current drag. */
     private float mLastTouchPos;            /* Position of the touch event before touchPos. */
@@ -122,6 +124,15 @@ abstract class Axis {
 
     Axis(SubdocumentScrollHelper subscroller) {
         mSubscroller = subscroller;
+        mOverscrollMode = View.OVER_SCROLL_IF_CONTENT_SCROLLS;
+    }
+
+    public void setOverScrollMode(int overscrollMode) {
+        mOverscrollMode = overscrollMode;
+    }
+
+    public int getOverScrollMode() {
+        return mOverscrollMode;
     }
 
     private float getViewportEnd() {
@@ -206,10 +217,17 @@ abstract class Axis {
         // apply to the top-level document) and only take into account axis locking.
         if (mSubscroller.scrolling()) {
             return !mScrollingDisabled;
-        } else {
-            return getViewportLength() <= getPageLength() - MIN_SCROLLABLE_DISTANCE &&
-                   !mScrollingDisabled;
         }
+
+        // if we are axis locked, return false
+        if (mScrollingDisabled) {
+            return false;
+        }
+
+        // there is scrollable space, and we're not disabled, or the document fits the viewport
+        // but we always allow overscroll anyway
+        return getViewportLength() <= getPageLength() - MIN_SCROLLABLE_DISTANCE ||
+               getOverScrollMode() == View.OVER_SCROLL_ALWAYS;
     }
 
     /*
@@ -294,14 +312,27 @@ abstract class Axis {
 
     // Performs displacement of the viewport position according to the current velocity.
     void displace() {
-        if (!scrollable()) {
+        // if this isn't scrollable just return
+        if (!scrollable())
             return;
-        }
 
         if (mFlingState == FlingStates.PANNING)
             mDisplacement += (mLastTouchPos - mTouchPos) * getEdgeResistance(false);
         else
             mDisplacement += mVelocity;
+
+        // if overscroll is disabled and we're trying to overscroll, reset the displacement
+        // to remove any excess. Using getExcess alone isn't enough here since it relies on
+        // getOverscroll which doesn't take into account any new displacment being applied
+        if (getOverScrollMode() == View.OVER_SCROLL_NEVER) {
+            if (mDisplacement + getOrigin() < getPageStart()) {
+                mDisplacement = getPageStart() - getOrigin();
+                stopFling();
+            } else if (mDisplacement + getViewportEnd() > getPageEnd()) {
+                mDisplacement = getPageEnd() - getViewportEnd();
+                stopFling();
+            }
+        }
     }
 
     float resetDisplacement() {

mobile/android/base/ui/PanZoomController.java

@@ -1112,4 +1112,13 @@ public class PanZoomController
         checkMainThread();
         bounce();
     }
+
+    public void setOverScrollMode(int overscrollMode) {
+        mX.setOverScrollMode(overscrollMode);
+        mY.setOverScrollMode(overscrollMode);
+    }
+
+    public int getOverScrollMode() {
+        return mX.getOverScrollMode();
+    }
 }