Bug 1325440 - Use 16:9 keyline for BottomSheet menu r=sebastian

Newer versions of the support library do this automatically, but we need to
roll our own implentation for now.

16:9 keyline means that the top of the menu is placed such that a 16:9 window
of application content is still visible above the menu. This is illustrated in:
https://material.io/guidelines/layout/metrics-keylines.html#metrics-keylines-keylines-spacing
(The menu itself is _not_ 16:9.)

MozReview-Commit-ID: FSUdssb5eBN

--HG--
extra : rebase_source : 735cfb9ce7f78e4247780011c76850560f67d40e

mobile/android/base/java/org/mozilla/gecko/home/activitystream/menu/BottomSheetContextMenu.java

@@ -4,9 +4,11 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 package org.mozilla.gecko.home.activitystream.menu;
 
+import android.app.Activity;
 import android.content.Context;
 import android.support.annotation.NonNull;
 import android.support.annotation.Nullable;
+import android.support.design.widget.BottomSheetBehavior;
 import android.support.design.widget.BottomSheetDialog;
 import android.support.design.widget.NavigationView;
 import android.view.LayoutInflater;
@@ -35,6 +37,9 @@ import static org.mozilla.gecko.activitystream.ActivityStream.extractLabel;
 
     private final NavigationView navigationView;
 
+    final View content;
+    final View activityView;
+
     public BottomSheetContextMenu(final Context context,
                                   final ActivityStreamTelemetry.Extras.Builder telemetryExtraBuilder,
                                   final MenuMode mode,
@@ -50,10 +55,13 @@ import static org.mozilla.gecko.activitystream.ActivityStream.extractLabel;
                 onUrlOpenListener,
                 onUrlOpenInBackgroundListener);
 
-        final LayoutInflater inflater = LayoutInflater.from(context);
-        final View content = inflater.inflate(R.layout.activity_stream_contextmenu_bottomsheet, null);
+        // The View encompassing the activity area
+        this.activityView = ((Activity) context).findViewById(android.R.id.content);
 
         bottomSheetDialog = new BottomSheetDialog(context);
+        final LayoutInflater inflater = LayoutInflater.from(context);
+        this.content = inflater.inflate(R.layout.activity_stream_contextmenu_bottomsheet, (ViewGroup) activityView, false);
+
         bottomSheetDialog.setContentView(content);
 
         ((TextView) content.findViewById(R.id.title)).setText(item.getTitle());
@@ -95,6 +103,19 @@ import static org.mozilla.gecko.activitystream.ActivityStream.extractLabel;
 
     @Override
     public void show() {
+        // Try to use a 16:9 "keyline", i.e. we leave a 16:9 window of activity content visible
+        // above the menu. We only do this in portrait mode - in landscape mode, 16:9 is likely
+        // to be similar to the size of the display, so we'd only show very little, or even none of,
+        // the menu.
+        // Note that newer versions of the support library (possibly 25+) will do this automatically,
+        // so we can remove that code then.
+        if (activityView.getHeight() > activityView.getWidth()) {
+            final int peekHeight = activityView.getHeight() - (activityView.getWidth() * 9 / 16);
+
+            BottomSheetBehavior<View> bsBehaviour = BottomSheetBehavior.from((View) content.getParent());
+            bsBehaviour.setPeekHeight(peekHeight);
+        }
+
         bottomSheetDialog.show();
     }
 

mobile/android/base/java/org/mozilla/gecko/home/activitystream/stream/HighlightItem.java

@@ -81,7 +81,7 @@ public class HighlightItem extends StreamItem implements IconCallback {
                         .set(ActivityStreamTelemetry.Contract.ACTION_POSITION, position)
                         .forHighlightSource(highlight.getSource());
 
-                ActivityStreamContextMenu.show(v.getContext(),
+                ActivityStreamContextMenu.show(itemView.getContext(),
                         menuButton,
                         extras,
                         ActivityStreamContextMenu.MenuMode.HIGHLIGHT,

mobile/android/base/java/org/mozilla/gecko/home/activitystream/topsites/TopSitesCard.java

@@ -63,7 +63,7 @@ import java.util.concurrent.Future;
                         .forTopSite(topSite)
                         .set(ActivityStreamTelemetry.Contract.ACTION_POSITION, absolutePosition);
 
-                ActivityStreamContextMenu.show(v.getContext(),
+                ActivityStreamContextMenu.show(itemView.getContext(),
                         menuButton,
                         extras,
                         ActivityStreamContextMenu.MenuMode.TOPSITE,