Bug 1137483 - Center SearchEngineBar when it doesn't fill the screen. r=liuche

mobile/android/base/home/SearchEngineBar.java

@@ -14,6 +14,7 @@ import android.view.View;
 import android.view.ViewGroup;
 import android.widget.AdapterView;
 import android.widget.BaseAdapter;
+import android.widget.FrameLayout;
 
 import org.mozilla.gecko.R;
 import org.mozilla.gecko.widget.FaviconView;
@@ -33,24 +34,12 @@ public class SearchEngineBar extends TwoWayView
     private final SearchEngineAdapter adapter;
     private OnSearchBarClickListener onSearchBarClickListener;
 
-    private final Paint dividerPaint;
-
     public SearchEngineBar(final Context context, final AttributeSet attrs) {
         super(context, attrs);
 
         adapter = new SearchEngineAdapter();
         setAdapter(adapter);
         setOnItemClickListener(this);
-
-        dividerPaint = new Paint();
-        dividerPaint.setColor(getResources().getColor(R.color.divider_light));
-    }
-
-    @Override
-    public void onDraw(final Canvas canvas) {
-        super.onDraw(canvas);
-
-        canvas.drawLine(0, 0, getWidth(), 0, dividerPaint);
     }
 
     @Override
@@ -112,4 +101,33 @@ public class SearchEngineBar extends TwoWayView
             return view;
         }
     }
+
+    /**
+     * A Container to surround the SearchEngineBar. This is necessary so we can draw
+     * a divider across the entire width of the screen, but have the inner list layout
+     * not take up the full width of the screen so it can be centered within this container
+     * if there aren't enough items that it needs to scroll.
+     *
+     * Note: a better implementation would have this View inflating an inner layout so
+     * the containing layout doesn't need two "SearchEngineBar" Views but it wasn't
+     * worth the refactor time.
+     */
+    @SuppressWarnings("unused") // via XML
+    public static class SearchEngineBarContainer extends FrameLayout {
+        private final Paint dividerPaint;
+
+        public SearchEngineBarContainer(final Context context, final AttributeSet attrs) {
+            super(context, attrs);
+
+            dividerPaint = new Paint();
+            dividerPaint.setColor(getResources().getColor(R.color.divider_light));
+        }
+
+        @Override
+        public void onDraw(final Canvas canvas) {
+            super.onDraw(canvas);
+
+            canvas.drawLine(0, 0, getWidth(), 0, dividerPaint);
+        }
+    }
 }

mobile/android/base/resources/layout/browser_search.xml

@@ -19,24 +19,26 @@
             android:layout_height="0dp"
             android:layout_weight="1" />
 
-    <!-- The desired layout_height is 48dp. We add paddingTop so we have
-         space to dynamically draw the divider in onDraw. Preferably, we'd
-         wrap_content on the inner layout, but TwoWayView ignores wrap_content. :(
-
-         Note: the layout_height value is shared with the inner layout
-         (search_engine_bar_item at the time of this writing).
-
-         listSelector is too slow for showing pressed state
-         so we set the pressed colors on the child. -->
-    <org.mozilla.gecko.home.SearchEngineBar
-          android:id="@+id/search_engine_bar"
+    <view class="org.mozilla.gecko.home.SearchEngineBar$SearchEngineBarContainer"
           android:layout_width="match_parent"
-          android:layout_height="49dp"
-          android:paddingTop="1dp"
-          android:orientation="horizontal"
-          android:background="#fff"
-          android:choiceMode="singleChoice"
-          android:listSelector="@android:color/transparent"
-          android:cacheColorHint="@android:color/transparent"/>
+          android:layout_height="wrap_content"
+          android:background="#fff">
+
+        <!-- We add a marginTop so the outer container can draw a divider.
+
+             listSelector is too slow for showing pressed state
+             so we set the pressed colors on the child. -->
+        <org.mozilla.gecko.home.SearchEngineBar
+              android:id="@+id/search_engine_bar"
+              android:layout_width="wrap_content"
+              android:layout_height="48dp"
+              android:layout_marginTop="1dp"
+              android:orientation="horizontal"
+              android:layout_gravity="center_horizontal"
+              android:choiceMode="singleChoice"
+              android:listSelector="@android:color/transparent"
+              android:cacheColorHint="@android:color/transparent"/>
+
+   </view>
 
 </LinearLayout>

mobile/android/base/resources/layout/search_engine_bar_item.xml

@@ -11,7 +11,7 @@
      View (browser_search at the time of this writing). -->
 <FrameLayout
     xmlns:android="http://schemas.android.com/apk/res/android"
-    android:layout_height="48dp"
+    android:layout_height="match_parent"
     android:layout_width="72dp"
     android:background="@color/pressed_about_page_header_grey">