Page in PagedTileLayout only changes when needed

Made sure that pages are not changed unnecesarily on events that do not
modify the page structure.

Saves current page on destruction, to be restored later. In particular
in the case of switching to Dark theme on entering battery saver mode
(it destroys QSFragment).

Test: manual && runtest
Change-Id: I941f0a7728139257d5c5dd3646df16aaf1805470
Fixes: 117171669

packages/SystemUI/src/com/android/systemui/qs/PagedTileLayout.java

@@ -6,7 +6,9 @@ import android.animation.AnimatorSet;
 import android.animation.ObjectAnimator;
 import android.animation.PropertyValuesHolder;
 import android.content.Context;
+import android.content.res.Configuration;
 import android.content.res.Resources;
+import android.os.Bundle;
 import android.util.AttributeSet;
 import android.util.Log;
 import android.view.LayoutInflater;
@@ -29,6 +31,7 @@ import java.util.Set;
 public class PagedTileLayout extends ViewPager implements QSTileLayout {
 
     private static final boolean DEBUG = false;
+    private static final String CURRENT_PAGE = "current_page";
 
     private static final String TAG = "PagedTileLayout";
     private static final int REVEAL_SCROLL_DURATION_MILLIS = 750;
@@ -54,6 +57,9 @@ public class PagedTileLayout extends ViewPager implements QSTileLayout {
     private AnimatorSet mBounceAnimatorSet;
     private float mLastExpansion;
     private boolean mDistributeTiles = false;
+    private int mPageToRestore = -1;
+    private int mLayoutOrientation;
+    private int mLayoutDirection;
 
     public PagedTileLayout(Context context, AttributeSet attrs) {
         super(context, attrs);
@@ -61,13 +67,37 @@ public class PagedTileLayout extends ViewPager implements QSTileLayout {
         setAdapter(mAdapter);
         setOnPageChangeListener(mOnPageChangeListener);
         setCurrentItem(0, false);
+        mLayoutOrientation = getResources().getConfiguration().orientation;
+        mLayoutDirection = getLayoutDirection();
+    }
+
+    public void saveInstanceState(Bundle outState) {
+        outState.putInt(CURRENT_PAGE, getCurrentItem());
+    }
+
+    public void restoreInstanceState(Bundle savedInstanceState) {
+        // There's only 1 page at this point. We want to restore the correct page once the
+        // pages have been inflated
+        mPageToRestore = savedInstanceState.getInt(CURRENT_PAGE, -1);
+    }
+
+    @Override
+    protected void onConfigurationChanged(Configuration newConfig) {
+        super.onConfigurationChanged(newConfig);
+        if (mLayoutOrientation != newConfig.orientation) {
+            mLayoutOrientation = newConfig.orientation;
+            setCurrentItem(0, false);
+        }
     }
 
     @Override
     public void onRtlPropertiesChanged(int layoutDirection) {
         super.onRtlPropertiesChanged(layoutDirection);
-        setAdapter(mAdapter);
-        setCurrentItem(0, false);
+        if (mLayoutDirection != layoutDirection) {
+            mLayoutDirection = layoutDirection;
+            setAdapter(mAdapter);
+            setCurrentItem(0, false);
+        }
     }
 
     @Override
@@ -218,7 +248,10 @@ public class PagedTileLayout extends ViewPager implements QSTileLayout {
         mPageIndicator.setNumPages(mPages.size());
         setAdapter(mAdapter);
         mAdapter.notifyDataSetChanged();
-        setCurrentItem(0, false);
+        if (mPageToRestore != -1) {
+            setCurrentItem(mPageToRestore, false);
+            mPageToRestore = -1;
+        }
     }
 
     @Override

packages/SystemUI/src/com/android/systemui/qs/QSFragment.java

@@ -103,6 +103,9 @@ public class QSFragment extends Fragment implements QS, CommandQueue.Callbacks {
             setListening(savedInstanceState.getBoolean(EXTRA_LISTENING));
             setEditLocation(view);
             mQSCustomizer.restoreInstanceState(savedInstanceState);
+            if (mQsExpanded) {
+                mQSPanel.getTileLayout().restoreInstanceState(savedInstanceState);
+            }
         }
         SysUiServiceProvider.getComponent(getContext(), CommandQueue.class).addCallbacks(this);
     }
@@ -127,6 +130,9 @@ public class QSFragment extends Fragment implements QS, CommandQueue.Callbacks {
         outState.putBoolean(EXTRA_EXPANDED, mQsExpanded);
         outState.putBoolean(EXTRA_LISTENING, mListening);
         mQSCustomizer.saveInstanceState(outState);
+        if (mQsExpanded) {
+            mQSPanel.getTileLayout().saveInstanceState(outState);
+        }
     }
 
     @VisibleForTesting

packages/SystemUI/src/com/android/systemui/qs/QSPanel.java

@@ -25,6 +25,7 @@ import android.content.Context;
 import android.content.res.Configuration;
 import android.content.res.Resources;
 import android.metrics.LogMaker;
+import android.os.Bundle;
 import android.os.Handler;
 import android.os.Message;
 import android.service.quicksettings.Tile;
@@ -666,6 +667,11 @@ public class QSPanel extends LinearLayout implements Tunable, Callback, Brightne
     }
 
     public interface QSTileLayout {
+
+        default void saveInstanceState(Bundle outState) {}
+
+        default void restoreInstanceState(Bundle savedInstanceState) {}
+
         void addTile(TileRecord tile);
 
         void removeTile(TileRecord tile);