Showing default activity in activity chooser view only if enough space.

1. While a default target is very convenient, having two targets for the
   widget on a phone takes too much space and the apps do not have room
   to add other essential affordances to the action bar. Making the default
   activity show only of the screen is large enough - the action bar
   accommodates at least four targets i.e. 500dip.

2. Fixed a bug where changing the backing model of an ActivityChooserView
   when the view is not shown did not remove the observer for the old
   model, hence the View can get into a state where it responds to changes
   of two models while presenting only one. Also in such a case the view
   would leak since the singleton model will keep a handle to it.

3. Updated the documentation of share action provider to explain how a
   a developer can change the backing history file and refresh the UI
   based on the historical data in that file.

bug:6447692

Change-Id: Id5c9e54cd5df322ded8574ba028cb680e628243b

Author: sganov

core/java/android/widget/ActivityChooserModel.java

@@ -760,6 +760,16 @@ private void pruneHistoricalRecordsForPackageLocked(String packageName) {
         }
     }
 
+    /**
+     * Gets whether the given observer is already registered.
+     *
+     * @param observer The observer.
+     * @return True if already registered.
+     */
+    public boolean isRegisteredObserver(DataSetObserver observer) {
+        return mObservers.contains(observer);
+    }
+
     /**
      * Represents a record in the history.
      */

core/java/android/widget/ActivityChooserView.java

@@ -20,8 +20,10 @@
 
 import android.content.Context;
 import android.content.Intent;
+import android.content.pm.ActivityInfo;
 import android.content.pm.PackageManager;
 import android.content.pm.ResolveInfo;
+import android.content.res.Configuration;
 import android.content.res.Resources;
 import android.content.res.TypedArray;
 import android.database.DataSetObserver;
@@ -173,6 +175,11 @@ public void onGlobalLayout() {
      */
     private int mDefaultActionButtonContentDescription;
 
+    /**
+     * Whether this view has a default activity affordance.
+     */
+    private boolean mHasDefaultActivity;
+
     /**
      * Create a new instance.
      *
@@ -245,6 +252,8 @@ public void onChanged() {
         Resources resources = context.getResources();
         mListPopupMaxWidth = Math.max(resources.getDisplayMetrics().widthPixels / 2,
               resources.getDimensionPixelSize(com.android.internal.R.dimen.config_prefDialogWidth));
+
+        updateHasDefaultActivity();
     }
 
     /**
@@ -258,6 +267,21 @@ public void setActivityChooserModel(ActivityChooserModel dataModel) {
         }
     }
 
+    @Override
+    protected void onConfigurationChanged(Configuration newConfig) {
+        Configuration oldConfig = mContext.getResources().getConfiguration();
+        final int changed = oldConfig.diff(newConfig);
+        if ((changed & ActivityInfo.CONFIG_SCREEN_SIZE) != 0
+                || (changed & ActivityInfo.CONFIG_ORIENTATION) != 0) {
+            updateHasDefaultActivity();
+        }
+    }
+
+    private void updateHasDefaultActivity() {
+        mHasDefaultActivity = mContext.getResources().getBoolean(
+                R.bool.activity_chooser_view_has_default_activity);
+    }
+
     /**
      * Sets the background for the button that expands the activity
      * overflow list.
@@ -383,7 +407,8 @@ public boolean isShowingPopup() {
     protected void onAttachedToWindow() {
         super.onAttachedToWindow();
         ActivityChooserModel dataModel = mAdapter.getDataModel();
-        if (dataModel != null) {
+        if (dataModel != null
+                && !dataModel.isRegisteredObserver(mModelDataSetOberver)) {
             dataModel.registerObserver(mModelDataSetOberver);
         }
         mIsAttachedToWindow = true;
@@ -393,7 +418,8 @@ protected void onAttachedToWindow() {
     protected void onDetachedFromWindow() {
         super.onDetachedFromWindow();
         ActivityChooserModel dataModel = mAdapter.getDataModel();
-        if (dataModel != null) {
+        if (dataModel != null
+                && dataModel.isRegisteredObserver(mModelDataSetOberver)) {
             dataModel.unregisterObserver(mModelDataSetOberver);
         }
         ViewTreeObserver viewTreeObserver = getViewTreeObserver();
@@ -496,7 +522,7 @@ private void updateAppearance() {
         // Default activity button.
         final int activityCount = mAdapter.getActivityCount();
         final int historySize = mAdapter.getHistorySize();
-        if (activityCount > 0 && historySize > 0) {
+        if (mHasDefaultActivity && activityCount > 0 && historySize > 0) {
             mDefaultActivityButton.setVisibility(VISIBLE);
             ResolveInfo activity = mAdapter.getDefaultActivity();
             PackageManager packageManager = mContext.getPackageManager();
@@ -512,9 +538,9 @@ private void updateAppearance() {
         }
         // Activity chooser content.
         if (mDefaultActivityButton.getVisibility() == VISIBLE) {
-            mActivityChooserContent.setBackgroundDrawable(mActivityChooserContentBackground);
+            mActivityChooserContent.setBackground(mActivityChooserContentBackground);
         } else {
-            mActivityChooserContent.setBackgroundDrawable(null);
+            mActivityChooserContent.setBackground(null);
         }
     }
 
@@ -577,7 +603,7 @@ public void onClick(View view) {
         // OnLongClickListener#onLongClick
         @Override
         public boolean onLongClick(View view) {
-            if (view == mDefaultActivityButton) {
+            if (mHasDefaultActivity && view == mDefaultActivityButton) {
                 if (mAdapter.getCount() > 0) {
                     mIsSelectingDefaultActivity = true;
                     showPopupUnchecked(mInitialActivityCount);
@@ -630,14 +656,16 @@ private class ActivityChooserViewAdapter extends BaseAdapter {
 
         public void setDataModel(ActivityChooserModel dataModel) {
             ActivityChooserModel oldDataModel = mAdapter.getDataModel();
-            if (oldDataModel != null && isShown()) {
+            if (oldDataModel != null) {
                 oldDataModel.unregisterObserver(mModelDataSetOberver);
             }
             mDataModel = dataModel;
-            if (dataModel != null && isShown()) {
+            if (dataModel != null) {
                 dataModel.registerObserver(mModelDataSetOberver);
+                notifyDataSetChanged();
+            } else {
+                notifyDataSetInvalidated();
             }
-            notifyDataSetChanged();
         }
 
         @Override

core/java/android/widget/ShareActionProvider.java

@@ -44,6 +44,7 @@
  * <code>
  *  // In Activity#onCreateOptionsMenu
  *  public boolean onCreateOptionsMenu(Menu menu) {
+ *      getManuInflater().inflate(R.menu.my_menu, menu);
  *      // Get the menu item.
  *      MenuItem menuItem = menu.findItem(R.id.my_menu_item);
  *      // Get the provider and hold onto it to set/change the share intent.
@@ -239,7 +240,11 @@ public void onPrepareSubMenu(SubMenu subMenu) {
      * <p>
      * <strong>Note:</strong> The history file name can be set any time, however
      * only the action views created by {@link #onCreateActionView()} after setting
-     * the file name will be backed by the provided file.
+     * the file name will be backed by the provided file. Hence, if you are using
+     * a share action provider on a menu item and want to change the history file
+     * based on the type of the currently selected item, you need to call
+     * {@link android.app.Activity#invalidateOptionsMenu()} to force the system
+     * to recreate the menu UI.
      * <p>
      *
      * @param shareHistoryFile The share history file name.

core/res/res/values-w500dp/bools.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- Copyright (C) 2012 The Android Open Source Project
+
+     Licensed under the Apache License, Version 2.0 (the "License");
+     you may not use this file except in compliance with the License.
+     You may obtain a copy of the License at
+
+          http://www.apache.org/licenses/LICENSE-2.0
+
+     Unless required by applicable law or agreed to in writing, software
+     distributed under the License is distributed on an "AS IS" BASIS,
+     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+     See the License for the specific language governing permissions and
+     limitations under the License.
+-->
+
+<resources>
+    <bool name="activity_chooser_view_has_default_activity">true</bool>
+</resources>

core/res/res/values/bools.xml

@@ -22,4 +22,5 @@
     <bool name="show_ongoing_ime_switcher">true</bool>
     <bool name="action_bar_expanded_action_views_exclusive">true</bool>
     <bool name="target_honeycomb_needs_options_menu">true</bool>
+    <bool name="activity_chooser_view_has_default_activity">false</bool>
 </resources>

core/res/res/values/public.xml

@@ -1376,6 +1376,7 @@
   <java-symbol type="bool" name="config_wifi_dual_band_support" />
   <java-symbol type="bool" name="config_wimaxEnabled" />
   <java-symbol type="bool" name="show_ongoing_ime_switcher" />
+  <java-symbol type="bool" name="activity_chooser_view_has_default_activity" />
   <java-symbol type="color" name="config_defaultNotificationColor" />
   <java-symbol type="drawable" name="ic_notification_ime_default" />
   <java-symbol type="drawable" name="stat_notify_car_mode" />