src/com/android/mail/browse/ConversationPagerAdapter.java - platform/packages/apps/UnifiedEmail - Git at Google

 /*
  * Copyright (C) 2012 Google Inc.
  * Licensed to 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.
  */

 package com.android.mail.browse;

 import android.app.Fragment;
 import android.app.FragmentManager;
 import android.content.res.Resources;
 import android.database.Cursor;
 import android.database.DataSetObserver;
 import android.os.Bundle;
 import android.os.Parcelable;
 import android.support.v4.view.ViewPager;
 import android.view.ViewGroup;

 import com.android.mail.providers.Account;
 import com.android.mail.providers.Conversation;
 import com.android.mail.providers.Folder;
 import com.android.mail.providers.FolderObserver;
 import com.android.mail.providers.UIProvider;
 import com.android.mail.ui.AbstractConversationViewFragment;
 import com.android.mail.ui.ActivityController;
 import com.android.mail.ui.ConversationViewFragment;
 import com.android.mail.ui.SecureConversationViewFragment;
 import com.android.mail.utils.FragmentStatePagerAdapter2;
 import com.android.mail.utils.LogUtils;

 public class ConversationPagerAdapter extends FragmentStatePagerAdapter2
         implements ViewPager.OnPageChangeListener {

     private final DataSetObserver mListObserver = new ListObserver();
     private final FolderObserver mFolderObserver = new FolderObserver() {
         @Override
         public void onChanged(Folder newFolder) {
             notifyDataSetChanged();
         }
     };
     private ActivityController mController;
     private final Bundle mCommonFragmentArgs;
     private final Conversation mInitialConversation;
     private final Account mAccount;
     private final Folder mFolder;
     /**
      * In singleton mode, this adapter ignores the cursor contents and size, and acts as if the
      * data set size is exactly size=1, with {@link #getDefaultConversation()} at position 0.
      */
     private boolean mSingletonMode = false;
     /**
      * Similar to singleton mode, but once enabled, detached mode is permanent for this adapter.
      */
     private boolean mDetachedMode = false;
     /**
      * True iff we are in the process of handling a dataset change.
      */
     private boolean mInDataSetChange = false;
     /**
      * Need to keep this around to look up pager title strings.
      */
     private Resources mResources;
     /**
      * This isn't great to create a circular dependency, but our usage of {@link #getPageTitle(int)}
      * requires knowing which page is the currently visible to dynamically name offscreen pages
      * "newer" and "older". And {@link #setPrimaryItem(ViewGroup, int, Object)} does not work well
      * because it isn't updated as often as {@link ViewPager#getCurrentItem()} is.
      * <p>
      * We must be careful to null out this reference when the pager and adapter are decoupled to
      * minimize dangling references.
      */
     private ViewPager mPager;
     private boolean mSanitizedHtml;

     private boolean mStopListeningMode = false;

     /**
      * After {@link #stopListening()} is called, this contains the last-known count of this adapter.
      * We keep this around and use it in lieu of the Cursor's true count until imminent destruction
      * to satisfy two opposing requirements:
      * <ol>
      * <li>The ViewPager always likes to know about all dataset changes via notifyDatasetChanged.
      * <li>Destructive changes during pager destruction (e.g. mode transition from conversation mode
      * to list mode) must be ignored, or else ViewPager will shift focus onto a neighboring
      * conversation and <b>mark it read</b>.
      * </ol>
      *
      */
     private int mLastKnownCount;

     private static final String LOG_TAG = ConversationPagerController.LOG_TAG;

     private static final String BUNDLE_DETACHED_MODE =
             ConversationPagerAdapter.class.getName() + "-detachedmode";

     public ConversationPagerAdapter(Resources res, FragmentManager fm, Account account,
             Folder folder, Conversation initialConversation) {
         super(fm, false /* enableSavedStates */);
         mResources = res;
         mCommonFragmentArgs = AbstractConversationViewFragment.makeBasicArgs(account);
         mInitialConversation = initialConversation;
         mAccount = account;
         mFolder = folder;
         mSanitizedHtml = mAccount.supportsCapability
                 (UIProvider.AccountCapabilities.SANITIZED_HTML);
     }

     public boolean matches(Account account, Folder folder) {
         return mAccount != null && mFolder != null && mAccount.matches(account)
                 && mFolder.equals(folder);
     }

     public void setSingletonMode(boolean enabled) {
         if (mSingletonMode != enabled) {
             mSingletonMode = enabled;
             notifyDataSetChanged();
         }
     }

     public boolean isSingletonMode() {
         return mSingletonMode;
     }

     public boolean isDetached() {
         return mDetachedMode;
     }

     /**
      * Returns true if singleton mode or detached mode have been enabled, or if the current cursor
      * is null.
      * @param cursor the current conversation cursor (obtained through {@link #getCursor()}.
      * @return
      */
     public boolean isPagingDisabled(Cursor cursor) {
         return mSingletonMode || mDetachedMode || cursor == null;
     }

     private ConversationCursor getCursor() {
         if (mDetachedMode) {
             // In detached mode, the pager is decoupled from the cursor. Nothing should rely on the
             // cursor at this point.
             return null;
         }
         if (mController == null) {
             // Happens when someone calls setActivityController(null) on us. This is done in
             // ConversationPagerController.stopListening() to indicate that the Conversation View
             // is going away *very* soon.
             LogUtils.i(LOG_TAG, "Pager adapter has a null controller. If the conversation view"
                     + " is going away, this is fine.  Otherwise, the state is inconsistent");
             return null;
         }

         return mController.getConversationListCursor();
     }

     @Override
     public Fragment getItem(int position) {
         final Conversation c;
         final ConversationCursor cursor = getCursor();

         if (isPagingDisabled(cursor)) {
             // cursor-less adapter is a size-1 cursor that points to mInitialConversation.
             // sanity-check
             if (position != 0) {
                 LogUtils.wtf(LOG_TAG, "pager cursor is null and position is non-zero: %d",
                         position);
             }
             c = getDefaultConversation();
             c.position = 0;
         } else {
             if (!cursor.moveToPosition(position)) {
                 LogUtils.wtf(LOG_TAG, "unable to seek to ConversationCursor pos=%d (%s)", position,
                         cursor);
                 return null;
             }
             cursor.notifyUIPositionChange();
             c = cursor.getConversation();
             c.position = position;
         }
         final AbstractConversationViewFragment f = getConversationViewFragment(c);
         LogUtils.d(LOG_TAG, "IN PagerAdapter.getItem, frag=%s conv=%s this=%s", f, c, this);
         return f;
     }

     private AbstractConversationViewFragment getConversationViewFragment(Conversation c) {
         if (mSanitizedHtml) {
             return ConversationViewFragment.newInstance(mCommonFragmentArgs, c);
         } else {
             return SecureConversationViewFragment.newInstance(mCommonFragmentArgs, c);
         }
     }

     @Override
     public int getCount() {
         if (mStopListeningMode) {
             if (LogUtils.isLoggable(LOG_TAG, LogUtils.DEBUG)) {
                 final Cursor cursor = getCursor();
                 LogUtils.d(LOG_TAG,
                         "IN CPA.getCount stopListeningMode, returning lastKnownCount=%d."
                         + " cursor=%s real count=%s", mLastKnownCount, cursor,
                         (cursor != null) ? cursor.getCount() : "N/A");
             }
             return mLastKnownCount;
         }

         final Cursor cursor = getCursor();
         if (isPagingDisabled(cursor)) {
             LogUtils.d(LOG_TAG, "IN CPA.getCount, returning 1 (effective singleton). cursor=%s",
                     cursor);
             return 1;
         }
         return cursor.getCount();
     }

     @Override
     public int getItemPosition(Object item) {
         if (!(item instanceof AbstractConversationViewFragment)) {
             LogUtils.wtf(LOG_TAG, "getItemPosition received unexpected item: %s", item);
         }

         final AbstractConversationViewFragment fragment = (AbstractConversationViewFragment) item;
         return getConversationPosition(fragment.getConversation());
     }

     @Override
     public void setPrimaryItem(ViewGroup container, int position, Object object) {
         LogUtils.d(LOG_TAG, "IN PagerAdapter.setPrimaryItem, pos=%d, frag=%s", position,
                 object);
         super.setPrimaryItem(container, position, object);
     }

     @Override
     public Parcelable saveState() {
         LogUtils.d(LOG_TAG, "IN PagerAdapter.saveState. this=%s", this);
         Bundle state = (Bundle) super.saveState(); // superclass uses a Bundle
         if (state == null) {
             state = new Bundle();
         }
         state.putBoolean(BUNDLE_DETACHED_MODE, mDetachedMode);
         return state;
     }

     @Override
     public void restoreState(Parcelable state, ClassLoader loader) {
         super.restoreState(state, loader);
         if (state != null) {
             Bundle b = (Bundle) state;
             b.setClassLoader(loader);
             final boolean detached = b.getBoolean(BUNDLE_DETACHED_MODE);
             setDetachedMode(detached);
         }
         LogUtils.d(LOG_TAG, "OUT PagerAdapter.restoreState. this=%s", this);
     }

     private void setDetachedMode(boolean detached) {
         if (mDetachedMode == detached) {
             return;
         }
         mDetachedMode = detached;
         if (mDetachedMode) {
             mController.setDetachedMode();
         }
         notifyDataSetChanged();
     }

     @Override
     public String toString() {
         final StringBuilder sb = new StringBuilder(super.toString());
         sb.setLength(sb.length() - 1);
         sb.append(" detachedMode=");
         sb.append(mDetachedMode);
         sb.append(" singletonMode=");
         sb.append(mSingletonMode);
         sb.append(" mController=");
         sb.append(mController);
         sb.append(" mPager=");
         sb.append(mPager);
         sb.append(" mStopListening=");
         sb.append(mStopListeningMode);
         sb.append(" mLastKnownCount=");
         sb.append(mLastKnownCount);
         sb.append(" cursor=");
         sb.append(getCursor());
         sb.append("}");
         return sb.toString();
     }

     @Override
     public void notifyDataSetChanged() {
         if (mInDataSetChange) {
             LogUtils.i(LOG_TAG, "CPA ignoring dataset change generated during dataset change");
             return;
         }

         mInDataSetChange = true;
         // If we are in detached mode, changes to the cursor are of no interest to us, but they may
         // be to parent classes.

         // when the currently visible item disappears from the dataset:
         //   if the new version of the currently visible item has zero messages:
         //     notify the list controller so it can handle this 'current conversation gone' case
         //     (by backing out of conversation mode)
         //   else
         //     'detach' the conversation view from the cursor, keeping the current item as-is but
         //     disabling swipe (effectively the same as singleton mode)
         if (mController != null && !mDetachedMode && mPager != null) {
             final Conversation currConversation = mController.getCurrentConversation();
             final int pos = getConversationPosition(currConversation);
             final ConversationCursor cursor = getCursor();
             if (pos == POSITION_NONE && cursor != null && currConversation != null) {
                 // enable detached mode and do no more here. the fragment itself will figure out
                 // if the conversation is empty (using message list cursor) and back out if needed.
                 setDetachedMode(true);
                 LogUtils.i(LOG_TAG, "CPA: current conv is gone, reverting to detached mode. c=%s",
                         currConversation.uri);

                 final int currentItem = mPager.getCurrentItem();

                 final AbstractConversationViewFragment fragment =
                         (AbstractConversationViewFragment) getFragmentAt(currentItem);

                 if (fragment != null) {
                     fragment.onDetachedModeEntered();
                 } else {
                     LogUtils.e(LOG_TAG,
                             "CPA: notifyDataSetChanged: fragment null, current item: %d",
                             currentItem);
                 }
             } else {
                 // notify unaffected fragment items of the change, so they can re-render
                 // (the change may have been to the labels for a single conversation, for example)
                 final AbstractConversationViewFragment frag = (cursor == null) ? null :
                         (AbstractConversationViewFragment) getFragmentAt(pos);
                 if (frag != null && cursor.moveToPosition(pos) && frag.isUserVisible()) {
                     // reload what we think is in the current position.
                     final Conversation conv = cursor.getConversation();
                     conv.position = pos;
                     frag.onConversationUpdated(conv);
                     mController.setCurrentConversation(conv);
                 }
             }
         } else {
             LogUtils.d(LOG_TAG, "in CPA.notifyDataSetChanged, doing nothing. this=%s", this);
         }

         super.notifyDataSetChanged();
         mInDataSetChange = false;
     }

     @Override
     public void setItemVisible(Fragment item, boolean visible) {
         super.setItemVisible(item, visible);
         final AbstractConversationViewFragment fragment = (AbstractConversationViewFragment) item;
         fragment.setExtraUserVisibleHint(visible);
     }

     private Conversation getDefaultConversation() {
         Conversation c = (mController != null) ? mController.getCurrentConversation() : null;
         if (c == null) {
             c = mInitialConversation;
         }
         return c;
     }

     public int getConversationPosition(Conversation conv) {
         if (conv == null) {
             return POSITION_NONE;
         }

         final ConversationCursor cursor = getCursor();
         if (isPagingDisabled(cursor)) {
             final Conversation def = getDefaultConversation();
             if (!conv.equals(def)) {
                 LogUtils.d(LOG_TAG, "unable to find conversation in singleton mode. c=%s def=%s",
                         conv, def);
                 return POSITION_NONE;
             }
             LogUtils.d(LOG_TAG, "in CPA.getConversationPosition returning 0, conv=%s this=%s",
                     conv, this);
             return 0;
         }

         // cursor is guaranteed to be non-null because isPagingDisabled() above checks for null
         // cursor.

         int result = POSITION_NONE;
         final int pos = cursor.getConversationPosition(conv.id);
         if (pos >= 0) {
             LogUtils.d(LOG_TAG, "pager adapter found repositioned convo %s at pos=%d",
                     conv, pos);
             result = pos;
         }

         LogUtils.d(LOG_TAG, "in CPA.getConversationPosition (normal), conv=%s pos=%s this=%s",
                 conv, result, this);
         return result;
     }

     public void setPager(ViewPager pager) {
         if (mPager != null) {
             mPager.setOnPageChangeListener(null);
         }
         mPager = pager;
         if (mPager != null) {
             mPager.setOnPageChangeListener(this);
         }
     }

     public void setActivityController(ActivityController controller) {
         boolean wasNull = (mController == null);
         if (mController != null && !mStopListeningMode) {
             mController.unregisterConversationListObserver(mListObserver);
             mController.unregisterFolderObserver(mFolderObserver);
         }
         mController = controller;
         if (mController != null && !mStopListeningMode) {
             mController.registerConversationListObserver(mListObserver);
             mFolderObserver.initialize(mController);
             if (!wasNull) {
                 notifyDataSetChanged();
             }
         } else {
             // We're being torn down; do not notify.
             // Let the pager controller manage pager lifecycle.
         }
     }

     /**
      * See {@link ConversationPagerController#stopListening()}.
      */
     public void stopListening() {
         if (mStopListeningMode) {
             // Do nothing since we're already in stop listening mode.  This avoids repeated
             // unregister observer calls.
             return;
         }

         // disable the observer, but save off the current count, in case the Pager asks for it
         // from now until imminent destruction

         if (mController != null) {
             mController.unregisterConversationListObserver(mListObserver);
             mFolderObserver.unregisterAndDestroy();
         }
         mLastKnownCount = getCount();
         mStopListeningMode = true;
         LogUtils.d(LOG_TAG, "CPA.stopListening, this=%s", this);
     }

     @Override
     public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
         // no-op
     }

     @Override
     public void onPageSelected(int position) {
         if (mController == null) {
             return;
         }
         final ConversationCursor cursor = getCursor();
         if (cursor == null || !cursor.moveToPosition(position)) {
             // No valid cursor or it doesn't have the position we want. Bail.
             return;
         }
         final Conversation c = cursor.getConversation();
         c.position = position;
         LogUtils.d(LOG_TAG, "pager adapter setting current conv: %s", c);
         mController.setCurrentConversation(c);
     }

     @Override
     public void onPageScrollStateChanged(int state) {
         // no-op
     }

     // update the pager dataset as the Controller's cursor changes
     private class ListObserver extends DataSetObserver {
         @Override
         public void onChanged() {
             notifyDataSetChanged();
         }
         @Override
         public void onInvalidated() {
         }
     }

 }
	/*
	* Copyright (C) 2012 Google Inc.
	* Licensed to 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.
	*/

	package com.android.mail.browse;

	import android.app.Fragment;
	import android.app.FragmentManager;
	import android.content.res.Resources;
	import android.database.Cursor;
	import android.database.DataSetObserver;
	import android.os.Bundle;
	import android.os.Parcelable;
	import android.support.v4.view.ViewPager;
	import android.view.ViewGroup;

	import com.android.mail.providers.Account;
	import com.android.mail.providers.Conversation;
	import com.android.mail.providers.Folder;
	import com.android.mail.providers.FolderObserver;
	import com.android.mail.providers.UIProvider;
	import com.android.mail.ui.AbstractConversationViewFragment;
	import com.android.mail.ui.ActivityController;
	import com.android.mail.ui.ConversationViewFragment;
	import com.android.mail.ui.SecureConversationViewFragment;
	import com.android.mail.utils.FragmentStatePagerAdapter2;
	import com.android.mail.utils.LogUtils;

	public class ConversationPagerAdapter extends FragmentStatePagerAdapter2
	implements ViewPager.OnPageChangeListener {

	private final DataSetObserver mListObserver = new ListObserver();
	private final FolderObserver mFolderObserver = new FolderObserver() {
	@Override
	public void onChanged(Folder newFolder) {
	notifyDataSetChanged();
	}
	};
	private ActivityController mController;
	private final Bundle mCommonFragmentArgs;
	private final Conversation mInitialConversation;
	private final Account mAccount;
	private final Folder mFolder;
	/**
	* In singleton mode, this adapter ignores the cursor contents and size, and acts as if the
	* data set size is exactly size=1, with {@link #getDefaultConversation()} at position 0.
	*/
	private boolean mSingletonMode = false;
	/**
	* Similar to singleton mode, but once enabled, detached mode is permanent for this adapter.
	*/
	private boolean mDetachedMode = false;
	/**
	* True iff we are in the process of handling a dataset change.
	*/
	private boolean mInDataSetChange = false;
	/**
	* Need to keep this around to look up pager title strings.
	*/
	private Resources mResources;
	/**
	* This isn't great to create a circular dependency, but our usage of {@link #getPageTitle(int)}
	* requires knowing which page is the currently visible to dynamically name offscreen pages
	* "newer" and "older". And {@link #setPrimaryItem(ViewGroup, int, Object)} does not work well
	* because it isn't updated as often as {@link ViewPager#getCurrentItem()} is.
	* <p>
	* We must be careful to null out this reference when the pager and adapter are decoupled to
	* minimize dangling references.
	*/
	private ViewPager mPager;
	private boolean mSanitizedHtml;

	private boolean mStopListeningMode = false;

	/**
	* After {@link #stopListening()} is called, this contains the last-known count of this adapter.
	* We keep this around and use it in lieu of the Cursor's true count until imminent destruction
	* to satisfy two opposing requirements:
	* <ol>
	* <li>The ViewPager always likes to know about all dataset changes via notifyDatasetChanged.
	* <li>Destructive changes during pager destruction (e.g. mode transition from conversation mode
	* to list mode) must be ignored, or else ViewPager will shift focus onto a neighboring
	* conversation and <b>mark it read</b>.
	* </ol>
	*
	*/
	private int mLastKnownCount;

	private static final String LOG_TAG = ConversationPagerController.LOG_TAG;

	private static final String BUNDLE_DETACHED_MODE =
	ConversationPagerAdapter.class.getName() + "-detachedmode";

	public ConversationPagerAdapter(Resources res, FragmentManager fm, Account account,
	Folder folder, Conversation initialConversation) {
	super(fm, false /* enableSavedStates */);
	mResources = res;
	mCommonFragmentArgs = AbstractConversationViewFragment.makeBasicArgs(account);
	mInitialConversation = initialConversation;
	mAccount = account;
	mFolder = folder;
	mSanitizedHtml = mAccount.supportsCapability
	(UIProvider.AccountCapabilities.SANITIZED_HTML);
	}

	public boolean matches(Account account, Folder folder) {
	return mAccount != null && mFolder != null && mAccount.matches(account)
	&& mFolder.equals(folder);
	}

	public void setSingletonMode(boolean enabled) {
	if (mSingletonMode != enabled) {
	mSingletonMode = enabled;
	notifyDataSetChanged();
	}
	}

	public boolean isSingletonMode() {
	return mSingletonMode;
	}

	public boolean isDetached() {
	return mDetachedMode;
	}

	/**
	* Returns true if singleton mode or detached mode have been enabled, or if the current cursor
	* is null.
	* @param cursor the current conversation cursor (obtained through {@link #getCursor()}.
	* @return
	*/
	public boolean isPagingDisabled(Cursor cursor) {
	return mSingletonMode \|\| mDetachedMode \|\| cursor == null;
	}

	private ConversationCursor getCursor() {
	if (mDetachedMode) {
	// In detached mode, the pager is decoupled from the cursor. Nothing should rely on the
	// cursor at this point.
	return null;
	}
	if (mController == null) {
	// Happens when someone calls setActivityController(null) on us. This is done in
	// ConversationPagerController.stopListening() to indicate that the Conversation View
	// is going away very soon.
	LogUtils.i(LOG_TAG, "Pager adapter has a null controller. If the conversation view"
	+ " is going away, this is fine. Otherwise, the state is inconsistent");
	return null;
	}

	return mController.getConversationListCursor();
	}

	@Override
	public Fragment getItem(int position) {
	final Conversation c;
	final ConversationCursor cursor = getCursor();

	if (isPagingDisabled(cursor)) {
	// cursor-less adapter is a size-1 cursor that points to mInitialConversation.
	// sanity-check
	if (position != 0) {
	LogUtils.wtf(LOG_TAG, "pager cursor is null and position is non-zero: %d",
	position);
	}
	c = getDefaultConversation();
	c.position = 0;
	} else {
	if (!cursor.moveToPosition(position)) {
	LogUtils.wtf(LOG_TAG, "unable to seek to ConversationCursor pos=%d (%s)", position,
	cursor);
	return null;
	}
	cursor.notifyUIPositionChange();
	c = cursor.getConversation();
	c.position = position;
	}
	final AbstractConversationViewFragment f = getConversationViewFragment(c);
	LogUtils.d(LOG_TAG, "IN PagerAdapter.getItem, frag=%s conv=%s this=%s", f, c, this);
	return f;
	}

	private AbstractConversationViewFragment getConversationViewFragment(Conversation c) {
	if (mSanitizedHtml) {
	return ConversationViewFragment.newInstance(mCommonFragmentArgs, c);
	} else {
	return SecureConversationViewFragment.newInstance(mCommonFragmentArgs, c);
	}
	}

	@Override
	public int getCount() {
	if (mStopListeningMode) {
	if (LogUtils.isLoggable(LOG_TAG, LogUtils.DEBUG)) {
	final Cursor cursor = getCursor();
	LogUtils.d(LOG_TAG,
	"IN CPA.getCount stopListeningMode, returning lastKnownCount=%d."
	+ " cursor=%s real count=%s", mLastKnownCount, cursor,
	(cursor != null) ? cursor.getCount() : "N/A");
	}
	return mLastKnownCount;
	}

	final Cursor cursor = getCursor();
	if (isPagingDisabled(cursor)) {
	LogUtils.d(LOG_TAG, "IN CPA.getCount, returning 1 (effective singleton). cursor=%s",
	cursor);
	return 1;
	}
	return cursor.getCount();
	}

	@Override
	public int getItemPosition(Object item) {
	if (!(item instanceof AbstractConversationViewFragment)) {
	LogUtils.wtf(LOG_TAG, "getItemPosition received unexpected item: %s", item);
	}

	final AbstractConversationViewFragment fragment = (AbstractConversationViewFragment) item;
	return getConversationPosition(fragment.getConversation());
	}

	@Override
	public void setPrimaryItem(ViewGroup container, int position, Object object) {
	LogUtils.d(LOG_TAG, "IN PagerAdapter.setPrimaryItem, pos=%d, frag=%s", position,
	object);
	super.setPrimaryItem(container, position, object);
	}

	@Override
	public Parcelable saveState() {
	LogUtils.d(LOG_TAG, "IN PagerAdapter.saveState. this=%s", this);
	Bundle state = (Bundle) super.saveState(); // superclass uses a Bundle
	if (state == null) {
	state = new Bundle();
	}
	state.putBoolean(BUNDLE_DETACHED_MODE, mDetachedMode);
	return state;
	}

	@Override
	public void restoreState(Parcelable state, ClassLoader loader) {
	super.restoreState(state, loader);
	if (state != null) {
	Bundle b = (Bundle) state;
	b.setClassLoader(loader);
	final boolean detached = b.getBoolean(BUNDLE_DETACHED_MODE);
	setDetachedMode(detached);
	}
	LogUtils.d(LOG_TAG, "OUT PagerAdapter.restoreState. this=%s", this);
	}

	private void setDetachedMode(boolean detached) {
	if (mDetachedMode == detached) {
	return;
	}
	mDetachedMode = detached;
	if (mDetachedMode) {
	mController.setDetachedMode();
	}
	notifyDataSetChanged();
	}

	@Override
	public String toString() {
	final StringBuilder sb = new StringBuilder(super.toString());
	sb.setLength(sb.length() - 1);
	sb.append(" detachedMode=");
	sb.append(mDetachedMode);
	sb.append(" singletonMode=");
	sb.append(mSingletonMode);
	sb.append(" mController=");
	sb.append(mController);
	sb.append(" mPager=");
	sb.append(mPager);
	sb.append(" mStopListening=");
	sb.append(mStopListeningMode);
	sb.append(" mLastKnownCount=");
	sb.append(mLastKnownCount);
	sb.append(" cursor=");
	sb.append(getCursor());
	sb.append("}");
	return sb.toString();
	}

	@Override
	public void notifyDataSetChanged() {
	if (mInDataSetChange) {
	LogUtils.i(LOG_TAG, "CPA ignoring dataset change generated during dataset change");
	return;
	}

	mInDataSetChange = true;
	// If we are in detached mode, changes to the cursor are of no interest to us, but they may
	// be to parent classes.

	// when the currently visible item disappears from the dataset:
	// if the new version of the currently visible item has zero messages:
	// notify the list controller so it can handle this 'current conversation gone' case
	// (by backing out of conversation mode)
	// else
	// 'detach' the conversation view from the cursor, keeping the current item as-is but
	// disabling swipe (effectively the same as singleton mode)
	if (mController != null && !mDetachedMode && mPager != null) {
	final Conversation currConversation = mController.getCurrentConversation();
	final int pos = getConversationPosition(currConversation);
	final ConversationCursor cursor = getCursor();
	if (pos == POSITION_NONE && cursor != null && currConversation != null) {
	// enable detached mode and do no more here. the fragment itself will figure out
	// if the conversation is empty (using message list cursor) and back out if needed.
	setDetachedMode(true);
	LogUtils.i(LOG_TAG, "CPA: current conv is gone, reverting to detached mode. c=%s",
	currConversation.uri);

	final int currentItem = mPager.getCurrentItem();

	final AbstractConversationViewFragment fragment =
	(AbstractConversationViewFragment) getFragmentAt(currentItem);

	if (fragment != null) {
	fragment.onDetachedModeEntered();
	} else {
	LogUtils.e(LOG_TAG,
	"CPA: notifyDataSetChanged: fragment null, current item: %d",
	currentItem);
	}
	} else {
	// notify unaffected fragment items of the change, so they can re-render
	// (the change may have been to the labels for a single conversation, for example)
	final AbstractConversationViewFragment frag = (cursor == null) ? null :
	(AbstractConversationViewFragment) getFragmentAt(pos);
	if (frag != null && cursor.moveToPosition(pos) && frag.isUserVisible()) {
	// reload what we think is in the current position.
	final Conversation conv = cursor.getConversation();
	conv.position = pos;
	frag.onConversationUpdated(conv);
	mController.setCurrentConversation(conv);
	}
	}
	} else {
	LogUtils.d(LOG_TAG, "in CPA.notifyDataSetChanged, doing nothing. this=%s", this);
	}

	super.notifyDataSetChanged();
	mInDataSetChange = false;
	}

	@Override
	public void setItemVisible(Fragment item, boolean visible) {
	super.setItemVisible(item, visible);
	final AbstractConversationViewFragment fragment = (AbstractConversationViewFragment) item;
	fragment.setExtraUserVisibleHint(visible);
	}

	private Conversation getDefaultConversation() {
	Conversation c = (mController != null) ? mController.getCurrentConversation() : null;
	if (c == null) {
	c = mInitialConversation;
	}
	return c;
	}

	public int getConversationPosition(Conversation conv) {
	if (conv == null) {
	return POSITION_NONE;
	}

	final ConversationCursor cursor = getCursor();
	if (isPagingDisabled(cursor)) {
	final Conversation def = getDefaultConversation();
	if (!conv.equals(def)) {
	LogUtils.d(LOG_TAG, "unable to find conversation in singleton mode. c=%s def=%s",
	conv, def);
	return POSITION_NONE;
	}
	LogUtils.d(LOG_TAG, "in CPA.getConversationPosition returning 0, conv=%s this=%s",
	conv, this);
	return 0;
	}

	// cursor is guaranteed to be non-null because isPagingDisabled() above checks for null
	// cursor.

	int result = POSITION_NONE;
	final int pos = cursor.getConversationPosition(conv.id);
	if (pos >= 0) {
	LogUtils.d(LOG_TAG, "pager adapter found repositioned convo %s at pos=%d",
	conv, pos);
	result = pos;
	}

	LogUtils.d(LOG_TAG, "in CPA.getConversationPosition (normal), conv=%s pos=%s this=%s",
	conv, result, this);
	return result;
	}

	public void setPager(ViewPager pager) {
	if (mPager != null) {
	mPager.setOnPageChangeListener(null);
	}
	mPager = pager;
	if (mPager != null) {
	mPager.setOnPageChangeListener(this);
	}
	}

	public void setActivityController(ActivityController controller) {
	boolean wasNull = (mController == null);
	if (mController != null && !mStopListeningMode) {
	mController.unregisterConversationListObserver(mListObserver);
	mController.unregisterFolderObserver(mFolderObserver);
	}
	mController = controller;
	if (mController != null && !mStopListeningMode) {
	mController.registerConversationListObserver(mListObserver);
	mFolderObserver.initialize(mController);
	if (!wasNull) {
	notifyDataSetChanged();
	}
	} else {
	// We're being torn down; do not notify.
	// Let the pager controller manage pager lifecycle.
	}
	}

	/**
	* See {@link ConversationPagerController#stopListening()}.
	*/
	public void stopListening() {
	if (mStopListeningMode) {
	// Do nothing since we're already in stop listening mode. This avoids repeated
	// unregister observer calls.
	return;
	}

	// disable the observer, but save off the current count, in case the Pager asks for it
	// from now until imminent destruction

	if (mController != null) {
	mController.unregisterConversationListObserver(mListObserver);
	mFolderObserver.unregisterAndDestroy();
	}
	mLastKnownCount = getCount();
	mStopListeningMode = true;
	LogUtils.d(LOG_TAG, "CPA.stopListening, this=%s", this);
	}

	@Override
	public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
	// no-op
	}

	@Override
	public void onPageSelected(int position) {
	if (mController == null) {
	return;
	}
	final ConversationCursor cursor = getCursor();
	if (cursor == null \|\| !cursor.moveToPosition(position)) {
	// No valid cursor or it doesn't have the position we want. Bail.
	return;
	}
	final Conversation c = cursor.getConversation();
	c.position = position;
	LogUtils.d(LOG_TAG, "pager adapter setting current conv: %s", c);
	mController.setCurrentConversation(c);
	}

	@Override
	public void onPageScrollStateChanged(int state) {
	// no-op
	}

	// update the pager dataset as the Controller's cursor changes
	private class ListObserver extends DataSetObserver {
	@Override
	public void onChanged() {
	notifyDataSetChanged();
	}
	@Override
	public void onInvalidated() {
	}
	}

	}