| /* |
| * Copyright (C) 2015 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.messaging.ui; |
| |
| import android.content.Context; |
| import android.database.ContentObserver; |
| import android.database.Cursor; |
| import android.database.DataSetObserver; |
| import android.os.Handler; |
| import android.support.v7.widget.RecyclerView; |
| import android.util.Log; |
| import android.view.ViewGroup; |
| import android.widget.FilterQueryProvider; |
| |
| /** |
| * Copy of CursorAdapter suited for RecyclerView. |
| * |
| * TODO: BUG 16327984. Replace this with a framework supported CursorAdapter for |
| * RecyclerView when one is available. |
| */ |
| public abstract class CursorRecyclerAdapter<VH extends RecyclerView.ViewHolder> |
| extends RecyclerView.Adapter<VH> { |
| /** |
| * This field should be made private, so it is hidden from the SDK. |
| * {@hide} |
| */ |
| protected boolean mDataValid; |
| /** |
| * This field should be made private, so it is hidden from the SDK. |
| * {@hide} |
| */ |
| protected boolean mAutoRequery; |
| /** |
| * This field should be made private, so it is hidden from the SDK. |
| * {@hide} |
| */ |
| protected Cursor mCursor; |
| /** |
| * This field should be made private, so it is hidden from the SDK. |
| * {@hide} |
| */ |
| protected Context mContext; |
| /** |
| * This field should be made private, so it is hidden from the SDK. |
| * {@hide} |
| */ |
| protected int mRowIDColumn; |
| /** |
| * This field should be made private, so it is hidden from the SDK. |
| * {@hide} |
| */ |
| protected ChangeObserver mChangeObserver; |
| /** |
| * This field should be made private, so it is hidden from the SDK. |
| * {@hide} |
| */ |
| protected DataSetObserver mDataSetObserver; |
| /** |
| * This field should be made private, so it is hidden from the SDK. |
| * {@hide} |
| */ |
| protected FilterQueryProvider mFilterQueryProvider; |
| |
| /** |
| * If set the adapter will call requery() on the cursor whenever a content change |
| * notification is delivered. Implies {@link #FLAG_REGISTER_CONTENT_OBSERVER}. |
| * |
| * @deprecated This option is discouraged, as it results in Cursor queries |
| * being performed on the application's UI thread and thus can cause poor |
| * responsiveness or even Application Not Responding errors. As an alternative, |
| * use {@link android.app.LoaderManager} with a {@link android.content.CursorLoader}. |
| */ |
| @Deprecated |
| public static final int FLAG_AUTO_REQUERY = 0x01; |
| |
| /** |
| * If set the adapter will register a content observer on the cursor and will call |
| * {@link #onContentChanged()} when a notification comes in. Be careful when |
| * using this flag: you will need to unset the current Cursor from the adapter |
| * to avoid leaks due to its registered observers. This flag is not needed |
| * when using a CursorAdapter with a |
| * {@link android.content.CursorLoader}. |
| */ |
| public static final int FLAG_REGISTER_CONTENT_OBSERVER = 0x02; |
| |
| /** |
| * Recommended constructor. |
| * |
| * @param c The cursor from which to get the data. |
| * @param context The context |
| * @param flags Flags used to determine the behavior of the adapter; may |
| * be any combination of {@link #FLAG_AUTO_REQUERY} and |
| * {@link #FLAG_REGISTER_CONTENT_OBSERVER}. |
| */ |
| public CursorRecyclerAdapter(final Context context, final Cursor c, final int flags) { |
| init(context, c, flags); |
| } |
| |
| void init(final Context context, final Cursor c, int flags) { |
| if ((flags & FLAG_AUTO_REQUERY) == FLAG_AUTO_REQUERY) { |
| flags |= FLAG_REGISTER_CONTENT_OBSERVER; |
| mAutoRequery = true; |
| } else { |
| mAutoRequery = false; |
| } |
| final boolean cursorPresent = c != null; |
| mCursor = c; |
| mDataValid = cursorPresent; |
| mContext = context; |
| mRowIDColumn = cursorPresent ? c.getColumnIndexOrThrow("_id") : -1; |
| if ((flags & FLAG_REGISTER_CONTENT_OBSERVER) == FLAG_REGISTER_CONTENT_OBSERVER) { |
| mChangeObserver = new ChangeObserver(); |
| mDataSetObserver = new MyDataSetObserver(); |
| } else { |
| mChangeObserver = null; |
| mDataSetObserver = null; |
| } |
| |
| if (cursorPresent) { |
| if (mChangeObserver != null) { |
| c.registerContentObserver(mChangeObserver); |
| } |
| if (mDataSetObserver != null) { |
| c.registerDataSetObserver(mDataSetObserver); |
| } |
| } |
| } |
| |
| /** |
| * Returns the cursor. |
| * @return the cursor. |
| */ |
| public Cursor getCursor() { |
| return mCursor; |
| } |
| |
| @Override |
| public int getItemCount() { |
| if (mDataValid && mCursor != null) { |
| return mCursor.getCount(); |
| } else { |
| return 0; |
| } |
| } |
| |
| /** |
| * @see android.support.v7.widget.RecyclerView.Adapter#getItem(int) |
| */ |
| public Object getItem(final int position) { |
| if (mDataValid && mCursor != null) { |
| mCursor.moveToPosition(position); |
| return mCursor; |
| } else { |
| return null; |
| } |
| } |
| |
| /** |
| * @see android.support.v7.widget.RecyclerView.Adapter#getItemId(int) |
| */ |
| @Override |
| public long getItemId(final int position) { |
| if (mDataValid && mCursor != null) { |
| if (mCursor.moveToPosition(position)) { |
| return mCursor.getLong(mRowIDColumn); |
| } else { |
| return 0; |
| } |
| } else { |
| return 0; |
| } |
| } |
| |
| @Override |
| public VH onCreateViewHolder(final ViewGroup parent, final int viewType) { |
| return createViewHolder(mContext, parent, viewType); |
| } |
| |
| @Override |
| public void onBindViewHolder(final VH holder, final int position) { |
| if (!mDataValid) { |
| throw new IllegalStateException("this should only be called when the cursor is valid"); |
| } |
| if (!mCursor.moveToPosition(position)) { |
| throw new IllegalStateException("couldn't move cursor to position " + position); |
| } |
| bindViewHolder(holder, mContext, mCursor); |
| } |
| /** |
| * Bind an existing view to the data pointed to by cursor |
| * @param view Existing view, returned earlier by newView |
| * @param context Interface to application's global information |
| * @param cursor The cursor from which to get the data. The cursor is already |
| * moved to the correct position. |
| */ |
| public abstract void bindViewHolder(VH holder, Context context, Cursor cursor); |
| |
| /** |
| * @see android.support.v7.widget.RecyclerView.Adapter#createViewHolder(Context, ViewGroup, int) |
| */ |
| public abstract VH createViewHolder(Context context, ViewGroup parent, int viewType); |
| |
| /** |
| * Change the underlying cursor to a new cursor. If there is an existing cursor it will be |
| * closed. |
| * |
| * @param cursor The new cursor to be used |
| */ |
| public void changeCursor(final Cursor cursor) { |
| final Cursor old = swapCursor(cursor); |
| if (old != null) { |
| old.close(); |
| } |
| } |
| |
| /** |
| * Swap in a new Cursor, returning the old Cursor. Unlike |
| * {@link #changeCursor(Cursor)}, the returned old Cursor is <em>not</em> |
| * closed. |
| * |
| * @param newCursor The new cursor to be used. |
| * @return Returns the previously set Cursor, or null if there wasa not one. |
| * If the given new Cursor is the same instance is the previously set |
| * Cursor, null is also returned. |
| */ |
| public Cursor swapCursor(final Cursor newCursor) { |
| if (newCursor == mCursor) { |
| return null; |
| } |
| final Cursor oldCursor = mCursor; |
| if (oldCursor != null) { |
| if (mChangeObserver != null) { |
| oldCursor.unregisterContentObserver(mChangeObserver); |
| } |
| if (mDataSetObserver != null) { |
| oldCursor.unregisterDataSetObserver(mDataSetObserver); |
| } |
| } |
| mCursor = newCursor; |
| if (newCursor != null) { |
| if (mChangeObserver != null) { |
| newCursor.registerContentObserver(mChangeObserver); |
| } |
| if (mDataSetObserver != null) { |
| newCursor.registerDataSetObserver(mDataSetObserver); |
| } |
| mRowIDColumn = newCursor.getColumnIndexOrThrow("_id"); |
| mDataValid = true; |
| // notify the observers about the new cursor |
| notifyDataSetChanged(); |
| } else { |
| mRowIDColumn = -1; |
| mDataValid = false; |
| // notify the observers about the lack of a data set |
| notifyDataSetChanged(); |
| } |
| return oldCursor; |
| } |
| |
| /** |
| * <p>Converts the cursor into a CharSequence. Subclasses should override this |
| * method to convert their results. The default implementation returns an |
| * empty String for null values or the default String representation of |
| * the value.</p> |
| * |
| * @param cursor the cursor to convert to a CharSequence |
| * @return a CharSequence representing the value |
| */ |
| public CharSequence convertToString(final Cursor cursor) { |
| return cursor == null ? "" : cursor.toString(); |
| } |
| |
| /** |
| * Called when the {@link ContentObserver} on the cursor receives a change notification. |
| * The default implementation provides the auto-requery logic, but may be overridden by |
| * sub classes. |
| * |
| * @see ContentObserver#onChange(boolean) |
| */ |
| protected void onContentChanged() { |
| if (mAutoRequery && mCursor != null && !mCursor.isClosed()) { |
| if (false) { |
| Log.v("Cursor", "Auto requerying " + mCursor + " due to update"); |
| } |
| mDataValid = mCursor.requery(); |
| } |
| } |
| |
| private class ChangeObserver extends ContentObserver { |
| public ChangeObserver() { |
| super(new Handler()); |
| } |
| |
| @Override |
| public boolean deliverSelfNotifications() { |
| return true; |
| } |
| |
| @Override |
| public void onChange(final boolean selfChange) { |
| onContentChanged(); |
| } |
| } |
| |
| private class MyDataSetObserver extends DataSetObserver { |
| @Override |
| public void onChanged() { |
| mDataValid = true; |
| notifyDataSetChanged(); |
| } |
| |
| @Override |
| public void onInvalidated() { |
| mDataValid = false; |
| notifyDataSetChanged(); |
| } |
| } |
| |
| } |