| /* |
| * Copyright (C) 2007 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.music; |
| |
| import android.database.AbstractCursor; |
| import android.database.Cursor; |
| import android.database.DataSetObserver; |
| import android.util.Log; |
| |
| /** |
| * A variant of MergeCursor that sorts the cursors being merged. If decent |
| * performance is ever obtained, it can be put back under android.database. |
| */ |
| public class SortCursor extends AbstractCursor |
| { |
| private static final String TAG = "SortCursor"; |
| private Cursor mCursor; // updated in onMove |
| private Cursor[] mCursors; |
| private int [] mSortColumns; |
| private final int ROWCACHESIZE = 64; |
| private int mRowNumCache[] = new int[ROWCACHESIZE]; |
| private int mCursorCache[] = new int[ROWCACHESIZE]; |
| private int mCurRowNumCache[][]; |
| private int mLastCacheHit = -1; |
| |
| private DataSetObserver mObserver = new DataSetObserver() { |
| |
| @Override |
| public void onChanged() { |
| // Reset our position so the optimizations in move-related code |
| // don't screw us over |
| mPos = -1; |
| } |
| |
| @Override |
| public void onInvalidated() { |
| mPos = -1; |
| } |
| }; |
| |
| public SortCursor(Cursor[] cursors, String sortcolumn) |
| { |
| mCursors = cursors; |
| |
| int length = mCursors.length; |
| mSortColumns = new int[length]; |
| for (int i = 0 ; i < length ; i++) { |
| if (mCursors[i] == null) continue; |
| |
| // Register ourself as a data set observer |
| mCursors[i].registerDataSetObserver(mObserver); |
| |
| mCursors[i].moveToFirst(); |
| |
| // We don't catch the exception |
| mSortColumns[i] = mCursors[i].getColumnIndexOrThrow(sortcolumn); |
| } |
| mCursor = null; |
| String smallest = ""; |
| for (int j = 0 ; j < length; j++) { |
| if (mCursors[j] == null || mCursors[j].isAfterLast()) |
| continue; |
| String current = mCursors[j].getString(mSortColumns[j]); |
| if (mCursor == null || current.compareToIgnoreCase(smallest) < 0) { |
| smallest = current; |
| mCursor = mCursors[j]; |
| } |
| } |
| |
| for (int i = mRowNumCache.length - 1; i >= 0; i--) { |
| mRowNumCache[i] = -2; |
| } |
| mCurRowNumCache = new int[ROWCACHESIZE][length]; |
| } |
| |
| @Override |
| public int getCount() |
| { |
| int count = 0; |
| int length = mCursors.length; |
| for (int i = 0 ; i < length ; i++) { |
| if (mCursors[i] != null) { |
| count += mCursors[i].getCount(); |
| } |
| } |
| return count; |
| } |
| |
| @Override |
| public boolean onMove(int oldPosition, int newPosition) |
| { |
| if (oldPosition == newPosition) |
| return true; |
| |
| /* Find the right cursor |
| * Because the client of this cursor (the listadapter/view) tends |
| * to jump around in the cursor somewhat, a simple cache strategy |
| * is used to avoid having to search all cursors from the start. |
| * TODO: investigate strategies for optimizing random access and |
| * reverse-order access. |
| */ |
| |
| int cache_entry = newPosition % ROWCACHESIZE; |
| |
| if (mRowNumCache[cache_entry] == newPosition) { |
| int which = mCursorCache[cache_entry]; |
| mCursor = mCursors[which]; |
| if (mCursor == null) { |
| Log.w(TAG, "onMove: cache results in a null cursor."); |
| return false; |
| } |
| mCursor.moveToPosition(mCurRowNumCache[cache_entry][which]); |
| mLastCacheHit = cache_entry; |
| return true; |
| } |
| |
| mCursor = null; |
| int length = mCursors.length; |
| |
| if (mLastCacheHit >= 0) { |
| for (int i = 0; i < length; i++) { |
| if (mCursors[i] == null) continue; |
| mCursors[i].moveToPosition(mCurRowNumCache[mLastCacheHit][i]); |
| } |
| } |
| |
| if (newPosition < oldPosition || oldPosition == -1) { |
| for (int i = 0 ; i < length; i++) { |
| if (mCursors[i] == null) continue; |
| mCursors[i].moveToFirst(); |
| } |
| oldPosition = 0; |
| } |
| if (oldPosition < 0) { |
| oldPosition = 0; |
| } |
| |
| // search forward to the new position |
| int smallestIdx = -1; |
| for(int i = oldPosition; i <= newPosition; i++) { |
| String smallest = ""; |
| smallestIdx = -1; |
| for (int j = 0 ; j < length; j++) { |
| if (mCursors[j] == null || mCursors[j].isAfterLast()) { |
| continue; |
| } |
| String current = mCursors[j].getString(mSortColumns[j]); |
| if (smallestIdx < 0 || current.compareToIgnoreCase(smallest) < 0) { |
| smallest = current; |
| smallestIdx = j; |
| } |
| } |
| if (i == newPosition) break; |
| if (mCursors[smallestIdx] != null) { |
| mCursors[smallestIdx].moveToNext(); |
| } |
| } |
| mCursor = mCursors[smallestIdx]; |
| mRowNumCache[cache_entry] = newPosition; |
| mCursorCache[cache_entry] = smallestIdx; |
| for (int i = 0; i < length; i++) { |
| if (mCursors[i] != null) { |
| mCurRowNumCache[cache_entry][i] = mCursors[i].getPosition(); |
| } |
| } |
| mLastCacheHit = -1; |
| return true; |
| } |
| |
| @Override |
| public String getString(int column) |
| { |
| return mCursor.getString(column); |
| } |
| |
| @Override |
| public short getShort(int column) |
| { |
| return mCursor.getShort(column); |
| } |
| |
| @Override |
| public int getInt(int column) |
| { |
| return mCursor.getInt(column); |
| } |
| |
| @Override |
| public long getLong(int column) |
| { |
| return mCursor.getLong(column); |
| } |
| |
| @Override |
| public float getFloat(int column) |
| { |
| return mCursor.getFloat(column); |
| } |
| |
| @Override |
| public double getDouble(int column) |
| { |
| return mCursor.getDouble(column); |
| } |
| |
| @Override |
| public int getType(int column) { |
| return mCursor.getType(column); |
| } |
| |
| @Override |
| public boolean isNull(int column) |
| { |
| return mCursor.isNull(column); |
| } |
| |
| @Override |
| public byte[] getBlob(int column) |
| { |
| return mCursor.getBlob(column); |
| } |
| |
| @Override |
| public String[] getColumnNames() |
| { |
| if (mCursor != null) { |
| return mCursor.getColumnNames(); |
| } else { |
| // All of the cursors may be empty, but they can still return |
| // this information. |
| int length = mCursors.length; |
| for (int i = 0 ; i < length ; i++) { |
| if (mCursors[i] != null) { |
| return mCursors[i].getColumnNames(); |
| } |
| } |
| throw new IllegalStateException("No cursor that can return names"); |
| } |
| } |
| |
| @Override |
| public void deactivate() |
| { |
| int length = mCursors.length; |
| for (int i = 0 ; i < length ; i++) { |
| if (mCursors[i] == null) continue; |
| mCursors[i].deactivate(); |
| } |
| } |
| |
| @Override |
| public void close() { |
| int length = mCursors.length; |
| for (int i = 0 ; i < length ; i++) { |
| if (mCursors[i] == null) continue; |
| mCursors[i].close(); |
| } |
| } |
| |
| @Override |
| public void registerDataSetObserver(DataSetObserver observer) { |
| int length = mCursors.length; |
| for (int i = 0 ; i < length ; i++) { |
| if (mCursors[i] != null) { |
| mCursors[i].registerDataSetObserver(observer); |
| } |
| } |
| } |
| |
| @Override |
| public void unregisterDataSetObserver(DataSetObserver observer) { |
| int length = mCursors.length; |
| for (int i = 0 ; i < length ; i++) { |
| if (mCursors[i] != null) { |
| mCursors[i].unregisterDataSetObserver(observer); |
| } |
| } |
| } |
| |
| @Override |
| public boolean requery() |
| { |
| int length = mCursors.length; |
| for (int i = 0 ; i < length ; i++) { |
| if (mCursors[i] == null) continue; |
| |
| if (mCursors[i].requery() == false) { |
| return false; |
| } |
| } |
| |
| return true; |
| } |
| } |