Add DragSortCursorAdapter helper classes

These classes take care of virtualizing the reordering of
data coming from a Cursor. They act just like the
CursorAdapter, ResourceCursorAdapter, and SimpleCursorAdapter
classes from the android library.

Also, since it is common to implement the drag-sort Listeners
as part of a custom ListAdapter, DSLV now recognizes if
the ListAdapter given to it implements a Listener interface.
If so, the provided ListAdapter replaces the current
Listeners.

demo/AndroidManifest.xml

@@ -23,5 +23,7 @@
                   android:label="Background handle" />
         <activity android:name="Sections"
                   android:label="Sections" />
+        <activity android:name="CursorDSLV"
+                  android:label="DB backed" />
     </application>
 </manifest> 

demo/res/layout/cursor_main.xml

@@ -0,0 +1,19 @@
+<?xml version="1.0" encoding="utf-8"?>
+<com.mobeta.android.dslv.DragSortListView
+    xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:dslv="http://schemas.android.com/apk/res/com.mobeta.android.demodslv"
+    android:id="@android:id/list"
+    android:layout_width="fill_parent"
+    android:layout_height="fill_parent"
+    android:padding="5dp"
+    android:layout_margin="10dp"
+    android:dividerHeight="1px"
+    dslv:drag_enabled="true"
+    dslv:collapsed_height="1px"
+    dslv:drag_scroll_start="0.33"
+    dslv:float_alpha="0.6"
+    dslv:slide_shuffle_speed="0.3"
+    dslv:drag_start_mode="onDown"
+    dslv:drag_handle_id="@id/drag_handle"
+    dslv:remove_enabled="true"
+    dslv:remove_mode="flingLeft" />

demo/res/values/strings.xml

@@ -7,6 +7,7 @@
         <item>Warp</item>
         <item>Background handle</item>
         <item>Sections</item>
+        <item>CursorAdapter</item>
     </string-array>
     <string-array name="activity_descs">
         <item>
@@ -32,6 +33,11 @@
             Demonstrates floating View control from a custom
             FloatViewManager. Restrict item drags to list sections.
         </item>
+        <item>
+            Demonstrates usage of the DragSortCursorAdapter class,
+            which abstracts drag-sorts with a remapping of Cursor
+            positions to ListView positions.
+        </item>
     </string-array>
     <string name="ok">OK</string>
     <string name="cancel">Cancel</string>

demo/src/com/mobeta/android/demodslv/AbstractCursorLoader.java

@@ -0,0 +1,135 @@
+/*
+ * Copyright (c) 2011-2012 CommonsWare, LLC
+ * portions Copyright (C) 2011 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.mobeta.android.demodslv;
+
+import android.support.v4.content.AsyncTaskLoader;
+import android.content.Context;
+import android.database.Cursor;
+
+abstract public class AbstractCursorLoader extends AsyncTaskLoader<Cursor> {
+  abstract protected Cursor buildCursor();
+  Cursor lastCursor=null;
+
+  public AbstractCursorLoader(Context context) {
+    super(context);
+  }
+
+  /** 
+   * Runs on a worker thread, loading in our data. Delegates
+   * the real work to concrete subclass' buildCursor() method. 
+   */
+  @Override
+  public Cursor loadInBackground() {
+    Cursor cursor=buildCursor();
+
+    if (cursor!=null) {
+      // Ensure the cursor window is filled
+      cursor.getCount();
+    }
+
+    return(cursor);
+  }
+
+  /**
+   * Runs on the UI thread, routing the results from the
+   * background thread to whatever is using the Cursor
+   * (e.g., a CursorAdapter).
+   */
+  @Override
+  public void deliverResult(Cursor cursor) {
+    if (isReset()) {
+      // An async query came in while the loader is stopped
+      if (cursor!=null) {
+        cursor.close();
+      }
+
+      return;
+    }
+
+    Cursor oldCursor=lastCursor;
+    lastCursor=cursor;
+
+    if (isStarted()) {
+      super.deliverResult(cursor);
+    }
+
+    if (oldCursor!=null && oldCursor!=cursor && !oldCursor.isClosed()) {
+      oldCursor.close();
+    }
+  }
+
+  /**
+   * Starts an asynchronous load of the list data.
+   * When the result is ready the callbacks will be called
+   * on the UI thread. If a previous load has been completed
+   * and is still valid the result may be passed to the
+   * callbacks immediately.
+   * 
+   * Must be called from the UI thread.
+   */
+  @Override
+  protected void onStartLoading() {
+    if (lastCursor!=null) {
+      deliverResult(lastCursor);
+    }
+    if (takeContentChanged() || lastCursor==null) {
+      forceLoad();
+    }
+  }
+
+  /**
+   * Must be called from the UI thread, triggered by a
+   * call to stopLoading().
+   */
+  @Override
+  protected void onStopLoading() {
+    // Attempt to cancel the current load task if possible.
+    cancelLoad();
+  }
+
+  /**
+   * Must be called from the UI thread, triggered by a
+   * call to cancel(). Here, we make sure our Cursor
+   * is closed, if it still exists and is not already closed.
+   */
+  @Override
+  public void onCanceled(Cursor cursor) {
+    if (cursor!=null && !cursor.isClosed()) {
+      cursor.close();
+    }
+  }
+
+  /**
+   * Must be called from the UI thread, triggered by a
+   * call to reset(). Here, we make sure our Cursor
+   * is closed, if it still exists and is not already closed.
+   */
+  @Override
+  protected void onReset() {
+    super.onReset();
+
+    // Ensure the loader is stopped
+    onStopLoading();
+
+    if (lastCursor!=null && !lastCursor.isClosed()) {
+      lastCursor.close();
+    }
+
+    lastCursor=null;
+  }
+}

demo/src/com/mobeta/android/demodslv/ContentChangingTask.java

@@ -0,0 +1,33 @@
+/* Copyright (c) 2012 -- CommonsWare, LLC
+
+   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.mobeta.android.demodslv;
+
+import android.os.AsyncTask;
+import android.support.v4.content.Loader;
+
+public abstract class ContentChangingTask<T1, T2, T3> extends
+    AsyncTask<T1, T2, T3> {
+  private Loader<?> loader=null;
+
+  ContentChangingTask(Loader<?> loader) {
+    this.loader=loader;
+  }
+
+  @Override
+  protected void onPostExecute(T3 param) {
+    loader.onContentChanged();
+  }
+}

demo/src/com/mobeta/android/demodslv/CursorDSLV.java

@@ -0,0 +1,111 @@
+package com.mobeta.android.demodslv;
+
+import java.util.List;
+import java.util.ArrayList;
+
+import com.mobeta.android.dslv.DragSortListView;
+import com.mobeta.android.dslv.SimpleDragSortCursorAdapter;
+import com.mobeta.android.dslv.SimpleFloatViewManager;
+
+import android.content.Context;
+import android.content.ContentValues;
+import android.database.Cursor;
+import android.database.sqlite.SQLiteDatabase;
+import android.database.sqlite.SQLiteOpenHelper;
+import android.os.Bundle;
+import android.support.v4.app.FragmentActivity;
+import android.support.v4.app.LoaderManager.LoaderCallbacks;
+import android.support.v4.content.Loader;
+import android.widget.ArrayAdapter;
+import android.widget.TextView;
+import android.view.View;
+import android.view.ViewGroup;
+
+
+public class CursorDSLV extends FragmentActivity implements LoaderCallbacks<Cursor> {
+
+    private SimpleDragSortCursorAdapter adapter;
+
+    private SQLiteOpenHelper mOpenHelper;
+
+    private class OpenHelper extends SQLiteOpenHelper {
+
+        private static final int DATABASE_VERSION = 1;
+        private static final String DATABASE_NAME = "jazz";
+        public static final String TABLE_NAME = "jazz_artists";
+        private static final String ARTIST_NAME = "name";
+        private static final String TABLE_CREATE =
+                "CREATE TABLE " + TABLE_NAME + " (" +
+                "_id PRIMARY_KEY, " +
+                ARTIST_NAME + " TEXT);";
+
+        private Context mContext;
+
+        OpenHelper(Context context) {
+            super(context, DATABASE_NAME, null, DATABASE_VERSION);
+            mContext = context;
+        }
+
+        @Override
+        public void onCreate(SQLiteDatabase db) {
+            db.execSQL(TABLE_CREATE);
+
+            // get jazz names
+            String[] artistNames = mContext.getResources().getStringArray(R.array.jazz_artist_names);
+
+            ContentValues v = new ContentValues();
+            int id = 0;
+            for (String artist : artistNames) {
+                v.put("_id", id);
+                v.put(ARTIST_NAME, artist);
+                db.insert(TABLE_NAME, null, v);
+                v.clear();
+                id++;
+            }
+        }
+
+        @Override
+        public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {
+            // do nothing
+        }
+    }
+
+
+    /** Called when the activity is first created. */
+    @Override
+    public void onCreate(Bundle savedInstanceState) {
+        super.onCreate(savedInstanceState);
+        setContentView(R.layout.cursor_main);
+
+        String[] cols = {"name"};
+        int[] ids = {R.id.text};
+        adapter = new SimpleDragSortCursorAdapter(this,
+                R.layout.list_item_handle_right, null, cols, ids, 0);
+
+        DragSortListView dslv = (DragSortListView) findViewById(android.R.id.list);
+        dslv.setAdapter(adapter);
+
+        mOpenHelper = new OpenHelper(this);
+        getSupportLoaderManager().initLoader(0, null, this);
+    }
+
+    //Loader callbacks
+    @Override
+    public Loader<Cursor> onCreateLoader(int loaderId, Bundle args) {
+        Loader<Cursor> loader = new SQLiteCursorLoader(this, mOpenHelper,
+                "SELECT _id, name "
+                + "FROM " + OpenHelper.TABLE_NAME
+                + " ORDER BY name", null);
+        return loader;
+    }
+
+    @Override
+    public void onLoadFinished(Loader<Cursor> loader, Cursor cursor) {
+        adapter.changeCursor(cursor);
+    }
+
+    @Override
+    public void onLoaderReset(Loader<Cursor> loader) {
+        adapter.changeCursor(null);
+    }
+}