Catch changes to the ListAdapter's data sets

Despite the CursorAdapter documentation, onContentChanged doesn't
appear to have any requery logic by default.

And CursorTreeAdapter doesn't offer to do any such action, or provide
an interface of the same kind as onContentChanged.

So simply replace the adapter whenever the dataset changes. This keeps
the cursor refresh off the UI thread and lets the progress spinner
appear when refreshing.

This is closer to the current recommendation in Cursor.requery()'s
documentation, which is to instead recreate the Cursor in a background
thread.

Note that we can't replace the SimpleCursor*Adapter's Cursor here as
that will trigger the DataSetObserver again, leading to an infinite
loop.

MLPFIM/src/com/bubblesworth/soundboard/mlpfim/AboutActivity.java

@@ -12,6 +12,7 @@
 import android.content.res.AssetFileDescriptor;
 import android.content.res.Resources;
 import android.database.Cursor;
+import android.database.DataSetObserver;
 import android.graphics.Typeface;
 import android.media.AudioManager;
 import android.media.MediaPlayer;
@@ -63,9 +64,24 @@ public boolean setViewValue(View view, Cursor cursor, int columnIndex) {
 		}
 	}
 
-	private ProgressDialog spinner;
+	private GetCreditsCursor taskHolder;
 
 	private class GetCreditsCursor extends AsyncTask<Void, Void, Cursor> {
+		private ProgressDialog spinner;
+
+		@Override
+		protected void onPreExecute() {
+			super.onPreExecute();
+			if (taskHolder != null)
+				taskHolder.cancel(false);
+			taskHolder = this;
+			Resources resources = getResources();
+			spinner = ProgressDialog.show(AboutActivity.this,
+					resources.getString(R.string.dialog_loading_title),
+					resources.getString(R.string.dialog_loading_message), true,
+					false);
+		}
+
 		protected Cursor doInBackground(Void... voids) {
 			String[] columns = { CreditColumns._ID, CreditColumns.CREDIT_NAME,
 					CreditColumns.CREDIT_LINK };
@@ -83,6 +99,21 @@ protected void onPostExecute(Cursor result) {
 
 			adapter.setViewBinder(new AboutViewBinder());
 			setListAdapter(adapter);
+
+			adapter.registerDataSetObserver(new DataSetObserver() {
+				@Override
+				public void onChanged() {
+					new GetCreditsCursor().execute();
+				}
+			});
+			taskHolder = null;
+		}
+
+		@Override
+		protected void onCancelled() {
+			spinner.dismiss();
+			taskHolder = null;
+			super.onCancelled();
 		}
 	}
 
@@ -94,11 +125,6 @@ protected void onPostExecute(Cursor result) {
 	@Override
 	protected void onCreate(Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
-		Resources resources = getResources();
-		spinner = ProgressDialog.show(this,
-				resources.getString(R.string.dialog_loading_title),
-				resources.getString(R.string.dialog_loading_message), true,
-				false);
 		new GetCreditsCursor().execute();
 		onWindowFocusChanged(hasWindowFocus());
 	}

MLPFIM/src/com/bubblesworth/soundboard/mlpfim/SoundChooserActivity.java

@@ -12,6 +12,7 @@
 import android.content.pm.PackageManager;
 import android.content.res.Resources;
 import android.database.Cursor;
+import android.database.DataSetObserver;
 import android.media.AudioManager;
 import android.media.RingtoneManager;
 import android.net.Uri;
@@ -65,9 +66,24 @@ protected Cursor getChildrenCursor(Cursor arg0) {
 		}
 	};
 
-	private ProgressDialog spinner;
+	private GetCategoryCursor taskHolder;
 
 	private class GetCategoryCursor extends AsyncTask<Void, Void, Cursor> {
+		private ProgressDialog spinner;
+
+		@Override
+		protected void onPreExecute() {
+			super.onPreExecute();
+			if (taskHolder != null)
+				taskHolder.cancel(false);
+			taskHolder = this;
+			Resources resources = getResources();
+			spinner = ProgressDialog.show(SoundChooserActivity.this,
+					resources.getString(R.string.dialog_loading_title),
+					resources.getString(R.string.dialog_loading_message), true,
+					false);
+		}
+
 		protected Cursor doInBackground(Void... voids) {
 			String[] columns = { SoundColumns._ID, SoundColumns.DESCRIPTION,
 					SoundColumns.ICON };
@@ -79,31 +95,40 @@ protected void onPostExecute(Cursor result) {
 			spinner.dismiss();
 			if (result.getCount() == 0) {
 				showDialog(DIALOG_NO_CONTENT);
-			} else {
-				SimpleCursorTreeAdapter adapter = new MySimpleCursorTreeAdapter(
-						SoundChooserActivity.this, result,
-						R.layout.icon_expandable_list_item, new String[] {
-								SoundColumns.DESCRIPTION, SoundColumns.ICON },
-						new int[] { R.id.listText, R.id.listIcon },
-						R.layout.icon_list_item, new String[] {
-								SoundColumns.DESCRIPTION, SoundColumns.ICON },
-						new int[] { R.id.listText, R.id.listIcon });
-				setListAdapter(adapter);
 			}
+			SimpleCursorTreeAdapter adapter = new MySimpleCursorTreeAdapter(
+					SoundChooserActivity.this, result,
+					R.layout.icon_expandable_list_item, new String[] {
+							SoundColumns.DESCRIPTION, SoundColumns.ICON },
+					new int[] { R.id.listText, R.id.listIcon },
+					R.layout.icon_list_item, new String[] {
+							SoundColumns.DESCRIPTION, SoundColumns.ICON },
+					new int[] { R.id.listText, R.id.listIcon });
+			setListAdapter(adapter);
+
+			adapter.registerDataSetObserver(new DataSetObserver() {
+				@Override
+				public void onChanged() {
+					new GetCategoryCursor().execute();
+				}
+			});
+			taskHolder = null;
+		}
+
+		@Override
+		protected void onCancelled() {
+			spinner.dismiss();
+			taskHolder = null;
+			super.onCancelled();
 		}
 	}
 
 	/** Called when the activity is first created. */
 	@Override
 	public void onCreate(Bundle savedInstanceState) {
 		super.onCreate(savedInstanceState);
-		Resources resources = getResources();
 		widgetConfig = getIntent().getAction().equals(
 				"com.bubblesworth.soundboard.APPWIDGET_CONFIGURE");
-		spinner = ProgressDialog.show(this,
-				resources.getString(R.string.dialog_loading_title),
-				resources.getString(R.string.dialog_loading_message), true,
-				false);
 		new GetCategoryCursor().execute();
 		if (widgetConfig) {
 			setResult(RESULT_CANCELED);