1 files changed, 85 insertions, 0 deletions
diff --git a/src/com/android/dreams/phototable/CursorPhotoSource.java b/src/com/android/dreams/phototable/CursorPhotoSource.java
new file mode 100644
index 0000000..f010a92
--- /dev/null
+++ b/src/com/android/dreams/phototable/CursorPhotoSource.java
@@ -0,0 +1,85 @@
+/*
+ * Copyright (C) 2013 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.dreams.phototable;
+
+import android.content.Context;
+import android.content.SharedPreferences;
+import android.database.Cursor;
+
+/**
+ * Common implementation for sources that load images from a cursor.
+ */
+public abstract class CursorPhotoSource extends PhotoSource {
+
+    // An invalid cursor position to represent the uninitialized state.
+    protected static final int UNINITIALIZED = -1;
+    // An invalid cursor position to represent the error state.
+    protected static final int INVALID = -2;
+
+    public CursorPhotoSource(Context context, SharedPreferences settings) {
+        super(context, settings);
+    }
+
+    public CursorPhotoSource(Context context, SharedPreferences settings, PhotoSource fallback) {
+      super(context, settings, fallback);
+    }
+
+    @Override
+    protected ImageData naturalNext(ImageData current) {
+        if (current.cursor == null || current.cursor.isClosed()) {
+            openCursor(current);
+        }
+        findPosition(current);
+        current.cursor.moveToPosition(current.position);
+        current.cursor.moveToNext();
+        ImageData data = null;
+        if (!current.cursor.isAfterLast()) {
+            data = unpackImageData(current.cursor, null);
+            data.cursor = current.cursor;
+            data.position = current.cursor.getPosition();
+        }
+        return data;
+    }
+
+    @Override
+    protected ImageData naturalPrevious(ImageData current) {
+        if (current.cursor == null || current.cursor.isClosed()) {
+            openCursor(current);
+        }
+        findPosition(current);
+        current.cursor.moveToPosition(current.position);
+        current.cursor.moveToPrevious();
+        ImageData data = null;
+        if (!current.cursor.isBeforeFirst()) {
+            data = unpackImageData(current.cursor, null);
+            data.cursor = current.cursor;
+            data.position = current.cursor.getPosition();
+        }
+        return data;
+    }
+
+    @Override
+    protected void donePaging(ImageData current) {
+        if (current.cursor != null && !current.cursor.isClosed()) {
+            current.cursor.close();
+        }
+    }
+
+    protected abstract void openCursor(ImageData data);
+    protected abstract void findPosition(ImageData data);
+    protected abstract ImageData unpackImageData(Cursor cursor, ImageData data);
+}
+