1 files changed, 47 insertions, 8 deletions

diff --git a/src/com/android/dreams/phototable/PhotoSource.java b/src/com/android/dreams/phototable/PhotoSource.java
index 32d41c7..d9d4ab9 100644
--- a/src/com/android/dreams/phototable/PhotoSource.java
+++ b/src/com/android/dreams/phototable/PhotoSource.java
@@ -23,16 +23,15 @@ import android.database.Cursor;
 import android.graphics.Bitmap;
 import android.graphics.BitmapFactory;
 import android.graphics.Matrix;
-import android.net.Uri;
-import android.provider.MediaStore;
 import android.util.Log;
 
+import java.io.BufferedInputStream;
 import java.io.FileNotFoundException;
-import java.io.InputStream;
 import java.io.IOException;
-import java.io.BufferedInputStream;
+import java.io.InputStream;
 import java.util.Collection;
 import java.util.Collections;
+import java.util.HashMap;
 import java.util.LinkedList;
 import java.util.Random;
 
@@ -43,9 +42,6 @@ public abstract class PhotoSource {
     private static final String TAG = "PhotoTable.PhotoSource";
     private static final boolean DEBUG = false;
 
-    // An invalid cursor position to represent the uninitialized state.
-    protected static final int INVALID = -2;
-
     // This should be large enough for BitmapFactory to decode the header so
     // that we can mark and reset the input stream to avoid duplicate network i/o
     private static final int BUFFER_SIZE = 128 * 1024;
@@ -55,9 +51,19 @@ public abstract class PhotoSource {
         public String url;
         public int orientation;
 
+        protected String albumId;
+        protected Cursor cursor;
+        protected int position;
+
         InputStream getStream(int longSide) {
             return PhotoSource.this.getStream(this, longSide);
         }
+        ImageData naturalNext() {
+            return PhotoSource.this.naturalNext(this);
+        }
+        ImageData naturalPrevious() {
+            return PhotoSource.this.naturalPrevious(this);
+        }
     }
 
     public class AlbumData {
@@ -79,6 +85,7 @@ public abstract class PhotoSource {
     private final float mMaxCropRatio;
     private final int mBadImageSkipLimit;
     private final PhotoSource mFallbackSource;
+    private final HashMap<Bitmap, ImageData> mImageMap;
 
     protected final Context mContext;
     protected final Resources mResources;
@@ -102,6 +109,7 @@ public abstract class PhotoSource {
         mMaxQueueSize = mResources.getInteger(R.integer.image_queue_size);
         mMaxCropRatio = mResources.getInteger(R.integer.max_crop_ratio) / 1000000f;
         mBadImageSkipLimit = mResources.getInteger(R.integer.bad_image_skip_limit);
+        mImageMap = new HashMap<Bitmap, ImageData>();
         mRNG = new Random();
         mFallbackSource = fallbackSource;
     }
@@ -124,11 +132,11 @@ public abstract class PhotoSource {
                 if (mImageQueue.isEmpty()) {
                     fillQueue();
                 }
-
                 imageData = mImageQueue.poll();
             }
             if (imageData != null) {
                 image = load(imageData, options, longSide, shortSide);
+                mImageMap.put(image, imageData);
                 imageData = null;
             }
 
@@ -259,7 +267,38 @@ public abstract class PhotoSource {
         }
     }
 
+    public Bitmap naturalNext(Bitmap current, BitmapFactory.Options options,
+            int longSide, int shortSide) {
+        Bitmap image = null;
+        ImageData data = mImageMap.get(current);
+        if (data != null) {
+          ImageData next = data.naturalNext();
+          if (next != null) {
+            image = load(next, options, longSide, shortSide);
+            mImageMap.put(image, next);
+          }
+        }
+        return image;
+    }
+
+    public Bitmap naturalPrevious(Bitmap current, BitmapFactory.Options options,
+            int longSide, int shortSide) {
+        Bitmap image = null;
+        ImageData data = mImageMap.get(current);
+        if (current != null) {
+          ImageData prev = data.naturalPrevious();
+          if (prev != null) {
+            image = load(prev, options, longSide, shortSide);
+            mImageMap.put(image, prev);
+          }
+        }
+        return image;
+    }
+
     protected abstract InputStream getStream(ImageData data, int longSide);
     protected abstract Collection<ImageData> findImages(int howMany);
+    protected abstract ImageData naturalNext(ImageData current);
+    protected abstract ImageData naturalPrevious(ImageData current);
+
     public abstract Collection<AlbumData> findAlbums();
 }