Extract constants/boilerplate

Change-Id: I52ba51bab6ec12f2925384c1eedbba96e02bfa97

2 files changed, 506 insertions, 449 deletions

diff --git a/src/com/android/gallery3d/provider/CanvasProvider.java b/src/com/android/gallery3d/provider/CanvasProvider.java
index 95c02dc7a..76cf4887d 100644
--- a/src/com/android/gallery3d/provider/CanvasProvider.java
+++ b/src/com/android/gallery3d/provider/CanvasProvider.java
@@ -18,13 +18,9 @@ package com.android.gallery3d.provider;
 
 import android.app.Activity;
 import android.content.ActivityNotFoundException;
-import android.content.ContentProvider;
 import android.content.ContentResolver;
-import android.content.ContentValues;
 import android.content.Intent;
-import android.content.UriMatcher;
 import android.content.res.Configuration;
-import android.database.Cursor;
 import android.database.MatrixCursor;
 import android.graphics.Bitmap;
 import android.graphics.Bitmap.CompressFormat;
@@ -32,7 +28,6 @@ import android.net.Uri;
 import android.os.AsyncTask;
 import android.os.Binder;
 import android.os.ParcelFileDescriptor;
-import android.provider.BaseColumns;
 import android.util.Log;
 
 import com.android.gallery3d.app.GalleryApp;
@@ -51,229 +46,38 @@ import com.google.android.canvas.provider.CanvasContract;
 import java.io.IOException;
 import java.io.OutputStream;
 import java.util.ArrayList;
-import java.util.HashMap;
 import java.util.List;
 
-public class CanvasProvider extends ContentProvider {
+public class CanvasProvider extends CanvasProviderBase {
 
     private static final String TAG = "GalleryCanvasProvider";
 
-    private static final String AUTHORITY = "com.android.gallery3d.provider.CanvasProvider";
-
-    public static Uri NOTIFY_CHANGED_URI = Uri.parse("content://" + AUTHORITY);
-
-    private static final String PATH_IMAGE = "image";
-
-    private static final String PATH_LAUNCHER = "launcher";
-    private static final String PATH_LAUNCHER_ITEM = PATH_LAUNCHER + "/"
-            + CanvasContract.PATH_LAUNCHER_ITEM;
-    private static final String PATH_BROWSE = "browse";
-    private static final String PATH_BROWSE_HEADERS = PATH_BROWSE + "/"
-            + CanvasContract.PATH_BROWSE_HEADERS;
-
-    private static final int LAUNCHER = 1;
-    private static final int LAUNCHER_ITEMS = 2;
-    private static final int LAUNCHER_ITEM_ID = 3;
-    private static final int BROWSE_HEADERS = 4;
-    private static final int BROWSE = 5;
-    private static final int IMAGE = 6;
-
-    private static final Uri BROWSER_ROOT_URI = Uri.parse("content://" + AUTHORITY + "/" + PATH_BROWSE);
-
-    private static final UriMatcher sUriMatcher = new UriMatcher(
-            UriMatcher.NO_MATCH);
-
-    static {
-        sUriMatcher.addURI(AUTHORITY, PATH_LAUNCHER, LAUNCHER);
-        sUriMatcher.addURI(AUTHORITY, PATH_LAUNCHER_ITEM, LAUNCHER_ITEMS);
-        sUriMatcher.addURI(AUTHORITY, PATH_LAUNCHER_ITEM + "/#",
-                LAUNCHER_ITEM_ID);
-        sUriMatcher.addURI(AUTHORITY, PATH_BROWSE_HEADERS, BROWSE_HEADERS);
-        sUriMatcher.addURI(AUTHORITY, PATH_BROWSE + "/#", BROWSE);
-        sUriMatcher.addURI(AUTHORITY, PATH_IMAGE + "/*", IMAGE);
-    }
-
-    private static final HashMap<String, Integer> LAUNCHER_COLUMN_CASES = new HashMap<String, Integer>();
-    private static final String[] LAUNCHER_PROJECTION_ALL;
-
-    private static final int LAUNCHER_CASE_ID = 0;
-    private static final int LAUNCHER_CASE_COUNT = 1;
-    private static final int LAUNCHER_CASE_NAME = 2;
-    private static final int LAUNCHER_CASE_IMPORTANCE = 3;
-    private static final int LAUNCHER_CASE_DISPLAY_NAME = 4;
-    private static final int LAUNCHER_CASE_VISIBLE_COUNT = 5;
-    private static final int LAUNCHER_CASE_CROP_ALLOWED = 6;
-    private static final int LAUNCHER_CASE_CACHE_TIME = 7;
-    private static final int LAUNCHER_CASE_INTENT_URI = 8;
-
-    static {
-        LAUNCHER_COLUMN_CASES
-                .put(CanvasContract.Launcher._ID, LAUNCHER_CASE_ID);
-        LAUNCHER_COLUMN_CASES.put(CanvasContract.Launcher._COUNT,
-                LAUNCHER_CASE_COUNT);
-        LAUNCHER_COLUMN_CASES.put(CanvasContract.Launcher.NAME,
-                LAUNCHER_CASE_NAME);
-        LAUNCHER_COLUMN_CASES.put(CanvasContract.Launcher.IMPORTANCE,
-                LAUNCHER_CASE_IMPORTANCE);
-        LAUNCHER_COLUMN_CASES.put(CanvasContract.Launcher.DISPLAY_NAME,
-                LAUNCHER_CASE_DISPLAY_NAME);
-        LAUNCHER_COLUMN_CASES.put(CanvasContract.Launcher.VISIBLE_COUNT,
-                LAUNCHER_CASE_VISIBLE_COUNT);
-        LAUNCHER_COLUMN_CASES.put(CanvasContract.Launcher.IMAGE_CROP_ALLOWED,
-                LAUNCHER_CASE_CROP_ALLOWED);
-        LAUNCHER_COLUMN_CASES.put(CanvasContract.Launcher.CACHE_TIME_MS,
-                LAUNCHER_CASE_CACHE_TIME);
-        LAUNCHER_COLUMN_CASES.put(CanvasContract.Launcher.INTENT_URI,
-                LAUNCHER_CASE_INTENT_URI);
-
-        LAUNCHER_PROJECTION_ALL = LAUNCHER_COLUMN_CASES.keySet().toArray(
-                new String[] {});
-    }
-
-    private static final HashMap<String, Integer> CLUSTER_COLUMN_CASES = new HashMap<String, Integer>();
-    private static final String[] CLUSTER_PROJECTION_ALL;
-
-    private static final int CLUSTER_CASE_ID = 0;
-    private static final int CLUSTER_CASE_COUNT = 1;
-    private static final int CLUSTER_CASE_PARENT_ID = 2;
-    private static final int CLUSTER_CASE_IMAGE_URI = 3;
-
-    static {
-        CLUSTER_COLUMN_CASES.put(CanvasContract.LauncherItem._ID,
-                CLUSTER_CASE_ID);
-        CLUSTER_COLUMN_CASES.put(CanvasContract.LauncherItem._COUNT,
-                CLUSTER_CASE_COUNT);
-        CLUSTER_COLUMN_CASES.put(CanvasContract.LauncherItem.PARENT_ID,
-                CLUSTER_CASE_PARENT_ID);
-        CLUSTER_COLUMN_CASES.put(CanvasContract.LauncherItem.IMAGE_URI,
-                CLUSTER_CASE_IMAGE_URI);
-
-        CLUSTER_PROJECTION_ALL = CLUSTER_COLUMN_CASES.keySet().toArray(
-                new String[] {});
-    }
-
-    private static final HashMap<String, Integer> BROWSE_HEADER_COLUMN_CASES = new HashMap<String, Integer>();
-    private static final String[] BROWSE_HEADER_PROJECTION_ALL;
-
-    private static final int BROWSE_HEADER_CASE_ID = 0;
-    private static final int BROWSE_HEADER_CASE_COUNT = 1;
-    private static final int BROWSE_HEADER_CASE_NAME = 2;
-    private static final int BROWSE_HEADER_CASE_DISPLAY_NAME = 3;
-    private static final int BROWSE_HEADER_CASE_ICON_URI = 4;
-    private static final int BROWSE_HEADER_CASE_BADGE_URI = 5;
-    private static final int BROWSE_HEADER_CASE_COLOR_HINT = 6;
-    private static final int BROWSE_HEADER_CASE_TEXT_COLOR_HINT = 7;
-    private static final int BROWSE_HEADER_CASE_BG_IMAGE_URI = 8;
-    private static final int BROWSE_HEADER_CASE_EXPAND_GROUP = 9;
-    private static final int BROWSE_HEADER_CASE_WRAP = 10;
-    private static final int BROWSE_HEADER_CASE_DEFAULT_ITEM_WIDTH = 11;
-    private static final int BROWSE_HEADER_CASE_DEFAULT_ITEM_HEIGHT = 12;
-
-    static {
-        BROWSE_HEADER_COLUMN_CASES.put(CanvasContract.BrowseHeaders._ID,
-                BROWSE_HEADER_CASE_ID);
-        BROWSE_HEADER_COLUMN_CASES.put(CanvasContract.BrowseHeaders._COUNT,
-                BROWSE_HEADER_CASE_COUNT);
-        BROWSE_HEADER_COLUMN_CASES.put(CanvasContract.BrowseHeaders.NAME,
-                BROWSE_HEADER_CASE_NAME);
-        BROWSE_HEADER_COLUMN_CASES.put(
-                CanvasContract.BrowseHeaders.DISPLAY_NAME,
-                BROWSE_HEADER_CASE_DISPLAY_NAME);
-        BROWSE_HEADER_COLUMN_CASES.put(CanvasContract.BrowseHeaders.ICON_URI,
-                BROWSE_HEADER_CASE_ICON_URI);
-        BROWSE_HEADER_COLUMN_CASES.put(CanvasContract.BrowseHeaders.BADGE_URI,
-                BROWSE_HEADER_CASE_BADGE_URI);
-        BROWSE_HEADER_COLUMN_CASES.put(CanvasContract.BrowseHeaders.COLOR_HINT,
-                BROWSE_HEADER_CASE_COLOR_HINT);
-        BROWSE_HEADER_COLUMN_CASES.put(
-                CanvasContract.BrowseHeaders.TEXT_COLOR_HINT,
-                BROWSE_HEADER_CASE_TEXT_COLOR_HINT);
-        BROWSE_HEADER_COLUMN_CASES.put(
-                CanvasContract.BrowseHeaders.BG_IMAGE_URI,
-                BROWSE_HEADER_CASE_BG_IMAGE_URI);
-        BROWSE_HEADER_COLUMN_CASES.put(
-                CanvasContract.BrowseHeaders.EXPAND_GROUP,
-                BROWSE_HEADER_CASE_EXPAND_GROUP);
-        BROWSE_HEADER_COLUMN_CASES.put(CanvasContract.BrowseHeaders.WRAP_ITEMS,
-                BROWSE_HEADER_CASE_WRAP);
-        BROWSE_HEADER_COLUMN_CASES.put(
-                CanvasContract.BrowseHeaders.DEFAULT_ITEM_WIDTH,
-                BROWSE_HEADER_CASE_DEFAULT_ITEM_WIDTH);
-        BROWSE_HEADER_COLUMN_CASES.put(
-                CanvasContract.BrowseHeaders.DEFAULT_ITEM_HEIGHT,
-                BROWSE_HEADER_CASE_DEFAULT_ITEM_HEIGHT);
-
-        BROWSE_HEADER_PROJECTION_ALL = BROWSE_HEADER_COLUMN_CASES.keySet()
-                .toArray(new String[] {});
-    }
-
-    private static final HashMap<String, Integer> BROWSE_COLUMN_CASES = new HashMap<String, Integer>();
-    private static final String[] BROWSE_PROJECTION_ALL;
-
-    private static final int BROWSE_CASE_ID = 0;
-    private static final int BROWSE_CASE_COUNT = 1;
-    private static final int BROWSE_CASE_PARENT_ID = 2;
-    private static final int BROWSE_CASE_DISPLAY_NAME = 3;
-    private static final int BROWSE_CASE_DISPLAY_DESCRIPTION = 4;
-    private static final int BROWSE_CASE_IMAGE_URI = 5;
-    private static final int BROWSE_CASE_WIDTH = 6;
-    private static final int BROWSE_CASE_HEIGHT = 7;
-    private static final int BROWSE_CASE_INTENT_URI = 8;
-
-    static {
-        BROWSE_COLUMN_CASES.put(CanvasContract.BrowseItems._ID, BROWSE_CASE_ID);
-        BROWSE_COLUMN_CASES.put(CanvasContract.BrowseItems._COUNT,
-                BROWSE_CASE_COUNT);
-        BROWSE_COLUMN_CASES.put(CanvasContract.BrowseItems.PARENT_ID,
-                BROWSE_CASE_PARENT_ID);
-        BROWSE_COLUMN_CASES.put(CanvasContract.BrowseItems.DISPLAY_NAME,
-                BROWSE_CASE_DISPLAY_NAME);
-        BROWSE_COLUMN_CASES.put(CanvasContract.BrowseItems.DISPLAY_DESCRIPTION,
-                BROWSE_CASE_DISPLAY_DESCRIPTION);
-        BROWSE_COLUMN_CASES.put(CanvasContract.BrowseItems.IMAGE_URI,
-                BROWSE_CASE_IMAGE_URI);
-        BROWSE_COLUMN_CASES.put(CanvasContract.BrowseItems.WIDTH,
-                BROWSE_CASE_WIDTH);
-        BROWSE_COLUMN_CASES.put(CanvasContract.BrowseItems.HEIGHT,
-                BROWSE_CASE_HEIGHT);
-        BROWSE_COLUMN_CASES.put(CanvasContract.BrowseItems.INTENT_URI,
-                BROWSE_CASE_INTENT_URI);
-
-        BROWSE_PROJECTION_ALL = BROWSE_COLUMN_CASES.keySet().toArray(
-                new String[] {});
-    }
-
-    // The max clusters that we'll return for a single launcher
-    private static final int MAX_CLUSTER_SIZE = 3;
-    // The max amount of items we'll return for a cluster
-    private static final int MAX_CLUSTER_ITEM_SIZE = 10;
-    private static final Integer CACHE_TIME_MS = 1*1000;
-
-    private DataManager mDataManager;
+    DataManager mDataManager;
     private MediaSet mRootSet;
-    private ArrayList<Cluster> mClusters = new ArrayList<Cluster>(MAX_CLUSTER_SIZE);
-
-    @Override
-    public boolean onCreate() {
-        GalleryApp app = (GalleryApp) getContext().getApplicationContext();
-        mDataManager = app.getDataManager();
-        return true;
-    }
 
     private final static SyncListener sNullSyncListener = new SyncListener() {
+
         @Override
         public void onSyncDone(MediaSet mediaSet, int resultCode) {
         }
     };
 
     private final ContentListener mChangedListener = new ContentListener() {
+
         @Override
         public void onContentDirty() {
-            getContext().getContentResolver().notifyChange(
-                    NOTIFY_CHANGED_URI, null, false);
+            getContext().getContentResolver().notifyChange(NOTIFY_CHANGED_URI,
+                    null, false);
         }
     };
 
+    @Override
+    public boolean onCreate() {
+        GalleryApp app = (GalleryApp) getContext().getApplicationContext();
+        mDataManager = app.getDataManager();
+        return true;
+    }
+
     private MediaSet loadRootMediaSet() {
         if (mRootSet == null) {
             String path = mDataManager.getTopSetPath(DataManager.INCLUDE_ALL);
@@ -298,14 +102,11 @@ public class CanvasProvider extends ContentProvider {
         set.loadIfDirty();
     }
 
-    private void loadClustersIfEmpty() {
-        if (mClusters.size() > 0) {
-            return;
-        }
-
+    @Override
+    protected void loadClusters(List<Cluster> clusters) {
         MediaSet root = loadRootMediaSet();
         int count = root.getSubMediaSetCount();
-        for (int i = 0; i < count && mClusters.size() < MAX_CLUSTER_SIZE; i++) {
+        for (int i = 0; i < count && clusters.size() < MAX_CLUSTER_SIZE; i++) {
             MediaSet set = root.getSubMediaSet(i);
             loadMediaSet(set);
             Log.d(TAG, "Building set: " + set.getName());
@@ -316,10 +117,12 @@ public class CanvasProvider extends ContentProvider {
             bob.intent(intent);
             bob.imageCropAllowed(true);
             bob.cacheTimeMs(CACHE_TIME_MS);
-            int itemCount = Math.min(set.getMediaItemCount(), MAX_CLUSTER_ITEM_SIZE);
+            int itemCount = Math.min(set.getMediaItemCount(),
+                    MAX_CLUSTER_ITEM_SIZE);
             List<MediaItem> items = set.getMediaItem(0, itemCount);
             if (itemCount != items.size()) {
-                Log.d(TAG, "Size mismatch, expected " + itemCount + ", got " + items.size());
+                Log.d(TAG, "Size mismatch, expected " + itemCount + ", got "
+                        + items.size());
             }
             // This is done because not all items may have been synced yet
             itemCount = items.size();
@@ -330,65 +133,12 @@ public class CanvasProvider extends ContentProvider {
             for (MediaItem item : items) {
                 bob.addItem(createImageUri(item));
             }
-            mClusters.add(bob.build());
-        }
-    }
-
-    @Override
-    public Cursor query(Uri uri, String[] projection, String selection,
-            String[] selectionArgs, String sortOrder) {
-        long identity = Binder.clearCallingIdentity();
-        try {
-            MatrixCursor c;
-            int match = sUriMatcher.match(uri);
-            Log.d(TAG, "query: " + uri.toString() + ", match = " + match);
-            switch (match) {
-            case LAUNCHER:
-                if (projection == null) {
-                    projection = LAUNCHER_PROJECTION_ALL;
-                }
-                c = new MatrixCursor(projection);
-                buildClusters(projection, c);
-                break;
-            case LAUNCHER_ITEMS:
-                if (projection == null) {
-                    projection = CLUSTER_PROJECTION_ALL;
-                }
-                c = new MatrixCursor(projection);
-                buildMultiCluster(projection, c, uri);
-                break;
-            case LAUNCHER_ITEM_ID:
-                if (projection == null) {
-                    projection = CLUSTER_PROJECTION_ALL;
-                }
-                c = new MatrixCursor(projection);
-                buildSingleCluster(projection, c, uri);
-                break;
-            case BROWSE_HEADERS:
-                if (projection == null) {
-                    projection = BROWSE_HEADER_PROJECTION_ALL;
-                }
-                c = new MatrixCursor(projection);
-                buildBrowseHeaders(projection, c);
-                break;
-            case BROWSE:
-                if (projection == null) {
-                    projection = BROWSE_PROJECTION_ALL;
-                }
-                c = new MatrixCursor(projection);
-                buildBrowseRow(projection, c, uri);
-                break;
-            default:
-                c = new MatrixCursor(new String[] {BaseColumns._ID});
-                break;
-            }
-            return c;
-        } finally {
-            Binder.restoreCallingIdentity(identity);
+            clusters.add(bob.build());
         }
     }
 
     private static final JobContext sJobStub = new JobContext() {
+
         @Override
         public boolean isCancelled() {
             return false;
@@ -412,11 +162,14 @@ public class CanvasProvider extends ContentProvider {
             MediaItem item = (MediaItem) mDataManager.getMediaObject(path);
             Job<Bitmap> job = item.requestImage(MediaItem.TYPE_MICROTHUMBNAIL);
             final Bitmap bitmap = job.run(sJobStub);
-            final ParcelFileDescriptor[] fds = ParcelFileDescriptor.createPipe();
+            final ParcelFileDescriptor[] fds = ParcelFileDescriptor
+                    .createPipe();
             AsyncTask<Object, Object, Object> task = new AsyncTask<Object, Object, Object>() {
+
                 @Override
                 protected Object doInBackground(Object... params) {
-                    OutputStream stream = new ParcelFileDescriptor.AutoCloseOutputStream(fds[1]);
+                    OutputStream stream = new ParcelFileDescriptor.AutoCloseOutputStream(
+                            fds[1]);
                     bitmap.compress(CompressFormat.PNG, 100, stream);
                     try {
                         fds[1].close();
@@ -426,7 +179,8 @@ public class CanvasProvider extends ContentProvider {
                     return null;
                 }
             };
-            task.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR, (Object[])null);
+            task.executeOnExecutor(AsyncTask.THREAD_POOL_EXECUTOR,
+                    (Object[]) null);
 
             return fds[0];
         } catch (IOException e) {
@@ -441,107 +195,14 @@ public class CanvasProvider extends ContentProvider {
         // for which to proxy to avoid things with
         // android.permission.ACCESS_APP_BROWSE_DATA being able to make
         // any request it wants on our behalf.
-        return new Uri.Builder()
-                .scheme(ContentResolver.SCHEME_CONTENT)
-                .authority(AUTHORITY)
-                .path(PATH_IMAGE)
+        return new Uri.Builder().scheme(ContentResolver.SCHEME_CONTENT)
+                .authority(AUTHORITY).path(PATH_IMAGE)
                 .appendQueryParameter("path", item.getPath().toString())
                 .build();
     }
 
-    private void buildClusters(String[] projection, MatrixCursor c) {
-        mClusters.clear();
-        loadClustersIfEmpty();
-
-        int clusterCount = mClusters.size();
-        for (Cluster cluster : mClusters) {
-
-            Object[] row = new Object[projection.length];
-            long id = cluster.getId();
-            for (int j = 0; j < projection.length; j++) {
-                if (!LAUNCHER_COLUMN_CASES.containsKey(projection[j])) {
-                    continue;
-                }
-                int column = LAUNCHER_COLUMN_CASES.get(projection[j]);
-                Object obj = null;
-                switch (column) {
-                    case LAUNCHER_CASE_ID:
-                        obj = id;
-                        break;
-                    case LAUNCHER_CASE_COUNT:
-                        obj = clusterCount;
-                        break;
-                    case LAUNCHER_CASE_NAME:
-                        obj = cluster.getName();
-                        break;
-                    case LAUNCHER_CASE_IMPORTANCE:
-                        obj = cluster.getImportance();
-                        break;
-                    case LAUNCHER_CASE_DISPLAY_NAME:
-                        obj = cluster.getDisplayName();
-                        break;
-                    case LAUNCHER_CASE_VISIBLE_COUNT:
-                        obj = cluster.getVisibleCount();
-                        break;
-                    case LAUNCHER_CASE_CACHE_TIME:
-                        obj = cluster.getCacheTimeMs();
-                        break;
-                    case LAUNCHER_CASE_INTENT_URI:
-                        obj = cluster.getIntent().toUri(Intent.URI_INTENT_SCHEME);
-                        break;
-                    case LAUNCHER_CASE_CROP_ALLOWED:
-                        obj = cluster.isImageCropAllowed();
-                        break;
-                }
-                row[j] = obj;
-            }
-            c.addRow(row);
-        }
-    }
-
-    private void buildMultiCluster(String[] projection, MatrixCursor c, Uri uri) {
-        for (int index = 0; index < mClusters.size(); ++index) {
-            buildSingleCluster(projection, c,
-                    uri.buildUpon().appendPath(String.valueOf(index)).build());
-        }
-    }
-
-    private void buildSingleCluster(String[] projection, MatrixCursor c, Uri uri) {
-        loadClustersIfEmpty();
-
-        int parentId = Integer.parseInt(uri.getLastPathSegment());
-
-        Cluster cluster = mClusters.get(parentId);
-        int numItems = Math.min(cluster.getItemCount(), MAX_CLUSTER_ITEM_SIZE);
-        for (int i = 0; i < numItems; i++) {
-            Cluster.ClusterItem item = cluster.getItem(i);
-            Object[] row = new Object[projection.length];
-
-            for (int j = 0; j < projection.length; j++) {
-                if (!CLUSTER_COLUMN_CASES.containsKey(projection[j])) {
-                    continue;
-                }
-                int column = CLUSTER_COLUMN_CASES.get(projection[j]);
-                switch (column) {
-                    case CLUSTER_CASE_ID:
-                        row[j] = i;
-                        break;
-                    case CLUSTER_CASE_COUNT:
-                        row[j] = numItems;
-                        break;
-                    case CLUSTER_CASE_PARENT_ID:
-                        row[j] = parentId;
-                        break;
-                    case CLUSTER_CASE_IMAGE_URI:
-                        row[j] = item.getImageUri();
-                        break;
-                }
-            }
-            c.addRow(row);
-        }
-    }
-
-    private void buildBrowseHeaders(String[] projection, MatrixCursor c) {
+    @Override
+    protected void buildBrowseHeaders(String[] projection, MatrixCursor c) {
         // TODO: All images
         MediaSet root = loadRootMediaSet();
         int itemCount = root.getSubMediaSetCount();
@@ -555,36 +216,37 @@ public class CanvasProvider extends ContentProvider {
                 int column = BROWSE_HEADER_COLUMN_CASES.get(projection[j]);
                 Object obj = null;
                 switch (column) {
-                    case BROWSE_HEADER_CASE_ID:
-                        obj = i;
-                        break;
-                    case BROWSE_HEADER_CASE_COUNT:
-                        obj = itemCount;
-                        break;
-                    case BROWSE_HEADER_CASE_NAME:
-                    case BROWSE_HEADER_CASE_DISPLAY_NAME:
-                        obj = item.getName();
-                        break;
-                    case BROWSE_HEADER_CASE_ICON_URI:
-                        break;
-                    case BROWSE_HEADER_CASE_BADGE_URI:
-                        break;
-                    case BROWSE_HEADER_CASE_COLOR_HINT:
-                        break;
-                    case BROWSE_HEADER_CASE_TEXT_COLOR_HINT:
-                        break;
-                    case BROWSE_HEADER_CASE_BG_IMAGE_URI:
-                        break;
-                    case BROWSE_HEADER_CASE_EXPAND_GROUP:
-                        obj = 0;
-                        break;
-                    case BROWSE_HEADER_CASE_WRAP:
-                        obj = i % 2;
-                        break;
-                    case BROWSE_HEADER_CASE_DEFAULT_ITEM_WIDTH:
-                    case BROWSE_HEADER_CASE_DEFAULT_ITEM_HEIGHT:
-                        obj = MediaItem.getTargetSize(MediaItem.TYPE_MICROTHUMBNAIL);
-                        break;
+                case BROWSE_HEADER_CASE_ID:
+                    obj = i;
+                    break;
+                case BROWSE_HEADER_CASE_COUNT:
+                    obj = itemCount;
+                    break;
+                case BROWSE_HEADER_CASE_NAME:
+                case BROWSE_HEADER_CASE_DISPLAY_NAME:
+                    obj = item.getName();
+                    break;
+                case BROWSE_HEADER_CASE_ICON_URI:
+                    break;
+                case BROWSE_HEADER_CASE_BADGE_URI:
+                    break;
+                case BROWSE_HEADER_CASE_COLOR_HINT:
+                    break;
+                case BROWSE_HEADER_CASE_TEXT_COLOR_HINT:
+                    break;
+                case BROWSE_HEADER_CASE_BG_IMAGE_URI:
+                    break;
+                case BROWSE_HEADER_CASE_EXPAND_GROUP:
+                    obj = 0;
+                    break;
+                case BROWSE_HEADER_CASE_WRAP:
+                    obj = i % 2;
+                    break;
+                case BROWSE_HEADER_CASE_DEFAULT_ITEM_WIDTH:
+                case BROWSE_HEADER_CASE_DEFAULT_ITEM_HEIGHT:
+                    obj = MediaItem
+                            .getTargetSize(MediaItem.TYPE_MICROTHUMBNAIL);
+                    break;
                 }
                 header[j] = obj;
             }
@@ -592,7 +254,8 @@ public class CanvasProvider extends ContentProvider {
         }
     }
 
-    private void buildBrowseRow(String[] projection, MatrixCursor c, Uri uri) {
+    @Override
+    protected void buildBrowseRow(String[] projection, MatrixCursor c, Uri uri) {
         int row = Integer.parseInt(uri.getLastPathSegment());
         MediaSet album = loadRootMediaSet().getSubMediaSet(row);
         loadMediaSet(album);
@@ -609,29 +272,31 @@ public class CanvasProvider extends ContentProvider {
                 int column = BROWSE_COLUMN_CASES.get(projection[j]);
                 Object obj = null;
                 switch (column) {
-                    case BROWSE_CASE_ID:
-                        obj = i;
-                        break;
-                    case BROWSE_CASE_COUNT:
-                        obj = itemCount;
-                        break;
-                    case BROWSE_CASE_DISPLAY_NAME:
-                        obj = item.getName();
-                        break;
-                    case BROWSE_CASE_DISPLAY_DESCRIPTION:
-                        obj = item.getFilePath();
-                        break;
-                    case BROWSE_CASE_IMAGE_URI:
-                        obj = createImageUri(item);
-                        break;
-                    case BROWSE_CASE_WIDTH:
-                    case BROWSE_CASE_HEIGHT:
-                        obj = MediaItem.getTargetSize(MediaItem.TYPE_MICROTHUMBNAIL);
-                        break;
-                    case BROWSE_CASE_INTENT_URI:
-                        Intent intent = new Intent(Intent.ACTION_VIEW, item.getContentUri());
-                        obj = intent.toUri(Intent.URI_INTENT_SCHEME);
-                        break;
+                case BROWSE_CASE_ID:
+                    obj = i;
+                    break;
+                case BROWSE_CASE_COUNT:
+                    obj = itemCount;
+                    break;
+                case BROWSE_CASE_DISPLAY_NAME:
+                    obj = item.getName();
+                    break;
+                case BROWSE_CASE_DISPLAY_DESCRIPTION:
+                    obj = item.getFilePath();
+                    break;
+                case BROWSE_CASE_IMAGE_URI:
+                    obj = createImageUri(item);
+                    break;
+                case BROWSE_CASE_WIDTH:
+                case BROWSE_CASE_HEIGHT:
+                    obj = MediaItem
+                            .getTargetSize(MediaItem.TYPE_MICROTHUMBNAIL);
+                    break;
+                case BROWSE_CASE_INTENT_URI:
+                    Intent intent = new Intent(Intent.ACTION_VIEW,
+                            item.getContentUri());
+                    obj = intent.toUri(Intent.URI_INTENT_SCHEME);
+                    break;
                 }
                 header[j] = obj;
             }
@@ -639,36 +304,17 @@ public class CanvasProvider extends ContentProvider {
         }
     }
 
-    @Override
-    public String getType(Uri uri) {
-        return null;
-    }
-
-    @Override
-    public Uri insert(Uri uri, ContentValues values) {
-        throw new UnsupportedOperationException("Insert not supported");
-    }
-
-    @Override
-    public int delete(Uri uri, String selection, String[] selectionArgs) {
-        throw new UnsupportedOperationException("Delete not supported");
-    }
-
-    @Override
-    public int update(Uri uri, ContentValues values, String selection,
-            String[] selectionArgs) {
-        throw new UnsupportedOperationException("Update not supported");
-    }
-
     // TODO: Remove once b/8079561 is resolved
     public static boolean startBrowseActivity(Activity activity) {
         Configuration config = activity.getResources().getConfiguration();
         if (config.touchscreen == Configuration.TOUCHSCREEN_NOTOUCH) {
             try {
-                Intent intent = CanvasContract.getBrowseIntent(BROWSER_ROOT_URI, 0);
+                Intent intent = CanvasContract.getBrowseIntent(
+                        BROWSER_ROOT_URI, 0);
                 activity.startActivity(intent);
                 return true;
-            } catch (ActivityNotFoundException ex) {}
+            } catch (ActivityNotFoundException ex) {
+            }
         }
         return false;
     }
diff --git a/src/com/android/gallery3d/provider/CanvasProviderBase.java b/src/com/android/gallery3d/provider/CanvasProviderBase.java
new file mode 100644
index 000000000..9e0c1de53
--- /dev/null
+++ b/src/com/android/gallery3d/provider/CanvasProviderBase.java
@@ -0,0 +1,411 @@
+/*
+ * 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.gallery3d.provider;
+
+import android.content.ContentProvider;
+import android.content.ContentValues;
+import android.content.Intent;
+import android.content.UriMatcher;
+import android.database.Cursor;
+import android.database.MatrixCursor;
+import android.net.Uri;
+import android.os.Binder;
+import android.provider.BaseColumns;
+
+import com.google.android.canvas.data.Cluster;
+import com.google.android.canvas.provider.CanvasContract;
+
+import java.util.ArrayList;
+import java.util.HashMap;
+import java.util.List;
+
+public abstract class CanvasProviderBase extends ContentProvider {
+
+    protected static final String AUTHORITY = "com.android.gallery3d.provider.CanvasProvider";
+    public static Uri NOTIFY_CHANGED_URI = Uri.parse("content://" + AUTHORITY);
+
+    // ***************************************************
+    // Provider path and URI matching
+    // ***************************************************
+
+    protected static final String PATH_IMAGE = "image";
+    protected static final String PATH_LAUNCHER = "launcher";
+    protected static final String PATH_LAUNCHER_ITEM = PATH_LAUNCHER + "/"
+            + CanvasContract.PATH_LAUNCHER_ITEM;
+    protected static final String PATH_BROWSE = "browse";
+    protected static final String PATH_BROWSE_HEADERS = PATH_BROWSE + "/"
+            + CanvasContract.PATH_BROWSE_HEADERS;
+
+    protected static final int LAUNCHER = 1;
+    protected static final int LAUNCHER_ITEMS = 2;
+    protected static final int LAUNCHER_ITEM_ID = 3;
+    protected static final int BROWSE_HEADERS = 4;
+    protected static final int BROWSE = 5;
+    protected static final int IMAGE = 6;
+    protected static final Uri BROWSER_ROOT_URI = Uri.parse("content://"
+            + AUTHORITY + "/" + PATH_BROWSE);
+    protected static final UriMatcher sUriMatcher = new UriMatcher(
+            UriMatcher.NO_MATCH);
+
+    static {
+        sUriMatcher.addURI(AUTHORITY, PATH_LAUNCHER, LAUNCHER);
+        sUriMatcher.addURI(AUTHORITY, PATH_LAUNCHER_ITEM, LAUNCHER_ITEMS);
+        sUriMatcher.addURI(AUTHORITY, PATH_LAUNCHER_ITEM + "/#",
+                LAUNCHER_ITEM_ID);
+        sUriMatcher.addURI(AUTHORITY, PATH_BROWSE_HEADERS, BROWSE_HEADERS);
+        sUriMatcher.addURI(AUTHORITY, PATH_BROWSE + "/#", BROWSE);
+        sUriMatcher.addURI(AUTHORITY, PATH_IMAGE + "/*", IMAGE);
+    }
+
+    // ***************************************************
+    // Columns and projections
+    // ***************************************************
+
+    protected static final HashMap<String, Integer> LAUNCHER_COLUMN_CASES = new HashMap<String, Integer>();
+    protected static final String[] LAUNCHER_PROJECTION_ALL;
+    protected static final int LAUNCHER_CASE_ID = 0;
+    protected static final int LAUNCHER_CASE_COUNT = 1;
+    protected static final int LAUNCHER_CASE_NAME = 2;
+    protected static final int LAUNCHER_CASE_IMPORTANCE = 3;
+    protected static final int LAUNCHER_CASE_DISPLAY_NAME = 4;
+    protected static final int LAUNCHER_CASE_VISIBLE_COUNT = 5;
+    protected static final int LAUNCHER_CASE_CROP_ALLOWED = 6;
+    protected static final int LAUNCHER_CASE_CACHE_TIME = 7;
+    protected static final int LAUNCHER_CASE_INTENT_URI = 8;
+
+    static {
+        LAUNCHER_COLUMN_CASES.put(BaseColumns._ID, LAUNCHER_CASE_ID);
+        LAUNCHER_COLUMN_CASES.put(BaseColumns._COUNT, LAUNCHER_CASE_COUNT);
+        LAUNCHER_COLUMN_CASES.put(CanvasContract.Launcher.NAME,
+                LAUNCHER_CASE_NAME);
+        LAUNCHER_COLUMN_CASES.put(CanvasContract.Launcher.IMPORTANCE,
+                LAUNCHER_CASE_IMPORTANCE);
+        LAUNCHER_COLUMN_CASES.put(CanvasContract.Launcher.DISPLAY_NAME,
+                LAUNCHER_CASE_DISPLAY_NAME);
+        LAUNCHER_COLUMN_CASES.put(CanvasContract.Launcher.VISIBLE_COUNT,
+                LAUNCHER_CASE_VISIBLE_COUNT);
+        LAUNCHER_COLUMN_CASES.put(CanvasContract.Launcher.IMAGE_CROP_ALLOWED,
+                LAUNCHER_CASE_CROP_ALLOWED);
+        LAUNCHER_COLUMN_CASES.put(CanvasContract.Launcher.CACHE_TIME_MS,
+                LAUNCHER_CASE_CACHE_TIME);
+        LAUNCHER_COLUMN_CASES.put(CanvasContract.Launcher.INTENT_URI,
+                LAUNCHER_CASE_INTENT_URI);
+
+        LAUNCHER_PROJECTION_ALL = LAUNCHER_COLUMN_CASES.keySet().toArray(
+                new String[] {});
+    }
+
+    protected static final HashMap<String, Integer> CLUSTER_COLUMN_CASES = new HashMap<String, Integer>();
+    protected static final String[] CLUSTER_PROJECTION_ALL;
+    protected static final int CLUSTER_CASE_ID = 0;
+    protected static final int CLUSTER_CASE_COUNT = 1;
+    protected static final int CLUSTER_CASE_PARENT_ID = 2;
+    protected static final int CLUSTER_CASE_IMAGE_URI = 3;
+
+    static {
+        CLUSTER_COLUMN_CASES.put(BaseColumns._ID, CLUSTER_CASE_ID);
+        CLUSTER_COLUMN_CASES.put(BaseColumns._COUNT, CLUSTER_CASE_COUNT);
+        CLUSTER_COLUMN_CASES.put(CanvasContract.LauncherItem.PARENT_ID,
+                CLUSTER_CASE_PARENT_ID);
+        CLUSTER_COLUMN_CASES.put(CanvasContract.LauncherItem.IMAGE_URI,
+                CLUSTER_CASE_IMAGE_URI);
+
+        CLUSTER_PROJECTION_ALL = CLUSTER_COLUMN_CASES.keySet().toArray(
+                new String[] {});
+    }
+
+    protected static final HashMap<String, Integer> BROWSE_HEADER_COLUMN_CASES = new HashMap<String, Integer>();
+    protected static final String[] BROWSE_HEADER_PROJECTION_ALL;
+    protected static final int BROWSE_HEADER_CASE_ID = 0;
+    protected static final int BROWSE_HEADER_CASE_COUNT = 1;
+    protected static final int BROWSE_HEADER_CASE_NAME = 2;
+    protected static final int BROWSE_HEADER_CASE_DISPLAY_NAME = 3;
+    protected static final int BROWSE_HEADER_CASE_ICON_URI = 4;
+    protected static final int BROWSE_HEADER_CASE_BADGE_URI = 5;
+    protected static final int BROWSE_HEADER_CASE_COLOR_HINT = 6;
+    protected static final int BROWSE_HEADER_CASE_TEXT_COLOR_HINT = 7;
+    protected static final int BROWSE_HEADER_CASE_BG_IMAGE_URI = 8;
+    protected static final int BROWSE_HEADER_CASE_EXPAND_GROUP = 9;
+    protected static final int BROWSE_HEADER_CASE_WRAP = 10;
+    protected static final int BROWSE_HEADER_CASE_DEFAULT_ITEM_WIDTH = 11;
+    protected static final int BROWSE_HEADER_CASE_DEFAULT_ITEM_HEIGHT = 12;
+
+    static {
+        BROWSE_HEADER_COLUMN_CASES.put(BaseColumns._ID, BROWSE_HEADER_CASE_ID);
+        BROWSE_HEADER_COLUMN_CASES.put(BaseColumns._COUNT,
+                BROWSE_HEADER_CASE_COUNT);
+        BROWSE_HEADER_COLUMN_CASES.put(CanvasContract.BrowseHeaders.NAME,
+                BROWSE_HEADER_CASE_NAME);
+        BROWSE_HEADER_COLUMN_CASES.put(
+                CanvasContract.BrowseHeaders.DISPLAY_NAME,
+                BROWSE_HEADER_CASE_DISPLAY_NAME);
+        BROWSE_HEADER_COLUMN_CASES.put(CanvasContract.BrowseHeaders.ICON_URI,
+                BROWSE_HEADER_CASE_ICON_URI);
+        BROWSE_HEADER_COLUMN_CASES.put(CanvasContract.BrowseHeaders.BADGE_URI,
+                BROWSE_HEADER_CASE_BADGE_URI);
+        BROWSE_HEADER_COLUMN_CASES.put(CanvasContract.BrowseHeaders.COLOR_HINT,
+                BROWSE_HEADER_CASE_COLOR_HINT);
+        BROWSE_HEADER_COLUMN_CASES.put(
+                CanvasContract.BrowseHeaders.TEXT_COLOR_HINT,
+                BROWSE_HEADER_CASE_TEXT_COLOR_HINT);
+        BROWSE_HEADER_COLUMN_CASES.put(
+                CanvasContract.BrowseHeaders.BG_IMAGE_URI,
+                BROWSE_HEADER_CASE_BG_IMAGE_URI);
+        BROWSE_HEADER_COLUMN_CASES.put(
+                CanvasContract.BrowseHeaders.EXPAND_GROUP,
+                BROWSE_HEADER_CASE_EXPAND_GROUP);
+        BROWSE_HEADER_COLUMN_CASES.put(CanvasContract.BrowseHeaders.WRAP_ITEMS,
+                BROWSE_HEADER_CASE_WRAP);
+        BROWSE_HEADER_COLUMN_CASES.put(
+                CanvasContract.BrowseHeaders.DEFAULT_ITEM_WIDTH,
+                BROWSE_HEADER_CASE_DEFAULT_ITEM_WIDTH);
+        BROWSE_HEADER_COLUMN_CASES.put(
+                CanvasContract.BrowseHeaders.DEFAULT_ITEM_HEIGHT,
+                BROWSE_HEADER_CASE_DEFAULT_ITEM_HEIGHT);
+
+        BROWSE_HEADER_PROJECTION_ALL = BROWSE_HEADER_COLUMN_CASES.keySet()
+                .toArray(new String[] {});
+    }
+
+    protected static final HashMap<String, Integer> BROWSE_COLUMN_CASES = new HashMap<String, Integer>();
+    protected static final String[] BROWSE_PROJECTION_ALL;
+    protected static final int BROWSE_CASE_ID = 0;
+    protected static final int BROWSE_CASE_COUNT = 1;
+    protected static final int BROWSE_CASE_PARENT_ID = 2;
+    protected static final int BROWSE_CASE_DISPLAY_NAME = 3;
+    protected static final int BROWSE_CASE_DISPLAY_DESCRIPTION = 4;
+    protected static final int BROWSE_CASE_IMAGE_URI = 5;
+    protected static final int BROWSE_CASE_WIDTH = 6;
+    protected static final int BROWSE_CASE_HEIGHT = 7;
+    protected static final int BROWSE_CASE_INTENT_URI = 8;
+
+    static {
+        BROWSE_COLUMN_CASES.put(BaseColumns._ID, BROWSE_CASE_ID);
+        BROWSE_COLUMN_CASES.put(BaseColumns._COUNT, BROWSE_CASE_COUNT);
+        BROWSE_COLUMN_CASES.put(CanvasContract.BrowseItems.PARENT_ID,
+                BROWSE_CASE_PARENT_ID);
+        BROWSE_COLUMN_CASES.put(CanvasContract.BrowseItems.DISPLAY_NAME,
+                BROWSE_CASE_DISPLAY_NAME);
+        BROWSE_COLUMN_CASES.put(CanvasContract.BrowseItems.DISPLAY_DESCRIPTION,
+                BROWSE_CASE_DISPLAY_DESCRIPTION);
+        BROWSE_COLUMN_CASES.put(CanvasContract.BrowseItems.IMAGE_URI,
+                BROWSE_CASE_IMAGE_URI);
+        BROWSE_COLUMN_CASES.put(CanvasContract.BrowseItems.WIDTH,
+                BROWSE_CASE_WIDTH);
+        BROWSE_COLUMN_CASES.put(CanvasContract.BrowseItems.HEIGHT,
+                BROWSE_CASE_HEIGHT);
+        BROWSE_COLUMN_CASES.put(CanvasContract.BrowseItems.INTENT_URI,
+                BROWSE_CASE_INTENT_URI);
+
+        BROWSE_PROJECTION_ALL = BROWSE_COLUMN_CASES.keySet().toArray(
+                new String[] {});
+    }
+
+    // ***************************************************
+    // Configuration stuff
+    // ***************************************************
+
+    // The max clusters that we'll return for a single launcher
+    protected static final int MAX_CLUSTER_SIZE = 3;
+    // The max amount of items we'll return for a cluster
+    protected static final int MAX_CLUSTER_ITEM_SIZE = 10;
+    protected static final Integer CACHE_TIME_MS = 1 * 1000;
+
+    private ArrayList<Cluster> mClusters = new ArrayList<Cluster>(
+            MAX_CLUSTER_SIZE);
+
+    @Override
+    public Cursor query(Uri uri, String[] projection, String selection,
+            String[] selectionArgs, String sortOrder) {
+        long identity = Binder.clearCallingIdentity();
+        try {
+            MatrixCursor c;
+            int match = sUriMatcher.match(uri);
+            switch (match) {
+            case LAUNCHER:
+                if (projection == null) {
+                    projection = LAUNCHER_PROJECTION_ALL;
+                }
+                c = new MatrixCursor(projection);
+                buildClusters(projection, c);
+                break;
+            case LAUNCHER_ITEMS:
+                if (projection == null) {
+                    projection = CLUSTER_PROJECTION_ALL;
+                }
+                c = new MatrixCursor(projection);
+                buildMultiCluster(projection, c, uri);
+                break;
+            case LAUNCHER_ITEM_ID:
+                if (projection == null) {
+                    projection = CLUSTER_PROJECTION_ALL;
+                }
+                c = new MatrixCursor(projection);
+                buildSingleCluster(projection, c, uri);
+                break;
+            case BROWSE_HEADERS:
+                if (projection == null) {
+                    projection = BROWSE_HEADER_PROJECTION_ALL;
+                }
+                c = new MatrixCursor(projection);
+                buildBrowseHeaders(projection, c);
+                break;
+            case BROWSE:
+                if (projection == null) {
+                    projection = BROWSE_PROJECTION_ALL;
+                }
+                c = new MatrixCursor(projection);
+                buildBrowseRow(projection, c, uri);
+                break;
+            default:
+                c = new MatrixCursor(new String[] { BaseColumns._ID });
+                break;
+            }
+            return c;
+        } finally {
+            Binder.restoreCallingIdentity(identity);
+        }
+    }
+
+    private void loadClustersIfEmpty() {
+        if (mClusters.size() > 0) {
+            return;
+        }
+        loadClusters(mClusters);
+    }
+
+    private void buildClusters(String[] projection, MatrixCursor c) {
+        mClusters.clear();
+        loadClustersIfEmpty();
+
+        int clusterCount = mClusters.size();
+        for (Cluster cluster : mClusters) {
+
+            Object[] row = new Object[projection.length];
+            long id = cluster.getId();
+            for (int j = 0; j < projection.length; j++) {
+                if (!LAUNCHER_COLUMN_CASES.containsKey(projection[j])) {
+                    continue;
+                }
+                int column = LAUNCHER_COLUMN_CASES.get(projection[j]);
+                Object obj = null;
+                switch (column) {
+                case LAUNCHER_CASE_ID:
+                    obj = id;
+                    break;
+                case LAUNCHER_CASE_COUNT:
+                    obj = clusterCount;
+                    break;
+                case LAUNCHER_CASE_NAME:
+                    obj = cluster.getName();
+                    break;
+                case LAUNCHER_CASE_IMPORTANCE:
+                    obj = cluster.getImportance();
+                    break;
+                case LAUNCHER_CASE_DISPLAY_NAME:
+                    obj = cluster.getDisplayName();
+                    break;
+                case LAUNCHER_CASE_VISIBLE_COUNT:
+                    obj = cluster.getVisibleCount();
+                    break;
+                case LAUNCHER_CASE_CACHE_TIME:
+                    obj = cluster.getCacheTimeMs();
+                    break;
+                case LAUNCHER_CASE_INTENT_URI:
+                    obj = cluster.getIntent().toUri(Intent.URI_INTENT_SCHEME);
+                    break;
+                case LAUNCHER_CASE_CROP_ALLOWED:
+                    obj = cluster.isImageCropAllowed();
+                    break;
+                }
+                row[j] = obj;
+            }
+            c.addRow(row);
+        }
+    }
+
+    private void buildMultiCluster(String[] projection, MatrixCursor c, Uri uri) {
+        for (int index = 0; index < mClusters.size(); ++index) {
+            buildSingleCluster(projection, c,
+                    uri.buildUpon().appendPath(String.valueOf(index)).build());
+        }
+    }
+
+    private void buildSingleCluster(String[] projection, MatrixCursor c, Uri uri) {
+        loadClustersIfEmpty();
+
+        int parentId = Integer.parseInt(uri.getLastPathSegment());
+
+        Cluster cluster = mClusters.get(parentId);
+        int numItems = Math.min(cluster.getItemCount(), MAX_CLUSTER_ITEM_SIZE);
+        for (int i = 0; i < numItems; i++) {
+            Cluster.ClusterItem item = cluster.getItem(i);
+            Object[] row = new Object[projection.length];
+
+            for (int j = 0; j < projection.length; j++) {
+                if (!CLUSTER_COLUMN_CASES.containsKey(projection[j])) {
+                    continue;
+                }
+                int column = CLUSTER_COLUMN_CASES.get(projection[j]);
+                switch (column) {
+                case CLUSTER_CASE_ID:
+                    row[j] = i;
+                    break;
+                case CLUSTER_CASE_COUNT:
+                    row[j] = numItems;
+                    break;
+                case CLUSTER_CASE_PARENT_ID:
+                    row[j] = parentId;
+                    break;
+                case CLUSTER_CASE_IMAGE_URI:
+                    row[j] = item.getImageUri();
+                    break;
+                }
+            }
+            c.addRow(row);
+        }
+    }
+
+    @Override
+    public String getType(Uri uri) {
+        return null;
+    }
+
+    @Override
+    public Uri insert(Uri uri, ContentValues values) {
+        throw new UnsupportedOperationException("Insert not supported");
+    }
+
+    @Override
+    public int delete(Uri uri, String selection, String[] selectionArgs) {
+        throw new UnsupportedOperationException("Delete not supported");
+    }
+
+    @Override
+    public int update(Uri uri, ContentValues values, String selection,
+            String[] selectionArgs) {
+        throw new UnsupportedOperationException("Update not supported");
+    }
+
+    protected abstract void loadClusters(List<Cluster> clusters);
+
+    protected abstract void buildBrowseRow(String[] projection, MatrixCursor c,
+            Uri uri);
+
+    protected abstract void buildBrowseHeaders(String[] projection,
+            MatrixCursor c);
+}