1 files changed, 108 insertions, 0 deletions
diff --git a/src/com/android/gallery3d/ui/BitmapLoader.java b/src/com/android/gallery3d/ui/BitmapLoader.java
new file mode 100644
index 000000000..a708a90f3
--- /dev/null
+++ b/src/com/android/gallery3d/ui/BitmapLoader.java
@@ -0,0 +1,108 @@
+/*
+ * Copyright (C) 2010 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.ui;
+
+import android.graphics.Bitmap;
+
+import com.android.photos.data.GalleryBitmapPool;
+import com.android.gallery3d.util.Future;
+import com.android.gallery3d.util.FutureListener;
+
+// We use this class to
+//     1.) load bitmaps in background.
+//     2.) as a place holder for the loaded bitmap
+public abstract class BitmapLoader implements FutureListener<Bitmap> {
+    @SuppressWarnings("unused")
+    private static final String TAG = "BitmapLoader";
+
+    /* Transition Map:
+     *   INIT -> REQUESTED, RECYCLED
+     *   REQUESTED -> INIT (cancel), LOADED, ERROR, RECYCLED
+     *   LOADED, ERROR -> RECYCLED
+     */
+    private static final int STATE_INIT = 0;
+    private static final int STATE_REQUESTED = 1;
+    private static final int STATE_LOADED = 2;
+    private static final int STATE_ERROR = 3;
+    private static final int STATE_RECYCLED = 4;
+
+    private int mState = STATE_INIT;
+    // mTask is not null only when a task is on the way
+    private Future<Bitmap> mTask;
+    private Bitmap mBitmap;
+
+    @Override
+    public void onFutureDone(Future<Bitmap> future) {
+        synchronized (this) {
+            mTask = null;
+            mBitmap = future.get();
+            if (mState == STATE_RECYCLED) {
+                if (mBitmap != null) {
+                    GalleryBitmapPool.getInstance().put(mBitmap);
+                    mBitmap = null;
+                }
+                return; // don't call callback
+            }
+            if (future.isCancelled() && mBitmap == null) {
+                if (mState == STATE_REQUESTED) mTask = submitBitmapTask(this);
+                return; // don't call callback
+            } else {
+                mState = mBitmap == null ? STATE_ERROR : STATE_LOADED;
+            }
+        }
+        onLoadComplete(mBitmap);
+    }
+
+    public synchronized void startLoad() {
+        if (mState == STATE_INIT) {
+            mState = STATE_REQUESTED;
+            if (mTask == null) mTask = submitBitmapTask(this);
+        }
+    }
+
+    public synchronized void cancelLoad() {
+        if (mState == STATE_REQUESTED) {
+            mState = STATE_INIT;
+            if (mTask != null) mTask.cancel();
+        }
+    }
+
+    // Recycle the loader and the bitmap
+    public synchronized void recycle() {
+        mState = STATE_RECYCLED;
+        if (mBitmap != null) {
+            GalleryBitmapPool.getInstance().put(mBitmap);
+            mBitmap = null;
+        }
+        if (mTask != null) mTask.cancel();
+    }
+
+    public synchronized boolean isRequestInProgress() {
+        return mState == STATE_REQUESTED;
+    }
+
+    public synchronized boolean isRecycled() {
+        return mState == STATE_RECYCLED;
+    }
+
+    public synchronized Bitmap getBitmap() {
+        return mBitmap;
+    }
+
+    abstract protected Future<Bitmap> submitBitmapTask(FutureListener<Bitmap> l);
+    abstract protected void onLoadComplete(Bitmap bitmap);
+}