media: Update ImageReader APIs

Bug: 10461757
Change-Id: Ic04e4c41965e3d417b29004f3f08e0cd56b8f4cb

7 files changed, 548 insertions, 118 deletions

diff --git a/api/current.txt b/api/current.txt
index 1a9b77c..b0a18de 100644
--- a/api/current.txt
+++ b/api/current.txt
@@ -12332,7 +12332,7 @@ package android.media {
     field public static final int EULER_Z = 2; // 0x2
   }
 
-  public abstract interface Image implements java.lang.AutoCloseable {
+  public abstract class Image implements java.lang.AutoCloseable {
     method public abstract void close();
     method public abstract int getFormat();
     method public abstract int getHeight();
@@ -12341,23 +12341,30 @@ package android.media {
     method public abstract int getWidth();
   }
 
-  public static abstract interface Image.Plane {
+  public static abstract class Image.Plane {
     method public abstract java.nio.ByteBuffer getBuffer();
     method public abstract int getPixelStride();
     method public abstract int getRowStride();
   }
 
-  public final class ImageReader implements java.lang.AutoCloseable {
-    ctor public ImageReader(int, int, int, int);
+  public class ImageReader implements java.lang.AutoCloseable {
+    method public android.media.Image acquireLatestImage() throws android.media.ImageReader.MaxImagesAcquiredException;
+    method public android.media.Image acquireNextImage() throws android.media.ImageReader.MaxImagesAcquiredException;
     method public void close();
     method public int getHeight();
     method public int getImageFormat();
     method public int getMaxImages();
-    method public android.media.Image getNextImage();
     method public android.view.Surface getSurface();
     method public int getWidth();
-    method public void releaseImage(android.media.Image);
-    method public void setImageAvailableListener(android.media.ImageReader.OnImageAvailableListener, android.os.Handler);
+    method public static android.media.ImageReader newInstance(int, int, int, int);
+    method public void setOnImageAvailableListener(android.media.ImageReader.OnImageAvailableListener, android.os.Handler);
+  }
+
+  public static class ImageReader.MaxImagesAcquiredException extends java.lang.Exception {
+    ctor public ImageReader.MaxImagesAcquiredException();
+    ctor public ImageReader.MaxImagesAcquiredException(java.lang.String);
+    ctor public ImageReader.MaxImagesAcquiredException(java.lang.String, java.lang.Throwable);
+    ctor public ImageReader.MaxImagesAcquiredException(java.lang.Throwable);
   }
 
   public static abstract interface ImageReader.OnImageAvailableListener {
diff --git a/core/tests/coretests/src/android/hardware/display/VirtualDisplayTest.java b/core/tests/coretests/src/android/hardware/display/VirtualDisplayTest.java
index ebecf2e..8278579 100644
--- a/core/tests/coretests/src/android/hardware/display/VirtualDisplayTest.java
+++ b/core/tests/coretests/src/android/hardware/display/VirtualDisplayTest.java
@@ -26,6 +26,7 @@ import android.hardware.display.DisplayManager;
 import android.hardware.display.VirtualDisplay;
 import android.media.Image;
 import android.media.ImageReader;
+import android.media.ImageReader.MaxImagesAcquiredException;
 import android.os.Bundle;
 import android.os.Handler;
 import android.os.Looper;
@@ -83,8 +84,8 @@ public class VirtualDisplayTest extends AndroidTestCase {
 
         mImageReaderLock.lock();
         try {
-            mImageReader = new ImageReader(WIDTH, HEIGHT, PixelFormat.RGBA_8888, 2);
-            mImageReader.setImageAvailableListener(mImageListener, mHandler);
+            mImageReader = ImageReader.newInstance(WIDTH, HEIGHT, PixelFormat.RGBA_8888, 2);
+            mImageReader.setOnImageAvailableListener(mImageListener, mHandler);
             mSurface = mImageReader.getSurface();
         } finally {
             mImageReaderLock.unlock();
@@ -409,19 +410,11 @@ public class VirtualDisplayTest extends AndroidTestCase {
                 }
 
                 Log.d(TAG, "New image available from virtual display.");
-                Image image = reader.getNextImage();
+
+                // Get the latest buffer.
+                Image image = reader.acquireLatestImage();
                 if (image != null) {
                     try {
-                        // Get the latest buffer.
-                        for (;;) {
-                            Image nextImage = reader.getNextImage();
-                            if (nextImage == null) {
-                                break;
-                            }
-                            reader.releaseImage(image);
-                            image = nextImage;
-                        }
-
                         // Scan for colors.
                         int color = scanImage(image);
                         synchronized (this) {
@@ -431,9 +424,12 @@ public class VirtualDisplayTest extends AndroidTestCase {
                             }
                         }
                     } finally {
-                        reader.releaseImage(image);
+                        image.close();
                     }
                 }
+            } catch (MaxImagesAcquiredException e) {
+                // We should never try to consume more buffers than maxImages.
+                throw new IllegalStateException(e);
             } finally {
                 mImageReaderLock.unlock();
             }
diff --git a/media/java/android/media/Image.java b/media/java/android/media/Image.java
index 9f442f5..915b09e 100644
--- a/media/java/android/media/Image.java
+++ b/media/java/android/media/Image.java
@@ -16,20 +16,19 @@
 
 package android.media;
 
-import android.graphics.ImageFormat;
 import java.nio.ByteBuffer;
 import java.lang.AutoCloseable;
 
 /**
  * <p>A single complete image buffer to use with a media source such as a
  * {@link MediaCodec} or a
- * {@link android.hardware.camera2.CameraDevice}.</p>
+ * {@link android.hardware.camera2.CameraDevice CameraDevice}.</p>
  *
  * <p>This class allows for efficient direct application access to the pixel
  * data of the Image through one or more
  * {@link java.nio.ByteBuffer ByteBuffers}. Each buffer is encapsulated in a
  * {@link Plane} that describes the layout of the pixel data in that plane. Due
- * to this direct access, and unlike the {@link android.graphics.Bitmap} class,
+ * to this direct access, and unlike the {@link android.graphics.Bitmap Bitmap} class,
  * Images are not directly usable as as UI resources.</p>
  *
  * <p>Since Images are often directly produced or consumed by hardware
@@ -40,19 +39,29 @@ import java.lang.AutoCloseable;
  * from various media sources, not closing old Image objects will prevent the
  * availability of new Images once
  * {@link ImageReader#getMaxImages the maximum outstanding image count} is
- * reached.</p>
+ * reached. When this happens, the function acquiring new Images will typically
+ * throw a
+ * {@link ImageReader.MaxImagesAcquiredException MaxImagesAcquiredException}.</p>
  *
  * @see ImageReader
  */
-public interface Image extends AutoCloseable {
+public abstract class Image implements AutoCloseable {
+    /**
+     * @hide
+     */
+    protected Image() {
+    }
+
     /**
      * Get the format for this image. This format determines the number of
      * ByteBuffers needed to represent the image, and the general layout of the
      * pixel data in each in ByteBuffer.
      *
+     * <p>
      * The format is one of the values from
-     * {@link android.graphics.ImageFormat}. The mapping between the formats and
-     * the planes is as follows:
+     * {@link android.graphics.ImageFormat ImageFormat}. The mapping between the
+     * formats and the planes is as follows:
+     * </p>
      *
      * <table>
      * <tr>
@@ -61,13 +70,14 @@ public interface Image extends AutoCloseable {
      *   <th>Layout details</th>
      * </tr>
      * <tr>
-     *   <td>{@link android.graphics.ImageFormat#JPEG}</td>
+     *   <td>{@link android.graphics.ImageFormat#JPEG JPEG}</td>
      *   <td>1</td>
      *   <td>Compressed data, so row and pixel strides are 0. To uncompress, use
-     *      {@link android.graphics.BitmapFactory#decodeByteArray}.</td>
+     *      {@link android.graphics.BitmapFactory#decodeByteArray BitmapFactory#decodeByteArray}.
+     *   </td>
      * </tr>
      * <tr>
-     *   <td>{@link android.graphics.ImageFormat#YUV_420_888}</td>
+     *   <td>{@link android.graphics.ImageFormat#YUV_420_888 YUV_420_888}</td>
      *   <td>3</td>
      *   <td>A luminance plane followed by the Cb and Cr chroma planes.
      *     The chroma planes have half the width and height of the luminance
@@ -75,53 +85,60 @@ public interface Image extends AutoCloseable {
      *     Each plane has its own row stride and pixel stride.</td>
      * </tr>
      * <tr>
-     *   <td>{@link android.graphics.ImageFormat#RAW_SENSOR}</td>
+     *   <td>{@link android.graphics.ImageFormat#RAW_SENSOR RAW_SENSOR}</td>
      *   <td>1</td>
      *   <td>A single plane of raw sensor image data, with 16 bits per color
      *     sample. The details of the layout need to be queried from the source of
      *     the raw sensor data, such as
-     *     {@link android.hardware.camera2.CameraDevice}.
+     *     {@link android.hardware.camera2.CameraDevice CameraDevice}.
      *   </td>
      * </tr>
      * </table>
      *
      * @see android.graphics.ImageFormat
      */
-    public int getFormat();
+    public abstract int getFormat();
 
     /**
      * The width of the image in pixels. For formats where some color channels
      * are subsampled, this is the width of the largest-resolution plane.
      */
-    public int getWidth();
+    public abstract int getWidth();
 
     /**
      * The height of the image in pixels. For formats where some color channels
      * are subsampled, this is the height of the largest-resolution plane.
      */
-    public int getHeight();
+    public abstract int getHeight();
 
     /**
-     * Get the timestamp associated with this frame. The timestamp is measured
-     * in nanoseconds, and is monotonically increasing. However, the zero point
-     * and whether the timestamp can be compared against other sources of time
-     * or images depend on the source of this image.
+     * Get the timestamp associated with this frame.
+     * <p>
+     * The timestamp is measured in nanoseconds, and is monotonically
+     * increasing. However, the zero point and whether the timestamp can be
+     * compared against other sources of time or images depend on the source of
+     * this image.
+     * </p>
      */
-    public long getTimestamp();
+    public abstract long getTimestamp();
 
     /**
      * Get the array of pixel planes for this Image. The number of planes is
      * determined by the format of the Image.
      */
-    public Plane[] getPlanes();
+    public abstract Plane[] getPlanes();
 
     /**
-     * Free up this frame for reuse. After calling this method, calling any
-     * methods on this Image will result in an IllegalStateException, and
-     * attempting to read from ByteBuffers returned by an earlier
-     * {@code Plane#getBuffer} call will have undefined behavior.
+     * Free up this frame for reuse.
+     * <p>
+     * After calling this method, calling any methods on this {@code Image} will
+     * result in an {@link IllegalStateException}, and attempting to read from
+     * {@link ByteBuffer ByteBuffers} returned by an earlier
+     * {@link Plane#getBuffer} call will have undefined behavior.
+     * </p>
      */
-    public void close();
+    @Override
+    public abstract void close();
 
     /**
      * <p>A single color plane of image data.</p>
@@ -134,29 +151,41 @@ public interface Image extends AutoCloseable {
      *
      * @see #getFormat
      */
-    public interface Plane {
+    public static abstract class Plane {
         /**
-         * <p>The row stride for this color plane, in bytes.
+         * @hide
+         */
+        protected Plane() {
+        }
+
+        /**
+         * <p>The row stride for this color plane, in bytes.</p>
          *
          * <p>This is the distance between the start of two consecutive rows of
-         * pixels in the image.</p>
+         * pixels in the image. The row stride is always greater than 0.</p>
          */
-        public int getRowStride();
+        public abstract int getRowStride();
         /**
          * <p>The distance between adjacent pixel samples, in bytes.</p>
          *
          * <p>This is the distance between two consecutive pixel values in a row
          * of pixels. It may be larger than the size of a single pixel to
-         * account for interleaved image data or padded formats.</p>
+         * account for interleaved image data or padded formats.
+         * The pixel stride is always greater than 0.</p>
          */
-        public int getPixelStride();
+        public abstract int getPixelStride();
         /**
-         * <p>Get a set of direct {@link java.nio.ByteBuffer byte buffers}
+         * <p>Get a direct {@link java.nio.ByteBuffer ByteBuffer}
          * containing the frame data.</p>
          *
+         * <p>In particular, the buffer returned will always have
+         * {@link java.nio.ByteBuffer#isDirect isDirect} return {@code true}, so
+         * the underlying data could be mapped as a pointer in JNI without doing
+         * any copies with {@code GetDirectBufferAddress}.</p>
+         *
          * @return the byte buffer containing the image data for this plane.
          */
-        public ByteBuffer getBuffer();
+        public abstract ByteBuffer getBuffer();
     }
 
 }
diff --git a/media/java/android/media/ImageReader.java b/media/java/android/media/ImageReader.java
index b14a899..e5bcb3e 100644
--- a/media/java/android/media/ImageReader.java
+++ b/media/java/android/media/ImageReader.java
@@ -40,41 +40,90 @@ import java.nio.ByteOrder;
  * <p>The image data is encapsulated in {@link Image} objects, and multiple such
  * objects can be accessed at the same time, up to the number specified by the
  * {@code maxImages} constructor parameter. New images sent to an ImageReader
- * through its Surface are queued until accessed through the
- * {@link #getNextImage} call. Due to memory limits, an image source will
+ * through its {@link Surface} are queued until accessed through the {@link #acquireLatestImage}
+ * or {@link #acquireNextImage} call. Due to memory limits, an image source will
  * eventually stall or drop Images in trying to render to the Surface if the
  * ImageReader does not obtain and release Images at a rate equal to the
  * production rate.</p>
  */
-public final class ImageReader implements AutoCloseable {
+public class ImageReader implements AutoCloseable {
+
+    /**
+     * <p>
+     * This exception is thrown when the user of an {@link ImageReader} tries to acquire a new
+     * {@link Image} when the maximum number of {@link Image Images} have already been acquired.
+     * The maximum number is determined by the {@code maxBuffers} argument of
+     * {@link ImageReader#newInstance newInstance}.
+     * </p>
+     *
+     * <p>
+     * To recover from this exception, release existing {@link Image images} back to the
+     * reader with {@link Image#close}.
+     * </p>
+     *
+     * @see Image#close
+     * @see ImageReader#acquireLatestImage
+     * @see ImageReader#acquireNextImage
+     */
+    public static class MaxImagesAcquiredException extends Exception {
+        /**
+         * Suppress Eclipse warnings
+         */
+        private static final long serialVersionUID = 761231231236L;
+
+        public MaxImagesAcquiredException() {
+        }
+
+        public MaxImagesAcquiredException(String message) {
+            super(message);
+        }
+
+        public MaxImagesAcquiredException(String message, Throwable throwable) {
+            super(message, throwable);
+        }
+
+        public MaxImagesAcquiredException(Throwable throwable) {
+            super(throwable);
+        }
+    }
 
     /**
      * <p>Create a new reader for images of the desired size and format.</p>
      *
-     * <p>The maxImages parameter determines the maximum number of {@link Image}
-     * objects that can be be acquired from the ImageReader
+     * <p>The {@code maxImages} parameter determines the maximum number of {@link Image}
+     * objects that can be be acquired from the {@code ImageReader}
      * simultaneously. Requesting more buffers will use up more memory, so it is
      * important to use only the minimum number necessary for the use case.</p>
      *
      * <p>The valid sizes and formats depend on the source of the image
      * data.</p>
      *
-     * @param width the width in pixels of the Images that this reader will
-     * produce.
-     * @param height the height in pixels of the Images that this reader will
-     * produce.
-     * @param format the format of the Image that this reader will produce. This
-     * must be one of the {@link android.graphics.ImageFormat} or
-     * {@link android.graphics.PixelFormat} constants.
-     * @param maxImages the maximum number of images the user will want to
-     * access simultaneously. This should be as small as possible to limit
-     * memory use. Once maxImages Images are obtained by the user, one of them
-     * has to be released before a new Image will become available for access
-     * through getNextImage(). Must be greater than 0.
+     * @param width
+     *            The width in pixels of the Images that this reader will produce.
+     * @param height
+     *            The height in pixels of the Images that this reader will produce.
+     * @param format
+     *            The format of the Image that this reader will produce. This
+     *            must be one of the {@link android.graphics.ImageFormat} or
+     *            {@link android.graphics.PixelFormat} constants.
+     * @param maxImages
+     *            The maximum number of images the user will want to
+     *            access simultaneously. This should be as small as possible to limit
+     *            memory use. Once maxImages Images are obtained by the user, one of them
+     *            has to be released before a new Image will become available for access
+     *            through {@link #acquireLatestImage()} or {@link #acquireNextImage()}.
+     *            Must be greater than 0.
      *
      * @see Image
      */
-    public ImageReader(int width, int height, int format, int maxImages) {
+    public static ImageReader newInstance(int width, int height, int format, int maxImages) {
+        return new ImageReader(width, height, format, maxImages);
+    }
+
+    /**
+     * @hide
+     */
+    protected ImageReader(int width, int height, int format, int maxImages) {
         mWidth = width;
         mHeight = height;
         mFormat = format;
@@ -96,33 +145,79 @@ public final class ImageReader implements AutoCloseable {
         mSurface = nativeGetSurface();
     }
 
+    /**
+     * The width of each {@link Image}, in pixels.
+     *
+     * <p>ImageReader guarantees that all Images acquired from ImageReader (for example, with
+     * {@link #acquireNextImage}) will have the same dimensions as specified in
+     * {@link #newInstance}.</p>
+     *
+     * @return the width of an Image
+     */
     public int getWidth() {
         return mWidth;
     }
 
+    /**
+     * The height of each {@link Image}, in pixels.
+     *
+     * <p>ImageReader guarantees that all Images acquired from ImageReader (for example, with
+     * {@link #acquireNextImage}) will have the same dimensions as specified in
+     * {@link #newInstance}.</p>
+     *
+     * @return the height of an Image
+     */
     public int getHeight() {
         return mHeight;
     }
 
+    /**
+     * The {@link ImageFormat image format} of each Image.
+     *
+     * <p>ImageReader guarantees that all {@link Image Images} acquired from ImageReader
+     *  (for example, with {@link #acquireNextImage}) will have the same format as specified in
+     * {@link #newInstance}.</p>
+     *
+     * @return the format of an Image
+     *
+     * @see ImageFormat
+     */
     public int getImageFormat() {
         return mFormat;
     }
 
+    /**
+     * Maximum number of images that can be acquired from the ImageReader by any time (for example,
+     * with {@link #acquireNextImage}).
+     *
+     * <p>An image is considered acquired after it's returned by a function from ImageReader, and
+     * until the Image is {@link Image#close closed} to release the image back to the ImageReader.
+     * </p>
+     *
+     * <p>Attempting to acquire more than {@code maxImages} concurrently will result in the
+     * acquire function throwing a {@link MaxImagesAcquiredException}. Furthermore,
+     * while the max number of images have been acquired by the ImageReader user, the producer
+     * enqueueing additional images may stall until at least one image has been released. </p>
+     *
+     * @return Maximum number of images for this ImageReader.
+     *
+     * @see Image#close
+     */
     public int getMaxImages() {
         return mMaxImages;
     }
 
     /**
-     * <p>Get a Surface that can be used to produce Images for this
-     * ImageReader.</p>
+     * <p>Get a {@link Surface} that can be used to produce {@link Image Images} for this
+     * {@code ImageReader}.</p>
      *
-     * <p>Until valid image data is rendered into this Surface, the
-     * {@link #getNextImage} method will return {@code null}. Only one source
+     * <p>Until valid image data is rendered into this {@link Surface}, the
+     * {@link #acquireNextImage} method will return {@code null}. Only one source
      * can be producing data into this Surface at the same time, although the
-     * same Surface can be reused with a different API once the first source is
-     * disconnected from the Surface.</p>
+     * same {@link Surface} can be reused with a different API once the first source is
+     * disconnected from the {@link Surface}.</p>
      *
-     * @return A Surface to use for a drawing target for various APIs.
+     * @return A {@link Surface} to use for a drawing target for various APIs.
      */
     public Surface getSurface() {
         return mSurface;
@@ -130,27 +225,96 @@ public final class ImageReader implements AutoCloseable {
 
     /**
      * <p>
-     * Get the next Image from the ImageReader's queue. Returns {@code null} if
+     * Acquire the latest {@link Image} from the ImageReader's queue, dropping older
+     * {@link Image images}. Returns {@code null} if no new image is available.
+     * </p>
+     * <p>
+     * This operation will acquire all the images possible from the ImageReader,
+     * but {@link #close} all images that aren't the latest. This function is
+     * recommended to use over {@link #acquireNextImage} for most use-cases, as it's
+     * more suited for real-time processing.
+     * </p>
+     * <p>
+     * Note that {@link #getMaxImages maxImages} should be at least 2 for
+     * {@link #acquireLatestImage} to be any different than {@link #acquireNextImage} -
+     * discarding all-but-the-newest {@link Image} requires temporarily acquiring two
+     * {@link Image Images} at once. Or more generally, calling {@link #acquireLatestImage}
+     * with less than two images of margin, that is
+     * {@code (maxImages - currentAcquiredImages < 2)} will not discard as expected.
+     * </p>
+     * <p>
+     * This operation will fail by throwing an {@link MaxImagesAcquiredException} if
+     * {@code maxImages} have been acquired with {@link #acquireLatestImage} or
+     * {@link #acquireNextImage}. In particular a sequence of {@link #acquireLatestImage}
+     * calls greater than {@link #getMaxImages} without calling {@link Image#close} in-between
+     * will exhaust the underlying queue. At such a time, {@link MaxImagesAcquiredException}
+     * will be thrown until more images are
+     * released with {@link Image#close}.
+     * </p>
+     *
+     * @return latest frame of image data, or {@code null} if no image data is available.
+     * @throws MaxImagesAcquiredException if too many images are currently acquired
+     */
+    public Image acquireLatestImage() throws MaxImagesAcquiredException {
+        Image image = acquireNextImage();
+        if (image == null) {
+            return null;
+        }
+        try {
+            for (;;) {
+                Image next = acquireNextImageNoThrow();
+                if (next == null) {
+                    Image result = image;
+                    image = null;
+                    return result;
+                }
+                image.close();
+                image = next;
+            }
+        } finally {
+            if (image != null) {
+                image.close();
+            }
+        }
+    }
+
+    private Image acquireNextImageNoThrow() {
+        try {
+            return acquireNextImage();
+        } catch (MaxImagesAcquiredException ex) {
+            return null;
+        }
+    }
+
+    /**
+     * <p>
+     * Acquire the next Image from the ImageReader's queue. Returns {@code null} if
      * no new image is available.
      * </p>
+     *
+     * <p><i>Warning:</i> Consider using {@link #acquireLatestImage()} instead, as it will
+     * automatically release older images, and allow slower-running processing routines to catch
+     * up to the newest frame. Usage of {@link #acquireNextImage} is recommended for
+     * batch/background processing. Incorrectly using this function can cause images to appear
+     * with an ever-increasing delay, followed by a complete stall where no new images seem to
+     * appear.
+     * </p>
+     *
      * <p>
-     * This operation will fail by throwing an
-     * {@link Surface.OutOfResourcesException OutOfResourcesException} if too
-     * many images have been acquired with {@link #getNextImage}. In particular
-     * a sequence of {@link #getNextImage} calls greater than {@link #getMaxImages}
-     * without calling {@link Image#close} or {@link #releaseImage} in-between
-     * will exhaust the underlying queue. At such a time,
-     * {@link Surface.OutOfResourcesException OutOfResourcesException} will be
-     * thrown until more images are released with {@link Image#close} or
-     * {@link #releaseImage}.
+     * This operation will fail by throwing an {@link MaxImagesAcquiredException} if
+     * {@code maxImages} have been acquired with {@link #acquireNextImage} or
+     * {@link #acquireLatestImage}. In particular a sequence of {@link #acquireNextImage} or
+     * {@link #acquireLatestImage} calls greater than {@link #getMaxImages maxImages} without
+     * calling {@link Image#close} in-between will exhaust the underlying queue. At such a time,
+     * {@link MaxImagesAcquiredException} will be thrown until more images are released with
+     * {@link Image#close}.
      * </p>
      *
-     * @return a new frame of image data, or {@code null} if no image data is
-     *         available.
-     * @throws Surface.OutOfResourcesException if too many images are currently
-     *         acquired
+     * @return a new frame of image data, or {@code null} if no image data is available.
+     * @throws MaxImagesAcquiredException if {@code maxImages} images are currently acquired
+     * @see #acquireLatestImage
      */
-    public Image getNextImage() {
+    public Image acquireNextImage() throws MaxImagesAcquiredException {
         SurfaceImage si = new SurfaceImage();
         if (nativeImageSetup(si)) {
             // create SurfacePlane objects
@@ -164,7 +328,7 @@ public final class ImageReader implements AutoCloseable {
     /**
      * <p>Return the frame to the ImageReader for reuse.</p>
      */
-    public void releaseImage(Image i) {
+    private void releaseImage(Image i) {
         if (! (i instanceof SurfaceImage) ) {
             throw new IllegalArgumentException(
                 "This image was not produced by an ImageReader");
@@ -183,13 +347,16 @@ public final class ImageReader implements AutoCloseable {
     /**
      * Register a listener to be invoked when a new image becomes available
      * from the ImageReader.
-     * @param listener the listener that will be run
-     * @param handler The handler on which the listener should be invoked, or null
-     * if the listener should be invoked on the calling thread's looper.
      *
-     * @throws IllegalArgumentException if no handler specified and the calling thread has no looper
+     * @param listener
+     *            The listener that will be run.
+     * @param handler
+     *            The handler on which the listener should be invoked, or null
+     *            if the listener should be invoked on the calling thread's looper.
+     * @throws IllegalArgumentException
+     *            If no handler specified and the calling thread has no looper.
      */
-   public void setImageAvailableListener(OnImageAvailableListener listener, Handler handler) {
+   public void setOnImageAvailableListener(OnImageAvailableListener listener, Handler handler) {
         mImageListener = listener;
 
         Looper looper;
@@ -206,12 +373,16 @@ public final class ImageReader implements AutoCloseable {
 
     /**
      * Callback interface for being notified that a new image is available.
+     *
+     * <p>
      * The onImageAvailable is called per image basis, that is, callback fires for every new frame
      * available from ImageReader.
+     * </p>
      */
     public interface OnImageAvailableListener {
         /**
          * Callback that is called when a new image is available from ImageReader.
+         *
          * @param reader the ImageReader the callback is associated with.
          * @see ImageReader
          * @see Image
@@ -220,12 +391,17 @@ public final class ImageReader implements AutoCloseable {
     }
 
     /**
-     * Free up all the resources associated with this ImageReader. After
-     * Calling this method, this ImageReader can not be used. calling
-     * any methods on this ImageReader and Images previously provided by {@link #getNextImage}
-     * will result in an IllegalStateException, and attempting to read from
-     * ByteBuffers returned by an earlier {@code Plane#getBuffer} call will
+     * Free up all the resources associated with this ImageReader.
+     *
+     * <p>
+     * After calling this method, this ImageReader can not be used. Calling
+     * any methods on this ImageReader and Images previously provided by
+     * {@link #acquireNextImage} or {@link #acquireLatestImage}
+     * will result in an {@link IllegalStateException}, and attempting to read from
+     * {@link ByteBuffer ByteBuffers} returned by an earlier
+     * {@link Image.Plane#getBuffer Plane#getBuffer} call will
      * have undefined behavior.
+     * </p>
      */
     @Override
     public void close() {
@@ -242,11 +418,14 @@ public final class ImageReader implements AutoCloseable {
     }
 
     /**
-     * Only a subset of the formats defined in {@link android.graphics.ImageFormat} and
-     * {@link android.graphics.PixelFormat} are supported by ImageReader. When reading RGB
-     * data from a surface, the formats defined in {@link android.graphics.PixelFormat}
-     * can be used, when reading YUV, JPEG or raw sensor data ( for example, from camera
-     *  or video decoder), formats from {@link android.graphics.ImageFormat} are used.
+     * Only a subset of the formats defined in
+     * {@link android.graphics.ImageFormat ImageFormat} and
+     * {@link android.graphics.PixelFormat PixelFormat} are supported by
+     * ImageReader. When reading RGB data from a surface, the formats defined in
+     * {@link android.graphics.PixelFormat PixelFormat} can be used, when
+     * reading YUV, JPEG or raw sensor data (for example, from camera or video
+     * decoder), formats from {@link android.graphics.ImageFormat ImageFormat}
+     * are used.
      */
     private int getNumPlanesFromFormat() {
         switch (mFormat) {
@@ -308,7 +487,7 @@ public final class ImageReader implements AutoCloseable {
      */
     private long mNativeContext;
 
-    private class SurfaceImage implements android.media.Image {
+    private class SurfaceImage extends android.media.Image {
         public SurfaceImage() {
             mIsImageValid = false;
         }
@@ -404,7 +583,7 @@ public final class ImageReader implements AutoCloseable {
                 mPlanes[i] = nativeCreatePlane(i);
             }
         }
-        private class SurfacePlane implements android.media.Image.Plane {
+        private class SurfacePlane extends android.media.Image.Plane {
             // SurfacePlane instance is created by native code when a new SurfaceImage is created
             private SurfacePlane(int index, int rowStride, int pixelStride) {
                 mIndex = index;
@@ -481,7 +660,7 @@ public final class ImageReader implements AutoCloseable {
     private synchronized native Surface nativeGetSurface();
     private synchronized native boolean nativeImageSetup(Image i);
 
-    /*
+    /**
      * We use a class initializer to allow the native code to cache some
      * field offsets.
      */
diff --git a/media/jni/android_media_ImageReader.cpp b/media/jni/android_media_ImageReader.cpp
index 94f20bc..56ae6b4 100644
--- a/media/jni/android_media_ImageReader.cpp
+++ b/media/jni/android_media_ImageReader.cpp
@@ -43,8 +43,8 @@
 
 using namespace android;
 
-static const char* const OutOfResourcesException =
-    "android/view/Surface$OutOfResourcesException";
+static const char* const MaxImagesAcquiredException =
+    "android/media/ImageReader$MaxImagesAcquiredException";
 
 enum {
     IMAGE_READER_MAX_NUM_PLANES = 3,
@@ -700,7 +700,7 @@ static jboolean ImageReader_imageSetup(JNIEnv* env, jobject thiz,
     if (buffer == NULL) {
         ALOGW("Unable to acquire a lockedBuffer, very likely client tries to lock more than"
             " maxImages buffers");
-        jniThrowException(env, OutOfResourcesException,
+        jniThrowException(env, MaxImagesAcquiredException,
                   "Too many outstanding images, close existing images"
                   " to be able to acquire more.");
         return false;
@@ -709,7 +709,7 @@ static jboolean ImageReader_imageSetup(JNIEnv* env, jobject thiz,
     if (res != NO_ERROR) {
         if (res != BAD_VALUE /*no buffers*/) {
             if (res == NOT_ENOUGH_DATA) {
-                jniThrowException(env, OutOfResourcesException,
+                jniThrowException(env, MaxImagesAcquiredException,
                           "Too many outstanding images, close existing images"
                           " to be able to acquire more.");
             } else {
diff --git a/media/tests/MediaFrameworkTest/src/com/android/mediaframeworktest/MediaFrameworkUnitTestRunner.java b/media/tests/MediaFrameworkTest/src/com/android/mediaframeworktest/MediaFrameworkUnitTestRunner.java
index ecdc287..64b12b7 100644
--- a/media/tests/MediaFrameworkTest/src/com/android/mediaframeworktest/MediaFrameworkUnitTestRunner.java
+++ b/media/tests/MediaFrameworkTest/src/com/android/mediaframeworktest/MediaFrameworkUnitTestRunner.java
@@ -49,6 +49,7 @@ public class MediaFrameworkUnitTestRunner extends InstrumentationTestRunner {
         addMediaPlayerStateUnitTests(suite);
         addMediaScannerUnitTests(suite);
         addCameraUnitTests(suite);
+        addImageReaderTests(suite);
         return suite;
     }
 
@@ -65,6 +66,10 @@ public class MediaFrameworkUnitTestRunner extends InstrumentationTestRunner {
         suite.addTestSuite(CameraMetadataTest.class);
     }
 
+    private void addImageReaderTests(TestSuite suite) {
+        suite.addTestSuite(ImageReaderTest.class);
+    }
+
     // Running all unit tests checking the state machine may be time-consuming.
     private void addMediaMetadataRetrieverStateUnitTests(TestSuite suite) {
         suite.addTestSuite(MediaMetadataRetrieverTest.class);
diff --git a/media/tests/MediaFrameworkTest/src/com/android/mediaframeworktest/unit/ImageReaderTest.java b/media/tests/MediaFrameworkTest/src/com/android/mediaframeworktest/unit/ImageReaderTest.java
new file mode 100644
index 0000000..900fff4
--- /dev/null
+++ b/media/tests/MediaFrameworkTest/src/com/android/mediaframeworktest/unit/ImageReaderTest.java
@@ -0,0 +1,214 @@
+/*
+ * 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.mediaframeworktest.unit;
+
+import static org.mockito.Mockito.*;
+
+import android.graphics.ImageFormat;
+import android.media.Image;
+import android.media.Image.Plane;
+import android.media.ImageReader;
+import android.media.ImageReader.OnImageAvailableListener;
+import android.media.ImageReader.MaxImagesAcquiredException;
+import android.test.AndroidTestCase;
+import android.test.suitebuilder.annotation.SmallTest;
+
+public class ImageReaderTest extends AndroidTestCase {
+
+    private static final String TAG = "ImageReaderTest-unit";
+
+    private static final int DEFAULT_WIDTH = 640;
+    private static final int DEFAULT_HEIGHT = 480;
+    private static final int DEFAULT_FORMAT = ImageFormat.YUV_420_888;
+    private static final int DEFAULT_MAX_IMAGES = 3;
+
+    private ImageReader mReader;
+    private Image mImage1;
+    private Image mImage2;
+    private Image mImage3;
+
+    @Override
+    protected void setUp() throws Exception {
+        super.setUp();
+
+        /**
+         * Workaround for mockito and JB-MR2 incompatibility
+         *
+         * Avoid java.lang.IllegalArgumentException: dexcache == null
+         * https://code.google.com/p/dexmaker/issues/detail?id=2
+         */
+        System.setProperty("dexmaker.dexcache", getContext().getCacheDir().toString());
+
+        // TODO: refactor above into one of the test runners
+
+        mReader = spy(ImageReader.newInstance(DEFAULT_WIDTH, DEFAULT_HEIGHT, DEFAULT_FORMAT,
+                DEFAULT_MAX_IMAGES));
+        mImage1 = mock(Image.class);
+        mImage2 = mock(Image.class);
+        mImage3 = mock(Image.class);
+
+        /**
+         * Ensure rest of classes are mockable
+         */
+        {
+            mock(Plane.class);
+            mock(OnImageAvailableListener.class);
+            mock(MaxImagesAcquiredException.class);
+        }
+
+    }
+
+    @Override
+    protected void tearDown() throws Exception {
+        mReader.close();
+
+        super.tearDown();
+    }
+
+    /**
+     * Return null when there is nothing in the image queue.
+     */
+    @SmallTest
+    public void testGetLatestImageEmpty() throws MaxImagesAcquiredException {
+        when(mReader.acquireNextImage()).thenReturn(null);
+        assertEquals(null, mReader.acquireLatestImage());
+    }
+
+    /**
+     * Return the last image from the image queue, close up the rest.
+     */
+    @SmallTest
+    public void testGetLatestImage1() throws MaxImagesAcquiredException {
+        when(mReader.acquireNextImage()).thenReturn(mImage1).thenReturn(null);
+        assertEquals(mImage1, mReader.acquireLatestImage());
+        verify(mImage1, never()).close();
+    }
+
+    /**
+     * Return the last image from the image queue, close up the rest.
+     */
+    @SmallTest
+    public void testGetLatestImage2() throws MaxImagesAcquiredException {
+        when(mReader.acquireNextImage()).thenReturn(mImage1).thenReturn(mImage2).thenReturn(null);
+        assertEquals(mImage2, mReader.acquireLatestImage());
+        verify(mImage1, atLeastOnce()).close();
+        verify(mImage2, never()).close();
+    }
+
+    /**
+     * Return the last image from the image queue, close up the rest.
+     */
+    @SmallTest
+    public void testGetLatestImage3() throws MaxImagesAcquiredException {
+        when(mReader.acquireNextImage()).thenReturn(mImage1).thenReturn(mImage2).
+                                         thenReturn(mImage3).
+                                         thenReturn(null);
+        assertEquals(mImage3, mReader.acquireLatestImage());
+        verify(mImage1, atLeastOnce()).close();
+        verify(mImage2, atLeastOnce()).close();
+        verify(mImage3, never()).close();
+    }
+
+    /**
+     * Return null if get a MaxImagesAcquiredException with no images in the queue.
+     */
+    @SmallTest
+    public void testGetLatestImageTooManyBuffersAcquiredEmpty()  throws MaxImagesAcquiredException {
+        when(mReader.acquireNextImage()).thenThrow(new MaxImagesAcquiredException());
+        try {
+            mReader.acquireLatestImage();
+            fail("Expected MaxImagesAcquiredException to be thrown");
+        } catch(MaxImagesAcquiredException e) {
+        }
+    }
+
+    /**
+     * Return the last image before we get a MaxImagesAcquiredException. Close up the rest.
+     */
+    @SmallTest
+    public void testGetLatestImageTooManyBuffersAcquired1() throws MaxImagesAcquiredException {
+        when(mReader.acquireNextImage()).thenReturn(mImage1).
+                                         thenThrow(new MaxImagesAcquiredException());
+        assertEquals(mImage1, mReader.acquireLatestImage());
+        verify(mImage1, never()).close();
+    }
+
+    /**
+     * Return the last image before we get a MaxImagesAcquiredException. Close up the rest.
+     */
+    @SmallTest
+    public void testGetLatestImageTooManyBuffersAcquired2() throws MaxImagesAcquiredException {
+
+        when(mReader.acquireNextImage()).thenReturn(mImage1).thenReturn(mImage2).
+                                         thenThrow(new MaxImagesAcquiredException());
+        assertEquals(mImage2, mReader.acquireLatestImage());
+        verify(mImage1, atLeastOnce()).close();
+        verify(mImage2, never()).close();
+    }
+
+    /**
+     * Return the last image before we get a MaxImagesAcquiredException. Close up the rest.
+     */
+    @SmallTest
+    public void testGetLatestImageTooManyBuffersAcquired3() throws MaxImagesAcquiredException {
+        when(mReader.acquireNextImage()).thenReturn(mImage1).thenReturn(mImage2).
+                                         thenReturn(mImage3).
+                                         thenThrow(new MaxImagesAcquiredException());
+        assertEquals(mImage3, mReader.acquireLatestImage());
+        verify(mImage1, atLeastOnce()).close();
+        verify(mImage2, atLeastOnce()).close();
+        verify(mImage3, never()).close();
+    }
+
+    /**
+     * All images are cleaned up when we get an unexpected Error.
+     */
+    @SmallTest
+    public void testGetLatestImageExceptionalError() throws MaxImagesAcquiredException {
+        when(mReader.acquireNextImage()).thenReturn(mImage1).thenReturn(mImage2).
+                                         thenReturn(mImage3).
+                                         thenThrow(new OutOfMemoryError());
+        try {
+            mReader.acquireLatestImage();
+            fail("Impossible");
+        } catch(OutOfMemoryError e) {
+        }
+
+        verify(mImage1, atLeastOnce()).close();
+        verify(mImage2, atLeastOnce()).close();
+        verify(mImage3, atLeastOnce()).close();
+    }
+
+    /**
+     * All images are cleaned up when we get an unexpected RuntimeException.
+     */
+    @SmallTest
+    public void testGetLatestImageExceptionalRuntime() throws MaxImagesAcquiredException {
+        when(mReader.acquireNextImage()).thenReturn(mImage1).thenReturn(mImage2).
+                                         thenReturn(mImage3).
+                                         thenThrow(new RuntimeException());
+        try {
+            mReader.acquireLatestImage();
+            fail("Impossible");
+        } catch(RuntimeException e) {
+        }
+
+        verify(mImage1, atLeastOnce()).close();
+        verify(mImage2, atLeastOnce()).close();
+        verify(mImage3, atLeastOnce()).close();
+    }
+}