Camera Extensions: Add Postview to sample

- Enable postview in extension samples
- Add sample postview feature to the
basic extension sample

Test: Camera CTS
Bug: 258295487
Change-Id: I98506f0edd6c2e7f2da0740a243bb564db82274d

18 files changed, 536 insertions, 3 deletions

diff --git a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/AutoImageCaptureExtenderImpl.java b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/AutoImageCaptureExtenderImpl.java
index 49a5a0ef..bd605708 100755
--- a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/AutoImageCaptureExtenderImpl.java
+++ b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/AutoImageCaptureExtenderImpl.java
@@ -95,6 +95,11 @@ public final class AutoImageCaptureExtenderImpl implements ImageCaptureExtenderI
         throw new RuntimeException("Stub, replace with implementation.");
     }
 
+    @Override
+    public List<Pair<Integer, Size[]>> getSupportedPostviewResolutions(Size captureSize) {
+        throw new RuntimeException("Stub, replace with implementation.");
+    }
+
     @Nullable
     @Override
     public Range<Long> getEstimatedCaptureLatencyRange(@NonNull Size captureOutputSize) {
@@ -127,4 +132,9 @@ public final class AutoImageCaptureExtenderImpl implements ImageCaptureExtenderI
     public Pair<Long, Long> getRealtimeCaptureLatency() {
         throw new RuntimeException("Stub, replace with implementation.");
     }
+
+    @Override
+    public boolean isPostviewAvailable() {
+        throw new RuntimeException("Stub, replace with implementation.");
+    }
 }
diff --git a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/BeautyImageCaptureExtenderImpl.java b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/BeautyImageCaptureExtenderImpl.java
index 4a7f9203..50c80407 100755
--- a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/BeautyImageCaptureExtenderImpl.java
+++ b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/BeautyImageCaptureExtenderImpl.java
@@ -95,6 +95,11 @@ public final class BeautyImageCaptureExtenderImpl implements ImageCaptureExtende
         throw new RuntimeException("Stub, replace with implementation.");
     }
 
+    @Override
+    public List<Pair<Integer, Size[]>> getSupportedPostviewResolutions(Size captureSize) {
+        throw new RuntimeException("Stub, replace with implementation.");
+    }
+
     @Nullable
     @Override
     public Range<Long> getEstimatedCaptureLatencyRange(@NonNull Size captureOutputSize) {
@@ -127,4 +132,9 @@ public final class BeautyImageCaptureExtenderImpl implements ImageCaptureExtende
     public Pair<Long, Long> getRealtimeCaptureLatency() {
         throw new RuntimeException("Stub, replace with implementation.");
     }
+
+    @Override
+    public boolean isPostviewAvailable() {
+        throw new RuntimeException("Stub, replace with implementation.");
+    }
 }
diff --git a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/BokehImageCaptureExtenderImpl.java b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/BokehImageCaptureExtenderImpl.java
index 576029c0..ee777cf9 100644
--- a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/BokehImageCaptureExtenderImpl.java
+++ b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/BokehImageCaptureExtenderImpl.java
@@ -95,6 +95,11 @@ public final class BokehImageCaptureExtenderImpl implements ImageCaptureExtender
         throw new RuntimeException("Stub, replace with implementation.");
     }
 
+    @Override
+    public List<Pair<Integer, Size[]>> getSupportedPostviewResolutions(Size captureSize) {
+        throw new RuntimeException("Stub, replace with implementation.");
+    }
+
     @Nullable
     @Override
     public Range<Long> getEstimatedCaptureLatencyRange(@NonNull Size captureOutputSize) {
@@ -127,4 +132,9 @@ public final class BokehImageCaptureExtenderImpl implements ImageCaptureExtender
     public Pair<Long, Long> getRealtimeCaptureLatency() {
         throw new RuntimeException("Stub, replace with implementation.");
     }
+
+    @Override
+    public boolean isPostviewAvailable() {
+        throw new RuntimeException("Stub, replace with implementation.");
+    }
 }
diff --git a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/CaptureProcessorImpl.java b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/CaptureProcessorImpl.java
index 3eee146a..f4719b8b 100644
--- a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/CaptureProcessorImpl.java
+++ b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/CaptureProcessorImpl.java
@@ -21,6 +21,7 @@ import android.graphics.ImageFormat;
 import android.hardware.camera2.TotalCaptureResult;
 import android.media.Image;
 import android.util.Pair;
+import android.util.Size;
 import android.view.Surface;
 
 import java.util.Map;
@@ -46,6 +47,29 @@ public interface CaptureProcessorImpl extends ProcessorImpl {
     void process(Map<Integer, Pair<Image, TotalCaptureResult>> results);
 
     /**
+     * Informs the CaptureProcessorImpl where it should write the postview output to.
+     * This will only be invoked once if a valid postview surface was set.
+     *
+     * @param surface A valid {@link ImageFormat#YUV_420_888} {@link Surface}
+     *                that the CaptureProcessorImpl should write data into.
+     * @since 1.4
+     */
+    void onPostviewOutputSurface(Surface surface);
+
+    /**
+     * Invoked when the Camera Framework changes the configured output resolution for
+     * still capture and postview.
+     *
+     * <p>After this call, {@link CaptureProcessorImpl} should expect any {@link Image} received as
+     * input for still capture and postview to be at the specified resolutions.
+     *
+     * @param size for the surface for still capture.
+     * @param postviewSize for the surface for postview.
+     * @since 1.4
+     */
+    void onResolutionUpdate(Size size, Size postviewSize);
+
+    /**
      * Process a set images captured that were requested.
      *
      * <p> The result of the processing step should be written to the {@link Surface} that was
@@ -63,4 +87,30 @@ public interface CaptureProcessorImpl extends ProcessorImpl {
      */
     void process(Map<Integer, Pair<Image, TotalCaptureResult>> results,
             ProcessResultImpl resultCallback, Executor executor);
+
+    /**
+     * Process a set images captured that were requested for both postview and
+     * still capture.
+     *
+     * <p> This processing method will be called if a postview was requested, therefore the
+     * processed postview should be written to the
+     * {@link Surface} received by {@link #onPostviewOutputSurface(Surface, int)}.
+     * The final result of the processing step should be written to the {@link Surface} that was
+     * received by {@link #onOutputSurface(Surface, int)}. Since postview should be available
+     * before the capture, it should be processed and written to the surface before
+     * the final capture is processed.
+     *
+     * @param results             The map of {@link ImageFormat#YUV_420_888} format images and
+     *                            metadata to process. The {@link Image} that are contained within
+     *                            the map will become invalid after this method completes, so no
+     *                            references to them should be kept.
+     * @param resultCallback      Capture result callback to be called once the capture result
+     *                            values of the processed image are ready.
+     * @param executor            The executor to run the callback on. If null then the callback
+     *                            will run on any arbitrary executor.
+     * @throws RuntimeException   if postview feature is not supported
+     * @since 1.4
+     */
+    void processWithPostview(Map<Integer, Pair<Image, TotalCaptureResult>> results,
+            ProcessResultImpl resultCallback, Executor executor);
 }
diff --git a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/HdrImageCaptureExtenderImpl.java b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/HdrImageCaptureExtenderImpl.java
index a505cb8b..f3fd2f3b 100644
--- a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/HdrImageCaptureExtenderImpl.java
+++ b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/HdrImageCaptureExtenderImpl.java
@@ -95,6 +95,11 @@ public final class HdrImageCaptureExtenderImpl implements ImageCaptureExtenderIm
         throw new RuntimeException("Stub, replace with implementation.");
     }
 
+    @Override
+    public List<Pair<Integer, Size[]>> getSupportedPostviewResolutions(Size captureSize) {
+        throw new RuntimeException("Stub, replace with implementation.");
+    }
+
     @Nullable
     @Override
     public Range<Long> getEstimatedCaptureLatencyRange(@NonNull Size captureOutputSize) {
@@ -127,4 +132,9 @@ public final class HdrImageCaptureExtenderImpl implements ImageCaptureExtenderIm
     public Pair<Long, Long> getRealtimeCaptureLatency() {
         throw new RuntimeException("Stub, replace with implementation.");
     }
+
+    @Override
+    public boolean isPostviewAvailable() {
+        throw new RuntimeException("Stub, replace with implementation.");
+    }
 }
diff --git a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/ImageCaptureExtenderImpl.java b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/ImageCaptureExtenderImpl.java
index cfc23b11..70c1804e 100644
--- a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/ImageCaptureExtenderImpl.java
+++ b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/ImageCaptureExtenderImpl.java
@@ -85,6 +85,21 @@ public interface ImageCaptureExtenderImpl extends ExtenderStateListener {
     List<Pair<Integer, Size[]>> getSupportedResolutions();
 
     /**
+     * Returns the customized supported postview resolutions for a still capture using
+     * its size.
+     *
+     * <p>Pair list composed with {@link ImageFormat} and {@link Size} array will be returned.
+     *
+     * <p>The returned resolutions should be subset of the supported sizes retrieved from
+     * {@link android.hardware.camera2.params.StreamConfigurationMap} for the camera device.
+     *
+     * @return the customized supported resolutions, or null to support all sizes retrieved from
+     *         {@link android.hardware.camera2.params.StreamConfigurationMap}.
+     * @since 1.4
+     */
+    List<Pair<Integer, Size[]>> getSupportedPostviewResolutions(Size captureSize);
+
+    /**
      * Returns the estimated capture latency range in milliseconds for the target capture
      * resolution.
      *
@@ -188,4 +203,15 @@ public interface ImageCaptureExtenderImpl extends ExtenderStateListener {
      * @since 1.4
      */
     Pair<Long, Long> getRealtimeCaptureLatency();
+
+    /**
+     * Indicates whether the extension supports the postview for still capture feature.
+     * If the extension is using HAL processing, false should be returned since the
+     * postview feature is not currently supported for this case.
+     *
+     * @return {@code true} in case postview for still capture is supported
+     * {@code false} otherwise.
+     * @since 1.4
+     */
+    boolean isPostviewAvailable();
 }
diff --git a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/NightImageCaptureExtenderImpl.java b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/NightImageCaptureExtenderImpl.java
index 829c8a09..6f0eaef9 100755
--- a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/NightImageCaptureExtenderImpl.java
+++ b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/NightImageCaptureExtenderImpl.java
@@ -95,6 +95,11 @@ public final class NightImageCaptureExtenderImpl implements ImageCaptureExtender
         throw new RuntimeException("Stub, replace with implementation.");
     }
 
+    @Override
+    public List<Pair<Integer, Size[]>> getSupportedPostviewResolutions(Size captureSize) {
+        throw new RuntimeException("Stub, replace with implementation.");
+    }
+
     @Nullable
     @Override
     public Range<Long> getEstimatedCaptureLatencyRange(@NonNull Size captureOutputSize) {
@@ -127,4 +132,9 @@ public final class NightImageCaptureExtenderImpl implements ImageCaptureExtender
     public Pair<Long, Long> getRealtimeCaptureLatency() {
         throw new RuntimeException("Stub, replace with implementation.");
     }
+
+    @Override
+    public boolean isPostviewAvailable() {
+        throw new RuntimeException("Stub, replace with implementation.");
+    }
 }
diff --git a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/advanced/AdvancedExtenderImpl.java b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/advanced/AdvancedExtenderImpl.java
index fcda9bee..abcbf5fd 100644
--- a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/advanced/AdvancedExtenderImpl.java
+++ b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/advanced/AdvancedExtenderImpl.java
@@ -124,6 +124,17 @@ public interface AdvancedExtenderImpl {
     Map<Integer, List<Size>> getSupportedCaptureOutputResolutions(String cameraId);
 
     /**
+     * Returns supported output format/size map for postview image. OEM is required to support
+     * both JPEG and YUV_420_888 format output.
+     *
+     * <p>The surface created with this supported format/size could configure
+     * intermediate surfaces(YUV/RAW..) and write the output to the output surface.</p>
+     *
+     * @since 1.4
+     */
+    Map<Integer, List<Size>> getSupportedPostviewResolutions(Size captureSize);
+
+    /**
      * Returns supported output sizes for Image Analysis (YUV_420_888 format).
      *
      * <p>OEM can optionally support a YUV surface for ImageAnalysis along with Preview/ImageCapture
@@ -194,4 +205,15 @@ public interface AdvancedExtenderImpl {
      * @since 1.4
      */
     boolean isCaptureProcessProgressAvailable();
+
+    /**
+     * Indicates whether the extension supports the postview for still capture feature.
+     * If the extension is using HAL processing, false should be returned since the
+     * postview feature is not currently supported for this case.
+     *
+     * @return {@code true} in case postview for still capture is supported
+     * {@code false} otherwise.
+     * @since 1.4
+     */
+    boolean isPostviewAvailable();
 }
diff --git a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/advanced/BaseAdvancedExtenderImpl.java b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/advanced/BaseAdvancedExtenderImpl.java
index 7041dae5..00b57058 100644
--- a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/advanced/BaseAdvancedExtenderImpl.java
+++ b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/advanced/BaseAdvancedExtenderImpl.java
@@ -116,6 +116,11 @@ public abstract class BaseAdvancedExtenderImpl implements AdvancedExtenderImpl {
     }
 
     @Override
+    public Map<Integer, List<Size>> getSupportedPostviewResolutions(Size captureSize) {
+        return new HashMap<>();
+    }
+
+    @Override
     public List<Size> getSupportedYuvAnalysisResolutions(
             String cameraId) {
         return null;
@@ -217,7 +222,8 @@ public abstract class BaseAdvancedExtenderImpl implements AdvancedExtenderImpl {
             // called. This is just a sample for earlier versions if wanting to redirect this call.
             OutputSurfaceConfigurationImplImpl surfaceConfigs =
                     new OutputSurfaceConfigurationImplImpl(previewSurfaceConfig,
-                    imageCaptureSurfaceConfig, imageAnalysisSurfaceConfig);
+                    imageCaptureSurfaceConfig, imageAnalysisSurfaceConfig,
+                    null /*postviewSurfaceConfig*/);
 
             return initSession(cameraId, cameraCharacteristicsMap, context, surfaceConfigs);
         }
@@ -452,6 +458,11 @@ public abstract class BaseAdvancedExtenderImpl implements AdvancedExtenderImpl {
         }
 
         @Override
+        public int startCaptureWithPostview(@NonNull CaptureCallback captureCallback) {
+            return startCapture(captureCallback);
+        }
+
+        @Override
         public int startCapture(@NonNull CaptureCallback captureCallback) {
             List<RequestProcessorImpl.Request> requestList = new ArrayList<>();
             addCaptureRequestParameters(requestList);
@@ -626,13 +637,16 @@ public abstract class BaseAdvancedExtenderImpl implements AdvancedExtenderImpl {
         private OutputSurfaceImpl mOutputPreviewSurfaceImpl;
         private OutputSurfaceImpl mOutputImageCaptureSurfaceImpl;
         private OutputSurfaceImpl mOutputImageAnalysisSurfaceImpl;
+        private OutputSurfaceImpl mOutputPostviewSurfaceImpl;
 
         public OutputSurfaceConfigurationImplImpl(OutputSurfaceImpl previewSurfaceConfig,
                 OutputSurfaceImpl imageCaptureSurfaceConfig,
-                OutputSurfaceImpl imageAnalysisSurfaceConfig) {
+                OutputSurfaceImpl imageAnalysisSurfaceConfig,
+                OutputSurfaceImpl postviewSurfaceConfig) {
             mOutputPreviewSurfaceImpl = previewSurfaceConfig;
             mOutputImageCaptureSurfaceImpl = imageCaptureSurfaceConfig;
             mOutputImageAnalysisSurfaceImpl = imageAnalysisSurfaceConfig;
+            mOutputPostviewSurfaceImpl = postviewSurfaceConfig;
         }
 
         @Override
@@ -649,6 +663,11 @@ public abstract class BaseAdvancedExtenderImpl implements AdvancedExtenderImpl {
         public OutputSurfaceImpl getImageAnalysisOutputSurface() {
             return mOutputImageAnalysisSurfaceImpl;
         }
+
+        @Override
+        public OutputSurfaceImpl getPostviewOutputSurface() {
+            return mOutputPostviewSurfaceImpl;
+        }
     }
 
     @Override
@@ -672,4 +691,9 @@ public abstract class BaseAdvancedExtenderImpl implements AdvancedExtenderImpl {
     public boolean isCaptureProcessProgressAvailable() {
         return true;
     }
+
+    @Override
+    public boolean isPostviewAvailable() {
+        return false;
+    }
 }
diff --git a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/advanced/OutputSurfaceConfigurationImpl.java b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/advanced/OutputSurfaceConfigurationImpl.java
index 8e470139..ca3832e3 100644
--- a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/advanced/OutputSurfaceConfigurationImpl.java
+++ b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/advanced/OutputSurfaceConfigurationImpl.java
@@ -30,4 +30,6 @@ public interface OutputSurfaceConfigurationImpl {
     public OutputSurfaceImpl getImageCaptureOutputSurface();
 
     public OutputSurfaceImpl getImageAnalysisOutputSurface();
+
+    public OutputSurfaceImpl getPostviewOutputSurface();
 }
diff --git a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/advanced/SessionProcessorImpl.java b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/advanced/SessionProcessorImpl.java
index 11e63956..8dbfadc2 100644
--- a/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/advanced/SessionProcessorImpl.java
+++ b/camera2/extensions/advancedSample/src/java/androidx/camera/extensions/impl/advanced/SessionProcessorImpl.java
@@ -224,6 +224,26 @@ public interface SessionProcessorImpl {
     void stopRepeating();
 
     /**
+     * Start a multi-frame capture with a postview. {@link #startCapture(CaptureCallback)}
+     * will be used for captures without a postview request.
+     *
+     * Postview will be available before the capture. Upon postview completion,
+     * {@code OnImageAvailableListener#onImageAvailable} will be called on the ImageReader
+     * that creates the postview output surface. When the capture is completed,
+     * {@link CaptureCallback#onCaptureSequenceCompleted} is called and
+     * {@code OnImageAvailableListener#onImageAvailable} will also be called on the ImageReader
+     * that creates the image capture output surface.
+     *
+     * <p>Only one capture can perform at a time. Starting a capture when another capture is
+     * running will cause onCaptureFailed to be called immediately.
+     *
+     * @param callback a callback to report the status.
+     * @return the id of the capture sequence.
+     * @since 1.4
+     */
+    int startCaptureWithPostview(CaptureCallback callback);
+
+    /**
      * Start a multi-frame capture.
      *
      * When the capture is completed, {@link CaptureCallback#onCaptureSequenceCompleted}
diff --git a/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/AutoImageCaptureExtenderImpl.java b/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/AutoImageCaptureExtenderImpl.java
index fa19a03a..30a79a6b 100755
--- a/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/AutoImageCaptureExtenderImpl.java
+++ b/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/AutoImageCaptureExtenderImpl.java
@@ -117,6 +117,26 @@ public final class AutoImageCaptureExtenderImpl implements ImageCaptureExtenderI
                     }
 
                     @Override
+                    public void onPostviewOutputSurface(Surface surface) {
+
+                    }
+
+                    @Override
+                    public void processWithPostview(
+                            Map<Integer, Pair<Image, TotalCaptureResult>> results,
+                            ProcessResultImpl resultCallback, Executor executor) {
+                        if (!isPostviewAvailable()) {
+                            throw new RuntimeException("The extension doesn't support postview");
+                        }
+
+                        if (resultCallback != null) {
+                            process(results, resultCallback, executor);
+                        } else {
+                            process(results);
+                        }
+                    }
+
+                    @Override
                     public void process(Map<Integer, Pair<Image, TotalCaptureResult>> results,
                             ProcessResultImpl resultCallback, Executor executor) {
                         throw new RuntimeException("The extension doesn't support capture " +
@@ -165,6 +185,11 @@ public final class AutoImageCaptureExtenderImpl implements ImageCaptureExtenderI
                     }
 
                     @Override
+                    public void onResolutionUpdate(Size size, Size postviewSize) {
+
+                    }
+
+                    @Override
                     public void onImageFormatUpdate(int imageFormat) {
 
                     }
@@ -245,6 +270,11 @@ public final class AutoImageCaptureExtenderImpl implements ImageCaptureExtenderI
     }
 
     @Override
+    public List<Pair<Integer, Size[]>> getSupportedPostviewResolutions(Size captureSize) {
+        return new ArrayList<>();
+    }
+
+    @Override
     public Range<Long> getEstimatedCaptureLatencyRange(Size captureOutputSize) {
         return null;
     }
@@ -273,4 +303,9 @@ public final class AutoImageCaptureExtenderImpl implements ImageCaptureExtenderI
     public Pair<Long, Long> getRealtimeCaptureLatency() {
         return null;
     }
+
+    @Override
+    public boolean isPostviewAvailable() {
+        return false;
+    }
 }
diff --git a/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/BeautyImageCaptureExtenderImpl.java b/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/BeautyImageCaptureExtenderImpl.java
index f769549b..c9b24206 100755
--- a/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/BeautyImageCaptureExtenderImpl.java
+++ b/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/BeautyImageCaptureExtenderImpl.java
@@ -119,6 +119,26 @@ public final class BeautyImageCaptureExtenderImpl implements ImageCaptureExtende
                     }
 
                     @Override
+                    public void onPostviewOutputSurface(Surface surface) {
+
+                    }
+
+                    @Override
+                    public void processWithPostview(
+                            Map<Integer, Pair<Image, TotalCaptureResult>> results,
+                            ProcessResultImpl resultCallback, Executor executor) {
+                        if (!isPostviewAvailable()) {
+                            throw new RuntimeException("The extension doesn't support postview");
+                        }
+
+                        if (resultCallback != null) {
+                            process(results, resultCallback, executor);
+                        } else {
+                            process(results);
+                        }
+                    }
+
+                    @Override
                     public void process(Map<Integer, Pair<Image, TotalCaptureResult>> results,
                             ProcessResultImpl resultCallback, Executor executor) {
                         throw new RuntimeException("The extension doesn't support capture " +
@@ -167,6 +187,11 @@ public final class BeautyImageCaptureExtenderImpl implements ImageCaptureExtende
                     }
 
                     @Override
+                    public void onResolutionUpdate(Size size, Size postviewSize) {
+
+                    }
+
+                    @Override
                     public void onImageFormatUpdate(int imageFormat) {
 
                     }
@@ -268,6 +293,11 @@ public final class BeautyImageCaptureExtenderImpl implements ImageCaptureExtende
     }
 
     @Override
+    public List<Pair<Integer, Size[]>> getSupportedPostviewResolutions(Size captureSize) {
+        return new ArrayList<>();
+    }
+
+    @Override
     public Range<Long> getEstimatedCaptureLatencyRange(Size captureOutputSize) {
         return null;
     }
@@ -296,4 +326,9 @@ public final class BeautyImageCaptureExtenderImpl implements ImageCaptureExtende
     public Pair<Long, Long> getRealtimeCaptureLatency() {
         return null;
     }
+
+    @Override
+    public boolean isPostviewAvailable() {
+        return false;
+    }
 }
diff --git a/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/BokehImageCaptureExtenderImpl.java b/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/BokehImageCaptureExtenderImpl.java
index d3412eb0..a72deef6 100644
--- a/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/BokehImageCaptureExtenderImpl.java
+++ b/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/BokehImageCaptureExtenderImpl.java
@@ -16,11 +16,13 @@
 package androidx.camera.extensions.impl;
 
 import android.content.Context;
+import android.graphics.ImageFormat;
 import android.hardware.camera2.CameraCharacteristics;
 import android.hardware.camera2.CaptureRequest;
 import android.hardware.camera2.CaptureResult;
 import android.hardware.camera2.TotalCaptureResult;
 import android.hardware.camera2.params.SessionConfiguration;
+import android.hardware.camera2.params.StreamConfigurationMap;
 import android.media.Image;
 import android.media.ImageWriter;
 import android.os.Build;
@@ -52,6 +54,8 @@ public final class BokehImageCaptureExtenderImpl implements ImageCaptureExtender
     private static final int SESSION_STAGE_ID = 101;
     private static final int MODE = CaptureRequest.CONTROL_AWB_MODE_SHADE;
 
+    private CameraCharacteristics mCameraCharacteristics;
+
     /**
      * @hide
      */
@@ -63,6 +67,7 @@ public final class BokehImageCaptureExtenderImpl implements ImageCaptureExtender
      */
     @Override
     public void init(String cameraId, CameraCharacteristics cameraCharacteristics) {
+        mCameraCharacteristics = cameraCharacteristics;
     }
 
     /**
@@ -105,6 +110,7 @@ public final class BokehImageCaptureExtenderImpl implements ImageCaptureExtender
         CaptureProcessorImpl captureProcessor =
                 new CaptureProcessorImpl() {
                     private ImageWriter mImageWriter;
+                    private ImageWriter mImageWriterPostview;
 
                     @Override
                     public void onOutputSurface(Surface surface, int imageFormat) {
@@ -114,6 +120,61 @@ public final class BokehImageCaptureExtenderImpl implements ImageCaptureExtender
                     }
 
                     @Override
+                    public void onPostviewOutputSurface(Surface surface) {
+                        if ((Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) &&
+                                mImageWriterPostview == null) {
+                            mImageWriterPostview = ImageWriter.newInstance(surface, 1);
+                        }
+                    }
+
+                    @Override
+                    public void processWithPostview(
+                            Map<Integer, Pair<Image, TotalCaptureResult>> results,
+                            ProcessResultImpl resultCallback, Executor executor) {
+
+                        Pair<Image, TotalCaptureResult> result = results.get(DEFAULT_STAGE_ID);
+                        if (result == null) {
+                            Log.w(TAG,
+                                    "Unable to process since images does not contain all " +
+                                    "stages.");
+                            return;
+                        } else {
+                            if (Build.VERSION.SDK_INT >= Build.VERSION_CODES.M) {
+                                Image image = mImageWriterPostview.dequeueInputImage();
+
+                                // Postview processing here
+                                ByteBuffer yByteBuffer = image.getPlanes()[0].getBuffer();
+                                ByteBuffer uByteBuffer = image.getPlanes()[2].getBuffer();
+                                ByteBuffer vByteBuffer = image.getPlanes()[1].getBuffer();
+
+                                // For sample, allocate empty buffer to match postview size
+                                yByteBuffer.put(ByteBuffer.allocate(image.getPlanes()[0]
+                                        .getBuffer().capacity()));
+                                uByteBuffer.put(ByteBuffer.allocate(image.getPlanes()[2]
+                                        .getBuffer().capacity()));
+                                vByteBuffer.put(ByteBuffer.allocate(image.getPlanes()[1]
+                                        .getBuffer().capacity()));
+                                Long sensorTimestamp =
+                                        result.second.get(CaptureResult.SENSOR_TIMESTAMP);
+                                if (sensorTimestamp != null) {
+                                    image.setTimestamp(sensorTimestamp);
+                                } else {
+                                    Log.e(TAG, "Sensor timestamp absent using default!");
+                                }
+
+                                mImageWriterPostview.queueInputImage(image);
+                            }
+                        }
+
+                        // Process still capture
+                        if (resultCallback != null) {
+                            process(results, resultCallback, executor);
+                        } else {
+                            process(results);
+                        }
+                    }
+
+                    @Override
                     public void process(Map<Integer, Pair<Image, TotalCaptureResult>> results,
                             ProcessResultImpl resultCallback, Executor executor) {
                         Pair<Image, TotalCaptureResult> result = results.get(DEFAULT_STAGE_ID);
@@ -242,6 +303,11 @@ public final class BokehImageCaptureExtenderImpl implements ImageCaptureExtender
                     }
 
                     @Override
+                    public void onResolutionUpdate(Size size, Size postviewSize) {
+
+                    }
+
+                    @Override
                     public void onImageFormatUpdate(int imageFormat) {
 
                     }
@@ -318,7 +384,59 @@ public final class BokehImageCaptureExtenderImpl implements ImageCaptureExtender
      */
     @Override
     public List<Pair<Integer, Size[]>> getSupportedResolutions() {
-        return null;
+        List<Pair<Integer, Size[]>> formatResolutionsPairList = new ArrayList<>();
+
+        StreamConfigurationMap map =
+                mCameraCharacteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
+
+        if (map != null) {
+            // The sample implementation only retrieves originally supported resolutions from
+            // CameraCharacteristics for JPEG and YUV_420_888 formats to return.
+            Size[] outputSizes = map.getOutputSizes(ImageFormat.JPEG);
+
+            if (outputSizes != null) {
+                formatResolutionsPairList.add(Pair.create(ImageFormat.JPEG, outputSizes));
+            }
+
+            outputSizes = map.getOutputSizes(ImageFormat.YUV_420_888);
+
+            if (outputSizes != null) {
+                formatResolutionsPairList.add(Pair.create(ImageFormat.YUV_420_888, outputSizes));
+            }
+        }
+
+        return formatResolutionsPairList;
+    }
+
+    @Override
+    public List<Pair<Integer, Size[]>> getSupportedPostviewResolutions(Size captureSize) {
+        // Sample for supported postview sizes, returns subset of supported resolutions for
+        // still capture that are less than its size and match the aspect ratio
+        List<Pair<Integer, Size[]>> res = new ArrayList<>();
+        List<Pair<Integer, Size[]>> captureSupportedResolutions = getSupportedResolutions();
+        float targetAr = ((float) captureSize.getWidth()) / captureSize.getHeight();
+
+        for (Pair<Integer, Size[]> elem : captureSupportedResolutions) {
+            Integer currFormat = elem.first;
+            Size[] currFormatSizes = elem.second;
+            List<Size> postviewSizes = new ArrayList<>();
+
+            for (Size s : currFormatSizes) {
+                if ((s.equals(captureSize)) || (s.getWidth() > captureSize.getWidth())
+                        || (s.getHeight() > captureSize.getHeight())) continue;
+                float currentAr = ((float) s.getWidth()) / s.getHeight();
+                if (Math.abs(targetAr - currentAr) < 0.01) {
+                    postviewSizes.add(s);
+                }
+            }
+
+            if (!postviewSizes.isEmpty()) {
+                res.add(new Pair<Integer, Size[]>(currFormat,
+                        postviewSizes.toArray(new Size[postviewSizes.size()])));
+            }
+        }
+
+        return res;
     }
 
     @Override
@@ -357,4 +475,9 @@ public final class BokehImageCaptureExtenderImpl implements ImageCaptureExtender
     public Pair<Long, Long> getRealtimeCaptureLatency() {
         return null;
     }
+
+    @Override
+    public boolean isPostviewAvailable() {
+        return true;
+    }
 }
diff --git a/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/CaptureProcessorImpl.java b/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/CaptureProcessorImpl.java
index 3eee146a..f4719b8b 100644
--- a/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/CaptureProcessorImpl.java
+++ b/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/CaptureProcessorImpl.java
@@ -21,6 +21,7 @@ import android.graphics.ImageFormat;
 import android.hardware.camera2.TotalCaptureResult;
 import android.media.Image;
 import android.util.Pair;
+import android.util.Size;
 import android.view.Surface;
 
 import java.util.Map;
@@ -46,6 +47,29 @@ public interface CaptureProcessorImpl extends ProcessorImpl {
     void process(Map<Integer, Pair<Image, TotalCaptureResult>> results);
 
     /**
+     * Informs the CaptureProcessorImpl where it should write the postview output to.
+     * This will only be invoked once if a valid postview surface was set.
+     *
+     * @param surface A valid {@link ImageFormat#YUV_420_888} {@link Surface}
+     *                that the CaptureProcessorImpl should write data into.
+     * @since 1.4
+     */
+    void onPostviewOutputSurface(Surface surface);
+
+    /**
+     * Invoked when the Camera Framework changes the configured output resolution for
+     * still capture and postview.
+     *
+     * <p>After this call, {@link CaptureProcessorImpl} should expect any {@link Image} received as
+     * input for still capture and postview to be at the specified resolutions.
+     *
+     * @param size for the surface for still capture.
+     * @param postviewSize for the surface for postview.
+     * @since 1.4
+     */
+    void onResolutionUpdate(Size size, Size postviewSize);
+
+    /**
      * Process a set images captured that were requested.
      *
      * <p> The result of the processing step should be written to the {@link Surface} that was
@@ -63,4 +87,30 @@ public interface CaptureProcessorImpl extends ProcessorImpl {
      */
     void process(Map<Integer, Pair<Image, TotalCaptureResult>> results,
             ProcessResultImpl resultCallback, Executor executor);
+
+    /**
+     * Process a set images captured that were requested for both postview and
+     * still capture.
+     *
+     * <p> This processing method will be called if a postview was requested, therefore the
+     * processed postview should be written to the
+     * {@link Surface} received by {@link #onPostviewOutputSurface(Surface, int)}.
+     * The final result of the processing step should be written to the {@link Surface} that was
+     * received by {@link #onOutputSurface(Surface, int)}. Since postview should be available
+     * before the capture, it should be processed and written to the surface before
+     * the final capture is processed.
+     *
+     * @param results             The map of {@link ImageFormat#YUV_420_888} format images and
+     *                            metadata to process. The {@link Image} that are contained within
+     *                            the map will become invalid after this method completes, so no
+     *                            references to them should be kept.
+     * @param resultCallback      Capture result callback to be called once the capture result
+     *                            values of the processed image are ready.
+     * @param executor            The executor to run the callback on. If null then the callback
+     *                            will run on any arbitrary executor.
+     * @throws RuntimeException   if postview feature is not supported
+     * @since 1.4
+     */
+    void processWithPostview(Map<Integer, Pair<Image, TotalCaptureResult>> results,
+            ProcessResultImpl resultCallback, Executor executor);
 }
diff --git a/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/HdrImageCaptureExtenderImpl.java b/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/HdrImageCaptureExtenderImpl.java
index e0f59558..25232635 100644
--- a/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/HdrImageCaptureExtenderImpl.java
+++ b/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/HdrImageCaptureExtenderImpl.java
@@ -132,6 +132,26 @@ public final class HdrImageCaptureExtenderImpl implements ImageCaptureExtenderIm
                     }
 
                     @Override
+                    public void onPostviewOutputSurface(Surface surface) {
+
+                    }
+
+                    @Override
+                    public void processWithPostview(
+                            Map<Integer, Pair<Image, TotalCaptureResult>> results,
+                            ProcessResultImpl resultCallback, Executor executor) {
+                        if (!isPostviewAvailable()) {
+                            throw new RuntimeException("The extension doesn't support postview");
+                        }
+
+                        if (resultCallback != null) {
+                            process(results, resultCallback, executor);
+                        } else {
+                            process(results);
+                        }
+                    }
+
+                    @Override
                     public void process(Map<Integer, Pair<Image, TotalCaptureResult>> results,
                             ProcessResultImpl resultCallback, Executor executor) {
                         Pair<Image, TotalCaptureResult> result = results.get(NORMAL_STAGE_ID);
@@ -279,6 +299,11 @@ public final class HdrImageCaptureExtenderImpl implements ImageCaptureExtenderIm
                     }
 
                     @Override
+                    public void onResolutionUpdate(Size size, Size postviewSize) {
+
+                    }
+
+                    @Override
                     public void onImageFormatUpdate(int imageFormat) {
 
                     }
@@ -347,6 +372,11 @@ public final class HdrImageCaptureExtenderImpl implements ImageCaptureExtenderIm
     }
 
     @Override
+    public List<Pair<Integer, Size[]>> getSupportedPostviewResolutions(Size captureSize) {
+        return new ArrayList<>();
+    }
+
+    @Override
     public Range<Long> getEstimatedCaptureLatencyRange(Size captureOutputSize) {
         return null;
     }
@@ -382,4 +412,9 @@ public final class HdrImageCaptureExtenderImpl implements ImageCaptureExtenderIm
     public Pair<Long, Long> getRealtimeCaptureLatency() {
         return null;
     }
+
+    @Override
+    public boolean isPostviewAvailable() {
+        return false;
+    }
 }
diff --git a/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/ImageCaptureExtenderImpl.java b/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/ImageCaptureExtenderImpl.java
index 8cb64ea2..37e7baf3 100644
--- a/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/ImageCaptureExtenderImpl.java
+++ b/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/ImageCaptureExtenderImpl.java
@@ -91,6 +91,21 @@ public interface ImageCaptureExtenderImpl extends ExtenderStateListener {
     List<Pair<Integer, Size[]>> getSupportedResolutions();
 
     /**
+     * Returns the customized supported postview resolutions for a still capture using
+     * its size.
+     *
+     * <p>Pair list composed with {@link ImageFormat} and {@link Size} array will be returned.
+     *
+     * <p>The returned resolutions should be subset of the supported sizes retrieved from
+     * {@link android.hardware.camera2.params.StreamConfigurationMap} for the camera device.
+     *
+     * @return the customized supported resolutions, or null to support all sizes retrieved from
+     *         {@link android.hardware.camera2.params.StreamConfigurationMap}.
+     * @since 1.4
+     */
+    List<Pair<Integer, Size[]>> getSupportedPostviewResolutions(Size captureSize);
+
+    /**
      * Returns the estimated capture latency range in milliseconds for the target capture
      * resolution.
      *
@@ -167,4 +182,15 @@ public interface ImageCaptureExtenderImpl extends ExtenderStateListener {
      * @since 1.4
      */
     Pair<Long, Long> getRealtimeCaptureLatency();
+
+    /**
+     * Indicates whether the extension supports the postview for still capture feature.
+     * If the extension is using HAL processing, false should be returned since the
+     * postview feature is not currently supported for this case.
+     *
+     * @return {@code true} in case postview for still capture is supported
+     * {@code false} otherwise.
+     * @since 1.4
+     */
+    boolean isPostviewAvailable();
 }
diff --git a/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/NightImageCaptureExtenderImpl.java b/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/NightImageCaptureExtenderImpl.java
index c233ef8f..e3317d94 100755
--- a/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/NightImageCaptureExtenderImpl.java
+++ b/camera2/extensions/sample/src/java/androidx/camera/extensions/impl/NightImageCaptureExtenderImpl.java
@@ -117,6 +117,26 @@ public final class NightImageCaptureExtenderImpl implements ImageCaptureExtender
                     }
 
                     @Override
+                    public void onPostviewOutputSurface(Surface surface) {
+
+                    }
+
+                    @Override
+                    public void processWithPostview(
+                            Map<Integer, Pair<Image, TotalCaptureResult>> results,
+                            ProcessResultImpl resultCallback, Executor executor) {
+                        if (!isPostviewAvailable()) {
+                            throw new RuntimeException("The extension doesn't support postview");
+                        }
+
+                        if (resultCallback != null) {
+                            process(results, resultCallback, executor);
+                        } else {
+                            process(results);
+                        }
+                    }
+
+                    @Override
                     public void process(Map<Integer, Pair<Image, TotalCaptureResult>> results,
                             ProcessResultImpl resultCallback, Executor executor) {
                         throw new RuntimeException("The extension doesn't support capture " +
@@ -165,6 +185,11 @@ public final class NightImageCaptureExtenderImpl implements ImageCaptureExtender
                     }
 
                     @Override
+                    public void onResolutionUpdate(Size size, Size postviewSize) {
+
+                    }
+
+                    @Override
                     public void onImageFormatUpdate(int imageFormat) {
 
                     }
@@ -245,6 +270,11 @@ public final class NightImageCaptureExtenderImpl implements ImageCaptureExtender
     }
 
     @Override
+    public List<Pair<Integer, Size[]>> getSupportedPostviewResolutions(Size captureSize) {
+        return new ArrayList<>();
+    }
+
+    @Override
     public Range<Long> getEstimatedCaptureLatencyRange(Size captureOutputSize) {
         return null;
     }
@@ -273,4 +303,9 @@ public final class NightImageCaptureExtenderImpl implements ImageCaptureExtender
     public Pair<Long, Long> getRealtimeCaptureLatency() {
         return null;
     }
+
+    @Override
+    public boolean isPostviewAvailable() {
+        return false;
+    }
 }