camera: (Legacy) Add support for SCENE_MODE == FACE_PRIORITY

Bug: 16898478
Change-Id: I4306f6380ea06e8bd95af8738e5dde1a42a8098c

Author: iam

core/java/android/hardware/camera2/legacy/LegacyFaceDetectMapper.java

@@ -48,9 +48,16 @@ public class LegacyFaceDetectMapper {
     private static final boolean VERBOSE = Log.isLoggable(TAG, Log.VERBOSE);
 
     private final Camera mCamera;
+    /** Is the camera capable of face detection? */
     private final boolean mFaceDetectSupported;
+    /** Is the camera is running face detection? */
     private boolean mFaceDetectEnabled = false;
+    /** Did the last request say to use SCENE_MODE = FACE_PRIORITY? */
+    private boolean mFaceDetectScenePriority = false;
+    /** Did the last request enable the face detect mode to ON? */
+    private boolean mFaceDetectReporting = false;
 
+    /** Synchronize access to all fields */
     private final Object mLock = new Object();
     private Camera.Face[] mFaces;
     private Camera.Face[] mFacesPrev;
@@ -129,6 +136,17 @@ public void processFaceDetectMode(CaptureRequest captureRequest,
             return;
         }
 
+        /*
+         * control.sceneMode
+         */
+        int sceneMode = ParamsUtils.getOrDefault(captureRequest, CONTROL_SCENE_MODE,
+                CONTROL_SCENE_MODE_DISABLED);
+        if (sceneMode == CONTROL_SCENE_MODE_FACE_PRIORITY && !mFaceDetectSupported) {
+            Log.w(TAG, "processFaceDetectMode - ignoring control.sceneMode == FACE_PRIORITY; " +
+                    "face detection is not available");
+            return;
+        }
+
         // Print some warnings out in case the values were wrong
         switch (fdMode) {
             case STATISTICS_FACE_DETECT_MODE_OFF:
@@ -145,7 +163,8 @@ public void processFaceDetectMode(CaptureRequest captureRequest,
                 return;
         }
 
-        boolean enableFaceDetect = fdMode != STATISTICS_FACE_DETECT_MODE_OFF;
+        boolean enableFaceDetect = (fdMode != STATISTICS_FACE_DETECT_MODE_OFF)
+                || (sceneMode == CONTROL_SCENE_MODE_FACE_PRIORITY);
         synchronized (mLock) {
             // Enable/disable face detection if it's changed since last time
             if (enableFaceDetect != mFaceDetectEnabled) {
@@ -166,6 +185,8 @@ public void processFaceDetectMode(CaptureRequest captureRequest,
                 }
 
                 mFaceDetectEnabled = enableFaceDetect;
+                mFaceDetectScenePriority = sceneMode == CONTROL_SCENE_MODE_FACE_PRIORITY;
+                mFaceDetectReporting = fdMode != STATISTICS_FACE_DETECT_MODE_OFF;
             }
         }
     }
@@ -177,6 +198,10 @@ public void processFaceDetectMode(CaptureRequest captureRequest,
      * <p>Face detect callbacks are processed in the background, and each call to
      * {@link #mapResultFaces} will have the latest faces as reflected by the camera1 callbacks.</p>
      *
+     * <p>If the scene mode was set to {@code FACE_PRIORITY} but face detection is disabled,
+     * the camera will still run face detection in the background, but no faces will be reported
+     * in the capture result.</p>
+     *
      * @param result a non-{@code null} result
      * @param legacyRequest a non-{@code null} request (read-only)
      */
@@ -186,16 +211,19 @@ public void mapResultFaces(CameraMetadataNative result, LegacyRequest legacyRequ
 
         Camera.Face[] faces, previousFaces;
         int fdMode;
+        boolean fdScenePriority;
         synchronized (mLock) {
-            fdMode = mFaceDetectEnabled ?
+            fdMode = mFaceDetectReporting ?
                             STATISTICS_FACE_DETECT_MODE_SIMPLE : STATISTICS_FACE_DETECT_MODE_OFF;
 
-            if (mFaceDetectEnabled) {
+            if (mFaceDetectReporting) {
                 faces = mFaces;
             } else {
                 faces = null;
             }
 
+            fdScenePriority = mFaceDetectScenePriority;
+
             previousFaces = mFacesPrev;
             mFacesPrev = faces;
         }
@@ -227,5 +255,10 @@ public void mapResultFaces(CameraMetadataNative result, LegacyRequest legacyRequ
 
         result.set(CaptureResult.STATISTICS_FACES, convertedFaces.toArray(new Face[0]));
         result.set(CaptureResult.STATISTICS_FACE_DETECT_MODE, fdMode);
+
+        // Override scene mode with FACE_PRIORITY if the request was using FACE_PRIORITY
+        if (fdScenePriority) {
+            result.set(CaptureResult.CONTROL_SCENE_MODE, CONTROL_SCENE_MODE_FACE_PRIORITY);
+        }
     }
 }

core/java/android/hardware/camera2/legacy/LegacyMetadataMapper.java

@@ -535,9 +535,16 @@ private static void mapControlOther(CameraMetadataNative m, Camera.Parameters p)
          * android.control.availableSceneModes
          */
         List<String> sceneModes = p.getSupportedSceneModes();
-        int[] supportedSceneModes = (sceneModes == null) ? new int[0] :
-                ArrayUtils.convertStringListToIntArray(sceneModes, sLegacySceneModes, sSceneModes);
-        m.set(CONTROL_AVAILABLE_SCENE_MODES, supportedSceneModes);
+        List<Integer> supportedSceneModes =
+                ArrayUtils.convertStringListToIntList(sceneModes, sLegacySceneModes, sSceneModes);
+        if (supportedSceneModes == null) { // camera1 doesn't support scene mode settings
+            supportedSceneModes = new ArrayList<Integer>();
+            supportedSceneModes.add(CONTROL_SCENE_MODE_DISABLED); // disabled is always available
+        }
+        if (p.getMaxNumDetectedFaces() > 0) { // always supports FACE_PRIORITY when face detecting
+            supportedSceneModes.add(CONTROL_SCENE_MODE_FACE_PRIORITY);
+        }
+        m.set(CONTROL_AVAILABLE_SCENE_MODES, ArrayUtils.toIntArray(supportedSceneModes));
     }
 
     private static void mapLens(CameraMetadataNative m, Camera.Parameters p) {
@@ -850,6 +857,11 @@ static int convertSceneModeFromLegacy(String mode) {
     }
 
     static String convertSceneModeToLegacy(int mode) {
+        if (mode == CONTROL_SCENE_MODE_FACE_PRIORITY) {
+            // OK: Let LegacyFaceDetectMapper handle turning face detection on/off
+            return Parameters.SCENE_MODE_AUTO;
+        }
+
         int index = ArrayUtils.getArrayIndex(sSceneModes, mode);
         if (index < 0) {
             return null;

core/java/android/hardware/camera2/legacy/LegacyRequestMapper.java

@@ -284,7 +284,7 @@ public static void convertRequestMetadata(LegacyRequest legacyRequest) {
                 switch (controlMode) {
                     case CONTROL_MODE_USE_SCENE_MODE: {
                         int sceneMode = ParamsUtils.getOrDefault(request, CONTROL_SCENE_MODE,
-                        /*defaultValue*/CONTROL_SCENE_MODE_DISABLED);
+                                /*defaultValue*/CONTROL_SCENE_MODE_DISABLED);
                         String legacySceneMode = LegacyMetadataMapper.
                                 convertSceneModeToLegacy(sceneMode);
                         if (legacySceneMode != null) {

core/java/android/hardware/camera2/legacy/LegacyResultMapper.java

@@ -35,9 +35,6 @@
 import java.util.List;
 
 import static com.android.internal.util.Preconditions.*;
-import static android.hardware.camera2.CameraMetadata.CONTROL_VIDEO_STABILIZATION_MODE_OFF;
-import static android.hardware.camera2.CameraMetadata.CONTROL_VIDEO_STABILIZATION_MODE_ON;
-import static android.hardware.camera2.CaptureRequest.CONTROL_VIDEO_STABILIZATION_MODE;
 import static android.hardware.camera2.CaptureResult.*;
 
 /**
@@ -166,6 +163,8 @@ private static CameraMetadataNative convertResultMetadata(LegacyRequest legacyRe
             int mode = LegacyMetadataMapper.convertSceneModeFromLegacy(legacySceneMode);
             if (mode != LegacyMetadataMapper.UNKNOWN_MODE) {
                 result.set(CaptureResult.CONTROL_SCENE_MODE, mode);
+                // In case of SCENE_MODE == FACE_PRIORITY, LegacyFaceDetectMapper will override
+                // the result to say SCENE_MODE == FACE_PRIORITY.
             }  else {
                 Log.w(TAG, "Unknown scene mode " + legacySceneMode +
                         " returned by camera HAL, setting to disabled.");

core/java/android/hardware/camera2/legacy/RequestThreadManager.java

@@ -725,9 +725,15 @@ public boolean handleMessage(Message msg) {
 
                         CameraMetadataNative result = mMapper.cachedConvertResultMetadata(
                                 mLastRequest, timestampMutable.value);
+                        /*
+                         * Order matters: The default result mapper is state-less; the
+                         * other mappers carry state and may override keys set by the default
+                         * mapper with their own values.
+                         */
+
                         // Update AF state
                         mFocusStateMapper.mapResultTriggers(result);
-                        // Update detected faces list
+                        // Update face-related results
                         mFaceDetectMapper.mapResultFaces(result, mLastRequest);
 
                         mDeviceState.setCaptureResult(holder, result);