improve camera2 to camera1 fallback on legacy devices.

Author: cristianocca

android/src/main/java/com/google/android/cameraview/Camera2.java

@@ -305,6 +305,7 @@ public void onSurfaceDestroyed() {
     boolean start() {
         if (!chooseCameraIdByFacing()) {
             mAspectRatio = mInitialRatio;
+            mCallback.onMountError();
             return false;
         }
         collectCameraInfo();
@@ -731,6 +732,33 @@ void setDeviceOrientation(int deviceOrientation) {
         //mPreview.setDisplayOrientation(deviceOrientation); // this is not needed and messes up the display orientation
     }
 
+
+    // This is a helper method to query Camera2 legacy status so we don't need
+    // to instantiate and set all its props in order to check if it is legacy or not
+    // and then fallback to Camera1. This way, legacy devices can fall back to Camera1 right away
+    // This method makes sure all cameras are not legacy, so further checks are not needed.
+    public static boolean isLegacy(Context context){
+        try{
+            CameraManager manager = (CameraManager) context.getSystemService(Context.CAMERA_SERVICE);
+            String[] ids = manager.getCameraIdList();
+            for (String id : ids) {
+                CameraCharacteristics characteristics = manager.getCameraCharacteristics(id);
+                Integer level = characteristics.get(
+                        CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL);
+                if (level == null ||
+                        level == CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL_LEGACY) {
+                    Log.w(TAG, "Camera2 can only run in legacy mode and should not be used.");
+                    return true;
+                }
+            }
+            return false;
+        }
+        catch(CameraAccessException ex){
+            Log.e(TAG, "Failed to check camera legacy status, returning true.", ex);
+            return true;
+        }
+    }
+
     /**
      * <p>Chooses a camera ID by the specified camera facing ({@link #mFacing}).</p>
      * <p>This rewrites {@link #mCameraId}, {@link #mCameraCharacteristics}, and optionally
@@ -742,19 +770,16 @@ private boolean chooseCameraIdByFacing() {
                 int internalFacing = INTERNAL_FACINGS.get(mFacing);
                 final String[] ids = mCameraManager.getCameraIdList();
                 if (ids.length == 0) { // No camera
-                    throw new RuntimeException("No camera available.");
+                    Log.e(TAG, "No cameras available.");
+                    return false;
                 }
                 for (String id : ids) {
                     CameraCharacteristics characteristics = mCameraManager.getCameraCharacteristics(id);
-                    Integer level = characteristics.get(
-                            CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL);
-                    if (level == null ||
-                            level == CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL_LEGACY) {
-                        continue;
-                    }
+
                     Integer internal = characteristics.get(CameraCharacteristics.LENS_FACING);
                     if (internal == null) {
-                        throw new NullPointerException("Unexpected state: LENS_FACING null");
+                        Log.e(TAG, "Unexpected state: LENS_FACING null");
+                        continue;
                     }
                     if (internal == internalFacing) {
                         mCameraId = id;
@@ -765,15 +790,11 @@ private boolean chooseCameraIdByFacing() {
                 // Not found
                 mCameraId = ids[0];
                 mCameraCharacteristics = mCameraManager.getCameraCharacteristics(mCameraId);
-                Integer level = mCameraCharacteristics.get(
-                        CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL);
-                if (level == null ||
-                        level == CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL_LEGACY) {
-                    return false;
-                }
+
                 Integer internal = mCameraCharacteristics.get(CameraCharacteristics.LENS_FACING);
                 if (internal == null) {
-                    throw new NullPointerException("Unexpected state: LENS_FACING null");
+                    Log.e(TAG, "Unexpected state: LENS_FACING null");
+                    return false;
                 }
                 for (int i = 0, count = INTERNAL_FACINGS.size(); i < count; i++) {
                     if (INTERNAL_FACINGS.valueAt(i) == internal) {
@@ -786,7 +807,8 @@ private boolean chooseCameraIdByFacing() {
                 mFacing = Constants.FACING_BACK;
                 return true;
             } catch (CameraAccessException e) {
-                throw new RuntimeException("Failed to get a list of camera devices", e);
+                Log.e(TAG, "Failed to get a list of camera devices", e);
+                return false;
             }
         }
         else{
@@ -796,17 +818,11 @@ private boolean chooseCameraIdByFacing() {
                 // for legacy hardware
                 mCameraCharacteristics = mCameraManager.getCameraCharacteristics(_mCameraId);
 
-                Integer level = mCameraCharacteristics.get(
-                        CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL);
-                if (level == null ||
-                        level == CameraCharacteristics.INFO_SUPPORTED_HARDWARE_LEVEL_LEGACY) {
-                    return false;
-                }
-
                 // set our facing variable so orientation also works as expected
                 Integer internal = mCameraCharacteristics.get(CameraCharacteristics.LENS_FACING);
                 if (internal == null) {
-                    throw new NullPointerException("Unexpected state: LENS_FACING null");
+                    Log.e(TAG, "Unexpected state: LENS_FACING null");
+                    return false;
                 }
                 for (int i = 0, count = INTERNAL_FACINGS.size(); i < count; i++) {
                     if (INTERNAL_FACINGS.valueAt(i) == internal) {
@@ -819,7 +835,8 @@ private boolean chooseCameraIdByFacing() {
                 return true;
             }
             catch(Exception e){
-                throw new RuntimeException("Failed to get camera characteristics", e);
+                Log.e(TAG, "Failed to get camera characteristics", e);
+                return false;
             }
         }
     }

android/src/main/java/com/google/android/cameraview/CameraView.java

@@ -126,7 +126,7 @@ public CameraView(Context context, AttributeSet attrs, int defStyleAttr, boolean
         // Internal setup
         final PreviewImpl preview = createPreviewImpl(context);
         mCallbacks = new CallbackBridge();
-        if (fallbackToOldApi || Build.VERSION.SDK_INT < 21) {
+        if (fallbackToOldApi || Build.VERSION.SDK_INT < 21 || Camera2.isLegacy(context)) {
             mImpl = new Camera1(mCallbacks, preview, mBgHandler);
         } else if (Build.VERSION.SDK_INT < 23) {
             mImpl = new Camera2(mCallbacks, preview, context, mBgHandler);
@@ -292,7 +292,7 @@ public void setUsingCamera2Api(boolean useCamera2) {
         boolean wasOpened = isCameraOpened();
         Parcelable state = onSaveInstanceState();
 
-        if (useCamera2) {
+        if (useCamera2 && !Camera2.isLegacy(mContext)) {
             if (wasOpened) {
                 stop();
             }
@@ -323,17 +323,20 @@ public void setUsingCamera2Api(boolean useCamera2) {
      * {@link Activity#onResume()}.
      */
     public void start() {
-        if (!mImpl.start()) {
-            if (mImpl.getView() != null) {
-                this.removeView(mImpl.getView());
-            }
-            //store the state and restore this state after fall back to Camera1
-            Parcelable state = onSaveInstanceState();
-            // Camera2 uses legacy hardware layer; fall back to Camera1
-            mImpl = new Camera1(mCallbacks, createPreviewImpl(getContext()), mBgHandler);
-            onRestoreInstanceState(state);
-            mImpl.start();
-        }
+        mImpl.start();
+
+        // this fallback is no longer needed and was too buggy/slow
+        // if (!mImpl.start()) {
+        //     if (mImpl.getView() != null) {
+        //         this.removeView(mImpl.getView());
+        //     }
+        //     //store the state and restore this state after fall back to Camera1
+        //     Parcelable state = onSaveInstanceState();
+        //     // Camera2 uses legacy hardware layer; fall back to Camera1
+        //     mImpl = new Camera1(mCallbacks, createPreviewImpl(getContext()), mBgHandler);
+        //     onRestoreInstanceState(state);
+        //     mImpl.start();
+        // }
     }
 
     /**