content: /*
   * Copyright 2017 Google Inc. All Rights Reserved.
   * 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 org.example.viotester.arcore; // NOTE: changed package name
  
  import android.app.Activity;
  import android.content.Context;
  import android.hardware.camera2.CameraAccessException;
  import android.hardware.camera2.CameraCharacteristics;
  import android.hardware.camera2.CameraManager;
  import android.hardware.display.DisplayManager;
  import android.hardware.display.DisplayManager.DisplayListener;
  import android.view.Display;
  import android.view.Surface;
  import android.view.WindowManager;
  import com.google.ar.core.Session;
  
  /**
   * Helper to track the display rotations. In particular, the 180 degree rotations are not notified
   * by the onSurfaceChanged() callback, and thus they require listening to the android display
   * events.
   */
  public final class DisplayRotationHelper implements DisplayListener {
      private boolean viewportChanged;
      private int viewportWidth;
      private int viewportHeight;
      private final Display display;
      private final DisplayManager displayManager;
      private final CameraManager cameraManager;
  
      /**
       * Constructs the DisplayRotationHelper but does not register the listener yet.
       *
       * @param context the Android {@link Context}.
       */
      public DisplayRotationHelper(Context context) {
          displayManager = (DisplayManager) context.getSystemService(Context.DISPLAY_SERVICE);
          cameraManager = (CameraManager) context.getSystemService(Context.CAMERA_SERVICE);
          WindowManager windowManager = (WindowManager) context.getSystemService(Context.WINDOW_SERVICE);
          display = windowManager.getDefaultDisplay();
      }
  
      /** Registers the display listener. Should be called from {@link Activity#onResume()}. */
      public void onResume() {
          displayManager.registerDisplayListener(this, null);
      }
  
      /** Unregisters the display listener. Should be called from {@link Activity#onPause()}. */
      public void onPause() {
          displayManager.unregisterDisplayListener(this);
      }
  
      /**
       * Records a change in surface dimensions. This will be later used by {@link
       * #updateSessionIfNeeded(Session)}. Should be called from {@link
       * android.opengl.GLSurfaceView.Renderer
       * #onSurfaceChanged(javax.microedition.khronos.opengles.GL10, int, int)}.
       *
       * @param width the updated width of the surface.
       * @param height the updated height of the surface.
       */
      public void onSurfaceChanged(int width, int height) {
          viewportWidth = width;
          viewportHeight = height;
          viewportChanged = true;
      }
  
      /**
       * Updates the session display geometry if a change was posted either by {@link
       * #onSurfaceChanged(int, int)} call or by {@link #onDisplayChanged(int)} system callback. This
       * function should be called explicitly before each call to {@link Session#update()}. This
       * function will also clear the 'pending update' (viewportChanged) flag.
       *
       * @param session the {@link Session} object to update if display geometry changed.
       */
      public void updateSessionIfNeeded(Session session) {
          if (viewportChanged) {
              int displayRotation = display.getRotation();
              session.setDisplayGeometry(displayRotation, viewportWidth, viewportHeight);
              viewportChanged = false;
          }
      }
  
      /**
       *  Returns the aspect ratio of the GL surface viewport while accounting for the display rotation
       *  relative to the device camera sensor orientation.
       */
      public float getCameraSensorRelativeViewportAspectRatio(String cameraId) {
          float aspectRatio;
          int cameraSensorToDisplayRotation = getCameraSensorToDisplayRotation(cameraId);
          switch (cameraSensorToDisplayRotation) {
              case 90:
              case 270:
                  aspectRatio = (float) viewportHeight / (float) viewportWidth;
                  break;
              case 0:
              case 180:
                  aspectRatio = (float) viewportWidth / (float) viewportHeight;
                  break;
              default:
                  throw new RuntimeException("Unhandled rotation: " + cameraSensorToDisplayRotation);
          }
          return aspectRatio;
      }
  
      /**
       * Returns the rotation of the back-facing camera with respect to the display. The value is one of
       * 0, 90, 180, 270.
       */
      public int getCameraSensorToDisplayRotation(String cameraId) {
          CameraCharacteristics characteristics;
          try {
              characteristics = cameraManager.getCameraCharacteristics(cameraId);
          } catch (CameraAccessException e) {
              throw new RuntimeException("Unable to determine display orientation", e);
          }
  
          // Camera sensor orientation.
          int sensorOrientation = characteristics.get(CameraCharacteristics.SENSOR_ORIENTATION);
  
          // Current display orientation.
          int displayOrientation = toDegrees(display.getRotation());
  
          // Make sure we return 0, 90, 180, or 270 degrees.
          return (sensorOrientation - displayOrientation + 360) % 360;
      }
  
      private int toDegrees(int rotation) {
          switch (rotation) {
              case Surface.ROTATION_0:
                  return 0;
              case Surface.ROTATION_90:
                  return 90;
              case Surface.ROTATION_180:
                  return 180;
              case Surface.ROTATION_270:
                  return 270;
              default:
                  throw new RuntimeException("Unknown rotation " + rotation);
          }
      }
  
      @Override
      public void onDisplayAdded(int displayId) {}
  
      @Override
      public void onDisplayRemoved(int displayId) {}
  
      @Override
      public void onDisplayChanged(int displayId) {
          viewportChanged = true;
      }
  }