1 /* 2 * Copyright 2018 Google LLC All Rights Reserved. 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.google.skar.examples.helloskar.helpers; 18 19 import android.app.Activity; 20 import android.content.Context; 21 import android.hardware.display.DisplayManager; 22 import android.hardware.display.DisplayManager.DisplayListener; 23 import android.view.Display; 24 import android.view.WindowManager; 25 26 import com.google.ar.core.Session; 27 28 /** 29 * Helper to track the display rotations. In particular, the 180 degree rotations are not notified 30 * by the onSurfaceChanged() callback, and thus they require listening to the android display 31 * events. 32 */ 33 public final class DisplayRotationHelper implements DisplayListener { 34 private boolean viewportChanged; 35 private int viewportWidth; 36 private int viewportHeight; 37 private final Context context; 38 private final Display display; 39 40 /** 41 * Constructs the DisplayRotationHelper but does not register the listener yet. 42 * 43 * @param context the Android {@link Context}. 44 */ DisplayRotationHelper(Context context)45 public DisplayRotationHelper(Context context) { 46 this.context = context; 47 display = context.getSystemService(WindowManager.class).getDefaultDisplay(); 48 } 49 50 /** 51 * Registers the display listener. Should be called from {@link Activity#onResume()}. 52 */ onResume()53 public void onResume() { 54 context.getSystemService(DisplayManager.class).registerDisplayListener(this, null); 55 } 56 57 /** 58 * Unregisters the display listener. Should be called from {@link Activity#onPause()}. 59 */ onPause()60 public void onPause() { 61 context.getSystemService(DisplayManager.class).unregisterDisplayListener(this); 62 } 63 64 /** 65 * Records a change in surface dimensions. This will be later used by {@link 66 * #updateSessionIfNeeded(Session)}. Should be called from {@link 67 * android.opengl.GLSurfaceView.Renderer 68 * #onSurfaceChanged(javax.microedition.khronos.opengles.GL10, int, int)}. 69 * 70 * @param width the updated width of the surface. 71 * @param height the updated height of the surface. 72 */ onSurfaceChanged(int width, int height)73 public void onSurfaceChanged(int width, int height) { 74 viewportWidth = width; 75 viewportHeight = height; 76 viewportChanged = true; 77 } 78 79 /** 80 * Updates the session display geometry if a change was posted either by {@link 81 * #onSurfaceChanged(int, int)} call or by {@link #onDisplayChanged(int)} system callback. This 82 * function should be called explicitly before each call to {@link Session#update()}. This 83 * function will also clear the 'pending update' (viewportChanged) flag. 84 * 85 * @param session the {@link Session} object to update if display geometry changed. 86 */ updateSessionIfNeeded(Session session)87 public void updateSessionIfNeeded(Session session) { 88 if (viewportChanged) { 89 int displayRotation = display.getRotation(); 90 session.setDisplayGeometry(displayRotation, viewportWidth, viewportHeight); 91 viewportChanged = false; 92 } 93 } 94 95 /** 96 * Returns the current rotation state of android display. Same as {@link Display#getRotation()}. 97 */ getRotation()98 public int getRotation() { 99 return display.getRotation(); 100 } 101 102 @Override onDisplayAdded(int displayId)103 public void onDisplayAdded(int displayId) { 104 } 105 106 @Override onDisplayRemoved(int displayId)107 public void onDisplayRemoved(int displayId) { 108 } 109 110 @Override onDisplayChanged(int displayId)111 public void onDisplayChanged(int displayId) { 112 viewportChanged = true; 113 } 114 } 115