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/*
* 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 com.google.skar.examples.helloskar.helpers;
import android.app.Activity;
import android.content.Context;
import android.hardware.display.DisplayManager;
import android.hardware.display.DisplayManager.DisplayListener;
import android.view.Display;
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 Context context;
private final Display display;
/**
* Constructs the DisplayRotationHelper but does not register the listener yet.
*
* @param context the Android {@link Context}.
*/
public DisplayRotationHelper(Context context) {
this.context = context;
display = context.getSystemService(WindowManager.class).getDefaultDisplay();
}
/**
* Registers the display listener. Should be called from {@link Activity#onResume()}.
*/
public void onResume() {
context.getSystemService(DisplayManager.class).registerDisplayListener(this, null);
}
/**
* Unregisters the display listener. Should be called from {@link Activity#onPause()}.
*/
public void onPause() {
context.getSystemService(DisplayManager.class).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 current rotation state of android display. Same as {@link Display#getRotation()}.
*/
public int getRotation() {
return display.getRotation();
}
@Override
public void onDisplayAdded(int displayId) {
}
@Override
public void onDisplayRemoved(int displayId) {
}
@Override
public void onDisplayChanged(int displayId) {
viewportChanged = true;
}
}
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