Add tutorial dialog for gesture navigation

Add new tutorial dialog for gesture navigation in order to teach
users how to use the gesture

Fixes: 133650388
Test: Manual
Change-Id: I7cc6a950af49044b27cf7ca41e3bcf67ef40b5fd

src/com/android/settings/accessibility/VideoPlayer.java

@@ -0,0 +1,149 @@
+/*
+ * Copyright (C) 2019 The Android Open Source Project
+ *
+ * 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.android.settings.accessibility;
+
+import android.content.Context;
+import android.graphics.SurfaceTexture;
+import android.media.MediaPlayer;
+import android.view.Surface;
+import android.view.TextureView;
+import android.view.TextureView.SurfaceTextureListener;
+
+import androidx.annotation.GuardedBy;
+import androidx.annotation.RawRes;
+
+/**
+ * Plays the video by {@link MediaPlayer} on {@link TextureView}, calls {@link #create(Context, int,
+ * TextureView)} to setup the listener for TextureView and start to play the video. Once this player
+ * is no longer used, call {@link #release()} so that MediaPlayer object can be released.
+ */
+public class VideoPlayer implements SurfaceTextureListener {
+    private final Context context;
+    private final Object mediaPlayerLock = new Object();
+    // Media player object can't be used after it has been released, so it will be set to null. But
+    // VideoPlayer is asynchronized, media player object might be paused or resumed again before
+    // released media player is set to null. Therefore, lock mediaPlayer and mediaPlayerState by
+    // mediaPlayerLock keep their states consistent.
+    @GuardedBy("mediaPlayerLock")
+    private MediaPlayer mediaPlayer;
+    @GuardedBy("mediaPlayerLock")
+    private State mediaPlayerState = State.NONE;
+    @RawRes
+    private final int videoRes;
+    private Surface animationSurface;
+
+
+    /**
+     * Creates a {@link MediaPlayer} for a given resource id and starts playback when the surface
+     * for
+     * a given {@link TextureView} is ready.
+     */
+    public static VideoPlayer create(Context context, @RawRes int videoRes,
+            TextureView textureView) {
+        return new VideoPlayer(context, videoRes, textureView);
+    }
+
+    private VideoPlayer(Context context, @RawRes int videoRes, TextureView textureView) {
+        this.context = context;
+        this.videoRes = videoRes;
+        textureView.setSurfaceTextureListener(this);
+    }
+
+    public void pause() {
+        synchronized (mediaPlayerLock) {
+            if (mediaPlayerState == State.STARTED) {
+                mediaPlayerState = State.PAUSED;
+                mediaPlayer.pause();
+            }
+        }
+    }
+
+    public void resume() {
+        synchronized (mediaPlayerLock) {
+            if (mediaPlayerState == State.PAUSED) {
+                mediaPlayer.start();
+                mediaPlayerState = State.STARTED;
+            }
+        }
+    }
+
+    /** Release media player when it's no longer needed. */
+    public void release() {
+        synchronized (mediaPlayerLock) {
+            if (mediaPlayerState != State.NONE && mediaPlayerState != State.END) {
+                mediaPlayerState = State.END;
+                mediaPlayer.release();
+                mediaPlayer = null;
+            }
+        }
+        if (animationSurface != null) {
+            animationSurface.release();
+            animationSurface = null;
+        }
+    }
+
+    @Override
+    public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {
+        animationSurface = new Surface(surface);
+        synchronized (mediaPlayerLock) {
+            mediaPlayer = MediaPlayer.create(context, videoRes);
+            mediaPlayerState = State.PREPARED;
+            mediaPlayer.setSurface(animationSurface);
+            mediaPlayer.setLooping(true);
+            mediaPlayer.start();
+            mediaPlayerState = State.STARTED;
+        }
+    }
+
+    @Override
+    public void onSurfaceTextureSizeChanged(SurfaceTexture surface, int width, int height) {
+    }
+
+    @Override
+    public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {
+        release();
+        return false;
+    }
+
+    @Override
+    public void onSurfaceTextureUpdated(SurfaceTexture surface) {
+    }
+
+    /**
+     * The state of MediaPlayer object. Refer to
+     * https://developer.android.com/reference/android/media/MediaPlayer#StateDiagram.
+     */
+    public enum State {
+        /** MediaPlayer objects has not be created. */
+        NONE,
+        /** MediaPlayer objects is created by create() method. */
+        PREPARED,
+        /** MediaPlayer is started. It can be paused by pause() method. */
+        STARTED,
+        /** MediaPlayer object is paused. Calling start() to resume it. */
+        PAUSED,
+        /**
+         * MediaPlayer object is stopped and cannot be started until calling prepare() or
+         * prepareAsync()
+         * methods.
+         */
+        STOPPED,
+        /** MediaPlayer object is released. It cannot be used again. */
+        END
+    }
+}
+