android camera2でのtextureViewをviewごとキャプチャーに失敗

PCスペック
Windows10 HOME 64bit
メモリ　32GB
プロセッサ　Intel Core i7-8700CPU 3.20GHz
Android Studio 3.4.1(最新ver)
デモ用端末(XPERIA OS:7.0 API 24)

camera2APIを使って，カメラアプリを開発しています．

1つ前の質問と似ているのですが，解決方法が異なってます．

こちらの記事を参考に，
画面ごとキャプチャーするやり方でtextureViewを抜き出そうと試しました．

しかし，キャプチャーして，保存された画像は真っ黒なもので，キャプチャーに失敗していまいました．
普通のviewやボタンのキャプチャーは成功するのですが，なぜtextureviewだけキャプチャーに失敗しているのかが解決できません．
コードにおかしな点があるのでしょうか...？

ちなみにsaveCaptureとgetViewCaptureがキャプチャーの役割を担うメソッドなのですが，引数1の型をTextureViewに揃えてもうまくいきませんでした．
なぜうまくいかないのか理由が知りたいです．

理由が分かった方がいましたら是非教えていただければ助かります．．

java
1package com.example.camera2api2;
2
3public class MainActivity extends AppCompatActivity {
4    private Camera mCamera;
5
6    private float scale = 1f;
7    private ScaleGestureDetector detector;
8    private File file;
9    private static final int REQUEST_MULTI_PERMISSIONS = 101;
10
11    private TextureView textureView;
12
13    @Override
14    protected void onCreate(Bundle savedInstanceState) {
15        super.onCreate(savedInstanceState);
16
17        setContentView(R.layout.activity_main);
18
19        textureView = (TextureView) findViewById(R.id.texture_view);
20        textureView.setSurfaceTextureListener(new TextureView.SurfaceTextureListener() {
21            @Override
22            public void onSurfaceTextureAvailable(SurfaceTexture surface, int width, int height) {
23                mCamera.open();
24             
25            }
26
27            @Override
28            public void onSurfaceTextureSizeChanged(SurfaceTexture surface, int width, int height) {
29
30            }
31
32            @Override
33            public boolean onSurfaceTextureDestroyed(SurfaceTexture surface) {
34                return false;
35            }
36
37            @Override
38            public void onSurfaceTextureUpdated(SurfaceTexture surface) {
39
40            }
41        });
42
43        mCamera = new Camera(textureView);
44        detector = new ScaleGestureDetector(this,new ScaleListener());
45    }
46
47    public boolean onTouchEvent(MotionEvent event) {
48        //re-route the Touch Events to the ScaleListener class
49        detector.onTouchEvent(event);
50        return super.onTouchEvent(event);
51    }
52
53    //スケールリスナークラス
54    private class ScaleListener extends ScaleGestureDetector.SimpleOnScaleGestureListener {
55        @Override
56        public boolean onScale(ScaleGestureDetector detector) {
57            scale *= detector.getScaleFactor();
58            mCamera.mTextureView.setScaleX(scale);
59            mCamera.mTextureView.setScaleY(scale);
60            return true;
61        }
62    }
63
64
65    @Override
66    protected void onResume() {
67        super.onResume();
68
69
70        Button button = (Button) findViewById(R.id.button);
71        button.setOnClickListener(new View.OnClickListener() {
72            @Override
73            public void onClick(View v) {
74                // 読み書きするファイル名を指定
75                file = new File(Environment.getExternalStorageDirectory().getPath()
76                        + "/DCIM/" + "capture.jpeg");
77                file.getParentFile().mkdir();// 指定したファイル名が無ければ作成する
78                // なぞった部分のviewを撮る
79                saveCapture(textureView, file);
80                
81            }
82        });
83    }
84
85    /**
86     * 撮ったキャプチャを保存
87     * @paramview
88     * @param書き込み先ファイルfile
89     */
90    public static void saveCapture(View view, File file) {
91        // キャプチャを撮る
92        Bitmap capture = getViewCapture(view);
93        FileOutputStream fos = null;
94        try {
95            fos = new FileOutputStream(file, false);
96            // 画像のフォーマットと画質と出力先を指定して保存
97            capture.compress(Bitmap.CompressFormat.JPEG, 100, fos);
98            fos.flush();
99        } catch (Exception e) {
100            e.printStackTrace();
101        } finally {
102            if (fos != null) {
103                try {
104                    fos.close();
105                } catch (IOException ie) {
106                    fos = null;
107                }
108            }
109        }
110    }
111
112    /**
113     * キャプチャを撮る
114     * @return 撮ったキャプチャ(Bitmap)
115     * @param撮りたいview
116     */
117    public static Bitmap getViewCapture(View view) {
118        view.setDrawingCacheEnabled(true);
119        // Viewのキャプチャを取得
120        Bitmap cache = view.getDrawingCache();
121        if (cache == null) {
122            return null;
123        }
124        Bitmap screenShot = Bitmap.createBitmap(cache);
125        view.setDrawingCacheEnabled(false);
126        return screenShot;
127    }
128
129
130
131
132    //カメラクラス
133    class Camera {
134        private CameraDevice mCamera;
135        private TextureView mTextureView;
136        private Size mCameraSize;
137        private CaptureRequest.Builder mPreviewBuilder;
138        private CameraCaptureSession mPreviewSession;
139
140
141
142        private CameraDevice.StateCallback mCameraDeviceCallback = new CameraDevice.StateCallback() {
143            @Override
144            public void onOpened(@NonNull CameraDevice camera) {
145                mCamera = camera;
146                createCaptureSession();
147            }
148
149            @Override
150            public void onDisconnected(@NonNull CameraDevice camera) {
151                camera.close();
152                mCamera = null;
153            }
154
155            @Override
156            public void onError(@NonNull CameraDevice camera, int error) {
157                camera.close();
158                mCamera = null;
159            }
160        };
161
162        CameraCaptureSession.StateCallback mCameraCaptureSessionCallback = new CameraCaptureSession.StateCallback() {
163            @Override
164            public void onConfigured(@NonNull CameraCaptureSession session) {
165                mPreviewSession = session;
166                updatePreview();
167            }
168
169            @Override
170            public void onConfigureFailed(@NonNull CameraCaptureSession session) {
171                Toast.makeText(MainActivity.this, "onConfigureFailed", Toast.LENGTH_LONG).show();
172            }
173        };
174
175        public Camera(TextureView textureView) {
176            mTextureView = textureView;
177        }
178
179        public void open() {
180            try {
181                CameraManager manager = (CameraManager) getSystemService(Context.CAMERA_SERVICE);
182                for (String cameraId : manager.getCameraIdList()) {
183                    CameraCharacteristics characteristics = manager.getCameraCharacteristics(cameraId);
184                    if (characteristics.get(CameraCharacteristics.LENS_FACING) == CameraCharacteristics.LENS_FACING_BACK) {
185                        StreamConfigurationMap map = characteristics.get(CameraCharacteristics.SCALER_STREAM_CONFIGURATION_MAP);
186                        mCameraSize = map.getOutputSizes(SurfaceTexture.class)[4];
187
188                        manager.openCamera(cameraId, mCameraDeviceCallback, null);
189
190                        return;
191                    }
192                }
193            } catch (CameraAccessException e) {
194                e.printStackTrace();
195            }
196        }
197
198        private void createCaptureSession() {
199            if (!mTextureView.isAvailable()) {
200                return;
201            }
202
203            SurfaceTexture texture = mTextureView.getSurfaceTexture();
204            texture.setDefaultBufferSize(mCameraSize.getWidth(), mCameraSize.getHeight());
205            Surface surface = new Surface(texture);
206            try {
207                mPreviewBuilder = mCamera.createCaptureRequest(CameraDevice.TEMPLATE_PREVIEW);
208            } catch (CameraAccessException e) {
209                e.printStackTrace();
210            }
211
212            mPreviewBuilder.addTarget(surface);
213            try {
214                mCamera.createCaptureSession(Collections.singletonList(surface), mCameraCaptureSessionCallback, null);
215            } catch (CameraAccessException e) {
216                e.printStackTrace();
217            }
218        }
219
220        private void updatePreview() {
221            mPreviewBuilder.set(CaptureRequest.CONTROL_AF_MODE, CaptureRequest.CONTROL_AF_MODE_CONTINUOUS_PICTURE);
222            HandlerThread thread = new HandlerThread("CameraPreview");
223            thread.start();
224            Handler backgroundHandler = new Handler(thread.getLooper());
225
226            try {
227                mPreviewSession.setRepeatingRequest(mPreviewBuilder.build(), null, backgroundHandler);
228            } catch (CameraAccessException e) {
229                e.printStackTrace();
230            }
231        }
232
233    }
234
235}