use custom CameraActivity example

Author: syakimchik

Samples/Basic/DocumentReader-sample/app/src/main/AndroidManifest.xml

@@ -20,6 +20,8 @@
                 <category android:name="android.intent.category.LAUNCHER" />
             </intent-filter>
         </activity>
+        <activity android:name=".CameraActivity"
+            android:screenOrientation="portrait"/>
     </application>
 
 </manifest>