Android: fix video probes when recording the camera.

The preview frame callback is cleared by the Android Camera whenever a
MediaRecorder is set up. We need to reset the callback after starting
the media recorder.

Change-Id: I604320b11eb3a7f6f8d7d3167d5aae371999be14
Reviewed-by: Christian Stromme <christian.stromme@theqtcompany.com>

src/plugins/android/src/mediacapture/qandroidcapturesession.cpp

@@ -233,9 +233,14 @@ void QAndroidCaptureSession::start()
     m_notifyTimer.start();
     updateDuration();
 
-    if (m_cameraSession)
+    if (m_cameraSession) {
         m_cameraSession->setReadyForCapture(false);
 
+        // Preview frame callback is cleared when setting up the camera with the media recorder.
+        // We need to reset it.
+        m_cameraSession->camera()->setupPreviewFrameCallback();
+    }
+
     m_state = QMediaRecorder::RecordingState;
     emit stateChanged(m_state);
 }

src/plugins/android/src/wrappers/jni/androidcamera.cpp

@@ -204,6 +204,7 @@ public:
 
     Q_INVOKABLE void takePicture();
 
+    Q_INVOKABLE void setupPreviewFrameCallback();
     Q_INVOKABLE void fetchEachFrame(bool fetch);
     Q_INVOKABLE void fetchLastPreviewFrame();
 
@@ -633,6 +634,12 @@ void AndroidCamera::takePicture()
     QMetaObject::invokeMethod(d, "takePicture", Qt::BlockingQueuedConnection);
 }
 
+void AndroidCamera::setupPreviewFrameCallback()
+{
+    Q_D(AndroidCamera);
+    QMetaObject::invokeMethod(d, "setupPreviewFrameCallback");
+}
+
 void AndroidCamera::fetchEachFrame(bool fetch)
 {
     Q_D(AndroidCamera);
@@ -1307,17 +1314,7 @@ void AndroidCameraPrivate::setJpegQuality(int quality)
 
 void AndroidCameraPrivate::startPreview()
 {
-    //We need to clear preview buffers queue here, but there is no method to do it
+    setupPreviewFrameCallback();
-    //Though just resetting preview callback do the trick
-    m_camera.callMethod<void>("setPreviewCallbackWithBuffer",
-                              "(Landroid/hardware/Camera$PreviewCallback;)V",
-                              jobject(0));
-    m_cameraListener.callMethod<void>("preparePreviewBuffer", "(Landroid/hardware/Camera;)V", m_camera.object());
-    QJNIObjectPrivate buffer = m_cameraListener.callObjectMethod<jbyteArray>("callbackBuffer");
-    m_camera.callMethod<void>("addCallbackBuffer", "([B)V", buffer.object());
-    m_camera.callMethod<void>("setPreviewCallbackWithBuffer",
-                              "(Landroid/hardware/Camera$PreviewCallback;)V",
-                              m_cameraListener.object());
     m_camera.callMethod<void>("startPreview");
     emit previewStarted();
 }
@@ -1338,6 +1335,21 @@ void AndroidCameraPrivate::takePicture()
                                               m_cameraListener.object());
 }
 
+void AndroidCameraPrivate::setupPreviewFrameCallback()
+{
+    //We need to clear preview buffers queue here, but there is no method to do it
+    //Though just resetting preview callback do the trick
+    m_camera.callMethod<void>("setPreviewCallbackWithBuffer",
+                              "(Landroid/hardware/Camera$PreviewCallback;)V",
+                              jobject(0));
+    m_cameraListener.callMethod<void>("preparePreviewBuffer", "(Landroid/hardware/Camera;)V", m_camera.object());
+    QJNIObjectPrivate buffer = m_cameraListener.callObjectMethod<jbyteArray>("callbackBuffer");
+    m_camera.callMethod<void>("addCallbackBuffer", "([B)V", buffer.object());
+    m_camera.callMethod<void>("setPreviewCallbackWithBuffer",
+                              "(Landroid/hardware/Camera$PreviewCallback;)V",
+                              m_cameraListener.object());
+}
+
 void AndroidCameraPrivate::fetchEachFrame(bool fetch)
 {
     m_cameraListener.callMethod<void>("fetchEachFrame", "(Z)V", fetch);

src/plugins/android/src/wrappers/jni/androidcamera.h

@@ -155,6 +155,7 @@ public:
 
     void takePicture();
 
+    void setupPreviewFrameCallback();
     void fetchEachFrame(bool fetch);
     void fetchLastPreviewFrame();
     QJNIObjectPrivate getCameraObject();