watch for zoom and max-zoom property changes.

camerabin can signal a change in those properties and we need to communicate those back to the application

src/plugins/gstreamer/camerabin/camerabinzoom.cpp

@@ -45,7 +45,9 @@ CameraBinZoom::CameraBinZoom(CameraBinSession *session)
     , m_requestedOpticalZoom(1.0)
     , m_requestedDigitalZoom(1.0)
 {
-
+    GstElement *camerabin = m_session->cameraBin();
+    g_signal_connect(G_OBJECT(camerabin), "notify::zoom", G_CALLBACK(updateZoom), this);
+    g_signal_connect(G_OBJECT(camerabin), "notify::max-zoom", G_CALLBACK(updateMaxZoom), this);
 }
 
 CameraBinZoom::~CameraBinZoom()
@@ -108,4 +110,32 @@ void CameraBinZoom::zoomTo(qreal optical, qreal digital)
         emit currentDigitalZoomChanged(digital);
 }
 
+void CameraBinZoom::updateZoom(GObject *o, GParamSpec *p, gpointer d)
+{
+    Q_UNUSED(p);
+
+    gfloat zoomFactor = 1.0;
+    g_object_get(o, ZOOM_PROPERTY, &zoomFactor, NULL);
+
+    CameraBinZoom *zoom = reinterpret_cast<CameraBinZoom *>(d);
+
+    QMetaObject::invokeMethod(zoom, "currentDigitalZoomChanged",
+                              Qt::QueuedConnection,
+                              Q_ARG(qreal, zoomFactor));
+}
+
+void CameraBinZoom::updateMaxZoom(GObject *o, GParamSpec *p, gpointer d)
+{
+    Q_UNUSED(p);
+
+    gfloat zoomFactor = 1.0;
+    g_object_get(o, MAX_ZOOM_PROPERTY, &zoomFactor, NULL);
+
+    CameraBinZoom *zoom = reinterpret_cast<CameraBinZoom *>(d);
+
+    QMetaObject::invokeMethod(zoom, "maximumOpticalZoomChanged",
+                              Qt::QueuedConnection,
+                              Q_ARG(qreal, zoomFactor));
+}
+
 QT_END_NAMESPACE

src/plugins/gstreamer/camerabin/camerabinzoom.h

@@ -35,6 +35,7 @@
 #define CAMERABINZOOMCONTROL_H
 
 #include <qcamerazoomcontrol.h>
+#include <gst/gst.h>
 
 QT_BEGIN_NAMESPACE
 
@@ -58,6 +59,9 @@ public:
     void zoomTo(qreal optical, qreal digital);
 
 private:
+    static void updateZoom(GObject *o, GParamSpec *p, gpointer d);
+    static void updateMaxZoom(GObject *o, GParamSpec *p, gpointer d);
+
     CameraBinSession *m_session;
     qreal m_requestedOpticalZoom;
     qreal m_requestedDigitalZoom;