directrenderer: update video surface on update

Else, changing the resolution is not taken into account correctly.
This is a follow-up of daemon sink's refactoring

Change-Id: If70d6f0ed40fa9c0a343b8cbbacf7461f3288d01

src/directrenderer.cpp

@@ -115,9 +115,11 @@ DirectRenderer::stopRendering()
 void
 DirectRenderer::update(const QSize& res, const QString&)
 {
+    stopRendering();
     Renderer::update(res);
 
     VideoManager::instance().registerSinkTarget(id(), pimpl_->target);
+    startRendering();
 }
 
 Frame

src/shmrenderer.cpp

@@ -245,6 +245,7 @@ ShmRenderer::~ShmRenderer()
 void
 ShmRenderer::update(const QSize& res, const QString& shmPath)
 {
+    Q_EMIT stopped();
     Renderer::update(res);
 
     if (!pimpl_->thread.isRunning())
@@ -252,6 +253,7 @@ ShmRenderer::update(const QSize& res, const QString& shmPath)
 
     pimpl_->path = shmPath;
     VideoManager::instance().startShmSink(id(), true);
+    Q_EMIT started();
 }
 
 Frame