From b2ba47cde2cb63163831f013947fa1edb4a29c8b Mon Sep 17 00:00:00 2001
From: Simon Rettberg
Date: Thu, 15 Nov 2018 12:26:13 +0100
Subject: [server] Fix adding/removing students to active projection

VNC server/client was not always properly started or stopped
when adding/removing students to currently running projection
with tutor as source.
---
 src/server/mainwindow/mainwindow.cpp | 34 +++++++++++++++++++++++++---------
 1 file changed, 25 insertions(+), 9 deletions(-)

diff --git a/src/server/mainwindow/mainwindow.cpp b/src/server/mainwindow/mainwindow.cpp
index ec69a4c..0abfdff 100644
--- a/src/server/mainwindow/mainwindow.cpp
+++ b/src/server/mainwindow/mainwindow.cpp
@@ -893,22 +893,38 @@ void MainWindow::onButtonTutorToStudent()
 	else if (getTutorFrame()->client() == nullptr)
 		QMessageBox::critical(this, tr("Projection"), sStrTutorOffline);
 	else {
+        auto sourceClient = getTutorFrame()->client();
+        auto destinationClient = getSelectedFrame()->client();
 		// If this is the first call in this mode clear the watchers
 		if (_mode != Mode::Multicast) {
-			for (QList<ConnectionFrame*>::iterator it(_clientFrames.begin()); it != _clientFrames.end(); ++it)
-				if ((*it)->client() != nullptr)
-					(*it)->client()->setDesiredProjectionSource(NO_SOURCE);
+            for (auto c : _clientFrames) {
+                if (c->client() != nullptr) {
+                    c->client()->stopVncClient();
+                }
+            }
 		}
 
 		// If "to" already watches "from" stop it
-		if (getSelectedFrame()->client()->desiredProjectionSource() == getTutorFrame()->client()->id() )
-			getSelectedFrame()->client()->setDesiredProjectionSource(NO_SOURCE);
-		else
-			getSelectedFrame()->client()->setDesiredProjectionSource(getTutorFrame()->client()->id());
+        if (destinationClient->desiredProjectionSource() == sourceClient->id() ) {
+            destinationClient->stopVncClient();
+        } else {
+            destinationClient->setDesiredProjectionSource(sourceClient->id());
+        }
 
 		disableButtons();
-		_mode = Mode::Multicast;
-		startVncServerIfNecessary(getTutorFrame()->client()->id());
+        int numClients = 0;
+        for (auto c : _clientFrames) {
+            if (c->client() != nullptr && c->client()->desiredProjectionSource() == sourceClient->id()) {
+                numClients++;
+            }
+        }
+        if (numClients == 0) {
+            _mode = Mode::None;
+            sourceClient->stopVncServer();
+        } else {
+            _mode = Mode::Multicast;
+            startVncServerIfNecessary(sourceClient->id());
+        }
 	}
 }
 
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