Support for client side cursors in the VNC plugin

Client side cursors are a major performance optimization,
avoiding the need to transmit images to the client
just because the cursor has moved.

Change-Id: Icdf4ff948571d39d82c86d251bca46390889d02f
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@qt.io>

src/plugins/platforms/vnc/qvnc.cpp

@@ -526,6 +526,9 @@ void QRfbRawEncoder::write()
 QVncClientCursor::QVncClientCursor(QVncServer *s)
     : server(s)
 {
+    QWindow *w = QGuiApplication::focusWindow();
+    QCursor c = w ? w->cursor() : QCursor(Qt::ArrowCursor);
+    changeCursor(&c, 0);
 }
 
 QVncClientCursor::~QVncClientCursor()
@@ -634,9 +637,6 @@ void QVncServer::init()
 
     connect(serverSocket, SIGNAL(newConnection()), this, SLOT(newConnection()));
 
-#ifndef QT_NO_QWS_CURSOR
-    qvnc_cursor = 0;
-#endif
     encoder = 0;
 }
 
@@ -646,10 +646,6 @@ QVncServer::~QVncServer()
     encoder = 0;
     delete client;
     client = 0;
-#ifndef QT_NO_QWS_CURSOR
-    delete qvnc_cursor;
-    qvnc_cursor = 0;
-#endif
 }
 
 void QVncServer::setDirty()
@@ -977,10 +973,8 @@ void QVncServer::setEncodings()
                 break;
             case Cursor:
                 supportCursor = true;
-                if (!qvnc_screen->screen()) {
-                    delete qvnc_cursor;
-                    qvnc_cursor = new QVncClientCursor(this);
-                }
+                qDebug() << "client side cursor supported.";
+                qvnc_screen->enableClientCursor();
                 break;
             case DesktopSize:
                 supportDesktopSize = true;
@@ -1259,10 +1253,7 @@ void QVncServer::checkUpdate()
         return;
 
     if (dirtyCursor) {
-#ifndef QT_NO_QWS_CURSOR
-        Q_ASSERT(qvnc_cursor);
-        qvnc_cursor->write();
-#endif
+        qvnc_screen->clientCursor->write();
         dirtyCursor = false;
         wantUpdate = false;
         return;
@@ -1287,11 +1278,7 @@ void QVncServer::discardClient()
     state = Disconnected;
     delete encoder;
     encoder = 0;
-#ifndef QT_NO_QWS_CURSOR
-    delete qvnc_cursor;
-    qvnc_cursor = 0;
-#endif
-
+    qvnc_screen->disableClientCursor();
     qvnc_screen->setPowerState(QPlatformScreen::PowerStateOff);
 }
 

src/plugins/platforms/vnc/qvnc_p.h

@@ -416,9 +416,6 @@ public:
     inline QTcpSocket* clientSocket() const { return client; }
     QImage screenImage() const;
     inline bool doPixelConversion() const { return needConversion; }
-#ifndef QT_NO_QWS_CURSOR
-    inline bool hasClientCursor() const { return qvnc_cursor != 0; }
-#endif
 
 private:
     void setPixelFormat();
@@ -464,10 +461,6 @@ private:
     bool dirtyCursor;
     int refreshRate;
     QVncScreen *qvnc_screen;
-#ifndef QT_NO_QWS_CURSOR
-    QVncClientCursor *qvnc_cursor;
-#endif
-
     QRfbEncoder *encoder;
 };
 

src/plugins/platforms/vnc/qvncscreen.cpp

@@ -40,6 +40,7 @@
 #include "qvncscreen.h"
 #include "qvnc_p.h"
 #include <QtPlatformSupport/private/qfbwindow_p.h>
+#include <QtPlatformSupport/private/qfbcursor_p.h>
 
 #include <QtGui/QPainter>
 
@@ -55,6 +56,8 @@ QVncScreen::QVncScreen(const QStringList &args)
 
 QVncScreen::~QVncScreen()
 {
+    if (clientCursor)
+        delete clientCursor;
 }
 
 bool QVncScreen::initialize()
@@ -67,7 +70,7 @@ bool QVncScreen::initialize()
     QFbScreen::initializeCompositor();
     QT_VNC_DEBUG() << "QVncScreen::init" << geometry();
 
-    mCursor = new QFbCursor(this);
+    disableClientCursor();
 
     switch (depth()) {
     case 32:
@@ -104,6 +107,27 @@ QRegion QVncScreen::doRedraw()
     return touched;
 }
 
+void QVncScreen::enableClientCursor()
+{
+    delete mCursor;
+    mCursor = 0;
+    clientCursor = new QVncClientCursor(vncServer);
+}
+
+void QVncScreen::disableClientCursor()
+{
+    if (vncServer && clientCursor) {
+        delete clientCursor;
+        clientCursor = 0;
+    }
+    mCursor = new QFbCursor(this);
+}
+
+QPlatformCursor *QVncScreen::cursor() const
+{
+    return mCursor ? static_cast<QPlatformCursor *>(mCursor) : static_cast<QPlatformCursor *>(clientCursor);
+}
+
 // grabWindow() grabs "from the screen" not from the backingstores.
 // In linuxfb's case it will also include the mouse cursor.
 QPixmap QVncScreen::grabWindow(WId wid, int x, int y, int width, int height) const

src/plugins/platforms/vnc/qvncscreen.h

@@ -49,6 +49,7 @@ class QFbCursor;
 class QTcpSocket;
 class QVncServer;
 class QVncDirtyMap;
+class QVncClientCursor;
 
 class QVncScreen : public QFbScreen
 {
@@ -64,7 +65,9 @@ public:
     QRegion doRedraw() Q_DECL_OVERRIDE;
     QImage *image() const { return mScreenImage; }
 
-//    QPlatformCursor *cursor() const Q_DECL_OVERRIDE { return mCursor; }
+    void enableClientCursor();
+    void disableClientCursor();
+    QPlatformCursor *cursor() const Q_DECL_OVERRIDE;
 
     void clearDirty() { dirtyRegion = QRegion(); }
 
@@ -76,7 +79,7 @@ public:
     QRegion dirtyRegion;
     int refreshRate = 30;
     QVncServer *vncServer = 0;
-
+    QVncClientCursor *clientCursor = 0;
 };
 
 QT_END_NAMESPACE