Windows QPA: Fix tablet event coords delay for tablets in pen mode

Now that the mouse mode check is only done once for the first event
after the TabletEnterProximityEvent, the m_oldGlobalPosF member has
lost its purpose and should be removed.

Worse, its value was used instead of currentGlobalPosF when in pen mode,
resulting in an unnecessary 1-frame delay in the reported positions
in the tablet events.

Task-number: QTBUG-36937
Change-Id: I6bd2db57898850a65088d9bb41fbfbd96eac54f5
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@qt.io>

2 files changed, 3 insertions, 7 deletions

diff --git a/src/plugins/platforms/windows/qwindowstabletsupport.cpp b/src/plugins/platforms/windows/qwindowstabletsupport.cpp
index 280519d39d..6acb62ad8f 100644
--- a/src/plugins/platforms/windows/qwindowstabletsupport.cpp
+++ b/src/plugins/platforms/windows/qwindowstabletsupport.cpp
@@ -489,11 +489,8 @@ bool QWindowsTabletSupport::translateTabletPacketEvent()
 
         const int z = currentDevice == QTabletEvent::FourDMouse ? int(packet.pkZ) : 0;
 
-        // This code is to delay the tablet data one cycle to sync with the mouse location.
-        QPointF globalPosF = m_oldGlobalPosF;
-        const QPointF currentGlobalPosF =
+        QPointF globalPosF =
             m_devices.at(m_currentDevice).scaleCoordinates(packet.pkX, packet.pkY, virtualDesktopArea);
-        m_oldGlobalPosF = currentGlobalPosF;
 
         QWindow *target = QGuiApplicationPrivate::tabletDevicePoint(uniqueId).target; // Pass to window that grabbed it.
 
@@ -501,10 +498,10 @@ bool QWindowsTabletSupport::translateTabletPacketEvent()
         const QPoint mouseLocation = QWindowsCursor::mousePosition();
         if (m_state == PenProximity) {
             m_state = PenDown;
-            m_mode = (mouseLocation - currentGlobalPosF).manhattanLength() > m_absoluteRange
+            m_mode = (mouseLocation - globalPosF).manhattanLength() > m_absoluteRange
                 ? MouseMode : PenMode;
             qCDebug(lcQpaTablet) << __FUNCTION__ << "mode=" << m_mode << "pen:"
-                << currentGlobalPosF << "mouse:" << mouseLocation;
+                << globalPosF << "mouse:" << mouseLocation;
         }
         if (m_mode == MouseMode)
             globalPosF = mouseLocation;
diff --git a/src/plugins/platforms/windows/qwindowstabletsupport.h b/src/plugins/platforms/windows/qwindowstabletsupport.h
index 340818c3f7..9379dd72d6 100644
--- a/src/plugins/platforms/windows/qwindowstabletsupport.h
+++ b/src/plugins/platforms/windows/qwindowstabletsupport.h
@@ -149,7 +149,6 @@ private:
     bool m_tiltSupport;
     QVector<QWindowsTabletDeviceData> m_devices;
     int m_currentDevice;
-    QPointF m_oldGlobalPosF;
     Mode m_mode = PenMode;
     State m_state = PenUp;
 };