Accept concurrent input from multiple tablet devices in QGuiApplication

As a follow-up to 352c357e6f enabling
support for multiple evdevtablet plugins at runtime (one per device),
we also need to adjust the way QGuiApplication handles the events
received from those plugins, in particular when multiple devices
are sending tablet events concurrently.

Replace the static members in QGuiApplication by a vector storing
the same data per-device, so tablet press/release events can be
recognized independently.

Change-Id: Ie0975cdb03a8f6d05903e2e2e57ceb9de73a74a4
Reviewed-by: Jake Petroules <jake.petroules@theqtcompany.com>

src/gui/kernel/qguiapplication.cpp

@@ -124,8 +124,6 @@ Qt::KeyboardModifiers QGuiApplicationPrivate::modifier_buttons = Qt::NoModifier;
 
 QPointF QGuiApplicationPrivate::lastCursorPosition(qInf(), qInf());
 
-Qt::MouseButtons QGuiApplicationPrivate::tabletState = Qt::NoButton;
-QWindow *QGuiApplicationPrivate::tabletPressTarget = 0;
 QWindow *QGuiApplicationPrivate::currentMouseWindow = 0;
 
 QString QGuiApplicationPrivate::styleOverride;
@@ -134,6 +132,8 @@ Qt::ApplicationState QGuiApplicationPrivate::applicationState = Qt::ApplicationI
 
 bool QGuiApplicationPrivate::highDpiScalingUpdated = false;
 
+QVector<QGuiApplicationPrivate::TabletPointData> QGuiApplicationPrivate::tabletDevicePoints;
+
 QPlatformIntegration *QGuiApplicationPrivate::platform_integration = 0;
 QPlatformTheme *QGuiApplicationPrivate::platform_theme = 0;
 
@@ -2198,12 +2198,26 @@ void QGuiApplicationPrivate::processFileOpenEvent(QWindowSystemInterfacePrivate:
     QGuiApplication::sendSpontaneousEvent(qApp, &event);
 }
 
+QGuiApplicationPrivate::TabletPointData &QGuiApplicationPrivate::tabletDevicePoint(qint64 deviceId)
+{
+    for (int i = 0; i < tabletDevicePoints.size(); ++i) {
+        TabletPointData &pointData = tabletDevicePoints[i];
+        if (pointData.deviceId == deviceId)
+            return pointData;
+    }
+
+    tabletDevicePoints.append(TabletPointData(deviceId));
+    return tabletDevicePoints.last();
+}
+
 void QGuiApplicationPrivate::processTabletEvent(QWindowSystemInterfacePrivate::TabletEvent *e)
 {
 #ifndef QT_NO_TABLETEVENT
+    TabletPointData &pointData = tabletDevicePoint(e->uid);
+
     QEvent::Type type = QEvent::TabletMove;
-    if (e->buttons != tabletState)
+    if (e->buttons != pointData.state)
-        type = (e->buttons > tabletState) ? QEvent::TabletPress : QEvent::TabletRelease;
+        type = (e->buttons > pointData.state) ? QEvent::TabletPress : QEvent::TabletRelease;
 
     QWindow *window = e->window.data();
     modifier_buttons = e->modifiers;
@@ -2219,14 +2233,14 @@ void QGuiApplicationPrivate::processTabletEvent(QWindowSystemInterfacePrivate::T
         }
         if (!window)
             return;
-        tabletPressTarget = window;
+        pointData.target = window;
     } else {
         if (e->nullWindow()) {
-            window = tabletPressTarget;
+            window = pointData.target;
             localValid = false;
         }
         if (type == QEvent::TabletRelease)
-            tabletPressTarget = 0;
+            pointData.target = Q_NULLPTR;
         if (!window)
             return;
     }
@@ -2235,7 +2249,7 @@ void QGuiApplicationPrivate::processTabletEvent(QWindowSystemInterfacePrivate::T
         QPointF delta = e->global - e->global.toPoint();
         local = window->mapFromGlobal(e->global.toPoint()) + delta;
     }
-    Qt::MouseButtons stateChange = e->buttons ^ tabletState;
+    Qt::MouseButtons stateChange = e->buttons ^ pointData.state;
     Qt::MouseButton button = Qt::NoButton;
     for (int check = Qt::LeftButton; check <= int(Qt::MaxMouseButton); check = check << 1) {
         if (check & stateChange) {
@@ -2249,7 +2263,7 @@ void QGuiApplicationPrivate::processTabletEvent(QWindowSystemInterfacePrivate::T
                     e->modifiers, e->uid, button, e->buttons);
     ev.setTimestamp(e->timestamp);
     QGuiApplication::sendSpontaneousEvent(window, &ev);
-    tabletState = e->buttons;
+    pointData.state = e->buttons;
 #else
     Q_UNUSED(e)
 #endif
@@ -2261,7 +2275,7 @@ void QGuiApplicationPrivate::processTabletEnterProximityEvent(QWindowSystemInter
     QTabletEvent ev(QEvent::TabletEnterProximity, QPointF(), QPointF(),
                     e->device, e->pointerType, 0, 0, 0,
                     0, 0, 0,
-                    Qt::NoModifier, e->uid, Qt::NoButton, tabletState);
+                    Qt::NoModifier, e->uid, Qt::NoButton, tabletDevicePoint(e->uid).state);
     ev.setTimestamp(e->timestamp);
     QGuiApplication::sendSpontaneousEvent(qGuiApp, &ev);
 #else
@@ -2275,7 +2289,7 @@ void QGuiApplicationPrivate::processTabletLeaveProximityEvent(QWindowSystemInter
     QTabletEvent ev(QEvent::TabletLeaveProximity, QPointF(), QPointF(),
                     e->device, e->pointerType, 0, 0, 0,
                     0, 0, 0,
-                    Qt::NoModifier, e->uid, Qt::NoButton, tabletState);
+                    Qt::NoModifier, e->uid, Qt::NoButton, tabletDevicePoint(e->uid).state);
     ev.setTimestamp(e->timestamp);
     QGuiApplication::sendSpontaneousEvent(qGuiApp, &ev);
 #else

src/gui/kernel/qguiapplication_p.h

@@ -198,13 +198,20 @@ public:
     static int mousePressY;
     static int mouse_double_click_distance;
     static QPointF lastCursorPosition;
-    static Qt::MouseButtons tabletState;
-    static QWindow *tabletPressTarget;
     static QWindow *currentMouseWindow;
     static QWindow *currentMousePressWindow;
     static Qt::ApplicationState applicationState;
     static bool highDpiScalingUpdated;
 
+    struct TabletPointData {
+        TabletPointData(qint64 devId = 0) : deviceId(devId), state(Qt::NoButton), target(Q_NULLPTR) {}
+        qint64 deviceId;
+        Qt::MouseButtons state;
+        QWindow *target;
+    };
+    static QVector<TabletPointData> tabletDevicePoints;
+    static TabletPointData &tabletDevicePoint(qint64 deviceId);
+
 #ifndef QT_NO_CLIPBOARD
     static QClipboard *qt_clipboard;
 #endif

src/gui/kernel/qwindow.cpp

@@ -1680,8 +1680,12 @@ void QWindow::destroy()
         QGuiApplicationPrivate::currentMouseWindow = parent();
     if (QGuiApplicationPrivate::currentMousePressWindow == this)
         QGuiApplicationPrivate::currentMousePressWindow = parent();
-    if (QGuiApplicationPrivate::tabletPressTarget == this)
+
-        QGuiApplicationPrivate::tabletPressTarget = parent();
+    for (int i = 0; i < QGuiApplicationPrivate::tabletDevicePoints.size(); ++i) {
+        QGuiApplicationPrivate::TabletPointData &pointData = QGuiApplicationPrivate::tabletDevicePoints[i];
+        if (pointData.target == this)
+            pointData.target = parent();
+    }
 
     bool wasVisible = isVisible();
     d->visibilityOnDestroy = wasVisible && d->platformWindow;

src/plugins/platforms/windows/qwindowstabletsupport.cpp

@@ -391,6 +391,7 @@ bool QWindowsTabletSupport::translateTabletPacketEvent()
 
     const int currentDevice = m_devices.at(m_currentDevice).currentDevice;
     const int currentPointer = m_devices.at(m_currentDevice).currentPointerType;
+    const qint64 uniqueId = m_devices.at(m_currentDevice).uniqueId;
 
     // The tablet can be used in 2 different modes, depending on it settings:
     // 1) Absolute (pen) mode:
@@ -407,7 +408,7 @@ bool QWindowsTabletSupport::translateTabletPacketEvent()
     const QRect virtualDesktopArea = QGuiApplication::primaryScreen()->virtualGeometry();
 
     qCDebug(lcQpaTablet) << __FUNCTION__ << "processing " << packetCount
-        << "target:" << QGuiApplicationPrivate::tabletPressTarget;
+        << "target:" << QGuiApplicationPrivate::tabletDevicePoint(uniqueId).target;
 
     const Qt::KeyboardModifiers keyboardModifiers = QWindowsKeyMapper::queryKeyboardModifiers();
 
@@ -420,7 +421,7 @@ bool QWindowsTabletSupport::translateTabletPacketEvent()
         QPointF globalPosF = m_oldGlobalPosF;
         m_oldGlobalPosF = m_devices.at(m_currentDevice).scaleCoordinates(packet.pkX, packet.pkY, virtualDesktopArea);
 
-        QWindow *target = QGuiApplicationPrivate::tabletPressTarget; // Pass to window that grabbed it.
+        QWindow *target = QGuiApplicationPrivate::tabletDevicePoint(uniqueId).target; // Pass to window that grabbed it.
         QPoint globalPos = globalPosF.toPoint();
 
         // Get Mouse Position and compare to tablet info
@@ -484,7 +485,7 @@ bool QWindowsTabletSupport::translateTabletPacketEvent()
                                                   static_cast<Qt::MouseButtons>(packet.pkButtons),
                                                   pressureNew, tiltX, tiltY,
                                                   tangentialPressure, rotation, z,
-                                                  m_devices.at(m_currentDevice).uniqueId,
+                                                  uniqueId,
                                                   keyboardModifiers);
     }
     return true;