Deliver QTabletEvents to pointer handlersv5.15.0-alpha1

At this time, there are not yet any specialized handlers to
do anything specifically with tablet events; but we demonstrate
how to use HoverHandler to detect the type of stylus in use,
and how to use PointHandler to draw on a Canvas.

Unfortunately, events of types TabletEnterProximity and
TabletLeaveProximity are not delivered to the window, only to
QGuiApplication.  So HoverHandler can detect when the stylus is moved
out of its parent Item (as long as it's still hovering over the tablet
surface), but cannot detect when the stylus leaves the tablet completely.
In Qt 5 that would require a custom application subclass
(see qtbase/examples/widgets/widgets/tablet/tabletapplication.cpp).

Fixes: QTBUG-79660
Change-Id: I81fdb99082dc41c0455085e6b6d3952402bf8742
Reviewed-by: Qt CI Bot <qt_ci_bot@qt-project.org>
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

4 files changed, 252 insertions, 17 deletions

diff --git a/src/quick/items/qquickevents.cpp b/src/quick/items/qquickevents.cpp
index 0a6faf04af..0a9abb3322 100644
--- a/src/quick/items/qquickevents.cpp
+++ b/src/quick/items/qquickevents.cpp
@@ -658,14 +658,73 @@ QQuickPointerDevice *QQuickPointerDevice::genericMouseDevice()
     return g_genericMouseDevice;
 }
 
-QQuickPointerDevice *QQuickPointerDevice::tabletDevice(qint64 id)
-{
-    auto it = g_tabletDevices->find(id);
+QQuickPointerDevice *QQuickPointerDevice::tabletDevice(const QTabletEvent *event)
+{
+    // QTabletEvent::uniqueId() is the same for the pointy end and the eraser end of the stylus.
+    // We need to make those unique. QTabletEvent::PointerType only needs 2 bits' worth of storage.
+    // The key into g_tabletDevices just needs to be unique; we don't need to extract uniqueId
+    // back out of it, because QQuickPointerDevice stores that separately anyway.
+    // So the shift-and-add can be thought of as a sort of hash function, even though
+    // most of the time the result will be recognizable because the uniqueId MSBs are often 0.
+    qint64 key = event->uniqueId() + (qint64(event->pointerType()) << 60);
+    auto it = g_tabletDevices->find(key);
     if (it != g_tabletDevices->end())
         return it.value();
 
-    // ### Figure out how to populate the tablet devices
-    return nullptr;
+    DeviceType type = UnknownDevice;
+    int buttonCount = 0;
+    Capabilities caps = Position | Pressure | Hover;
+    // TODO Qt 6: we can't know for sure about XTilt or YTilt until we have a
+    // QTabletDevice populated with capabilities provided by QPA plugins
+
+    switch (event->device()) {
+    case QTabletEvent::Stylus:
+        type = QQuickPointerDevice::Stylus;
+        buttonCount = 3;
+        break;
+    case QTabletEvent::RotationStylus:
+        type = QQuickPointerDevice::Stylus;
+        caps |= QQuickPointerDevice::Rotation;
+        buttonCount = 1;
+        break;
+    case QTabletEvent::Airbrush:
+        type = QQuickPointerDevice::Airbrush;
+        buttonCount = 2;
+        break;
+    case QTabletEvent::Puck:
+        type = QQuickPointerDevice::Puck;
+        buttonCount = 3;
+        break;
+    case QTabletEvent::FourDMouse:
+        type = QQuickPointerDevice::Mouse;
+        caps |= QQuickPointerDevice::Rotation;
+        buttonCount = 3;
+        break;
+    default:
+        type = QQuickPointerDevice::UnknownDevice;
+        break;
+    }
+
+    PointerType ptype = GenericPointer;
+    switch (event->pointerType()) {
+    case QTabletEvent::Pen:
+        ptype = Pen;
+        break;
+    case QTabletEvent::Eraser:
+        ptype = Eraser;
+        break;
+    case QTabletEvent::Cursor:
+        ptype = Cursor;
+        break;
+    case QTabletEvent::UnknownPointer:
+        break;
+    }
+
+    QQuickPointerDevice *device = new QQuickPointerDevice(type, ptype, caps, 1, buttonCount,
+        QLatin1String("tablet tool ") + QString::number(event->uniqueId()), event->uniqueId());
+
+    g_tabletDevices->insert(key, device);
+    return device;
 }
 
 /*!
@@ -1284,6 +1343,12 @@ QVector2D QQuickEventPoint::estimatedVelocity() const
 QQuickPointerEvent::~QQuickPointerEvent()
 {}
 
+QQuickPointerMouseEvent::QQuickPointerMouseEvent(QObject *parent, QQuickPointerDevice *device)
+    : QQuickSinglePointEvent(parent, device)
+{
+    m_point = new QQuickEventPoint(this);
+}
+
 QQuickPointerEvent *QQuickPointerMouseEvent::reset(QEvent *event)
 {
     auto ev = static_cast<QMouseEvent*>(event);
@@ -1398,6 +1463,12 @@ void QQuickPointerTouchEvent::localize(QQuickItem *target)
 }
 
 #if QT_CONFIG(gestures)
+QQuickPointerNativeGestureEvent::QQuickPointerNativeGestureEvent(QObject *parent, QQuickPointerDevice *device)
+    : QQuickSinglePointEvent(parent, device)
+{
+    m_point = new QQuickEventPoint(this);
+}
+
 QQuickPointerEvent *QQuickPointerNativeGestureEvent::reset(QEvent *event)
 {
     auto ev = static_cast<QNativeGestureEvent*>(event);
@@ -1560,6 +1631,12 @@ QQuickEventPoint *QQuickSinglePointEvent::point(int i) const
     \note Many platforms provide no such information. On such platforms,
     \c inverted always returns false.
 */
+QQuickPointerScrollEvent::QQuickPointerScrollEvent(QObject *parent, QQuickPointerDevice *device)
+    : QQuickSinglePointEvent(parent, device)
+{
+    m_point = new QQuickEventPoint(this);
+}
+
 QQuickPointerEvent *QQuickPointerScrollEvent::reset(QEvent *event)
 {
     m_event = static_cast<QInputEvent*>(event);
@@ -1832,6 +1909,81 @@ QMouseEvent *QQuickPointerTouchEvent::syntheticMouseEvent(int pointID, QQuickIte
     return &m_synthMouseEvent;
 }
 
+#if QT_CONFIG(tabletevent)
+QQuickPointerTabletEvent::QQuickPointerTabletEvent(QObject *parent, QQuickPointerDevice *device)
+    : QQuickSinglePointEvent(parent, device)
+{
+    m_point = new QQuickEventTabletPoint(this);
+}
+
+QQuickPointerEvent *QQuickPointerTabletEvent::reset(QEvent *event)
+{
+    auto ev = static_cast<QTabletEvent*>(event);
+    m_event = ev;
+    if (!event)
+        return this;
+
+    Q_ASSERT(m_device == QQuickPointerDevice::tabletDevice(ev));
+    m_device->eventDeliveryTargets().clear();
+    m_button = ev->button();
+    m_pressedButtons = ev->buttons();
+    static_cast<QQuickEventTabletPoint *>(m_point)->reset(ev);
+    return this;
+}
+
+QQuickEventTabletPoint::QQuickEventTabletPoint(QQuickPointerTabletEvent *parent)
+  : QQuickEventPoint(parent)
+{
+}
+
+void QQuickEventTabletPoint::reset(const QTabletEvent *ev)
+{
+    Qt::TouchPointState state = Qt::TouchPointStationary;
+    switch (ev->type()) {
+    case QEvent::TabletPress:
+        state = Qt::TouchPointPressed;
+        clearPassiveGrabbers();
+        break;
+    case QEvent::TabletRelease:
+        state = Qt::TouchPointReleased;
+        break;
+    case QEvent::TabletMove:
+        state = Qt::TouchPointMoved;
+        break;
+    default:
+        break;
+    }
+    QQuickEventPoint::reset(state, ev->posF(), 1, ev->timestamp());
+    m_rotation = ev->rotation();
+    m_pressure = ev->pressure();
+    m_tangentialPressure = ev->tangentialPressure();
+    m_tilt = QVector2D(ev->xTilt(), ev->yTilt());
+}
+
+bool QQuickPointerTabletEvent::isPressEvent() const
+{
+    auto me = static_cast<QTabletEvent *>(m_event);
+    return me->type() == QEvent::TabletPress;
+}
+
+bool QQuickPointerTabletEvent::isUpdateEvent() const
+{
+    auto me = static_cast<QTabletEvent *>(m_event);
+    return me->type() == QEvent::TabletMove;
+}
+
+bool QQuickPointerTabletEvent::isReleaseEvent() const
+{
+    auto me = static_cast<QTabletEvent *>(m_event);
+    return me->type() == QEvent::TabletRelease;
+}
+
+QTabletEvent *QQuickPointerTabletEvent::asTabletEvent() const
+{
+    return static_cast<QTabletEvent *>(m_event);
+}
+#endif // QT_CONFIG(tabletevent)
+
 #if QT_CONFIG(gestures)
 bool QQuickPointerNativeGestureEvent::isPressEvent() const
 {
diff --git a/src/quick/items/qquickevents_p_p.h b/src/quick/items/qquickevents_p_p.h
index 4615ce43d2..3a8028678e 100644
--- a/src/quick/items/qquickevents_p_p.h
+++ b/src/quick/items/qquickevents_p_p.h
@@ -476,8 +476,8 @@ class Q_QUICK_PRIVATE_EXPORT QQuickSinglePointEvent : public QQuickPointerEvent
 {
     Q_OBJECT
 public:
-    QQuickSinglePointEvent(QObject *parent = nullptr, QQuickPointerDevice *device = nullptr)
-        : QQuickPointerEvent(parent, device), m_point(new QQuickEventPoint(this)) { }
+    QQuickSinglePointEvent(QObject *parent, QQuickPointerDevice *device)
+        : QQuickPointerEvent(parent, device) { }
 
     void localize(QQuickItem *target) override;
     int pointCount() const override { return 1; }
@@ -491,7 +491,7 @@ public:
     bool hasExclusiveGrabber(const QQuickPointerHandler *handler) const override;
 
 protected:
-    QQuickEventPoint *m_point;
+    QQuickEventPoint *m_point = nullptr;
 
     Q_DISABLE_COPY(QQuickSinglePointEvent)
 };
@@ -505,8 +505,7 @@ class Q_QUICK_PRIVATE_EXPORT QQuickPointerMouseEvent : public QQuickSinglePointE
     QML_ADDED_IN_MINOR_VERSION(12)
 
 public:
-    QQuickPointerMouseEvent(QObject *parent = nullptr, QQuickPointerDevice *device = nullptr)
-        : QQuickSinglePointEvent(parent, device) { }
+    QQuickPointerMouseEvent(QObject *parent, QQuickPointerDevice *device);
 
     QQuickPointerEvent *reset(QEvent *) override;
     bool isPressEvent() const override;
@@ -568,6 +567,60 @@ private:
     Q_DISABLE_COPY(QQuickPointerTouchEvent)
 };
 
+#if QT_CONFIG(tabletevent)
+class Q_QUICK_PRIVATE_EXPORT QQuickEventTabletPoint : public QQuickEventPoint
+{
+    Q_OBJECT
+    Q_PROPERTY(qreal rotation READ rotation)
+    Q_PROPERTY(qreal pressure READ pressure)
+    Q_PROPERTY(qreal tangentialPressure READ tangentialPressure)
+    Q_PROPERTY(QVector2D tilt READ tilt)
+
+    QML_NAMED_ELEMENT(EventTabletPoint)
+    QML_UNCREATABLE("EventTouchPoint is only available as a member of PointerEvent.")
+    QML_ADDED_IN_MINOR_VERSION(15)
+
+public:
+    QQuickEventTabletPoint(QQuickPointerTabletEvent *parent);
+
+    void reset(const QTabletEvent *e);
+
+    qreal rotation() const { return m_rotation; }
+    qreal pressure() const { return m_pressure; }
+    qreal tangentialPressure() const { return m_tangentialPressure; }
+    QVector2D tilt() const { return m_tilt; }
+
+private:
+    qreal m_rotation;
+    qreal m_pressure;
+    qreal m_tangentialPressure;
+    QVector2D m_tilt;
+
+    friend class QQuickPointerTouchEvent;
+
+    Q_DISABLE_COPY(QQuickEventTabletPoint)
+};
+
+class Q_QUICK_PRIVATE_EXPORT QQuickPointerTabletEvent : public QQuickSinglePointEvent
+{
+    Q_OBJECT
+public:
+    QQuickPointerTabletEvent(QObject *parent, QQuickPointerDevice *device);
+
+    QQuickPointerEvent *reset(QEvent *) override;
+    bool isPressEvent() const override;
+    bool isUpdateEvent() const override;
+    bool isReleaseEvent() const override;
+    QQuickPointerTabletEvent *asPointerTabletEvent() override { return this; }
+    const QQuickPointerTabletEvent *asPointerTabletEvent() const override { return this; }
+    const QQuickEventTabletPoint *tabletPoint() const { return static_cast<QQuickEventTabletPoint *>(m_point); }
+
+    QTabletEvent *asTabletEvent() const;
+
+    Q_DISABLE_COPY(QQuickPointerTabletEvent)
+};
+#endif // QT_CONFIG(tabletevent)
+
 #if QT_CONFIG(gestures)
 class Q_QUICK_PRIVATE_EXPORT QQuickPointerNativeGestureEvent : public QQuickSinglePointEvent
 {
@@ -576,8 +629,7 @@ class Q_QUICK_PRIVATE_EXPORT QQuickPointerNativeGestureEvent : public QQuickSing
     Q_PROPERTY(qreal value READ value CONSTANT)
 
 public:
-    QQuickPointerNativeGestureEvent(QObject *parent = nullptr, QQuickPointerDevice *device = nullptr)
-        : QQuickSinglePointEvent(parent, device) { }
+    QQuickPointerNativeGestureEvent(QObject *parent, QQuickPointerDevice *device);
 
     QQuickPointerEvent *reset(QEvent *) override;
     bool isPressEvent() const override;
@@ -606,8 +658,7 @@ class Q_QUICK_PRIVATE_EXPORT QQuickPointerScrollEvent : public QQuickSinglePoint
     QML_ADDED_IN_MINOR_VERSION(14)
 
 public:
-    QQuickPointerScrollEvent(QObject *parent = nullptr, QQuickPointerDevice *device = nullptr)
-        : QQuickSinglePointEvent(parent, device) { }
+    QQuickPointerScrollEvent(QObject *parent, QQuickPointerDevice *device);
 
     QQuickPointerEvent *reset(QEvent *) override;
     void localize(QQuickItem *target) override;
@@ -712,7 +763,7 @@ public:
     static QQuickPointerDevice *touchDevice(const QTouchDevice *d);
     static QList<QQuickPointerDevice *> touchDevices();
     static QQuickPointerDevice *genericMouseDevice();
-    static QQuickPointerDevice *tabletDevice(qint64);
+    static QQuickPointerDevice *tabletDevice(const QTabletEvent *event);
 
     QVector<QQuickPointerHandler *> &eventDeliveryTargets() { return m_eventDeliveryTargets; }
 
diff --git a/src/quick/items/qquickwindow.cpp b/src/quick/items/qquickwindow.cpp
index 6c63b83511..dda0cfef3e 100644
--- a/src/quick/items/qquickwindow.cpp
+++ b/src/quick/items/qquickwindow.cpp
@@ -93,6 +93,7 @@ Q_LOGGING_CATEGORY(DBG_TOUCH, "qt.quick.touch")
 Q_LOGGING_CATEGORY(DBG_TOUCH_TARGET, "qt.quick.touch.target")
 Q_LOGGING_CATEGORY(DBG_MOUSE, "qt.quick.mouse")
 Q_LOGGING_CATEGORY(DBG_MOUSE_TARGET, "qt.quick.mouse.target")
+Q_LOGGING_CATEGORY(lcTablet, "qt.quick.tablet")
 Q_LOGGING_CATEGORY(lcWheelTarget, "qt.quick.wheel.target")
 Q_LOGGING_CATEGORY(lcGestureTarget, "qt.quick.gesture.target")
 Q_LOGGING_CATEGORY(DBG_HOVER_TRACE, "qt.quick.hover.trace")
@@ -2122,6 +2123,17 @@ void QQuickWindow::wheelEvent(QWheelEvent *event)
 }
 #endif // wheelevent
 
+#if QT_CONFIG(tabletevent)
+/*! \reimp */
+void QQuickWindow::tabletEvent(QTabletEvent *event)
+{
+    Q_D(QQuickWindow);
+    qCDebug(lcTablet) << event;
+    // TODO Qt 6: make sure TabletEnterProximity and TabletLeaveProximity are delivered here
+    d->deliverPointerEvent(d->pointerEventInstance(event));
+}
+#endif // tabletevent
+
 bool QQuickWindowPrivate::deliverTouchCancelEvent(QTouchEvent *event)
 {
     qCDebug(DBG_TOUCH) << event;
@@ -2400,8 +2412,12 @@ QQuickPointerEvent *QQuickWindowPrivate::pointerEventInstance(QQuickPointerDevic
 #endif
             ev = new QQuickPointerTouchEvent(q, device);
         break;
+    case QQuickPointerDevice::Stylus:
+    case QQuickPointerDevice::Airbrush:
+    case QQuickPointerDevice::Puck:
+        ev = new QQuickPointerTabletEvent(q, device);
+        break;
     default:
-        // TODO tablet event types
         break;
     }
     pointerEventInstances << ev;
@@ -2432,7 +2448,15 @@ QQuickPointerEvent *QQuickWindowPrivate::pointerEventInstance(QEvent *event) con
     case QEvent::TouchCancel:
         dev = QQuickPointerDevice::touchDevice(static_cast<QTouchEvent *>(event)->device());
         break;
-    // TODO tablet event types
+#if QT_CONFIG(tabletevent)
+    case QEvent::TabletPress:
+    case QEvent::TabletMove:
+    case QEvent::TabletRelease:
+    case QEvent::TabletEnterProximity:
+    case QEvent::TabletLeaveProximity:
+        dev = QQuickPointerDevice::tabletDevice(static_cast<QTabletEvent *>(event));
+        break;
+#endif
 #if QT_CONFIG(gestures)
     case QEvent::NativeGesture:
         dev = QQuickPointerDevice::touchDevice(static_cast<QNativeGestureEvent *>(event)->device());
@@ -2467,6 +2491,11 @@ void QQuickWindowPrivate::deliverPointerEvent(QQuickPointerEvent *event)
         deliverTouchEvent(event->asPointerTouchEvent());
     } else {
         deliverSinglePointEventUntilAccepted(event);
+        // If any handler got interested in the tablet event, we don't want to receive a synth-mouse event from QtGui
+        // TODO Qt 6: QTabletEvent will be accepted by default, like other events
+        if (event->asPointerTabletEvent() &&
+                (!event->point(0)->passiveGrabbers().isEmpty() || event->point(0)->exclusiveGrabber()))
+            event->setAccepted(true);
     }
 
     event->reset(nullptr);
diff --git a/src/quick/items/qquickwindow.h b/src/quick/items/qquickwindow.h
index d22bba4512..097627374c 100644
--- a/src/quick/items/qquickwindow.h
+++ b/src/quick/items/qquickwindow.h
@@ -252,6 +252,9 @@ protected:
 #if QT_CONFIG(wheelevent)
     void wheelEvent(QWheelEvent *) override;
 #endif
+#if QT_CONFIG(tabletevent)
+    void tabletEvent(QTabletEvent *) override;
+#endif
 
 private Q_SLOTS:
     void maybeUpdate();