Add QInputDevice::availableVirtualGeometry()

This property tells what part of the virtual desktop the input device
can access.

This is not a one-to-one mapping with a QScreen, because a Wacom tablet
might be configured to access a whole desktop, a whole screen, or an
area corresponding to the drawing area of one window; a mouse normally
can access the whole desktop (so QScreen::virtualGeometry() would be
identical to QInputDevice::availableVirtualGeometry()); a touchscreen
normally is mapped to one screen but could be mapped differently; etc.
It's possible to find the intersection of the rectangular area with the
screen(s) that it overlaps, though.

Task-number: QTBUG-78839
Change-Id: I9040e20fb5a3dec8a9a0dd827735826c4c1eea38
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

src/gui/kernel/qinputdevice.cpp

@@ -112,6 +112,29 @@ QInputDevice::QInputDevice(QInputDevicePrivate &d, QObject *parent)
 {
 }
 
+/*!
+    Returns the region within the \l{QScreen::availableVirtualGeometry}{virtual desktop}
+    that this device can access.
+
+    For example a \l {QInputDevice::DeviceType::TouchScreen}{TouchScreen} input
+    device is fixed in place upon a single physical screen, and usually
+    calibrated so that this area is the same as QScreen::geometry(); whereas a
+    \l {QInputDevice::DeviceType::Mouse}{Mouse} can probably access all screens
+    on the virtual desktop. A Wacom graphics tablet may be configured in a way
+    that it's mapped to all screens, or only to the screen where the user
+    prefers to create drawings, or to the window in which drawing occurs.
+    A \l {QInputDevice::DeviceType::Stylus}{Stylus} device that is integrated
+    with a touchscreen may be physically limited to that screen.
+
+    If the returned rectangle is \l {null}{QRect::isNull()}, it means this device
+    can access the entire virtual desktop.
+*/
+QRect QInputDevice::availableVirtualGeometry() const
+{
+    Q_D(const QInputDevice);
+    return d->availableVirtualGeometry;
+}
+
 /*!
     Returns the device name.
 

src/gui/kernel/qinputdevice.h

@@ -58,6 +58,7 @@ class Q_GUI_EXPORT QInputDevice : public QObject
     Q_PROPERTY(Capabilities capabilities READ capabilities CONSTANT)
     Q_PROPERTY(qint64 id READ id CONSTANT)
     Q_PROPERTY(QString seatName READ seatName CONSTANT)
+    Q_PROPERTY(QRect availableVirtualGeometry READ availableVirtualGeometry NOTIFY availableVirtualGeometryChanged)
 
 public:
     enum class DeviceType : qint16 {
@@ -106,12 +107,16 @@ public:
     bool hasCapability(Capability cap) const;
     qint64 id() const;
     QString seatName() const;
+    QRect availableVirtualGeometry() const;
 
     static QList<const QInputDevice *> devices();
     static const QInputDevice *primaryKeyboard(const QString& seatName = QString());
 
     bool operator==(const QInputDevice &other) const;
 
+Q_SIGNALS:
+    void availableVirtualGeometryChanged(QRect area);
+
 protected:
     QInputDevice(QInputDevicePrivate &d, QObject *parent = nullptr);
 

src/gui/kernel/qinputdevice_p.h

@@ -77,6 +77,7 @@ public:
     QString name;
     QString seatName;
     QString busId;
+    QRect availableVirtualGeometry;
     void *extra = nullptr;      // The QPA plugin can store arbitrary device-specific data here
     void *qqExtra = nullptr;    // Qt Quick can store arbitrary device-specific data here
     qint64 id = 0;
@@ -89,6 +90,17 @@ public:
     static bool isRegistered(const QInputDevice *dev);
     static const QInputDevice *fromId(qint64 id);  // window system ID (e.g. xinput id), not QPointingDeviceUniqueId
 
+    void setAvailableVirtualGeometry(QRect a)
+    {
+        if (a == availableVirtualGeometry)
+            return;
+
+        availableVirtualGeometry = a;
+        capabilities |= qint32(QInputDevice::Capability::NormalizedPosition);
+        Q_Q(QInputDevice);
+        emit q->availableVirtualGeometryChanged(availableVirtualGeometry);
+    }
+
     inline static QInputDevicePrivate *get(QInputDevice *q)
     {
         return static_cast<QInputDevicePrivate *>(QObjectPrivate::get(q));