add buttons to QTabletEvent

Until now, it has been necessary for tablet-oriented applications which
care about multi-button styli to reject each tablet event and wait for
the mouse event in order to know which buttons are pressed.  This patch
adds the new API and also the X11/xcb implementation.

[ChangeLog][QtCore][Tablet support] Added buttons to QTabletEvent

Task-number: QTBUG-39458
Change-Id: If2c9ec1ceacc1700a82686c5fc6f568f9111055a
Reviewed-by: Frederik Gladhorn <frederik.gladhorn@digia.com>

3 files changed, 36 insertions, 23 deletions

diff --git a/src/plugins/platforms/windows/qwindowstabletsupport.cpp b/src/plugins/platforms/windows/qwindowstabletsupport.cpp
index 164fc12743..d1737de907 100644
--- a/src/plugins/platforms/windows/qwindowstabletsupport.cpp
+++ b/src/plugins/platforms/windows/qwindowstabletsupport.cpp
@@ -479,8 +479,9 @@ bool QWindowsTabletSupport::translateTabletPacketEvent()
                 << tiltY << "tanP:" << tangentialPressure << "rotation:" << rotation;
         }
 
-        QWindowSystemInterface::handleTabletEvent(target, packet.pkButtons, localPos, globalPosF,
+        QWindowSystemInterface::handleTabletEvent(target, QPointF(localPos), globalPosF,
                                                   currentDevice, currentPointer,
+                                                  static_cast<Qt::MouseButtons>(packet.pkButtons),
                                                   pressureNew, tiltX, tiltY,
                                                   tangentialPressure, rotation, z,
                                                   m_devices.at(m_currentDevice).uniqueId,
diff --git a/src/plugins/platforms/xcb/qxcbconnection.h b/src/plugins/platforms/xcb/qxcbconnection.h
index 82ad027a50..354ba54e70 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.h
+++ b/src/plugins/platforms/xcb/qxcbconnection.h
@@ -509,11 +509,11 @@ private:
 #ifndef QT_NO_TABLETEVENT
     struct TabletData {
         TabletData() : deviceId(0), pointerType(QTabletEvent::UnknownPointer),
-            tool(QTabletEvent::Stylus), down(false), serialId(0), inProximity(false) { }
+            tool(QTabletEvent::Stylus), buttons(0), serialId(0), inProximity(false) { }
         int deviceId;
         QTabletEvent::PointerType pointerType;
         QTabletEvent::TabletDevice tool;
-        bool down;
+        Qt::MouseButtons buttons;
         qint64 serialId;
         bool inProximity;
         struct ValuatorClassInfo {
diff --git a/src/plugins/platforms/xcb/qxcbconnection_xi2.cpp b/src/plugins/platforms/xcb/qxcbconnection_xi2.cpp
index e21db89a20..512e574859 100644
--- a/src/plugins/platforms/xcb/qxcbconnection_xi2.cpp
+++ b/src/plugins/platforms/xcb/qxcbconnection_xi2.cpp
@@ -685,6 +685,19 @@ void QXcbConnection::xi2HandleScrollEvent(void *event, ScrollingDevice &scrollin
 #endif // XCB_USE_XINPUT21
 }
 
+static Qt::MouseButton xiToQtMouseButton(uint32_t b) {
+    switch (b) {
+    case 1: return Qt::LeftButton;
+    case 2: return Qt::MiddleButton;
+    case 3: return Qt::RightButton;
+    // 4-7 are for scrolling
+    default: break;
+    }
+    if (b >= 8 && b <= Qt::MaxMouseButton)
+        return static_cast<Qt::MouseButton>(Qt::BackButton << (b - 8));
+    return Qt::NoButton;
+}
+
 static QTabletEvent::TabletDevice toolIdToTabletDevice(quint32 toolId) {
     // keep in sync with wacom_intuos_inout() in Linux kernel driver wacom_wac.c
     switch (toolId) {
@@ -725,24 +738,22 @@ bool QXcbConnection::xi2HandleTabletEvent(void *event, TabletData *tabletData)
     Display *xDisplay = static_cast<Display *>(m_xlib_display);
     xXIGenericDeviceEvent *xiEvent = static_cast<xXIGenericDeviceEvent *>(event);
     switch (xiEvent->evtype) {
-    case XI_ButtonPress: // stylus down
-        if (reinterpret_cast<xXIDeviceEvent *>(event)->detail == 1) { // ignore the physical buttons on the stylus
-            tabletData->down = true;
-            xi2ReportTabletEvent(*tabletData, xiEvent);
-        } else
-            handled = false;
+    case XI_ButtonPress: {
+        Qt::MouseButton b = xiToQtMouseButton(reinterpret_cast<xXIDeviceEvent *>(event)->detail);
+        tabletData->buttons |= b;
+        xi2ReportTabletEvent(*tabletData, xiEvent);
         break;
-    case XI_ButtonRelease: // stylus up
-        if (reinterpret_cast<xXIDeviceEvent *>(event)->detail == 1) {
-            tabletData->down = false;
-            xi2ReportTabletEvent(*tabletData, xiEvent);
-        } else
-            handled = false;
+    }
+    case XI_ButtonRelease: {
+        Qt::MouseButton b = xiToQtMouseButton(reinterpret_cast<xXIDeviceEvent *>(event)->detail);
+        tabletData->buttons ^= b;
+        xi2ReportTabletEvent(*tabletData, xiEvent);
         break;
+    }
     case XI_Motion:
-        // Report TabletMove only when the stylus is touching the tablet.
-        // No possibility to report proximity motion (no suitable Qt event exists yet).
-        if (tabletData->down)
+        // Report TabletMove only when the stylus is touching the tablet or any button is pressed.
+        // TODO: report proximity (hover) motion (no suitable Qt event exists yet).
+        if (tabletData->buttons != Qt::NoButton)
             xi2ReportTabletEvent(*tabletData, xiEvent);
         break;
     case XI_PropertyEvent: {
@@ -862,15 +873,16 @@ void QXcbConnection::xi2ReportTabletEvent(TabletData &tabletData, void *event)
     }
 
     if (Q_UNLIKELY(debug_xinput))
-        qDebug("XI2 event on tablet %d with tool %d type %d seq %d detail %d pos %6.1f, %6.1f root pos %6.1f, %6.1f pressure %4.2lf tilt %d, %d rotation %6.2lf",
-            ev->deviceid, tabletData.tool, ev->type, ev->sequenceNumber, ev->detail,
+        qDebug("XI2 event on tablet %d with tool %d type %d seq %d detail %d pos %6.1f, %6.1f root pos %6.1f, %6.1f buttons 0x%x pressure %4.2lf tilt %d, %d rotation %6.2lf",
+            ev->deviceid, tabletData.tool, ev->evtype, ev->sequenceNumber, ev->detail,
             fixed1616ToReal(ev->event_x), fixed1616ToReal(ev->event_y),
             fixed1616ToReal(ev->root_x), fixed1616ToReal(ev->root_y),
-            pressure, xTilt, yTilt, rotation);
+            (int)tabletData.buttons, pressure, xTilt, yTilt, rotation);
 
-    QWindowSystemInterface::handleTabletEvent(window, tabletData.down, local, global,
+    QWindowSystemInterface::handleTabletEvent(window, local, global,
                                               tabletData.tool, tabletData.pointerType,
-                                              pressure, xTilt, yTilt, tangentialPressure,
+                                              tabletData.buttons, pressure,
+                                              xTilt, yTilt, tangentialPressure,
                                               rotation, 0, tabletData.serialId);
 }
 #endif // QT_NO_TABLETEVENT