xcb: Fix available geometry after rotation

QXcbVirtualDesktop::m_workArea is not updated after screen rotation
if _NET_WORKAREA is not updated, e.g. when a window manager is not
running.

Use width of -1 for m_workArea to indicate that _NET_WORKAREA is
not set and thus there is no need to find its intersection with
screens' geometries.

Pick-to: 5.15 6.0
Change-Id: Ic1f3ec23576ed8407a76cc2b9f84a145c67b1d4b
Reviewed-by: Liang Qi <liang.qi@qt.io>
(cherry picked from commit df28d75721f7e57f4421ed8c4b8131da742f3967)

2 files changed, 11 insertions, 6 deletions

diff --git a/src/plugins/platforms/xcb/qxcbscreen.cpp b/src/plugins/platforms/xcb/qxcbscreen.cpp
index 3d6b68ad6e..bf77e8f663 100644
--- a/src/plugins/platforms/xcb/qxcbscreen.cpp
+++ b/src/plugins/platforms/xcb/qxcbscreen.cpp
@@ -301,7 +301,7 @@ QRect QXcbVirtualDesktop::getWorkArea() const
         uint32_t *geom = (uint32_t*)xcb_get_property_value(workArea.get());
         r = QRect(geom[0], geom[1], geom[2], geom[3]);
     } else {
-        r = QRect(QPoint(), size());
+        r.setWidth(-1);
     }
     return r;
 }
@@ -316,6 +316,11 @@ void QXcbVirtualDesktop::updateWorkArea()
     }
 }
 
+QRect QXcbVirtualDesktop::availableGeometry(const QRect &screenGeometry) const
+{
+    return m_workArea.width() >= 0 ? screenGeometry & m_workArea : screenGeometry;
+}
+
 static inline QSizeF sizeInMillimeters(const QSize &size, const QDpi &dpi)
 {
     return QSizeF(Q_MM_PER_INCH * size.width() / dpi.first,
@@ -533,7 +538,7 @@ QXcbScreen::QXcbScreen(QXcbConnection *connection, QXcbVirtualDesktop *virtualDe
     } else if (xineramaScreenInfo) {
         m_geometry = QRect(xineramaScreenInfo->x_org, xineramaScreenInfo->y_org,
                            xineramaScreenInfo->width, xineramaScreenInfo->height);
-        m_availableGeometry = m_geometry & m_virtualDesktop->workArea();
+        m_availableGeometry = m_virtualDesktop->availableGeometry(m_geometry);
         m_sizeMillimeters = sizeInMillimeters(m_geometry.size(), m_virtualDesktop->dpi());
         if (xineramaScreenIdx > -1)
             m_outputName += QLatin1Char('-') + QString::number(xineramaScreenIdx);
@@ -543,7 +548,7 @@ QXcbScreen::QXcbScreen(QXcbConnection *connection, QXcbVirtualDesktop *virtualDe
         m_geometry = QRect(QPoint(), virtualDesktop->size());
 
     if (m_availableGeometry.isEmpty())
-        m_availableGeometry = m_geometry & m_virtualDesktop->workArea();
+        m_availableGeometry = m_virtualDesktop->availableGeometry(m_geometry);
 
     if (m_sizeMillimeters.isEmpty())
         m_sizeMillimeters = virtualDesktop->physicalSize();
@@ -789,7 +794,7 @@ void QXcbScreen::updateGeometry(const QRect &geometry, uint8_t rotation)
         m_sizeMillimeters = sizeInMillimeters(geometry.size(), m_virtualDesktop->dpi());
 
     m_geometry = geometry;
-    m_availableGeometry = geometry & m_virtualDesktop->workArea();
+    m_availableGeometry = m_virtualDesktop->availableGeometry(m_geometry);
     QWindowSystemInterface::handleScreenGeometryChange(QPlatformScreen::screen(), m_geometry, m_availableGeometry);
     if (m_orientation != oldOrientation)
         QWindowSystemInterface::handleScreenOrientationChange(QPlatformScreen::screen(), m_orientation);
@@ -797,7 +802,7 @@ void QXcbScreen::updateGeometry(const QRect &geometry, uint8_t rotation)
 
 void QXcbScreen::updateAvailableGeometry()
 {
-    QRect availableGeometry = m_geometry & m_virtualDesktop->workArea();
+    QRect availableGeometry = m_virtualDesktop->availableGeometry(m_geometry);
     if (m_availableGeometry != availableGeometry) {
         m_availableGeometry = availableGeometry;
         QWindowSystemInterface::handleScreenGeometryChange(QPlatformScreen::screen(), m_geometry, m_availableGeometry);
diff --git a/src/plugins/platforms/xcb/qxcbscreen.h b/src/plugins/platforms/xcb/qxcbscreen.h
index a074afb96e..2935cb72f9 100644
--- a/src/plugins/platforms/xcb/qxcbscreen.h
+++ b/src/plugins/platforms/xcb/qxcbscreen.h
@@ -88,8 +88,8 @@ public:
 
     bool compositingActive() const;
 
-    QRect workArea() const { return m_workArea; }
     void updateWorkArea();
+    QRect availableGeometry(const QRect &screenGeometry) const;
 
     void handleXFixesSelectionNotify(xcb_xfixes_selection_notify_event_t *notify_event);
     void subscribeToXFixesSelectionNotify();