Merge remote-tracking branch 'origin/5.5' into dev

Change-Id: If5d2e621c2fa5476c3ab687a3f4620c54fc3b32e

3 files changed, 39 insertions, 8 deletions

diff --git a/src/plugins/platforms/xcb/gl_integrations/gl_integrations.pro b/src/plugins/platforms/xcb/gl_integrations/gl_integrations.pro
index 29fddeabd4..29b6d1d2f7 100644
--- a/src/plugins/platforms/xcb/gl_integrations/gl_integrations.pro
+++ b/src/plugins/platforms/xcb/gl_integrations/gl_integrations.pro
@@ -4,6 +4,6 @@ contains(QT_CONFIG, egl):contains(QT_CONFIG, egl_x11) {
     SUBDIRS += xcb_egl
 }
 
-contains(QT_CONFIG, xcb-xlib):!contains(QT_CONFIG, opengles2) {
+contains(QT_CONFIG, xcb-xlib): contains(QT_CONFIG, opengl): !contains(QT_CONFIG, opengles2) {
     SUBDIRS += xcb_glx
 }
diff --git a/src/plugins/platforms/xcb/qxcbconnection.cpp b/src/plugins/platforms/xcb/qxcbconnection.cpp
index 11ff313144..0ca141526e 100644
--- a/src/plugins/platforms/xcb/qxcbconnection.cpp
+++ b/src/plugins/platforms/xcb/qxcbconnection.cpp
@@ -231,9 +231,8 @@ void QXcbConnection::updateScreens(const xcb_randr_notify_event_t *event)
 
             QXcbIntegration::instance()->destroyScreen(screen);
 
-            // QTBUG-40174, QTBUG-42985: If there are no outputs, then there must be
-            // no QScreen instances; a Qt application can survive this situation, and
-            // start rendering again later when there is a screen again.
+            // QTBUG-40174, QTBUG-42985: If all screens are removed, wait
+            // and start rendering again later if a screen becomes available.
 
         } else if (!screen && output.connection == XCB_RANDR_CONNECTION_CONNECTED) {
             // New XRandR output is available and it's enabled
@@ -293,13 +292,15 @@ void QXcbConnection::initializeScreens()
 {
     xcb_screen_iterator_t it = xcb_setup_roots_iterator(m_setup);
     int xcbScreenNumber = 0;    // screen number in the xcb sense
-    QXcbScreen* primaryScreen = NULL;
+    QXcbScreen* primaryScreen = Q_NULLPTR;
+    xcb_screen_t *xcbScreen = Q_NULLPTR;
+    bool hasOutputs = false;
     while (it.rem) {
         // Each "screen" in xcb terminology is a virtual desktop,
         // potentially a collection of separate juxtaposed monitors.
         // But we want a separate QScreen for each output (e.g. DVI-I-1, VGA-1, etc.)
         // which will become virtual siblings.
-        xcb_screen_t *xcbScreen = it.data;
+        xcbScreen = it.data;
         QList<QPlatformScreen *> siblings;
         int outputCount = 0;
         int connectedOutputCount = 0;
@@ -356,6 +357,7 @@ void QXcbConnection::initializeScreens()
                         QXcbScreen *screen = createScreen(xcbScreenNumber, xcbScreen, outputs[i], output.data());
                         siblings << screen;
                         ++connectedOutputCount;
+                        hasOutputs = true;
                         m_screens << screen;
 
                         // There can be multiple outputs per screen, use either
@@ -381,6 +383,20 @@ void QXcbConnection::initializeScreens()
         ++xcbScreenNumber;
     } // for each xcb screen
 
+    // If there's no randr extension, or there was some error above, or we found a
+    // screen which doesn't have outputs for some other reason (e.g. on VNC or ssh -X),
+    // but the dimensions are known anyway, and we don't already have any lingering
+    // (possibly disconnected) screens, then showing windows should be possible,
+    // so create one screen. (QTBUG-31389)
+    if (xcbScreen && !hasOutputs && xcbScreen->width_in_pixels > 0 && xcbScreen->height_in_pixels > 0 && m_screens.isEmpty()) {
+        QXcbScreen *screen = createScreen(0, xcbScreen, 0, Q_NULLPTR);
+        screen->setVirtualSiblings(QList<QPlatformScreen *>() << screen);
+        m_screens << screen;
+        primaryScreen = screen;
+        primaryScreen->setPrimary(true);
+        qCDebug(lcQpaScreen) << "found a screen with zero outputs" << screen;
+    }
+
     // Ensure the primary screen is first in the list
     if (primaryScreen) {
         Q_ASSERT(!m_screens.isEmpty());
diff --git a/src/plugins/platforms/xcb/qxcbwindow.cpp b/src/plugins/platforms/xcb/qxcbwindow.cpp
index 0dde679a7a..eabebffdab 100644
--- a/src/plugins/platforms/xcb/qxcbwindow.cpp
+++ b/src/plugins/platforms/xcb/qxcbwindow.cpp
@@ -319,6 +319,12 @@ void QXcbWindow::create()
     // currently no way to implement it for frame-exclusive geometries.
     QRect rect = window()->geometry();
     QPlatformWindow::setGeometry(rect);
+    QXcbScreen *currentScreen = xcbScreen();
+    QPlatformScreen *newScreen = screenForGeometry(rect);
+
+    if (newScreen != currentScreen)
+        QWindowSystemInterface::handleWindowScreenChanged(window(), newScreen->screen());
+
     const int dpr = int(devicePixelRatio());
 
     QSize minimumSize = window()->minimumSize();
@@ -583,9 +589,18 @@ void QXcbWindow::setGeometry(const QRect &rect)
 
     propagateSizeHints();
 
-    const QRect xRect = mapToNative(rect, int(devicePixelRatio()));
+    QXcbScreen *currentScreen = xcbScreen();
+    QPlatformScreen *newScreen = screenForGeometry(rect);
+    if (!newScreen)
+        newScreen = currentScreen;
+
+    const QRect xRect = mapToNative(rect, int(newScreen->devicePixelRatio()));
     const QRect wmGeometry = windowToWmGeometry(xRect);
 
+
+    if (newScreen != currentScreen)
+        QWindowSystemInterface::handleWindowScreenChanged(window(), newScreen->screen());
+
     if (qt_window_private(window())->positionAutomatic) {
         const quint32 mask = XCB_CONFIG_WINDOW_WIDTH | XCB_CONFIG_WINDOW_HEIGHT;
         const qint32 values[] = {
@@ -1919,7 +1934,7 @@ void QXcbWindow::handleConfigureNotifyEvent(const xcb_configure_notify_event_t *
     if (newScreen != screen()) {
         if (newScreen)
             QWindowSystemInterface::handleWindowScreenChanged(window(), newScreen->screen());
-        int newDpr = devicePixelRatio();
+        int newDpr = newScreen->devicePixelRatio();
         if (newDpr != dpr) {
             QRect newRect = mapGeometryFromNative(nativeRect, newDpr);
             QPlatformWindow::setGeometry(newRect);