1 files changed, 39 insertions, 27 deletions

diff --git a/src/plugins/platforms/cocoa/qcocoascreen.mm b/src/plugins/platforms/cocoa/qcocoascreen.mm
index eba12e98f2..203df61d82 100644
--- a/src/plugins/platforms/cocoa/qcocoascreen.mm
+++ b/src/plugins/platforms/cocoa/qcocoascreen.mm
@@ -1,12 +1,11 @@
 /****************************************************************************
 **
-** Copyright (C) 2021 The Qt Company Ltd.
+** Copyright (C) 2017 The Qt Company Ltd.
 ** Contact: https://www.qt.io/licensing/
 **
 ** This file is part of the plugins of the Qt Toolkit.
 **
-** $QT_BEGIN_LICENSE:COMM$
-**
+** $QT_BEGIN_LICENSE:LGPL$
 ** Commercial License Usage
 ** Licensees holding valid commercial Qt licenses may use this file in
 ** accordance with the commercial license agreement provided with the
@@ -15,25 +14,26 @@
 ** and conditions see https://www.qt.io/terms-conditions. For further
 ** information use the contact form at https://www.qt.io/contact-us.
 **
-** $QT_END_LICENSE$
-**
-**
-**
-**
-**
-**
-**
-**
-**
-**
-**
-**
-**
-**
-**
-**
+** GNU Lesser General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU Lesser
+** General Public License version 3 as published by the Free Software
+** Foundation and appearing in the file LICENSE.LGPL3 included in the
+** packaging of this file. Please review the following information to
+** ensure the GNU Lesser General Public License version 3 requirements
+** will be met: https://www.gnu.org/licenses/lgpl-3.0.html.
 **
+** GNU General Public License Usage
+** Alternatively, this file may be used under the terms of the GNU
+** General Public License version 2.0 or (at your option) the GNU General
+** Public license version 3 or any later version approved by the KDE Free
+** Qt Foundation. The licenses are as published by the Free Software
+** Foundation and appearing in the file LICENSE.GPL2 and LICENSE.GPL3
+** included in the packaging of this file. Please review the following
+** information to ensure the GNU General Public License requirements will
+** be met: https://www.gnu.org/licenses/gpl-2.0.html and
+** https://www.gnu.org/licenses/gpl-3.0.html.
 **
+** $QT_END_LICENSE$
 **
 ****************************************************************************/
 
@@ -106,6 +106,18 @@ void QCocoaScreen::initializeScreens()
 */
 void QCocoaScreen::updateScreens()
 {
+    // Adding, updating, or removing a screen below might trigger
+    // Qt or the application to move a window to a different screen,
+    // recursing back here via QCocoaWindow::windowDidChangeScreen.
+    // The update code is not re-entrant, so bail out if we end up
+    // in this situation. The screens will stabilize eventually.
+    static bool updatingScreens = false;
+    if (updatingScreens) {
+        qCInfo(lcQpaScreen) << "Skipping screen update, already updating";
+        return;
+    }
+    QBoolBlocker recursionGuard(updatingScreens);
+
     uint32_t displayCount = 0;
     if (CGGetOnlineDisplayList(0, nullptr, &displayCount) != kCGErrorSuccess)
         qFatal("Failed to get number of online displays");
@@ -267,7 +279,6 @@ void QCocoaScreen::update(CGDirectDisplayID displayId)
 
     const QRect previousGeometry = m_geometry;
     const QRect previousAvailableGeometry = m_availableGeometry;
-    const QDpi previousLogicalDpi = m_logicalDpi;
     const qreal previousRefreshRate = m_refreshRate;
 
     // The reference screen for the geometry is always the primary screen
@@ -282,8 +293,6 @@ void QCocoaScreen::update(CGDirectDisplayID displayId)
 
     CGSize size = CGDisplayScreenSize(m_displayId);
     m_physicalSize = QSizeF(size.width, size.height);
-    m_logicalDpi.first = 72;
-    m_logicalDpi.second = 72;
 
     QCFType<CGDisplayModeRef> displayMode = CGDisplayCopyDisplayMode(m_displayId);
     float refresh = CGDisplayModeGetRefreshRate(displayMode);
@@ -295,8 +304,6 @@ void QCocoaScreen::update(CGDirectDisplayID displayId)
 
     if (didChangeGeometry)
         QWindowSystemInterface::handleScreenGeometryChange(screen(), geometry(), availableGeometry());
-    if (m_logicalDpi != previousLogicalDpi)
-        QWindowSystemInterface::handleScreenLogicalDotsPerInchChange(screen(), m_logicalDpi.first, m_logicalDpi.second);
     if (m_refreshRate != previousRefreshRate)
         QWindowSystemInterface::handleScreenRefreshRateChange(screen(), m_refreshRate);
 }
@@ -309,6 +316,11 @@ void QCocoaScreen::requestUpdate()
 {
     Q_ASSERT(m_displayId);
 
+    if (!isOnline()) {
+        qCDebug(lcQpaScreenUpdates) << this << "is not online. Ignoring update request";
+        return;
+    }
+
     if (!m_displayLink) {
         CVDisplayLinkCreateWithCGDisplay(m_displayId, &m_displayLink);
         CVDisplayLinkSetOutputCallback(m_displayLink, [](CVDisplayLinkRef, const CVTimeStamp*,
@@ -625,8 +637,8 @@ bool QCocoaScreen::isOnline() const
     // returning -1 to signal that the displayId is invalid. Some functions
     // will also assert or even crash in this case, so it's important that
     // we double check if a display is online before calling other functions.
-    auto isOnline = CGDisplayIsOnline(m_displayId);
-    static const uint32_t kCGDisplayIsDisconnected = int32_t(-1);
+    int isOnline = CGDisplayIsOnline(m_displayId);
+    static const int kCGDisplayIsDisconnected = 0xffffffff;
     return isOnline != kCGDisplayIsDisconnected && isOnline;
 }