tdf#141578 Qt handle QtFrame screen changes

LO doesn't provide any way to notify screen changes / scaling
factors of a window and in fact doesn't really handle scaling
factors in VCL. The QWidget doesn't receive a resize event,
because it's size doesn't change, just the scaling factor.
So we trigger a faked resize on QWindow::screenChanged signal.

Change-Id: I6928c4c62d1c0995c70fea0088cff17849bcd1d4
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/132650
Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>
Tested-by: Jenkins
(cherry picked from commit 881cfbf77567194f5016a961d1c3db869734d68b)
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/132740
Reviewed-by: Jan-Marek Glogowski <glogow@fbihome.de>

4 files changed, 26 insertions, 8 deletions

diff --git a/vcl/inc/qt5/QtFrame.hxx b/vcl/inc/qt5/QtFrame.hxx
index 59ec093a2ed6..5ffaacf3ad94 100644
--- a/vcl/inc/qt5/QtFrame.hxx
+++ b/vcl/inc/qt5/QtFrame.hxx
@@ -25,6 +25,7 @@
 #include <vclpluginapi.h>
 
 #include "QtTools.hxx"
+#include "QtWidget.hxx"
 
 #include <headless/svpgdi.hxx>
 #include <vcl/svapp.hxx>
@@ -70,7 +71,7 @@ class VCLPLUG_QT_PUBLIC QtFrame : public QObject, public SalFrame
 
     friend class QtWidget;
 
-    QWidget* m_pQWidget;
+    QtWidget* m_pQWidget;
     QtMainWindow* m_pTopLevel;
 
     const bool m_bUseCairo;
@@ -134,6 +135,9 @@ class VCLPLUG_QT_PUBLIC QtFrame : public QObject, public SalFrame
 
     void fixICCCMwindowGroup();
 
+private Q_SLOTS:
+    void screenChanged(QScreen*);
+
 public:
     QtFrame(QtFrame* pParent, SalFrameStyleFlags nSalFrameStyle, bool bUseCairo);
     virtual ~QtFrame() override;
diff --git a/vcl/inc/qt5/QtWidget.hxx b/vcl/inc/qt5/QtWidget.hxx
index e2a22d3c9f18..575cef11014f 100644
--- a/vcl/inc/qt5/QtWidget.hxx
+++ b/vcl/inc/qt5/QtWidget.hxx
@@ -85,6 +85,7 @@ public:
 
     QtFrame& frame() const { return m_rFrame; }
     void endExtTextInput();
+    void fakeResize();
 
     static bool handleEvent(QtFrame&, const QWidget&, QEvent*);
     // key events might be propagated further down => call base on false
diff --git a/vcl/qt5/QtFrame.cxx b/vcl/qt5/QtFrame.cxx
index bcd95494dabd..c78417b3070a 100644
--- a/vcl/qt5/QtFrame.cxx
+++ b/vcl/qt5/QtFrame.cxx
@@ -30,7 +30,6 @@
 #include <QtSystem.hxx>
 #include <QtTools.hxx>
 #include <QtTransferable.hxx>
-#include <QtWidget.hxx>
 
 #include <QtCore/QMimeData>
 #include <QtCore/QPoint>
@@ -178,10 +177,12 @@ QtFrame::QtFrame(QtFrame* pParent, SalFrameStyleFlags nStyle, bool bUseCairo)
     else
         m_pQWidget = new QtWidget(*this, aWinFlags);
 
+    QWindow* pChildWindow = windowHandle();
+    connect(pChildWindow, &QWindow::screenChanged, this, &QtFrame::screenChanged);
+
     if (pParent && !(pParent->m_nStyle & SalFrameStyleFlags::PLUG))
     {
-        QWindow* pParentWindow = pParent->GetQWidget()->window()->windowHandle();
-        QWindow* pChildWindow = asChild()->window()->windowHandle();
+        QWindow* pParentWindow = pParent->windowHandle();
         if (pParentWindow && pChildWindow && (pParentWindow != pChildWindow))
             pChildWindow->setTransientParent(pParentWindow);
     }
@@ -193,6 +194,8 @@ QtFrame::QtFrame(QtFrame* pParent, SalFrameStyleFlags nStyle, bool bUseCairo)
     fixICCCMwindowGroup();
 }
 
+void QtFrame::screenChanged(QScreen*) { m_pQWidget->fakeResize(); }
+
 void QtFrame::FillSystemEnvData(SystemEnvData& rData, sal_IntPtr pWindow, QWidget* pWidget)
 {
     if (QGuiApplication::platformName() == "wayland")
@@ -343,7 +346,12 @@ bool QtFrame::PostEvent(std::unique_ptr<ImplSVEvent> pData)
     return true;
 }
 
-QWidget* QtFrame::asChild() const { return m_pTopLevel ? m_pTopLevel : m_pQWidget; }
+QWidget* QtFrame::asChild() const
+{
+    if (m_pTopLevel)
+        return m_pTopLevel;
+    return m_pQWidget;
+}
 
 qreal QtFrame::devicePixelRatioF() const { return asChild()->devicePixelRatioF(); }
 
@@ -864,9 +872,8 @@ void QtFrame::SetInputContext(SalInputContext* pContext)
 
 void QtFrame::EndExtTextInput(EndExtTextInputFlags /*nFlags*/)
 {
-    QtWidget* pQtWidget = static_cast<QtWidget*>(m_pQWidget);
-    if (pQtWidget)
-        pQtWidget->endExtTextInput();
+    if (m_pQWidget)
+        m_pQWidget->endExtTextInput();
 }
 
 OUString QtFrame::GetKeyName(sal_uInt16 nKeyCode)
diff --git a/vcl/qt5/QtWidget.cxx b/vcl/qt5/QtWidget.cxx
index ab8bf2dc0017..1fe2ce9a7159 100644
--- a/vcl/qt5/QtWidget.cxx
+++ b/vcl/qt5/QtWidget.cxx
@@ -135,6 +135,12 @@ void QtWidget::resizeEvent(QResizeEvent* pEvent)
     m_rFrame.CallCallback(SalEvent::Resize, nullptr);
 }
 
+void QtWidget::fakeResize()
+{
+    QResizeEvent aEvent(size(), QSize());
+    resizeEvent(&aEvent);
+}
+
 void QtWidget::fillSalAbstractMouseEvent(const QtFrame& rFrame, const QInputEvent* pQEvent,
                                          const QPoint& rPos, Qt::MouseButtons eButtons, int nWidth,
                                          SalAbstractMouseEvent& aSalEvent)