Patch for kf6 scaling

86abb6fd8a8f680f9fc5ff1db775845c9f4e254b.patch

@@ -0,0 +1,58 @@
+From 86abb6fd8a8f680f9fc5ff1db775845c9f4e254b Mon Sep 17 00:00:00 2001
+From: Michael Weghorn <m.weghorn@posteo.de>
+Date: Wed, 13 Mar 2024 12:27:12 +0100
+Subject: [PATCH] tdf#159915 qt: Force
+ Qt::HighDpiScaleFactorRoundingPolicy::Round
+
+For now, force `Qt::HighDpiScaleFactorRoundingPolicy::Round`
+for the HighDPI-scale factor rounding policy [1], which is the default
+for Qt 5, while Qt 6 defaults to `Qt::HighDpiScaleFactorRoundingPolicy::PassThrough`
+(see [2]), which resulted in broken rendering (e.g. "Help" -> "About"
+dialog not showing the whole content) when fractional display scaling like 150 %
+is configured in the KDE Plasma display settings (in contrast to manually setting the
+`QT_SCALE_FACTOR=1.5` env variable to apply scaling, which was working
+fine).
+
+Quoting from [3]:
+
+> The two principal options are whether fractional scale factors should be
+> rounded to an integer or not. Keeping the scale factor as-is will make
+> the user interface size match the OS setting exactly, but may cause
+> painting errors, for example with the Windows style.
+
+Manually setting the env variable `QT_SCALE_FACTOR_ROUNDING_POLICY="Round"`
+has the same effect (and can be used with LO versions not yet
+containing this fix).
+
+(There might be a way to adjust the way that scaling happens
+to make other policies work, but for now, just hard-code to
+the policy that is known to work.)
+
+[1] https://doc.qt.io/qt-6/qt.html#HighDpiScaleFactorRoundingPolicy-enum
+[2] https://doc.qt.io/qt-6/highdpi.html#environment-variable-reference
+[3] https://doc.qt.io/qt-6/qguiapplication.html#setHighDpiScaleFactorRoundingPolicy
+
+Change-Id: I8eb6911d4dd5faf00912b8f15a58e0bdace1995a
+Reviewed-on: https://gerrit.libreoffice.org/c/core/+/164768
+Tested-by: Jenkins
+Reviewed-by: Michael Weghorn <m.weghorn@posteo.de>
+---
+ vcl/qt5/QtInstance.cxx | 5 +++++
+ 1 file changed, 5 insertions(+)
+
+diff --git a/vcl/qt5/QtInstance.cxx b/vcl/qt5/QtInstance.cxx
+index 6b3bd0cc301ae..2801601115ecd 100644
+--- a/vcl/qt5/QtInstance.cxx
++++ b/vcl/qt5/QtInstance.cxx
+@@ -740,6 +740,11 @@ std::unique_ptr<QApplication> QtInstance::CreateQApplication(int& nArgc, char**
+     // for scaled icons in the native menus
+     QApplication::setAttribute(Qt::AA_UseHighDpiPixmaps);
+ #endif
++    // force Qt::HighDpiScaleFactorRoundingPolicy::Round, which is the Qt 5 default
++    // policy and prevents incorrect rendering with the Qt 6 default policy
++    // Qt::HighDpiScaleFactorRoundingPolicy::PassThrough (tdf#159915)
++    QGuiApplication::setHighDpiScaleFactorRoundingPolicy(
++        Qt::HighDpiScaleFactorRoundingPolicy::Round);
+ 
+     FreeableCStr session_manager;
+     if (getenv("SESSION_MANAGER") != nullptr)

libreoffice.spec

@@ -329,6 +329,8 @@ Patch11: lo-7.6-ppc64le-tests.patch
 # https://bugs.gentoo.org/917618
 # https://bugs.documentfoundation.org/show_bug.cgi?id=158108
 Patch12: libreoffice-7.5.8.2-icu-74-compatibility.patch
+# Patch for kf6 scaling.
+Patch13: 86abb6fd8a8f680f9fc5ff1db775845c9f4e254b.patch
 Patch500: 0001-disable-libe-book-support.patch
 # https://lists.freedesktop.org/archives/libreoffice/2023-September/090948.html
 Patch501: kahansum_test_fix_for_aarc64_s390x.patch