From 161c5693143783e0364d32c587497669747efc45 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Tor=20Arne=20Vestb=C3=B8?= <tor.arne.vestbo@qt.io>
Date: Thu, 6 Dec 2018 14:46:26 +0100
Subject: [PATCH] macOS: Reset font glyph caches when application theme changes

Our glyph caches on 10.14 are based on the application appearance, so when
the application goes from dark to light or light to dark, we need to reset
and re-populate the glyph-caches to account for the new appearance.

Change-Id: If019d8cfa33ffb2b14747444b2ff74b288992f55
Fixes: QTBUG-71018
Reviewed-by: Timur Pocheptsov <timur.pocheptsov@qt.io>
---
 src/gui/text/qfont_p.h                     | 2 +-
 src/plugins/platforms/cocoa/qcocoatheme.mm | 7 +++++++
 2 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/gui/text/qfont_p.h b/src/gui/text/qfont_p.h
index 350ba7ce3c..c5847f532b 100644
--- a/src/gui/text/qfont_p.h
+++ b/src/gui/text/qfont_p.h
@@ -210,7 +210,7 @@ private:
 };
 
 
-class Q_AUTOTEST_EXPORT QFontCache : public QObject
+class Q_GUI_EXPORT QFontCache : public QObject
 {
 public:
     // note: these static functions work on a per-thread basis
diff --git a/src/plugins/platforms/cocoa/qcocoatheme.mm b/src/plugins/platforms/cocoa/qcocoatheme.mm
index a2229159b5..240deeddbd 100644
--- a/src/plugins/platforms/cocoa/qcocoatheme.mm
+++ b/src/plugins/platforms/cocoa/qcocoatheme.mm
@@ -53,11 +53,13 @@
 #include "qcocoahelpers.h"
 
 #include <QtCore/qfileinfo.h>
+#include <QtGui/private/qfont_p.h>
 #include <QtGui/private/qguiapplication_p.h>
 #include <QtGui/private/qcoregraphics_p.h>
 #include <QtGui/qpainter.h>
 #include <QtGui/qtextformat.h>
 #include <QtFontDatabaseSupport/private/qcoretextfontdatabase_p.h>
+#include <QtFontDatabaseSupport/private/qfontengine_coretext_p.h>
 #include <QtThemeSupport/private/qabstractfileiconengine_p.h>
 #include <qpa/qplatformdialoghelper.h>
 #include <qpa/qplatformintegration.h>
@@ -162,6 +164,11 @@ void QCocoaTheme::handleSystemThemeChange()
     m_systemPalette = qt_mac_createSystemPalette();
     m_palettes = qt_mac_createRolePalettes();
 
+    if (QCoreTextFontEngine::fontSmoothing() == QCoreTextFontEngine::FontSmoothing::Grayscale) {
+        // Re-populate glyph caches based on the new appearance's assumed text fill color
+        QFontCache::instance()->clear();
+    }
+
     QWindowSystemInterface::handleThemeChange(nullptr);
 }