Windows QPA: Introduce command line options for DirectWrite

Add option "nodirectwrite" to turn off DirectWrite fonts
and "nocolorfonts" to turn off DirectWrite for colored fonts.

Task-number: QTBUG-55096
Task-number: QTBUG-55097
Change-Id: If12133fbd20dc7657b3616eff833a8e8c116e070
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>

3 files changed, 28 insertions, 12 deletions

diff --git a/src/plugins/platforms/windows/qwindowsfontdatabase.cpp b/src/plugins/platforms/windows/qwindowsfontdatabase.cpp
index 68a8fc5390..08769a3b39 100644
--- a/src/plugins/platforms/windows/qwindowsfontdatabase.cpp
+++ b/src/plugins/platforms/windows/qwindowsfontdatabase.cpp
@@ -40,6 +40,7 @@
 #include "qwindowsfontdatabase.h"
 #include "qwindowsfontdatabase_ft.h" // for default font
 #include "qwindowscontext.h"
+#include "qwindowsintegration.h"
 #include "qwindowsfontengine.h"
 #include "qwindowsfontenginedirectwrite.h"
 #include "qtwindows_additional.h"
@@ -112,6 +113,18 @@ static void createDirectWriteFactory(IDWriteFactory **factory)
 
     *factory = static_cast<IDWriteFactory *>(result);
 }
+
+static inline bool useDirectWrite(QFont::HintingPreference hintingPreference, bool isColorFont = false)
+{
+    const unsigned options = QWindowsIntegration::instance()->options();
+    if (Q_UNLIKELY(options & QWindowsIntegration::DontUseDirectWriteFonts))
+        return false;
+    if (isColorFont)
+        return (options & QWindowsIntegration::DontUseColorFonts) == 0;
+    return hintingPreference == QFont::PreferNoHinting
+        || hintingPreference == QFont::PreferVerticalHinting
+        || (QHighDpiScaling::isActive() && hintingPreference == QFont::PreferDefaultHinting);
+}
 #endif // !QT_NO_DIRECTWRITE
 
 // Helper classes for creating font engines directly from font data
@@ -1163,11 +1176,7 @@ QFontEngine *QWindowsFontDatabase::fontEngine(const QByteArray &fontData, qreal
     QFontEngine *fontEngine = 0;
 
 #if !defined(QT_NO_DIRECTWRITE)
-    bool useDirectWrite = (hintingPreference == QFont::PreferNoHinting)
-                       || (hintingPreference == QFont::PreferVerticalHinting)
-                       || (QHighDpiScaling::isActive() && hintingPreference == QFont::PreferDefaultHinting);
-
-    if (!useDirectWrite)
+    if (!useDirectWrite(hintingPreference))
 #endif
     {
         GUID guid;
@@ -1804,12 +1813,13 @@ QFontEngine *QWindowsFontDatabase::createEngine(const QFontDef &request,
                         isColorFont = true;
                 }
 #endif
-
-                bool useDirectWrite = (request.hintingPreference == QFont::PreferNoHinting)
-                                   || (request.hintingPreference == QFont::PreferVerticalHinting)
-                                   || (QHighDpiScaling::isActive() && request.hintingPreference == QFont::PreferDefaultHinting)
-                                   || isColorFont;
-                if (useDirectWrite) {
+                const QFont::HintingPreference hintingPreference =
+                    static_cast<QFont::HintingPreference>(request.hintingPreference);
+                const bool useDw = useDirectWrite(hintingPreference, isColorFont);
+                qCDebug(lcQpaFonts) << __FUNCTION__ << request.family << request.pointSize
+                    << "pt" << "hintingPreference=" << hintingPreference << "color=" << isColorFont
+                    << dpi << "dpi" << "useDirectWrite=" << useDw;
+                if (useDw) {
                     QWindowsFontEngineDirectWrite *fedw = new QWindowsFontEngineDirectWrite(directWriteFontFace,
                                                                                             request.pixelSize,
                                                                                             data);
diff --git a/src/plugins/platforms/windows/qwindowsintegration.cpp b/src/plugins/platforms/windows/qwindowsintegration.cpp
index f033e4235c..b6d2c16f89 100644
--- a/src/plugins/platforms/windows/qwindowsintegration.cpp
+++ b/src/plugins/platforms/windows/qwindowsintegration.cpp
@@ -199,6 +199,10 @@ static inline unsigned parseOptions(const QStringList &paramList,
             }
         } else if (param == QLatin1String("gl=gdi")) {
             options |= QWindowsIntegration::DisableArb;
+        } else if (param == QLatin1String("nodirectwrite")) {
+            options |= QWindowsIntegration::DontUseDirectWriteFonts;
+        } else if (param == QLatin1String("nocolorfonts")) {
+            options |= QWindowsIntegration::DontUseColorFonts;
         } else if (param == QLatin1String("nomousefromtouch")) {
             options |= QWindowsIntegration::DontPassOsMouseEventsSynthesizedFromTouch;
         } else if (parseIntOption(param, QLatin1String("verbose"), 0, INT_MAX, &QWindowsContext::verbose)
diff --git a/src/plugins/platforms/windows/qwindowsintegration.h b/src/plugins/platforms/windows/qwindowsintegration.h
index 9658ef711d..0c03274799 100644
--- a/src/plugins/platforms/windows/qwindowsintegration.h
+++ b/src/plugins/platforms/windows/qwindowsintegration.h
@@ -60,7 +60,9 @@ public:
         DisableArb = 0x4,
         NoNativeDialogs = 0x8,
         XpNativeDialogs = 0x10,
-        DontPassOsMouseEventsSynthesizedFromTouch = 0x20 // Do not pass OS-generated mouse events from touch.
+        DontPassOsMouseEventsSynthesizedFromTouch = 0x20, // Do not pass OS-generated mouse events from touch.
+        DontUseDirectWriteFonts = 0x40,
+        DontUseColorFonts = 0x80
     };
 
     explicit QWindowsIntegration(const QStringList &paramList);