minimal QPA: Make font DB creation more flexible

Prioritize CoreText over Fontconfig since the former is the
native one on macOS, and any other native font DB on its
respective platform. We introduce a new 'fontconfig' option
to allow using Fontconfig instead. This works similarly to
'freetype' overriding the default font engine on Windows. A
propos of which, 'freetype' now does the same on macOS.

Change-Id: Ic8168820d1d01fddc2f26e046abb65b8ab765f89
Reviewed-by: Jake Petroules <jake.petroules@qt.io>

3 files changed, 30 insertions, 7 deletions

diff --git a/src/plugins/platforms/minimal/minimal.pro b/src/plugins/platforms/minimal/minimal.pro
index 8cfb68824e..a1a2da547b 100644
--- a/src/plugins/platforms/minimal/minimal.pro
+++ b/src/plugins/platforms/minimal/minimal.pro
@@ -14,6 +14,8 @@ HEADERS =   qminimalintegration.h \
 
 OTHER_FILES += minimal.json
 
+qtConfig(freetype): QMAKE_USE_PRIVATE += freetype
+
 PLUGIN_TYPE = platforms
 PLUGIN_CLASS_NAME = QMinimalIntegrationPlugin
 !equals(TARGET, $$QT_DEFAULT_QPA_PLUGIN): PLUGIN_EXTENDS = -
diff --git a/src/plugins/platforms/minimal/qminimalintegration.cpp b/src/plugins/platforms/minimal/qminimalintegration.cpp
index 9fc7671feb..0c04608fca 100644
--- a/src/plugins/platforms/minimal/qminimalintegration.cpp
+++ b/src/plugins/platforms/minimal/qminimalintegration.cpp
@@ -54,11 +54,17 @@
 #  endif
 #elif defined(Q_OS_DARWIN)
 #  include <QtFontDatabaseSupport/private/qcoretextfontdatabase_p.h>
-#elif QT_CONFIG(fontconfig)
+#endif
+
+#if QT_CONFIG(fontconfig)
 #  include <QtFontDatabaseSupport/private/qgenericunixfontdatabase_p.h>
 #  include <qpa/qplatformfontdatabase.h>
 #endif
 
+#if QT_CONFIG(freetype)
+#include <QtFontDatabaseSupport/private/qfontengine_ft_p.h>
+#endif
+
 #if !defined(Q_OS_WIN)
 #include <QtEventDispatcherSupport/private/qgenericunixeventdispatcher_p.h>
 #elif defined(Q_OS_WINRT)
@@ -81,6 +87,8 @@ static inline unsigned parseOptions(const QStringList &paramList)
             options |= QMinimalIntegration::EnableFonts;
         else if (param == QLatin1String("freetype"))
             options |= QMinimalIntegration::FreeTypeFontDatabase;
+        else if (param == QLatin1String("fontconfig"))
+            options |= QMinimalIntegration::FontconfigDatabase;
     }
     return options;
 }
@@ -129,9 +137,7 @@ public:
 QPlatformFontDatabase *QMinimalIntegration::fontDatabase() const
 {
     if (!m_fontDatabase && (m_options & EnableFonts)) {
-#if QT_CONFIG(fontconfig)
-        m_fontDatabase = new QGenericUnixFontDatabase;
-#elif defined(Q_OS_WINRT)
+#if defined(Q_OS_WINRT)
         m_fontDatabase = new QWinRTFontDatabase;
 #elif defined(Q_OS_WIN)
         if (m_options & FreeTypeFontDatabase) {
@@ -142,10 +148,24 @@ QPlatformFontDatabase *QMinimalIntegration::fontDatabase() const
             m_fontDatabase = new QWindowsFontDatabase;
         }
 #elif defined(Q_OS_DARWIN)
-        m_fontDatabase = new QCoreTextFontDatabaseEngineFactory<QCoreTextFontEngine>;
+        if (!(m_options & FontconfigDatabase)) {
+            if (m_options & FreeTypeFontDatabase) {
+#  if QT_CONFIG(freetype)
+                m_fontDatabase = new QCoreTextFontDatabaseEngineFactory<QFontEngineFT>;
+#  endif // freetype
+            } else {
+                m_fontDatabase = new QCoreTextFontDatabaseEngineFactory<QCoreTextFontEngine>;
+            }
+        }
+#endif
+
+        if (!m_fontDatabase) {
+#if QT_CONFIG(fontconfig)
+            m_fontDatabase = new QGenericUnixFontDatabase;
 #else
-        m_fontDatabase = QPlatformIntegration::fontDatabase();
+            m_fontDatabase = QPlatformIntegration::fontDatabase();
 #endif
+        }
     }
     if (!m_fontDatabase)
         m_fontDatabase = new DummyFontDatabase;
diff --git a/src/plugins/platforms/minimal/qminimalintegration.h b/src/plugins/platforms/minimal/qminimalintegration.h
index bc7b23c83c..ad1bec2112 100644
--- a/src/plugins/platforms/minimal/qminimalintegration.h
+++ b/src/plugins/platforms/minimal/qminimalintegration.h
@@ -68,7 +68,8 @@ public:
     enum Options { // Options to be passed on command line or determined from environment
         DebugBackingStore = 0x1,
         EnableFonts = 0x2,
-        FreeTypeFontDatabase = 0x4
+        FreeTypeFontDatabase = 0x4,
+        FontconfigDatabase = 0x8
     };
 
     explicit QMinimalIntegration(const QStringList &parameters);