Move isDarkTheme() to QQuickStylePrivate

QQuickStyleAttached is being generalized to a recursive attached
object type that can be used for palettes too, which are planned
to be used for the upcoming image-based style.

Change-Id: I4c1d25624ee11bb0ec6cd5ee2656c36e622e2139
Reviewed-by: Mitch Curtis <mitch.curtis@qt.io>

1 files changed, 20 insertions, 0 deletions

diff --git a/src/quickcontrols2/qquickstyle.cpp b/src/quickcontrols2/qquickstyle.cpp
index d4e72efb..f154f0ce 100644
--- a/src/quickcontrols2/qquickstyle.cpp
+++ b/src/quickcontrols2/qquickstyle.cpp
@@ -43,7 +43,10 @@
 #include <QtCore/qsettings.h>
 #include <QtCore/qfileselector.h>
 #include <QtCore/qlibraryinfo.h>
+#include <QtGui/qcolor.h>
+#include <QtGui/qpalette.h>
 #include <QtGui/private/qguiapplication_p.h>
+#include <QtGui/qpa/qplatformtheme.h>
 #include <QtQml/private/qqmlmetatype_p.h>
 #include <QtQml/qqmlengine.h>
 #include <QtQml/qqmlfile.h>
@@ -329,6 +332,23 @@ QSharedPointer<QSettings> QQuickStylePrivate::settings(const QString &group)
     return QSharedPointer<QSettings>();
 }
 
+static bool qt_is_dark_system_theme()
+{
+    if (const QPlatformTheme *theme = QGuiApplicationPrivate::platformTheme()) {
+        if (const QPalette *systemPalette = theme->palette(QPlatformTheme::SystemPalette)) {
+            const QColor textColor = systemPalette->color(QPalette::WindowText);
+            return textColor.red() > 128 && textColor.blue() > 128 && textColor.green() > 128;
+        }
+    }
+    return false;
+}
+
+bool QQuickStylePrivate::isDarkSystemTheme()
+{
+    static bool dark = qt_is_dark_system_theme();
+    return dark;
+}
+
 /*!
     Returns the name of the application style.