1 files changed, 123 insertions, 0 deletions
diff --git a/src/plugins/platformthemes/gtk3/qgtk3portalinterface.cpp b/src/plugins/platformthemes/gtk3/qgtk3portalinterface.cpp
new file mode 100644
index 0000000000..1ffdda74fa
--- /dev/null
+++ b/src/plugins/platformthemes/gtk3/qgtk3portalinterface.cpp
@@ -0,0 +1,123 @@
+// Copyright (C) 2024 The Qt Company Ltd.
+// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR LGPL-3.0-only OR GPL-2.0-only OR GPL-3.0-only
+
+//
+//  W A R N I N G
+//  -------------
+//
+// This file is not part of the Qt API.  It exists purely as an
+// implementation detail.  This header file may change from version to
+// version without notice, or even be removed.
+//
+// We mean it.
+//
+
+#include "qgtk3portalinterface_p.h"
+#include "qgtk3storage_p.h"
+
+#include <QtDBus/QDBusArgument>
+#include <QtDBus/QDBusConnection>
+#include <QtDBus/QDBusMessage>
+#include <QtDBus/QDBusPendingCall>
+#include <QtDBus/QDBusPendingCallWatcher>
+#include <QtDBus/QDBusPendingReply>
+#include <QtDBus/QDBusVariant>
+#include <QtDBus/QtDBus>
+
+QT_BEGIN_NAMESPACE
+
+Q_LOGGING_CATEGORY(lcQGtk3PortalInterface, "qt.qpa.gtk");
+
+using namespace Qt::StringLiterals;
+
+static constexpr QLatin1StringView appearanceInterface("org.freedesktop.appearance");
+static constexpr QLatin1StringView colorSchemeKey("color-scheme");
+
+const QDBusArgument &operator>>(const QDBusArgument &argument, QMap<QString, QVariantMap> &map)
+{
+    argument.beginMap();
+    map.clear();
+
+    while (!argument.atEnd()) {
+        QString key;
+        QVariantMap value;
+        argument.beginMapEntry();
+        argument >> key >> value;
+        argument.endMapEntry();
+        map.insert(key, value);
+    }
+
+    argument.endMap();
+    return argument;
+}
+
+QGtk3PortalInterface::QGtk3PortalInterface(QGtk3Storage *s)
+    : m_storage(s) {
+    qRegisterMetaType<QDBusVariant>();
+    qDBusRegisterMetaType<QMap<QString, QVariantMap>>();
+
+    queryColorScheme();
+
+    if (!s) {
+        qCDebug(lcQGtk3PortalInterface) << "QGtk3PortalInterface instantiated without QGtk3Storage."
+                                        << "No reaction to runtime theme changes.";
+    }
+}
+
+Qt::ColorScheme QGtk3PortalInterface::colorScheme() const
+{
+   return m_colorScheme;
+}
+
+void QGtk3PortalInterface::queryColorScheme() {
+    QDBusConnection connection = QDBusConnection::sessionBus();
+    QDBusMessage message = QDBusMessage::createMethodCall(
+            "org.freedesktop.portal.Desktop"_L1,
+            "/org/freedesktop/portal/desktop"_L1,
+            "org.freedesktop.portal.Settings"_L1, "ReadAll"_L1);
+    message << QStringList{ appearanceInterface };
+
+    QDBusPendingCall pendingCall = connection.asyncCall(message);
+    QDBusPendingCallWatcher *watcher = new QDBusPendingCallWatcher(pendingCall, this);
+    QObject::connect(
+            watcher, &QDBusPendingCallWatcher::finished, this,
+            [this](QDBusPendingCallWatcher *watcher) {
+                QDBusPendingReply<QMap<QString, QVariantMap>> reply = *watcher;
+                if (reply.isValid()) {
+                    QMap<QString, QVariantMap> settings = reply.value();
+                    if (!settings.isEmpty()) {
+                        settingChanged(appearanceInterface, colorSchemeKey,
+                                       QDBusVariant(settings.value(appearanceInterface).value(colorSchemeKey)));
+                    }
+                } else {
+                    qCDebug(lcQGtk3PortalInterface) << "Failed to query org.freedesktop.portal.Settings: "
+                                                    << reply.error().message();
+                }
+                watcher->deleteLater();
+            });
+
+    QDBusConnection::sessionBus().connect(
+            "org.freedesktop.portal.Desktop"_L1, "/org/freedesktop/portal/desktop"_L1,
+            "org.freedesktop.portal.Settings"_L1, "SettingChanged"_L1, this,
+            SLOT(settingChanged(QString, QString, QDBusVariant)));
+}
+
+void QGtk3PortalInterface::settingChanged(const QString &group, const QString &key,
+                                          const QDBusVariant &value)
+{
+    if (group == appearanceInterface && key == colorSchemeKey) {
+        const uint colorScheme = value.variant().toUInt();
+        // From org.freedesktop.portal.Settings.xml
+        // "1" - Prefer dark appearance
+        Qt::ColorScheme newColorScheme = colorScheme == 1 ? Qt::ColorScheme::Dark : Qt::ColorScheme::Light;
+        if (m_colorScheme != newColorScheme) {
+            m_colorScheme = newColorScheme;
+            if (m_storage)
+                m_storage->handleThemeChange();
+        }
+    }
+}
+
+QT_END_NAMESPACE
+
+#include "moc_qgtk3portalinterface_p.cpp"