add linux file

client/platforms/linux/linuxutils.cpp

@@ -0,0 +1,120 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "linuxutils.h"
+
+#include <QApplication>
+#include <QDBusConnection>
+#include <QDBusVariant>
+#include <QGuiApplication>
+#include <QPalette>
+#include <QSettings>
+#include <QStyleHints>
+
+namespace {
+
+bool paletteSuggestsDarkTheme()
+{
+    const QPalette palette = QGuiApplication::palette();
+    const int windowLightness = palette.color(QPalette::Window).lightness();
+    const int textLightness = palette.color(QPalette::WindowText).lightness();
+
+    if (textLightness - windowLightness > 50) {
+        return true;
+    }
+    if (windowLightness - textLightness > 50) {
+        return false;
+    }
+
+    return windowLightness < 128;
+}
+
+class LinuxThemeObserver final : public QObject {
+    Q_OBJECT
+
+public:
+    explicit LinuxThemeObserver(std::function<void()> callback, QObject *parent = nullptr)
+        : QObject(parent)
+        , m_callback(std::move(callback))
+    {
+        QDBusConnection bus = QDBusConnection::sessionBus();
+        if (!bus.isConnected()) {
+            return;
+        }
+
+        bus.connect(QStringLiteral("org.freedesktop.portal.Desktop"),
+                    QStringLiteral("/org/freedesktop/portal/desktop"),
+                    QStringLiteral("org.freedesktop.portal.Settings"),
+                    QStringLiteral("SettingChanged"),
+                    this,
+                    SLOT(onPortalSettingChanged(QString, QString, QDBusVariant)));
+    }
+
+private slots:
+    void onPortalSettingChanged(const QString &namespaceName, const QString &key, const QDBusVariant &value)
+    {
+        Q_UNUSED(value);
+
+        if (namespaceName == QStringLiteral("org.freedesktop.appearance")
+            && key == QStringLiteral("color-scheme") && m_callback) {
+            m_callback();
+        }
+    }
+
+private:
+    std::function<void()> m_callback;
+};
+
+LinuxThemeObserver *g_themeObserver = nullptr;
+
+} // namespace
+
+bool LinuxUtils::isDarkTheme()
+{
+    if (QStyleHints *styleHints = QGuiApplication::styleHints()) {
+        switch (styleHints->colorScheme()) {
+        case Qt::ColorScheme::Dark:
+            return true;
+        case Qt::ColorScheme::Light:
+            return false;
+        case Qt::ColorScheme::Unknown:
+        default:
+            break;
+        }
+    }
+
+    QSettings settings(QSettings::IniFormat, QSettings::UserScope, QStringLiteral("gtk-3.0"),
+                       QStringLiteral("settings"));
+    const QString themeName = settings.value(QStringLiteral("gtk-theme-name")).toString();
+    if (themeName.contains(QStringLiteral("dark"), Qt::CaseInsensitive)) {
+        return true;
+    }
+    if (themeName.contains(QStringLiteral("light"), Qt::CaseInsensitive)) {
+        return false;
+    }
+
+    QSettings kdeSettings(QSettings::IniFormat, QSettings::UserScope, QStringLiteral("kdeglobals"));
+    const QString colorScheme = kdeSettings.value(QStringLiteral("General/ColorScheme")).toString();
+    if (colorScheme.contains(QStringLiteral("dark"), Qt::CaseInsensitive)) {
+        return true;
+    }
+    if (colorScheme.contains(QStringLiteral("light"), Qt::CaseInsensitive)) {
+        return false;
+    }
+
+    return paletteSuggestsDarkTheme();
+}
+
+void LinuxUtils::installThemeChangeObserver(std::function<void()> callback)
+{
+    if (!callback) {
+        return;
+    }
+
+    if (!g_themeObserver) {
+        g_themeObserver = new LinuxThemeObserver(std::move(callback), qApp);
+    }
+}
+
+#include "linuxutils.moc"

client/platforms/linux/linuxutils.h

@@ -0,0 +1,19 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#ifndef LINUXUTILS_H
+#define LINUXUTILS_H
+
+#include <functional>
+
+class LinuxUtils final {
+ public:
+  static bool isDarkTheme();
+  static void installThemeChangeObserver(std::function<void()> callback);
+
+ private:
+  LinuxUtils() = default;
+};
+
+#endif  // LINUXUTILS_H