[Linux] read settings from XDG desktop portal if available

ci/licenses_golden/licenses_flutter

@@ -2151,6 +2151,9 @@ FILE: ../../../flutter/shell/platform/linux/fl_settings.h
 FILE: ../../../flutter/shell/platform/linux/fl_settings_plugin.cc
 FILE: ../../../flutter/shell/platform/linux/fl_settings_plugin.h
 FILE: ../../../flutter/shell/platform/linux/fl_settings_plugin_test.cc
+FILE: ../../../flutter/shell/platform/linux/fl_settings_portal.cc
+FILE: ../../../flutter/shell/platform/linux/fl_settings_portal.h
+FILE: ../../../flutter/shell/platform/linux/fl_settings_portal_test.cc
 FILE: ../../../flutter/shell/platform/linux/fl_standard_message_codec.cc
 FILE: ../../../flutter/shell/platform/linux/fl_standard_message_codec_private.h
 FILE: ../../../flutter/shell/platform/linux/fl_standard_message_codec_test.cc

shell/platform/linux/BUILD.gn

@@ -131,6 +131,7 @@ source_set("flutter_linux_sources") {
     "fl_renderer_headless.cc",
     "fl_settings.cc",
     "fl_settings_plugin.cc",
+    "fl_settings_portal.cc",
     "fl_standard_message_codec.cc",
     "fl_standard_method_codec.cc",
     "fl_string_codec.cc",
@@ -208,6 +209,7 @@ executable("flutter_linux_unittests") {
     "fl_pixel_buffer_texture_test.cc",
     "fl_plugin_registrar_test.cc",
     "fl_settings_plugin_test.cc",
+    "fl_settings_portal_test.cc",
     "fl_standard_message_codec_test.cc",
     "fl_standard_method_codec_test.cc",
     "fl_string_codec_test.cc",

shell/platform/linux/fl_settings.cc

@@ -4,6 +4,7 @@
 
 #include "flutter/shell/platform/linux/fl_settings.h"
 #include "flutter/shell/platform/linux/fl_gnome_settings.h"
+#include "flutter/shell/platform/linux/fl_settings_portal.h"
 
 G_DEFINE_INTERFACE(FlSettings, fl_settings, G_TYPE_OBJECT)
 
@@ -44,6 +45,13 @@ void fl_settings_emit_changed(FlSettings* self) {
 }
 
 FlSettings* fl_settings_new() {
-  // TODO(jpnurmi): add support for other desktop environments
-  return FL_SETTINGS(fl_gnome_settings_new());
+  g_autoptr(FlSettingsPortal) portal = fl_settings_portal_new();
+
+  g_autoptr(GError) error = nullptr;
+  if (!fl_settings_portal_start(portal, &error)) {
+    g_debug("XDG desktop portal settings unavailable: %s", error->message);
+    return fl_gnome_settings_new();
+  }
+
+  return FL_SETTINGS(g_object_ref(portal));
 }

shell/platform/linux/fl_settings_portal.cc

@@ -0,0 +1,262 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "flutter/shell/platform/linux/fl_settings_portal.h"
+
+#include <gio/gio.h>
+#include <glib.h>
+
+static constexpr char kPortalName[] = "org.freedesktop.portal.Desktop";
+static constexpr char kPortalPath[] = "/org/freedesktop/portal/desktop";
+static constexpr char pPortalSettings[] = "org.freedesktop.portal.Settings";
+
+struct FlSetting {
+  const gchar* ns;
+  const gchar* key;
+  const GVariantType* type;
+};
+
+static constexpr char kXdgAppearance[] = "org.freedesktop.appearance";
+static const FlSetting kColorScheme = {
+    kXdgAppearance,
+    "color-scheme",
+    G_VARIANT_TYPE_UINT32,
+};
+
+static constexpr char kGnomeDesktopInterface[] = "org.gnome.desktop.interface";
+static const FlSetting kClockFormat = {
+    kGnomeDesktopInterface,
+    "clock-format",
+    G_VARIANT_TYPE_STRING,
+};
+static const FlSetting kGtkTheme = {
+    kGnomeDesktopInterface,
+    "gtk-theme",
+    G_VARIANT_TYPE_STRING,
+};
+static const FlSetting kTextScalingFactor = {
+    kGnomeDesktopInterface,
+    "text-scaling-factor",
+    G_VARIANT_TYPE_DOUBLE,
+};
+
+static const FlSetting all_settings[] = {
+    kClockFormat,
+    kColorScheme,
+    kGtkTheme,
+    kTextScalingFactor,
+};
+
+static constexpr char kClockFormat12Hour[] = "12h";
+static constexpr char kGtkThemeDarkSuffix[] = "-dark";
+
+typedef enum { DEFAULT, PREFER_DARK, PREFER_LIGHT } ColorScheme;
+
+struct _FlSettingsPortal {
+  GObject parent_instance;
+
+  GDBusProxy* dbus_proxy;
+  GVariantDict* values;
+};
+
+static void fl_settings_portal_iface_init(FlSettingsInterface* iface);
+
+G_DEFINE_TYPE_WITH_CODE(FlSettingsPortal,
+                        fl_settings_portal,
+                        G_TYPE_OBJECT,
+                        G_IMPLEMENT_INTERFACE(fl_settings_get_type(),
+                                              fl_settings_portal_iface_init))
+
+static gchar* format_key(const FlSetting* setting) {
+  return g_strconcat(setting->ns, "::", setting->key, nullptr);
+}
+
+static gboolean get_value(FlSettingsPortal* portal,
+                          const FlSetting* setting,
+                          GVariant** value) {
+  g_autofree const gchar* key = format_key(setting);
+  *value = g_variant_dict_lookup_value(portal->values, key, setting->type);
+  return *value != nullptr;
+}
+
+static void set_value(FlSettingsPortal* portal,
+                      const FlSetting* setting,
+                      GVariant* value) {
+  g_autofree const gchar* key = format_key(setting);
+
+  // ignore redundant changes from multiple XDG desktop portal backends
+  g_autoptr(GVariant) old_value =
+      g_variant_dict_lookup_value(portal->values, key, nullptr);
+  if (old_value != nullptr && value != nullptr &&
+      g_variant_equal(old_value, value)) {
+    return;
+  }
+
+  g_variant_dict_insert_value(portal->values, key, value);
+  fl_settings_emit_changed(FL_SETTINGS(portal));
+}
+
+// Based on
+// https://gitlab.gnome.org/GNOME/Initiatives/-/wikis/Dark-Style-Preference#other
+static gboolean settings_portal_read(GDBusProxy* proxy,
+                                     const gchar* ns,
+                                     const gchar* key,
+                                     GVariant** out) {
+  g_autoptr(GError) error = nullptr;
+  g_autoptr(GVariant) value =
+      g_dbus_proxy_call_sync(proxy, "Read", g_variant_new("(ss)", ns, key),
+                             G_DBUS_CALL_FLAGS_NONE, G_MAXINT, nullptr, &error);
+
+  if (error) {
+    if (error->domain == G_DBUS_ERROR &&
+        error->code == G_DBUS_ERROR_SERVICE_UNKNOWN) {
+      g_debug("XDG desktop portal unavailable: %s", error->message);
+      return false;
+    }
+
+    if (error->domain == G_DBUS_ERROR &&
+        error->code == G_DBUS_ERROR_UNKNOWN_METHOD) {
+      g_debug("XDG desktop portal settings unavailable: %s", error->message);
+      return false;
+    }
+
+    g_critical("Failed to read XDG desktop portal settings: %s",
+               error->message);
+    return false;
+  }
+
+  g_autoptr(GVariant) child = nullptr;
+  g_variant_get(value, "(v)", &child);
+  g_variant_get(child, "v", out);
+
+  return true;
+}
+
+static void settings_portal_changed_cb(GDBusProxy* proxy,
+                                       const char* sender_name,
+                                       const char* signal_name,
+                                       GVariant* parameters,
+                                       gpointer user_data) {
+  FlSettingsPortal* portal = FL_SETTINGS_PORTAL(user_data);
+  if (g_strcmp0(signal_name, "SettingChanged")) {
+    return;
+  }
+
+  FlSetting setting;
+  g_autoptr(GVariant) value = nullptr;
+  g_variant_get(parameters, "(&s&sv)", &setting.ns, &setting.key, &value);
+  set_value(portal, &setting, value);
+}
+
+static FlClockFormat fl_settings_portal_get_clock_format(FlSettings* settings) {
+  FlSettingsPortal* self = FL_SETTINGS_PORTAL(settings);
+
+  FlClockFormat clock_format = FL_CLOCK_FORMAT_24H;
+
+  g_autoptr(GVariant) value = nullptr;
+  if (get_value(self, &kClockFormat, &value)) {
+    const gchar* clock_format_str = g_variant_get_string(value, nullptr);
+    if (g_strcmp0(clock_format_str, kClockFormat12Hour) == 0) {
+      clock_format = FL_CLOCK_FORMAT_12H;
+    }
+  }
+
+  return clock_format;
+}
+
+static FlColorScheme fl_settings_portal_get_color_scheme(FlSettings* settings) {
+  FlSettingsPortal* self = FL_SETTINGS_PORTAL(settings);
+
+  FlColorScheme color_scheme = FL_COLOR_SCHEME_LIGHT;
+
+  g_autoptr(GVariant) value = nullptr;
+  if (get_value(self, &kColorScheme, &value)) {
+    if (g_variant_get_uint32(value) == PREFER_DARK) {
+      color_scheme = FL_COLOR_SCHEME_DARK;
+    }
+  } else if (get_value(self, &kGtkTheme, &value)) {
+    const gchar* gtk_theme_str = g_variant_get_string(value, nullptr);
+    if (g_str_has_suffix(gtk_theme_str, kGtkThemeDarkSuffix)) {
+      color_scheme = FL_COLOR_SCHEME_DARK;
+    }
+  }
+
+  return color_scheme;
+}
+
+static gdouble fl_settings_portal_get_text_scaling_factor(
+    FlSettings* settings) {
+  FlSettingsPortal* self = FL_SETTINGS_PORTAL(settings);
+
+  gdouble scaling_factor = 1.0;
+
+  g_autoptr(GVariant) value = nullptr;
+  if (get_value(self, &kTextScalingFactor, &value)) {
+    scaling_factor = g_variant_get_double(value);
+  }
+
+  return scaling_factor;
+}
+
+static void fl_settings_portal_dispose(GObject* object) {
+  FlSettingsPortal* self = FL_SETTINGS_PORTAL(object);
+
+  g_clear_object(&self->dbus_proxy);
+  g_clear_pointer(&self->values, g_variant_dict_unref);
+
+  G_OBJECT_CLASS(fl_settings_portal_parent_class)->dispose(object);
+}
+
+static void fl_settings_portal_class_init(FlSettingsPortalClass* klass) {
+  GObjectClass* object_class = G_OBJECT_CLASS(klass);
+  object_class->dispose = fl_settings_portal_dispose;
+}
+
+static void fl_settings_portal_iface_init(FlSettingsInterface* iface) {
+  iface->get_clock_format = fl_settings_portal_get_clock_format;
+  iface->get_color_scheme = fl_settings_portal_get_color_scheme;
+  iface->get_text_scaling_factor = fl_settings_portal_get_text_scaling_factor;
+}
+
+static void fl_settings_portal_init(FlSettingsPortal* self) {}
+
+FlSettingsPortal* fl_settings_portal_new() {
+  g_autoptr(GVariantDict) values = g_variant_dict_new(nullptr);
+  return fl_settings_portal_new_with_values(values);
+}
+
+FlSettingsPortal* fl_settings_portal_new_with_values(GVariantDict* values) {
+  g_return_val_if_fail(values != nullptr, nullptr);
+  FlSettingsPortal* portal =
+      FL_SETTINGS_PORTAL(g_object_new(fl_settings_portal_get_type(), nullptr));
+  portal->values = g_variant_dict_ref(values);
+  return portal;
+}
+
+gboolean fl_settings_portal_start(FlSettingsPortal* self, GError** error) {
+  g_return_val_if_fail(FL_IS_SETTINGS_PORTAL(self), false);
+  g_return_val_if_fail(self->dbus_proxy == nullptr, false);
+
+  self->dbus_proxy = g_dbus_proxy_new_for_bus_sync(
+      G_BUS_TYPE_SESSION, G_DBUS_PROXY_FLAGS_NONE, nullptr, kPortalName,
+      kPortalPath, pPortalSettings, nullptr, error);
+
+  if (self->dbus_proxy == nullptr) {
+    return false;
+  }
+
+  for (const FlSetting setting : all_settings) {
+    g_autoptr(GVariant) value = nullptr;
+    if (settings_portal_read(self->dbus_proxy, setting.ns, setting.key,
+                             &value)) {
+      set_value(self, &setting, value);
+    }
+  }
+
+  g_signal_connect_object(self->dbus_proxy, "g-signal",
+                          G_CALLBACK(settings_portal_changed_cb), self,
+                          GConnectFlags(0));
+
+  return true;
+}

shell/platform/linux/fl_settings_portal.h

@@ -0,0 +1,56 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#ifndef FLUTTER_SHELL_PLATFORM_LINUX_FL_SETTINGS_PORTAL_H_
+#define FLUTTER_SHELL_PLATFORM_LINUX_FL_SETTINGS_PORTAL_H_
+
+#include "flutter/shell/platform/linux/fl_settings.h"
+
+G_BEGIN_DECLS
+
+G_DECLARE_FINAL_TYPE(FlSettingsPortal,
+                     fl_settings_portal,
+                     FL,
+                     SETTINGS_PORTAL,
+                     GObject);
+
+/**
+ * FlSettingsPortal:
+ * #FlSettingsPortal reads settings from the XDG desktop portal.
+ */
+
+/**
+ * fl_settings_portal_new:
+ *
+ * Creates a new settings portal instance.
+ *
+ * Returns: a new #FlSettingsPortal.
+ */
+FlSettingsPortal* fl_settings_portal_new();
+
+/**
+ * fl_settings_portal_new_with_values:
+ * @values: (nullable): a #GVariantDict.
+ *
+ * Creates a new settings portal instance with initial values for testing.
+ *
+ * Returns: a new #FlSettingsPortal.
+ */
+FlSettingsPortal* fl_settings_portal_new_with_values(GVariantDict* values);
+
+/**
+ * fl_settings_portal_start:
+ * @portal: an #FlSettingsPortal.
+ * @error: (allow-none): #GError location to store the error occurring, or %NULL
+ *
+ * Reads the current settings and starts monitoring for changes in the desktop
+ * portal settings.
+ *
+ * Returns: %TRUE on success, or %FALSE if the portal is not available.
+ */
+gboolean fl_settings_portal_start(FlSettingsPortal* portal, GError** error);
+
+G_END_DECLS
+
+#endif  // FLUTTER_SHELL_PLATFORM_LINUX_FL_SETTINGS_PORTAL_H_