Implement settings channel for the Linux shell

ci/licenses_golden/licenses_flutter

@@ -1345,6 +1345,8 @@ FILE: ../../../flutter/shell/platform/linux/fl_renderer_wayland.cc
 FILE: ../../../flutter/shell/platform/linux/fl_renderer_wayland.h
 FILE: ../../../flutter/shell/platform/linux/fl_renderer_x11.cc
 FILE: ../../../flutter/shell/platform/linux/fl_renderer_x11.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_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

@@ -110,6 +110,7 @@ source_set("flutter_linux_sources") {
     "fl_renderer_headless.cc",
     "fl_renderer_wayland.cc",
     "fl_renderer_x11.cc",
+    "fl_settings_plugin.cc",
     "fl_standard_message_codec.cc",
     "fl_standard_method_codec.cc",
     "fl_string_codec.cc",

shell/platform/linux/fl_settings_plugin.cc

@@ -0,0 +1,120 @@
+// 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_plugin.h"
+
+#include <cstring>
+
+#include "flutter/shell/platform/linux/public/flutter_linux/fl_basic_message_channel.h"
+#include "flutter/shell/platform/linux/public/flutter_linux/fl_json_message_codec.h"
+
+static constexpr char kChannelName[] = "flutter/settings";
+static constexpr char kTextScaleFactorKey[] = "textScaleFactor";
+static constexpr char kAlwaysUse24HourFormatKey[] = "alwaysUse24HourFormat";
+static constexpr char kPlatformBrightnessKey[] = "platformBrightness";
+static constexpr char kPlatformBrightnessLight[] = "light";
+static constexpr char kPlatformBrightnessDark[] = "dark";
+
+static constexpr char kDesktopInterfaceSchema[] = "org.gnome.desktop.interface";
+static constexpr char kDesktopGtkThemeKey[] = "gtk-theme";
+static constexpr char kDesktopTextScalingFactorKey[] = "text-scaling-factor";
+static constexpr char kDesktopClockFormatKey[] = "clock-format";
+static constexpr char kClockFormat24Hour[] = "24h";
+
+struct _FlSettingsPlugin {
+  GObject parent_instance;
+
+  FlBasicMessageChannel* channel;
+
+  GSettings* interface_settings;
+};
+
+G_DEFINE_TYPE(FlSettingsPlugin, fl_settings_plugin, G_TYPE_OBJECT)
+
+// Sends the current settings to the Flutter engine.
+static void update_settings(FlSettingsPlugin* self) {
+  gdouble scaling_factor = 1.0;
+  gboolean always_use_24hr = FALSE;
+  const gchar* platform_brightness = kPlatformBrightnessLight;
+
+  if (self->interface_settings != nullptr) {
+    scaling_factor = g_settings_get_double(self->interface_settings,
+                                           kDesktopTextScalingFactorKey);
+    g_autofree gchar* clock_format =
+        g_settings_get_string(self->interface_settings, kDesktopClockFormatKey);
+    always_use_24hr = g_strcmp0(clock_format, kClockFormat24Hour) == 0;
+
+    // GTK doesn't have a specific flag for dark themes, so we have some
+    // hard-coded themes for Ubuntu (Yaru) and GNOME (Adwaita).
+    g_autofree gchar* gtk_theme =
+        g_settings_get_string(self->interface_settings, kDesktopGtkThemeKey);
+    if (g_strcmp0(gtk_theme, "Yaru-dark") == 0 ||
+        g_strcmp0(gtk_theme, "Adwaita-dark") == 0) {
+      platform_brightness = kPlatformBrightnessDark;
+    }
+  }
+
+  g_autoptr(FlValue) message = fl_value_new_map();
+  fl_value_set_string_take(message, kTextScaleFactorKey,
+                           fl_value_new_float(scaling_factor));
+  fl_value_set_string_take(message, kAlwaysUse24HourFormatKey,
+                           fl_value_new_bool(always_use_24hr));
+  fl_value_set_string_take(message, kPlatformBrightnessKey,
+                           fl_value_new_string(platform_brightness));
+  fl_basic_message_channel_send(self->channel, message, nullptr, nullptr,
+                                nullptr);
+}
+
+static void fl_settings_plugin_dispose(GObject* object) {
+  FlSettingsPlugin* self = FL_SETTINGS_PLUGIN(object);
+
+  g_clear_object(&self->channel);
+  g_clear_object(&self->interface_settings);
+
+  G_OBJECT_CLASS(fl_settings_plugin_parent_class)->dispose(object);
+}
+
+static void fl_settings_plugin_class_init(FlSettingsPluginClass* klass) {
+  G_OBJECT_CLASS(klass)->dispose = fl_settings_plugin_dispose;
+}
+
+static void fl_settings_plugin_init(FlSettingsPlugin* self) {}
+
+FlSettingsPlugin* fl_settings_plugin_new(FlBinaryMessenger* messenger) {
+  g_return_val_if_fail(FL_IS_BINARY_MESSENGER(messenger), nullptr);
+
+  FlSettingsPlugin* self =
+      FL_SETTINGS_PLUGIN(g_object_new(fl_settings_plugin_get_type(), nullptr));
+
+  g_autoptr(FlJsonMessageCodec) codec = fl_json_message_codec_new();
+  self->channel = fl_basic_message_channel_new(messenger, kChannelName,
+                                               FL_MESSAGE_CODEC(codec));
+
+  return self;
+}
+
+void fl_settings_plugin_start(FlSettingsPlugin* self) {
+  g_return_if_fail(FL_IS_SETTINGS_PLUGIN(self));
+
+  // If we are on GNOME, get settings from GSettings.
+  GSettingsSchemaSource* source = g_settings_schema_source_get_default();
+  if (source != nullptr) {
+    g_autoptr(GSettingsSchema) schema =
+        g_settings_schema_source_lookup(source, kDesktopInterfaceSchema, FALSE);
+    if (schema != nullptr) {
+      self->interface_settings = g_settings_new_full(schema, nullptr, nullptr);
+      g_signal_connect_object(
+          self->interface_settings, "changed::text-scaling-factor",
+          G_CALLBACK(update_settings), self, G_CONNECT_SWAPPED);
+      g_signal_connect_object(self->interface_settings, "changed::clock-format",
+                              G_CALLBACK(update_settings), self,
+                              G_CONNECT_SWAPPED);
+      g_signal_connect_object(self->interface_settings, "changed::gtk-theme",
+                              G_CALLBACK(update_settings), self,
+                              G_CONNECT_SWAPPED);
+    }
+  }
+
+  update_settings(self);
+}

shell/platform/linux/fl_settings_plugin.h

@@ -0,0 +1,44 @@
+// 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_PLUGIN_H_
+#define FLUTTER_SHELL_PLATFORM_LINUX_FL_SETTINGS_PLUGIN_H_
+
+#include "flutter/shell/platform/linux/public/flutter_linux/fl_binary_messenger.h"
+
+G_BEGIN_DECLS
+
+G_DECLARE_FINAL_TYPE(FlSettingsPlugin,
+                     fl_settings_plugin,
+                     FL,
+                     SETTINGS_PLUGIN,
+                     GObject);
+
+/**
+ * FlSettingsPlugin:
+ *
+ * #FlSettingsPlugin is a plugin that implements FIXME.
+ */
+
+/**
+ * fl_settings_plugin_new:
+ * @messenger: an #FlBinaryMessenger
+ *
+ * Creates a new plugin that implements FIXME.
+ *
+ * Returns: a new #FlSettingsPlugin
+ */
+FlSettingsPlugin* fl_settings_plugin_new(FlBinaryMessenger* messenger);
+
+/**
+ * fl_settings_plugin_start:
+ * @self: an #FlSettingsPlugin.
+ *
+ * Sends the current settings to the engine and updates when they change.
+ */
+void fl_settings_plugin_start(FlSettingsPlugin* plugin);
+
+G_END_DECLS
+
+#endif  // FLUTTER_SHELL_PLATFORM_LINUX_FL_SETTINGS_PLUGIN_H_

shell/platform/linux/fl_view.cc

@@ -17,6 +17,7 @@
 #include "flutter/shell/platform/linux/fl_plugin_registrar_private.h"
 #include "flutter/shell/platform/linux/fl_renderer_wayland.h"
 #include "flutter/shell/platform/linux/fl_renderer_x11.h"
+#include "flutter/shell/platform/linux/fl_settings_plugin.h"
 #include "flutter/shell/platform/linux/fl_text_input_plugin.h"
 #include "flutter/shell/platform/linux/public/flutter_linux/fl_engine.h"
 #include "flutter/shell/platform/linux/public/flutter_linux/fl_plugin_registry.h"
@@ -42,6 +43,7 @@ struct _FlView {
   FlKeyEventPlugin* key_event_plugin;
   FlMouseCursorPlugin* mouse_cursor_plugin;
   FlPlatformPlugin* platform_plugin;
+  FlSettingsPlugin* settings_plugin;
   FlTextInputPlugin* text_input_plugin;
 };
 
@@ -161,6 +163,7 @@ static void fl_view_constructed(GObject* object) {
   self->key_event_plugin = fl_key_event_plugin_new(messenger);
   self->mouse_cursor_plugin = fl_mouse_cursor_plugin_new(messenger, self);
   self->platform_plugin = fl_platform_plugin_new(messenger);
+  self->settings_plugin = fl_settings_plugin_new(messenger);
   self->text_input_plugin = fl_text_input_plugin_new(messenger, self);
 }
 
@@ -218,6 +221,7 @@ static void fl_view_dispose(GObject* object) {
   g_clear_object(&self->key_event_plugin);
   g_clear_object(&self->mouse_cursor_plugin);
   g_clear_object(&self->platform_plugin);
+  g_clear_object(&self->settings_plugin);
   g_clear_object(&self->text_input_plugin);
 
   G_OBJECT_CLASS(fl_view_parent_class)->dispose(object);
@@ -239,6 +243,8 @@ static void fl_view_realize(GtkWidget* widget) {
     g_warning("Failed to start Flutter engine: %s", error->message);
     return;
   }
+
+  fl_settings_plugin_start(self->settings_plugin);
 }
 
 // Implements GtkWidget::size-allocate.