[Linux][A11y] report disabled animations and high contrast accessibility features (#33313)

* FlEngine: add fl_engine_update_accessibility_features()
* FlSettings: add API for high-contrast & animations
* FlEngine: allow passing mock messenger at construction time
* FlSettingsPlugin: report accessibility features

Author: jpnurmi

shell/platform/linux/fl_engine.cc

@@ -73,6 +73,8 @@ G_DEFINE_TYPE_WITH_CODE(
     G_IMPLEMENT_INTERFACE(fl_plugin_registry_get_type(),
                           fl_engine_plugin_registry_iface_init))
 
+enum { PROP_0, PROP_BINARY_MESSENGER, PROP_LAST };
+
 // Parse a locale into its components.
 static void parse_locale(const gchar* locale,
                          gchar** language,
@@ -351,6 +353,22 @@ static void fl_engine_plugin_registry_iface_init(
   iface->get_registrar_for_plugin = fl_engine_get_registrar_for_plugin;
 }
 
+static void fl_engine_set_property(GObject* object,
+                                   guint prop_id,
+                                   const GValue* value,
+                                   GParamSpec* pspec) {
+  FlEngine* self = FL_ENGINE(object);
+  switch (prop_id) {
+    case PROP_BINARY_MESSENGER:
+      g_set_object(&self->binary_messenger,
+                   FL_BINARY_MESSENGER(g_value_get_object(value)));
+      break;
+    default:
+      G_OBJECT_WARN_INVALID_PROPERTY_ID(object, prop_id, pspec);
+      break;
+  }
+}
+
 static void fl_engine_dispose(GObject* object) {
   FlEngine* self = FL_ENGINE(object);
 
@@ -397,6 +415,15 @@ static void fl_engine_dispose(GObject* object) {
 
 static void fl_engine_class_init(FlEngineClass* klass) {
   G_OBJECT_CLASS(klass)->dispose = fl_engine_dispose;
+  G_OBJECT_CLASS(klass)->set_property = fl_engine_set_property;
+
+  g_object_class_install_property(
+      G_OBJECT_CLASS(klass), PROP_BINARY_MESSENGER,
+      g_param_spec_object(
+          "binary-messenger", "messenger", "Binary messenger",
+          fl_binary_messenger_get_type(),
+          static_cast<GParamFlags>(G_PARAM_WRITABLE | G_PARAM_CONSTRUCT_ONLY |
+                                   G_PARAM_STATIC_STRINGS)));
 }
 
 static void fl_engine_init(FlEngine* self) {
@@ -406,7 +433,6 @@ static void fl_engine_init(FlEngine* self) {
   FlutterEngineGetProcAddresses(&self->embedder_api);
 
   self->texture_registrar = fl_texture_registrar_new(self);
-  self->binary_messenger = fl_binary_messenger_new(self);
 }
 
 FlEngine* fl_engine_new(FlDartProject* project, FlRenderer* renderer) {
@@ -416,6 +442,7 @@ FlEngine* fl_engine_new(FlDartProject* project, FlRenderer* renderer) {
   FlEngine* self = FL_ENGINE(g_object_new(fl_engine_get_type(), nullptr));
   self->project = FL_DART_PROJECT(g_object_ref(project));
   self->renderer = FL_RENDERER(g_object_ref(renderer));
+  self->binary_messenger = fl_binary_messenger_new(self);
   return self;
 }
 
@@ -522,7 +549,7 @@ gboolean fl_engine_start(FlEngine* self, GError** error) {
   setup_locales(self);
 
   g_autoptr(FlSettings) settings = fl_settings_new();
-  self->settings_plugin = fl_settings_plugin_new(self->binary_messenger);
+  self->settings_plugin = fl_settings_plugin_new(self);
   fl_settings_plugin_start(self->settings_plugin, settings);
 
   result = self->embedder_api.UpdateSemanticsEnabled(self->engine, TRUE);
@@ -844,3 +871,14 @@ G_MODULE_EXPORT FlTextureRegistrar* fl_engine_get_texture_registrar(
   g_return_val_if_fail(FL_IS_ENGINE(self), nullptr);
   return self->texture_registrar;
 }
+
+void fl_engine_update_accessibility_features(FlEngine* self, int32_t flags) {
+  g_return_if_fail(FL_IS_ENGINE(self));
+
+  if (self->engine == nullptr) {
+    return;
+  }
+
+  self->embedder_api.UpdateAccessibilityFeatures(
+      self->engine, static_cast<FlutterAccessibilityFeature>(flags));
+}

shell/platform/linux/fl_engine_private.h

@@ -327,6 +327,15 @@ gboolean fl_engine_register_external_texture(FlEngine* engine,
 gboolean fl_engine_unregister_external_texture(FlEngine* engine,
                                                int64_t texture_id);
 
+/**
+ * fl_engine_update_accessibility_features:
+ * @engine: an #FlEngine.
+ * @flags: the features to enable in the accessibility tree.
+ *
+ * Tells the Flutter engine to update the flags on the accessibility tree.
+ */
+void fl_engine_update_accessibility_features(FlEngine* engine, int32_t flags);
+
 G_END_DECLS
 
 #endif  // FLUTTER_SHELL_PLATFORM_LINUX_FL_ENGINE_PRIVATE_H_

shell/platform/linux/fl_gnome_settings.cc

@@ -63,6 +63,14 @@ static FlColorScheme fl_gnome_settings_get_color_scheme(FlSettings* settings) {
   return color_scheme;
 }
 
+static gboolean fl_gnome_settings_get_enable_animations(FlSettings* settings) {
+  return true;
+}
+
+static gboolean fl_gnome_settings_get_high_contrast(FlSettings* settings) {
+  return false;
+}
+
 static gdouble fl_gnome_settings_get_text_scaling_factor(FlSettings* settings) {
   FlGnomeSettings* self = FL_GNOME_SETTINGS(settings);
 
@@ -133,6 +141,8 @@ static void fl_gnome_settings_class_init(FlGnomeSettingsClass* klass) {
 static void fl_gnome_settings_iface_init(FlSettingsInterface* iface) {
   iface->get_clock_format = fl_gnome_settings_get_clock_format;
   iface->get_color_scheme = fl_gnome_settings_get_color_scheme;
+  iface->get_enable_animations = fl_gnome_settings_get_enable_animations;
+  iface->get_high_contrast = fl_gnome_settings_get_high_contrast;
   iface->get_text_scaling_factor = fl_gnome_settings_get_text_scaling_factor;
 }
 

shell/platform/linux/fl_gnome_settings_test.cc

@@ -69,6 +69,16 @@ TEST_F(FlGnomeSettingsTest, GtkTheme) {
   EXPECT_EQ(fl_settings_get_color_scheme(settings), FL_COLOR_SCHEME_DARK);
 }
 
+TEST_F(FlGnomeSettingsTest, EnableAnimations) {
+  g_autoptr(FlSettings) settings = fl_gnome_settings_new();
+  EXPECT_TRUE(fl_settings_get_enable_animations(settings));
+}
+
+TEST_F(FlGnomeSettingsTest, HighContrast) {
+  g_autoptr(FlSettings) settings = fl_gnome_settings_new();
+  EXPECT_FALSE(fl_settings_get_high_contrast(settings));
+}
+
 TEST_F(FlGnomeSettingsTest, TextScalingFactor) {
   g_autoptr(GSettings) interface_settings =
       create_settings("ubuntu-20.04", "org.gnome.desktop.interface");

shell/platform/linux/fl_settings.cc

@@ -35,6 +35,14 @@ FlColorScheme fl_settings_get_color_scheme(FlSettings* self) {
   return FL_SETTINGS_GET_IFACE(self)->get_color_scheme(self);
 }
 
+gboolean fl_settings_get_enable_animations(FlSettings* self) {
+  return FL_SETTINGS_GET_IFACE(self)->get_enable_animations(self);
+}
+
+gboolean fl_settings_get_high_contrast(FlSettings* self) {
+  return FL_SETTINGS_GET_IFACE(self)->get_high_contrast(self);
+}
+
 gdouble fl_settings_get_text_scaling_factor(FlSettings* self) {
   return FL_SETTINGS_GET_IFACE(self)->get_text_scaling_factor(self);
 }

shell/platform/linux/fl_settings.h

@@ -43,6 +43,8 @@ struct _FlSettingsInterface {
   GTypeInterface parent;
   FlClockFormat (*get_clock_format)(FlSettings* settings);
   FlColorScheme (*get_color_scheme)(FlSettings* settings);
+  gboolean (*get_enable_animations)(FlSettings* settings);
+  gboolean (*get_high_contrast)(FlSettings* settings);
   gdouble (*get_text_scaling_factor)(FlSettings* settings);
 };
 
@@ -79,6 +81,31 @@ FlClockFormat fl_settings_get_clock_format(FlSettings* settings);
  */
 FlColorScheme fl_settings_get_color_scheme(FlSettings* settings);
 
+/**
+ * fl_settings_get_enable_animations:
+ * @settings: an #FlSettings.
+ *
+ * Whether animations should be enabled.
+ *
+ * This corresponds to `org.gnome.desktop.interface.enable-animations` in GNOME.
+ *
+ * Returns: %TRUE if animations are enabled.
+ */
+gboolean fl_settings_get_enable_animations(FlSettings* settings);
+
+/**
+ * fl_settings_get_high_contrast:
+ * @settings: an #FlSettings.
+ *
+ * Whether to use high contrast theme.
+ *
+ * This corresponds to `org.gnome.desktop.a11y.interface.high-contrast` in
+ * GNOME.
+ *
+ * Returns: %TRUE if high contrast is used.
+ */
+gboolean fl_settings_get_high_contrast(FlSettings* settings);
+
 /**
  * fl_settings_get_text_scaling_factor:
  * @settings: an #FlSettings.

shell/platform/linux/fl_settings_plugin.cc

@@ -6,7 +6,10 @@
 
 #include <gmodule.h>
 
+#include "flutter/shell/platform/embedder/embedder.h"
+#include "flutter/shell/platform/linux/fl_engine_private.h"
 #include "flutter/shell/platform/linux/public/flutter_linux/fl_basic_message_channel.h"
+#include "flutter/shell/platform/linux/public/flutter_linux/fl_binary_messenger.h"
 #include "flutter/shell/platform/linux/public/flutter_linux/fl_json_message_codec.h"
 
 static constexpr char kChannelName[] = "flutter/settings";
@@ -20,7 +23,7 @@ struct _FlSettingsPlugin {
   GObject parent_instance;
 
   FlBasicMessageChannel* channel;
-
+  FlEngine* engine;
   FlSettings* settings;
 };
 
@@ -54,6 +57,17 @@ static void update_settings(FlSettingsPlugin* self) {
       fl_value_new_string(to_platform_brightness(color_scheme)));
   fl_basic_message_channel_send(self->channel, message, nullptr, nullptr,
                                 nullptr);
+
+  if (self->engine != nullptr) {
+    int32_t flags = 0;
+    if (!fl_settings_get_enable_animations(self->settings)) {
+      flags |= kFlutterAccessibilityFeatureDisableAnimations;
+    }
+    if (fl_settings_get_high_contrast(self->settings)) {
+      flags |= kFlutterAccessibilityFeatureHighContrast;
+    }
+    fl_engine_update_accessibility_features(self->engine, flags);
+  }
 }
 
 static void fl_settings_plugin_dispose(GObject* object) {
@@ -62,6 +76,12 @@ static void fl_settings_plugin_dispose(GObject* object) {
   g_clear_object(&self->channel);
   g_clear_object(&self->settings);
 
+  if (self->engine != nullptr) {
+    g_object_remove_weak_pointer(G_OBJECT(self),
+                                 reinterpret_cast<gpointer*>(&(self->engine)));
+    self->engine = nullptr;
+  }
+
   G_OBJECT_CLASS(fl_settings_plugin_parent_class)->dispose(object);
 }
 
@@ -71,12 +91,17 @@ static void fl_settings_plugin_class_init(FlSettingsPluginClass* klass) {
 
 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* fl_settings_plugin_new(FlEngine* engine) {
+  g_return_val_if_fail(FL_IS_ENGINE(engine), nullptr);
 
   FlSettingsPlugin* self =
       FL_SETTINGS_PLUGIN(g_object_new(fl_settings_plugin_get_type(), nullptr));
 
+  self->engine = engine;
+  g_object_add_weak_pointer(G_OBJECT(self),
+                            reinterpret_cast<gpointer*>(&(self->engine)));
+
+  FlBinaryMessenger* messenger = fl_engine_get_binary_messenger(engine);
   g_autoptr(FlJsonMessageCodec) codec = fl_json_message_codec_new();
   self->channel = fl_basic_message_channel_new(messenger, kChannelName,
                                                FL_MESSAGE_CODEC(codec));

shell/platform/linux/fl_settings_plugin.h

@@ -6,7 +6,7 @@
 #define FLUTTER_SHELL_PLATFORM_LINUX_FL_SETTINGS_PLUGIN_H_
 
 #include "flutter/shell/platform/linux/fl_settings.h"
-#include "flutter/shell/platform/linux/public/flutter_linux/fl_binary_messenger.h"
+#include "flutter/shell/platform/linux/public/flutter_linux/fl_engine.h"
 
 G_BEGIN_DECLS
 
@@ -25,13 +25,13 @@ G_DECLARE_FINAL_TYPE(FlSettingsPlugin,
 
 /**
  * fl_settings_plugin_new:
- * @messenger: an #FlBinaryMessenger
+ * @messenger: an #FlEngine
  *
  * Creates a new plugin that sends user settings to the Flutter engine.
  *
  * Returns: a new #FlSettingsPlugin
  */
-FlSettingsPlugin* fl_settings_plugin_new(FlBinaryMessenger* messenger);
+FlSettingsPlugin* fl_settings_plugin_new(FlEngine* engine);
 
 /**
  * fl_settings_plugin_start:

shell/platform/linux/fl_settings_plugin_test.cc

@@ -3,6 +3,9 @@
 // found in the LICENSE file.
 
 #include "flutter/shell/platform/linux/fl_settings_plugin.h"
+#include "flutter/shell/platform/embedder/embedder.h"
+#include "flutter/shell/platform/embedder/test_utils/proc_table_replacement.h"
+#include "flutter/shell/platform/linux/fl_engine_private.h"
 #include "flutter/shell/platform/linux/public/flutter_linux/fl_binary_messenger.h"
 #include "flutter/shell/platform/linux/public/flutter_linux/fl_json_message_codec.h"
 #include "flutter/shell/platform/linux/public/flutter_linux/fl_value.h"
@@ -38,7 +41,9 @@ TEST(FlSettingsPluginTest, AlwaysUse24HourFormat) {
   ::testing::NiceMock<flutter::testing::MockSettings> settings;
   ::testing::NiceMock<flutter::testing::MockBinaryMessenger> messenger;
 
-  g_autoptr(FlSettingsPlugin) plugin = fl_settings_plugin_new(messenger);
+  g_autoptr(FlEngine) engine = FL_ENGINE(g_object_new(
+      fl_engine_get_type(), "binary-messenger", messenger, nullptr));
+  g_autoptr(FlSettingsPlugin) plugin = fl_settings_plugin_new(engine);
 
   g_autoptr(FlValue) use_12h = fl_value_new_bool(false);
   g_autoptr(FlValue) use_24h = fl_value_new_bool(true);
@@ -61,7 +66,9 @@ TEST(FlSettingsPluginTest, PlatformBrightness) {
   ::testing::NiceMock<flutter::testing::MockSettings> settings;
   ::testing::NiceMock<flutter::testing::MockBinaryMessenger> messenger;
 
-  g_autoptr(FlSettingsPlugin) plugin = fl_settings_plugin_new(messenger);
+  g_autoptr(FlEngine) engine = FL_ENGINE(g_object_new(
+      fl_engine_get_type(), "binary-messenger", messenger, nullptr));
+  g_autoptr(FlSettingsPlugin) plugin = fl_settings_plugin_new(engine);
 
   g_autoptr(FlValue) light = fl_value_new_string("light");
   g_autoptr(FlValue) dark = fl_value_new_string("dark");
@@ -84,7 +91,9 @@ TEST(FlSettingsPluginTest, TextScaleFactor) {
   ::testing::NiceMock<flutter::testing::MockSettings> settings;
   ::testing::NiceMock<flutter::testing::MockBinaryMessenger> messenger;
 
-  g_autoptr(FlSettingsPlugin) plugin = fl_settings_plugin_new(messenger);
+  g_autoptr(FlEngine) engine = FL_ENGINE(g_object_new(
+      fl_engine_get_type(), "binary-messenger", messenger, nullptr));
+  g_autoptr(FlSettingsPlugin) plugin = fl_settings_plugin_new(engine);
 
   g_autoptr(FlValue) one = fl_value_new_float(1.0);
   g_autoptr(FlValue) two = fl_value_new_float(2.0);
@@ -102,3 +111,57 @@ TEST(FlSettingsPluginTest, TextScaleFactor) {
 
   fl_settings_emit_changed(settings);
 }
+
+// MOCK_ENGINE_PROC is leaky by design
+// NOLINTBEGIN(clang-analyzer-core.StackAddressEscape)
+TEST(FlSettingsPluginTest, AccessibilityFeatures) {
+  g_autoptr(FlEngine) engine = make_mock_engine();
+  FlutterEngineProcTable* embedder_api = fl_engine_get_embedder_api(engine);
+
+  std::vector<FlutterAccessibilityFeature> calls;
+  embedder_api->UpdateAccessibilityFeatures = MOCK_ENGINE_PROC(
+      UpdateAccessibilityFeatures,
+      ([&calls](auto engine, FlutterAccessibilityFeature features) {
+        calls.push_back(features);
+        return kSuccess;
+      }));
+
+  g_autoptr(FlSettingsPlugin) plugin = fl_settings_plugin_new(engine);
+
+  ::testing::NiceMock<flutter::testing::MockSettings> settings;
+
+  EXPECT_CALL(settings, fl_settings_get_enable_animations(
+                            ::testing::Eq<FlSettings*>(settings)))
+      .WillOnce(::testing::Return(false))
+      .WillOnce(::testing::Return(true))
+      .WillOnce(::testing::Return(false))
+      .WillOnce(::testing::Return(true));
+
+  EXPECT_CALL(settings, fl_settings_get_high_contrast(
+                            ::testing::Eq<FlSettings*>(settings)))
+      .WillOnce(::testing::Return(true))
+      .WillOnce(::testing::Return(false))
+      .WillOnce(::testing::Return(false))
+      .WillOnce(::testing::Return(true));
+
+  fl_settings_plugin_start(plugin, settings);
+  EXPECT_THAT(calls, ::testing::SizeIs(1));
+  EXPECT_EQ(calls.back(), static_cast<FlutterAccessibilityFeature>(
+                              kFlutterAccessibilityFeatureDisableAnimations |
+                              kFlutterAccessibilityFeatureHighContrast));
+
+  fl_settings_emit_changed(settings);
+  EXPECT_THAT(calls, ::testing::SizeIs(2));
+  EXPECT_EQ(calls.back(), static_cast<FlutterAccessibilityFeature>(0));
+
+  fl_settings_emit_changed(settings);
+  EXPECT_THAT(calls, ::testing::SizeIs(3));
+  EXPECT_EQ(calls.back(), static_cast<FlutterAccessibilityFeature>(
+                              kFlutterAccessibilityFeatureDisableAnimations));
+
+  fl_settings_emit_changed(settings);
+  EXPECT_THAT(calls, ::testing::SizeIs(4));
+  EXPECT_EQ(calls.back(), static_cast<FlutterAccessibilityFeature>(
+                              kFlutterAccessibilityFeatureHighContrast));
+}
+// NOLINTEND(clang-analyzer-core.StackAddressEscape)