shell/platform/linux/fl_accessible_text_field.cc - mirrors/engine - Git at Google

 // 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_accessible_text_field.h"
 #include "flutter/shell/platform/linux/public/flutter_linux/fl_standard_message_codec.h"
 #include "flutter/shell/platform/linux/public/flutter_linux/fl_value.h"

 struct _FlAccessibleTextField {
   FlAccessibleNode parent_instance;

   gint selection_base;
   gint selection_extent;
   GtkEntryBuffer* buffer;
 };

 static void fl_accessible_text_iface_init(AtkTextIface* iface);
 static void fl_accessible_editable_text_iface_init(AtkEditableTextIface* iface);

 G_DEFINE_TYPE_WITH_CODE(
     FlAccessibleTextField,
     fl_accessible_text_field,
     FL_TYPE_ACCESSIBLE_NODE,
     G_IMPLEMENT_INTERFACE(ATK_TYPE_TEXT, fl_accessible_text_iface_init)
         G_IMPLEMENT_INTERFACE(ATK_TYPE_EDITABLE_TEXT,
                               fl_accessible_editable_text_iface_init))

 static gchar* get_substring(FlAccessibleTextField* self,
                             glong start,
                             glong end) {
   const gchar* value = gtk_entry_buffer_get_text(self->buffer);
   if (end == -1) {
     // g_utf8_substring() accepts -1 since 2.72
     end = g_utf8_strlen(value, -1);
   }
   return g_utf8_substring(value, start, end);
 }

 static void perform_set_text_action(FlAccessibleTextField* self,
                                     const char* text) {
   g_autoptr(FlValue) value = fl_value_new_string(text);
   g_autoptr(FlStandardMessageCodec) codec = fl_standard_message_codec_new();
   g_autoptr(GBytes) message =
       fl_message_codec_encode_message(FL_MESSAGE_CODEC(codec), value, nullptr);

   fl_accessible_node_perform_action(FL_ACCESSIBLE_NODE(self),
                                     kFlutterSemanticsActionSetText, message);
 }

 static void perform_set_selection_action(FlAccessibleTextField* self,
                                          gint base,
                                          gint extent) {
   g_autoptr(FlValue) value = fl_value_new_map();
   fl_value_set_string_take(value, "base", fl_value_new_int(base));
   fl_value_set_string_take(value, "extent", fl_value_new_int(extent));

   g_autoptr(FlStandardMessageCodec) codec = fl_standard_message_codec_new();
   g_autoptr(GBytes) message =
       fl_message_codec_encode_message(FL_MESSAGE_CODEC(codec), value, nullptr);

   fl_accessible_node_perform_action(
       FL_ACCESSIBLE_NODE(self), kFlutterSemanticsActionSetSelection, message);
 }

 // Implements GObject::dispose.
 static void fl_accessible_text_field_dispose(GObject* object) {
   FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(object);

   g_clear_object(&self->buffer);

   G_OBJECT_CLASS(fl_accessible_text_field_parent_class)->dispose(object);
 }

 // Implements FlAccessibleNode::set_value.
 static void fl_accessible_text_field_set_value(FlAccessibleNode* node,
                                                const gchar* value) {
   g_return_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(node));
   FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(node);

   if (g_strcmp0(gtk_entry_buffer_get_text(self->buffer), value) == 0) {
     return;
   }

   gtk_entry_buffer_set_text(self->buffer, value, -1);
 }

 // Implements FlAccessibleNode::set_text_selection.
 static void fl_accessible_text_field_set_text_selection(FlAccessibleNode* node,
                                                         gint base,
                                                         gint extent) {
   g_return_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(node));
   FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(node);

   gboolean caret_moved = extent != self->selection_extent;
   gboolean has_selection = base != extent;
   gboolean had_selection = self->selection_base != self->selection_extent;
   gboolean selection_changed = (has_selection || had_selection) &&
                                (caret_moved || base != self->selection_base);

   self->selection_base = base;
   self->selection_extent = extent;

   if (selection_changed) {
     g_signal_emit_by_name(self, "text-selection-changed", nullptr);
   }

   if (caret_moved) {
     g_signal_emit_by_name(self, "text-caret-moved", extent, nullptr);
   }
 }

 // Overrides FlAccessibleNode::perform_action.
 void fl_accessible_text_field_perform_action(FlAccessibleNode* self,
                                              FlutterSemanticsAction action,
                                              GBytes* data) {
   FlAccessibleNodeClass* parent_class =
       FL_ACCESSIBLE_NODE_CLASS(fl_accessible_text_field_parent_class);

   switch (action) {
     case kFlutterSemanticsActionMoveCursorForwardByCharacter:
     case kFlutterSemanticsActionMoveCursorBackwardByCharacter:
     case kFlutterSemanticsActionMoveCursorForwardByWord:
     case kFlutterSemanticsActionMoveCursorBackwardByWord: {
       // These actions require a boolean argument that indicates whether the
       // selection should be extended or collapsed when moving the cursor.
       g_autoptr(FlValue) extend_selection = fl_value_new_bool(false);
       g_autoptr(FlStandardMessageCodec) codec = fl_standard_message_codec_new();
       g_autoptr(GBytes) message = fl_message_codec_encode_message(
           FL_MESSAGE_CODEC(codec), extend_selection, nullptr);
       parent_class->perform_action(self, action, message);
       break;
     }
     default:
       parent_class->perform_action(self, action, data);
       break;
   }
 }

 // Implements AtkText::get_character_count.
 static gint fl_accessible_text_field_get_character_count(AtkText* text) {
   g_return_val_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(text), 0);
   FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(text);

   return gtk_entry_buffer_get_length(self->buffer);
 }

 // Implements AtkText::get_text.
 static gchar* fl_accessible_text_field_get_text(AtkText* text,
                                                 gint start_offset,
                                                 gint end_offset) {
   g_return_val_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(text), nullptr);
   FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(text);

   return get_substring(self, start_offset, end_offset);
 }

 // Implements AtkText::get_caret_offset.
 static gint fl_accessible_text_field_get_caret_offset(AtkText* text) {
   g_return_val_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(text), -1);
   FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(text);

   return self->selection_extent;
 }

 // Implements AtkText::set_caret_offset.
 static gboolean fl_accessible_text_field_set_caret_offset(AtkText* text,
                                                           gint offset) {
   g_return_val_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(text), false);
   FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(text);

   perform_set_selection_action(self, offset, offset);
   return true;
 }

 // Implements AtkText::get_n_selections.
 static gint fl_accessible_text_field_get_n_selections(AtkText* text) {
   g_return_val_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(text), 0);
   FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(text);

   if (self->selection_base == self->selection_extent) {
     return 0;
   }

   return 1;
 }

 // Implements AtkText::get_selection.
 static gchar* fl_accessible_text_field_get_selection(AtkText* text,
                                                      gint selection_num,
                                                      gint* start_offset,
                                                      gint* end_offset) {
   g_return_val_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(text), nullptr);
   FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(text);

   if (selection_num != 0 || self->selection_base == self->selection_extent) {
     return nullptr;
   }

   gint start = MIN(self->selection_base, self->selection_extent);
   gint end = MAX(self->selection_base, self->selection_extent);

   if (start_offset != nullptr) {
     *start_offset = start;
   }
   if (end_offset != nullptr) {
     *end_offset = end;
   }

   return get_substring(self, start, end);
 }

 // Implements AtkText::add_selection.
 static gboolean fl_accessible_text_field_add_selection(AtkText* text,
                                                        gint start_offset,
                                                        gint end_offset) {
   g_return_val_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(text), false);
   FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(text);

   if (self->selection_base != self->selection_extent) {
     return false;
   }

   perform_set_selection_action(self, start_offset, end_offset);
   return true;
 }

 // Implements AtkText::remove_selection.
 static gboolean fl_accessible_text_field_remove_selection(AtkText* text,
                                                           gint selection_num) {
   g_return_val_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(text), false);
   FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(text);

   if (selection_num != 0 || self->selection_base == self->selection_extent) {
     return false;
   }

   perform_set_selection_action(self, self->selection_extent,
                                self->selection_extent);
   return true;
 }

 // Implements AtkText::set_selection.
 static gboolean fl_accessible_text_field_set_selection(AtkText* text,
                                                        gint selection_num,
                                                        gint start_offset,
                                                        gint end_offset) {
   g_return_val_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(text), false);
   FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(text);

   if (selection_num != 0) {
     return false;
   }

   perform_set_selection_action(self, start_offset, end_offset);
   return true;
 }

 // Implements AtkEditableText::set_text_contents.
 static void fl_accessible_text_field_set_text_contents(
     AtkEditableText* editable_text,
     const gchar* string) {
   g_return_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(editable_text));
   FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(editable_text);

   perform_set_text_action(self, string);
 }

 // Implements AtkEditableText::insert_text.
 static void fl_accessible_text_field_insert_text(AtkEditableText* editable_text,
                                                  const gchar* string,
                                                  gint length,
                                                  gint* position) {
   g_return_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(editable_text));
   FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(editable_text);

   *position +=
       gtk_entry_buffer_insert_text(self->buffer, *position, string, length);

   perform_set_text_action(self, gtk_entry_buffer_get_text(self->buffer));
   perform_set_selection_action(self, *position, *position);
 }

 // Implements AtkEditableText::delete_text.
 static void fl_accessible_node_delete_text(AtkEditableText* editable_text,
                                            gint start_pos,
                                            gint end_pos) {
   g_return_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(editable_text));
   FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(editable_text);

   gtk_entry_buffer_delete_text(self->buffer, start_pos, end_pos - start_pos);

   perform_set_text_action(self, gtk_entry_buffer_get_text(self->buffer));
   perform_set_selection_action(self, start_pos, start_pos);
 }

 // Implement AtkEditableText::copy_text.
 static void fl_accessible_text_field_copy_text(AtkEditableText* editable_text,
                                                gint start_pos,
                                                gint end_pos) {
   g_return_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(editable_text));
   FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(editable_text);

   perform_set_selection_action(self, start_pos, end_pos);

   fl_accessible_node_perform_action(FL_ACCESSIBLE_NODE(editable_text),
                                     kFlutterSemanticsActionCopy, nullptr);
 }

 // Implements AtkEditableText::cut_text.
 static void fl_accessible_text_field_cut_text(AtkEditableText* editable_text,
                                               gint start_pos,
                                               gint end_pos) {
   g_return_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(editable_text));
   FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(editable_text);

   perform_set_selection_action(self, start_pos, end_pos);

   fl_accessible_node_perform_action(FL_ACCESSIBLE_NODE(editable_text),
                                     kFlutterSemanticsActionCut, nullptr);
 }

 // Implements AtkEditableText::paste_text.
 static void fl_accessible_text_field_paste_text(AtkEditableText* editable_text,
                                                 gint position) {
   g_return_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(editable_text));
   FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(editable_text);

   perform_set_selection_action(self, position, position);

   fl_accessible_node_perform_action(FL_ACCESSIBLE_NODE(editable_text),
                                     kFlutterSemanticsActionPaste, nullptr);
 }

 static void fl_accessible_text_field_class_init(
     FlAccessibleTextFieldClass* klass) {
   G_OBJECT_CLASS(klass)->dispose = fl_accessible_text_field_dispose;
   FL_ACCESSIBLE_NODE_CLASS(klass)->set_value =
       fl_accessible_text_field_set_value;
   FL_ACCESSIBLE_NODE_CLASS(klass)->set_text_selection =
       fl_accessible_text_field_set_text_selection;
   FL_ACCESSIBLE_NODE_CLASS(klass)->perform_action =
       fl_accessible_text_field_perform_action;
 }

 static void fl_accessible_text_iface_init(AtkTextIface* iface) {
   iface->get_character_count = fl_accessible_text_field_get_character_count;
   iface->get_text = fl_accessible_text_field_get_text;
   // TODO(jpnurmi): get_text_at/before/after_offset

   iface->get_caret_offset = fl_accessible_text_field_get_caret_offset;
   iface->set_caret_offset = fl_accessible_text_field_set_caret_offset;

   iface->get_n_selections = fl_accessible_text_field_get_n_selections;
   iface->get_selection = fl_accessible_text_field_get_selection;
   iface->add_selection = fl_accessible_text_field_add_selection;
   iface->remove_selection = fl_accessible_text_field_remove_selection;
   iface->set_selection = fl_accessible_text_field_set_selection;
 }

 static void fl_accessible_editable_text_iface_init(
     AtkEditableTextIface* iface) {
   iface->set_text_contents = fl_accessible_text_field_set_text_contents;
   iface->insert_text = fl_accessible_text_field_insert_text;
   iface->delete_text = fl_accessible_node_delete_text;

   iface->copy_text = fl_accessible_text_field_copy_text;
   iface->cut_text = fl_accessible_text_field_cut_text;
   iface->paste_text = fl_accessible_text_field_paste_text;
 }

 static void fl_accessible_text_field_init(FlAccessibleTextField* self) {
   self->selection_base = -1;
   self->selection_extent = -1;

   self->buffer = gtk_entry_buffer_new("", 0);

   g_signal_connect_object(
       self->buffer, "inserted-text",
       G_CALLBACK(+[](FlAccessibleTextField* self, guint position, gchar* chars,
                      guint n_chars) {
         g_signal_emit_by_name(self, "text-insert", position, n_chars, chars,
                               nullptr);
       }),
       self, G_CONNECT_SWAPPED);

   g_signal_connect_object(self->buffer, "deleted-text",
                           G_CALLBACK(+[](FlAccessibleTextField* self,
                                          guint position, guint n_chars) {
                             g_autofree gchar* chars = atk_text_get_text(
                                 ATK_TEXT(self), position, position + n_chars);
                             g_signal_emit_by_name(self, "text-remove", position,
                                                   n_chars, chars, nullptr);
                           }),
                           self, G_CONNECT_SWAPPED);
 }

 FlAccessibleNode* fl_accessible_text_field_new(FlEngine* engine, int32_t id) {
   return FL_ACCESSIBLE_NODE(g_object_new(fl_accessible_text_field_get_type(),
                                          "engine", engine, "id", id, nullptr));
 }
	// 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_accessible_text_field.h"
	#include "flutter/shell/platform/linux/public/flutter_linux/fl_standard_message_codec.h"
	#include "flutter/shell/platform/linux/public/flutter_linux/fl_value.h"

	struct _FlAccessibleTextField {
	FlAccessibleNode parent_instance;

	gint selection_base;
	gint selection_extent;
	GtkEntryBuffer* buffer;
	};

	static void fl_accessible_text_iface_init(AtkTextIface* iface);
	static void fl_accessible_editable_text_iface_init(AtkEditableTextIface* iface);

	G_DEFINE_TYPE_WITH_CODE(
	FlAccessibleTextField,
	fl_accessible_text_field,
	FL_TYPE_ACCESSIBLE_NODE,
	G_IMPLEMENT_INTERFACE(ATK_TYPE_TEXT, fl_accessible_text_iface_init)
	G_IMPLEMENT_INTERFACE(ATK_TYPE_EDITABLE_TEXT,
	fl_accessible_editable_text_iface_init))

	static gchar* get_substring(FlAccessibleTextField* self,
	glong start,
	glong end) {
	const gchar* value = gtk_entry_buffer_get_text(self->buffer);
	if (end == -1) {
	// g_utf8_substring() accepts -1 since 2.72
	end = g_utf8_strlen(value, -1);
	}
	return g_utf8_substring(value, start, end);
	}

	static void perform_set_text_action(FlAccessibleTextField* self,
	const char* text) {
	g_autoptr(FlValue) value = fl_value_new_string(text);
	g_autoptr(FlStandardMessageCodec) codec = fl_standard_message_codec_new();
	g_autoptr(GBytes) message =
	fl_message_codec_encode_message(FL_MESSAGE_CODEC(codec), value, nullptr);

	fl_accessible_node_perform_action(FL_ACCESSIBLE_NODE(self),
	kFlutterSemanticsActionSetText, message);
	}

	static void perform_set_selection_action(FlAccessibleTextField* self,
	gint base,
	gint extent) {
	g_autoptr(FlValue) value = fl_value_new_map();
	fl_value_set_string_take(value, "base", fl_value_new_int(base));
	fl_value_set_string_take(value, "extent", fl_value_new_int(extent));

	g_autoptr(FlStandardMessageCodec) codec = fl_standard_message_codec_new();
	g_autoptr(GBytes) message =
	fl_message_codec_encode_message(FL_MESSAGE_CODEC(codec), value, nullptr);

	fl_accessible_node_perform_action(
	FL_ACCESSIBLE_NODE(self), kFlutterSemanticsActionSetSelection, message);
	}

	// Implements GObject::dispose.
	static void fl_accessible_text_field_dispose(GObject* object) {
	FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(object);

	g_clear_object(&self->buffer);

	G_OBJECT_CLASS(fl_accessible_text_field_parent_class)->dispose(object);
	}

	// Implements FlAccessibleNode::set_value.
	static void fl_accessible_text_field_set_value(FlAccessibleNode* node,
	const gchar* value) {
	g_return_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(node));
	FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(node);

	if (g_strcmp0(gtk_entry_buffer_get_text(self->buffer), value) == 0) {
	return;
	}

	gtk_entry_buffer_set_text(self->buffer, value, -1);
	}

	// Implements FlAccessibleNode::set_text_selection.
	static void fl_accessible_text_field_set_text_selection(FlAccessibleNode* node,
	gint base,
	gint extent) {
	g_return_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(node));
	FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(node);

	gboolean caret_moved = extent != self->selection_extent;
	gboolean has_selection = base != extent;
	gboolean had_selection = self->selection_base != self->selection_extent;
	gboolean selection_changed = (has_selection \|\| had_selection) &&
	(caret_moved \|\| base != self->selection_base);

	self->selection_base = base;
	self->selection_extent = extent;

	if (selection_changed) {
	g_signal_emit_by_name(self, "text-selection-changed", nullptr);
	}

	if (caret_moved) {
	g_signal_emit_by_name(self, "text-caret-moved", extent, nullptr);
	}
	}

	// Overrides FlAccessibleNode::perform_action.
	void fl_accessible_text_field_perform_action(FlAccessibleNode* self,
	FlutterSemanticsAction action,
	GBytes* data) {
	FlAccessibleNodeClass* parent_class =
	FL_ACCESSIBLE_NODE_CLASS(fl_accessible_text_field_parent_class);

	switch (action) {
	case kFlutterSemanticsActionMoveCursorForwardByCharacter:
	case kFlutterSemanticsActionMoveCursorBackwardByCharacter:
	case kFlutterSemanticsActionMoveCursorForwardByWord:
	case kFlutterSemanticsActionMoveCursorBackwardByWord: {
	// These actions require a boolean argument that indicates whether the
	// selection should be extended or collapsed when moving the cursor.
	g_autoptr(FlValue) extend_selection = fl_value_new_bool(false);
	g_autoptr(FlStandardMessageCodec) codec = fl_standard_message_codec_new();
	g_autoptr(GBytes) message = fl_message_codec_encode_message(
	FL_MESSAGE_CODEC(codec), extend_selection, nullptr);
	parent_class->perform_action(self, action, message);
	break;
	}
	default:
	parent_class->perform_action(self, action, data);
	break;
	}
	}

	// Implements AtkText::get_character_count.
	static gint fl_accessible_text_field_get_character_count(AtkText* text) {
	g_return_val_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(text), 0);
	FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(text);

	return gtk_entry_buffer_get_length(self->buffer);
	}

	// Implements AtkText::get_text.
	static gchar* fl_accessible_text_field_get_text(AtkText* text,
	gint start_offset,
	gint end_offset) {
	g_return_val_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(text), nullptr);
	FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(text);

	return get_substring(self, start_offset, end_offset);
	}

	// Implements AtkText::get_caret_offset.
	static gint fl_accessible_text_field_get_caret_offset(AtkText* text) {
	g_return_val_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(text), -1);
	FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(text);

	return self->selection_extent;
	}

	// Implements AtkText::set_caret_offset.
	static gboolean fl_accessible_text_field_set_caret_offset(AtkText* text,
	gint offset) {
	g_return_val_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(text), false);
	FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(text);

	perform_set_selection_action(self, offset, offset);
	return true;
	}

	// Implements AtkText::get_n_selections.
	static gint fl_accessible_text_field_get_n_selections(AtkText* text) {
	g_return_val_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(text), 0);
	FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(text);

	if (self->selection_base == self->selection_extent) {
	return 0;
	}

	return 1;
	}

	// Implements AtkText::get_selection.
	static gchar* fl_accessible_text_field_get_selection(AtkText* text,
	gint selection_num,
	gint* start_offset,
	gint* end_offset) {
	g_return_val_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(text), nullptr);
	FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(text);

	if (selection_num != 0 \|\| self->selection_base == self->selection_extent) {
	return nullptr;
	}

	gint start = MIN(self->selection_base, self->selection_extent);
	gint end = MAX(self->selection_base, self->selection_extent);

	if (start_offset != nullptr) {
	*start_offset = start;
	}
	if (end_offset != nullptr) {
	*end_offset = end;
	}

	return get_substring(self, start, end);
	}

	// Implements AtkText::add_selection.
	static gboolean fl_accessible_text_field_add_selection(AtkText* text,
	gint start_offset,
	gint end_offset) {
	g_return_val_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(text), false);
	FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(text);

	if (self->selection_base != self->selection_extent) {
	return false;
	}

	perform_set_selection_action(self, start_offset, end_offset);
	return true;
	}

	// Implements AtkText::remove_selection.
	static gboolean fl_accessible_text_field_remove_selection(AtkText* text,
	gint selection_num) {
	g_return_val_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(text), false);
	FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(text);

	if (selection_num != 0 \|\| self->selection_base == self->selection_extent) {
	return false;
	}

	perform_set_selection_action(self, self->selection_extent,
	self->selection_extent);
	return true;
	}

	// Implements AtkText::set_selection.
	static gboolean fl_accessible_text_field_set_selection(AtkText* text,
	gint selection_num,
	gint start_offset,
	gint end_offset) {
	g_return_val_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(text), false);
	FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(text);

	if (selection_num != 0) {
	return false;
	}

	perform_set_selection_action(self, start_offset, end_offset);
	return true;
	}

	// Implements AtkEditableText::set_text_contents.
	static void fl_accessible_text_field_set_text_contents(
	AtkEditableText* editable_text,
	const gchar* string) {
	g_return_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(editable_text));
	FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(editable_text);

	perform_set_text_action(self, string);
	}

	// Implements AtkEditableText::insert_text.
	static void fl_accessible_text_field_insert_text(AtkEditableText* editable_text,
	const gchar* string,
	gint length,
	gint* position) {
	g_return_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(editable_text));
	FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(editable_text);

	*position +=
	gtk_entry_buffer_insert_text(self->buffer, *position, string, length);

	perform_set_text_action(self, gtk_entry_buffer_get_text(self->buffer));
	perform_set_selection_action(self, position, position);
	}

	// Implements AtkEditableText::delete_text.
	static void fl_accessible_node_delete_text(AtkEditableText* editable_text,
	gint start_pos,
	gint end_pos) {
	g_return_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(editable_text));
	FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(editable_text);

	gtk_entry_buffer_delete_text(self->buffer, start_pos, end_pos - start_pos);

	perform_set_text_action(self, gtk_entry_buffer_get_text(self->buffer));
	perform_set_selection_action(self, start_pos, start_pos);
	}

	// Implement AtkEditableText::copy_text.
	static void fl_accessible_text_field_copy_text(AtkEditableText* editable_text,
	gint start_pos,
	gint end_pos) {
	g_return_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(editable_text));
	FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(editable_text);

	perform_set_selection_action(self, start_pos, end_pos);

	fl_accessible_node_perform_action(FL_ACCESSIBLE_NODE(editable_text),
	kFlutterSemanticsActionCopy, nullptr);
	}

	// Implements AtkEditableText::cut_text.
	static void fl_accessible_text_field_cut_text(AtkEditableText* editable_text,
	gint start_pos,
	gint end_pos) {
	g_return_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(editable_text));
	FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(editable_text);

	perform_set_selection_action(self, start_pos, end_pos);

	fl_accessible_node_perform_action(FL_ACCESSIBLE_NODE(editable_text),
	kFlutterSemanticsActionCut, nullptr);
	}

	// Implements AtkEditableText::paste_text.
	static void fl_accessible_text_field_paste_text(AtkEditableText* editable_text,
	gint position) {
	g_return_if_fail(FL_IS_ACCESSIBLE_TEXT_FIELD(editable_text));
	FlAccessibleTextField* self = FL_ACCESSIBLE_TEXT_FIELD(editable_text);

	perform_set_selection_action(self, position, position);

	fl_accessible_node_perform_action(FL_ACCESSIBLE_NODE(editable_text),
	kFlutterSemanticsActionPaste, nullptr);
	}

	static void fl_accessible_text_field_class_init(
	FlAccessibleTextFieldClass* klass) {
	G_OBJECT_CLASS(klass)->dispose = fl_accessible_text_field_dispose;
	FL_ACCESSIBLE_NODE_CLASS(klass)->set_value =
	fl_accessible_text_field_set_value;
	FL_ACCESSIBLE_NODE_CLASS(klass)->set_text_selection =
	fl_accessible_text_field_set_text_selection;
	FL_ACCESSIBLE_NODE_CLASS(klass)->perform_action =
	fl_accessible_text_field_perform_action;
	}

	static void fl_accessible_text_iface_init(AtkTextIface* iface) {
	iface->get_character_count = fl_accessible_text_field_get_character_count;
	iface->get_text = fl_accessible_text_field_get_text;
	// TODO(jpnurmi): get_text_at/before/after_offset

	iface->get_caret_offset = fl_accessible_text_field_get_caret_offset;
	iface->set_caret_offset = fl_accessible_text_field_set_caret_offset;

	iface->get_n_selections = fl_accessible_text_field_get_n_selections;
	iface->get_selection = fl_accessible_text_field_get_selection;
	iface->add_selection = fl_accessible_text_field_add_selection;
	iface->remove_selection = fl_accessible_text_field_remove_selection;
	iface->set_selection = fl_accessible_text_field_set_selection;
	}

	static void fl_accessible_editable_text_iface_init(
	AtkEditableTextIface* iface) {
	iface->set_text_contents = fl_accessible_text_field_set_text_contents;
	iface->insert_text = fl_accessible_text_field_insert_text;
	iface->delete_text = fl_accessible_node_delete_text;

	iface->copy_text = fl_accessible_text_field_copy_text;
	iface->cut_text = fl_accessible_text_field_cut_text;
	iface->paste_text = fl_accessible_text_field_paste_text;
	}

	static void fl_accessible_text_field_init(FlAccessibleTextField* self) {
	self->selection_base = -1;
	self->selection_extent = -1;

	self->buffer = gtk_entry_buffer_new("", 0);

	g_signal_connect_object(
	self->buffer, "inserted-text",
	G_CALLBACK(+[](FlAccessibleTextField* self, guint position, gchar* chars,
	guint n_chars) {
	g_signal_emit_by_name(self, "text-insert", position, n_chars, chars,
	nullptr);
	}),
	self, G_CONNECT_SWAPPED);

	g_signal_connect_object(self->buffer, "deleted-text",
	G_CALLBACK(+[](FlAccessibleTextField* self,
	guint position, guint n_chars) {
	g_autofree gchar* chars = atk_text_get_text(
	ATK_TEXT(self), position, position + n_chars);
	g_signal_emit_by_name(self, "text-remove", position,
	n_chars, chars, nullptr);
	}),
	self, G_CONNECT_SWAPPED);
	}

	FlAccessibleNode* fl_accessible_text_field_new(FlEngine* engine, int32_t id) {
	return FL_ACCESSIBLE_NODE(g_object_new(fl_accessible_text_field_get_type(),
	"engine", engine, "id", id, nullptr));
	}