shell/platform/linux/fl_keyboard_manager.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_keyboard_manager.h"

 #include <cinttypes>

 /* Declare and define FlKeyboardPendingEvent */

 /**
  * FlKeyboardPendingEvent:
  * A record for events that have been received by the manager, but
  * dispatched to other objects, whose results have yet to return.
  *
  * This object is used by both the "pending_responds" list and the
  * "pending_redispatches" list.
  */
 G_DECLARE_FINAL_TYPE(FlKeyboardPendingEvent,
                      fl_keyboard_pending_event,
                      FL,
                      KEYBOARD_PENDING_EVENT,
                      GObject);

 struct _FlKeyboardPendingEvent {
   GObject parent_instance;

   // The target event.
   //
   // This is freed by #FlKeyboardPendingEvent.
   FlKeyEvent* event;

   // Self-incrementing ID attached to an event sent to the framework.
   //
   // Used to identify pending responds.
   uint64_t sequence_id;
   // The number of responders that haven't replied.
   size_t unreplied;
   // Whether any replied responders reported true (handled).
   bool any_handled;

   // A value calculated out of critical event information that can be used
   // to identify redispatched events.
   uint64_t hash;
 };

 G_DEFINE_TYPE(FlKeyboardPendingEvent, fl_keyboard_pending_event, G_TYPE_OBJECT)

 static void fl_keyboard_pending_event_dispose(GObject* object) {
   // Redundant, but added so that we don't get a warning about unused function
   // for FL_IS_KEYBOARD_PENDING_EVENT.
   g_return_if_fail(FL_IS_KEYBOARD_PENDING_EVENT(object));

   FlKeyboardPendingEvent* self = FL_KEYBOARD_PENDING_EVENT(object);
   fl_key_event_dispose(self->event);
   G_OBJECT_CLASS(fl_keyboard_pending_event_parent_class)->dispose(object);
 }

 static void fl_keyboard_pending_event_class_init(
     FlKeyboardPendingEventClass* klass) {
   G_OBJECT_CLASS(klass)->dispose = fl_keyboard_pending_event_dispose;
 }

 static void fl_keyboard_pending_event_init(FlKeyboardPendingEvent* self) {}

 // Calculates a unique ID for a given FlKeyEvent object to use for
 // identification of responses from the framework.
 static uint64_t fl_keyboard_manager_get_event_hash(FlKeyEvent* event) {
   // Combine the event timestamp, the type of event, and the hardware keycode
   // (scan code) of the event to come up with a unique id for this event that
   // can be derived solely from the event data itself, so that we can identify
   // whether or not we have seen this event already.
   guint64 type =
       static_cast<uint64_t>(event->is_press ? GDK_KEY_PRESS : GDK_KEY_RELEASE);
   guint64 keycode = static_cast<uint64_t>(event->keycode);
   return (event->time & 0xffffffff) | ((type & 0xffff) << 32) |
          ((keycode & 0xffff) << 48);
 }

 // Create a new FlKeyboardPendingEvent by providing the target event,
 // the sequence ID, and the number of responders that will reply.
 //
 // This will acquire the ownership of the event.
 FlKeyboardPendingEvent* fl_keyboard_pending_event_new(FlKeyEvent* event,
                                                       uint64_t sequence_id,
                                                       size_t to_reply) {
   FlKeyboardPendingEvent* self = FL_KEYBOARD_PENDING_EVENT(
       g_object_new(fl_keyboard_pending_event_get_type(), nullptr));

   self->event = event;
   self->sequence_id = sequence_id;
   self->unreplied = to_reply;
   self->any_handled = false;
   self->hash = fl_keyboard_manager_get_event_hash(event);
   return self;
 }

 /* Declare and define FlKeyboardManagerUserData */

 /**
  * FlKeyEmbedderUserData:
  * The user_data used when #FlKeyboardManagerUserData sends event to
  * responders.
  */
 #define FL_TYPE_KEYBOARD_MANAGER_USER_DATA \
   fl_keyboard_manager_user_data_get_type()
 G_DECLARE_FINAL_TYPE(FlKeyboardManagerUserData,
                      fl_keyboard_manager_user_data,
                      FL,
                      KEYBOARD_MANAGER_USER_DATA,
                      GObject);

 struct _FlKeyboardManagerUserData {
   GObject parent_instance;

   // A weak reference to the owner manager.
   FlKeyboardManager* manager;
   uint64_t sequence_id;
 };

 namespace {

 // Context variables for the foreach call used to dispatch events to responders.
 typedef struct {
   FlKeyEvent* event;
   FlKeyboardManagerUserData* user_data;
 } DispatchToResponderLoopContext;

 }  // namespace

 G_DEFINE_TYPE(FlKeyboardManagerUserData,
               fl_keyboard_manager_user_data,
               G_TYPE_OBJECT)

 static void fl_keyboard_manager_user_data_dispose(GObject* object) {
   g_return_if_fail(FL_IS_KEYBOARD_MANAGER_USER_DATA(object));
   FlKeyboardManagerUserData* self = FL_KEYBOARD_MANAGER_USER_DATA(object);
   if (self->manager != nullptr) {
     g_object_remove_weak_pointer(G_OBJECT(self->manager),
                                  reinterpret_cast<gpointer*>(&(self->manager)));
     self->manager = nullptr;
   }
 }

 static void fl_keyboard_manager_user_data_class_init(
     FlKeyboardManagerUserDataClass* klass) {
   G_OBJECT_CLASS(klass)->dispose = fl_keyboard_manager_user_data_dispose;
 }

 static void fl_keyboard_manager_user_data_init(
     FlKeyboardManagerUserData* self) {}

 // Creates a new FlKeyboardManagerUserData private class with all information.
 FlKeyboardManagerUserData* fl_keyboard_manager_user_data_new(
     FlKeyboardManager* manager,
     uint64_t sequence_id) {
   FlKeyboardManagerUserData* self = FL_KEYBOARD_MANAGER_USER_DATA(
       g_object_new(fl_keyboard_manager_user_data_get_type(), nullptr));

   self->manager = manager;
   // Add a weak pointer so we can know if the key event responder disappeared
   // while the framework was responding.
   g_object_add_weak_pointer(G_OBJECT(manager),
                             reinterpret_cast<gpointer*>(&(self->manager)));
   self->sequence_id = sequence_id;
   return self;
 }

 /* Define FlKeyboardManager */

 struct _FlKeyboardManager {
   GObject parent_instance;

   // The callback that unhandled events should be redispatched through.
   FlKeyboardManagerRedispatcher redispatch_callback;

   // A text plugin.
   //
   // Released by the manager on dispose.
   FlTextInputPlugin* text_input_plugin;

   // An array of #FlKeyResponder. Elements are added with
   // #fl_keyboard_manager_add_responder immediately after initialization and are
   // automatically released on dispose.
   GPtrArray* responder_list;

   // An array of #FlKeyboardPendingEvent.
   //
   // Its elements are *not* unreferenced when removed. When FlKeyboardManager is
   // disposed, this array will be set with a free_func so that the elements are
   // unreferenced when removed.
   GPtrArray* pending_responds;

   // An array of #FlKeyboardPendingEvent.
   //
   // Its elements are unreferenced when removed.
   GPtrArray* pending_redispatches;

   // The last sequence ID used. Increased by 1 by every use.
   uint64_t last_sequence_id;
 };

 G_DEFINE_TYPE(FlKeyboardManager, fl_keyboard_manager, G_TYPE_OBJECT);

 static void fl_keyboard_manager_dispose(GObject* object);

 static void fl_keyboard_manager_class_init(FlKeyboardManagerClass* klass) {
   G_OBJECT_CLASS(klass)->dispose = fl_keyboard_manager_dispose;
 }

 static void fl_keyboard_manager_init(FlKeyboardManager* self) {}

 static void fl_keyboard_manager_dispose(GObject* object) {
   FlKeyboardManager* self = FL_KEYBOARD_MANAGER(object);

   if (self->text_input_plugin != nullptr) {
     g_clear_object(&self->text_input_plugin);
   }
   g_ptr_array_free(self->responder_list, TRUE);
   g_ptr_array_set_free_func(self->pending_responds, g_object_unref);
   g_ptr_array_free(self->pending_responds, TRUE);
   g_ptr_array_free(self->pending_redispatches, TRUE);

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

 /* Implement FlKeyboardManager */

 // This is an exact copy of g_ptr_array_find_with_equal_func.  Somehow CI
 // reports that can not find symbol g_ptr_array_find_with_equal_func, despite
 // the fact that it runs well locally.
 gboolean g_ptr_array_find_with_equal_func1(GPtrArray* haystack,
                                            gconstpointer needle,
                                            GEqualFunc equal_func,
                                            guint* index_) {
   guint i;
   g_return_val_if_fail(haystack != NULL, FALSE);
   if (equal_func == NULL) {
     equal_func = g_direct_equal;
   }
   for (i = 0; i < haystack->len; i++) {
     if (equal_func(g_ptr_array_index(haystack, i), needle)) {
       if (index_ != NULL) {
         *index_ = i;
       }
       return TRUE;
     }
   }

   return FALSE;
 }

 // Compare a #FlKeyboardPendingEvent with the given sequence_id. The needle
 // should be a pointer to uint64_t sequence_id.
 static gboolean compare_pending_by_sequence_id(
     gconstpointer pending,
     gconstpointer needle_sequence_id) {
   uint64_t sequence_id = *reinterpret_cast<const uint64_t*>(needle_sequence_id);
   return static_cast<const FlKeyboardPendingEvent*>(pending)->sequence_id ==
          sequence_id;
 }

 // Compare a #FlKeyboardPendingEvent with the given hash. The #needle should be
 // a pointer to uint64_t hash.
 static gboolean compare_pending_by_hash(gconstpointer pending,
                                         gconstpointer needle_hash) {
   uint64_t hash = *reinterpret_cast<const uint64_t*>(needle_hash);
   return static_cast<const FlKeyboardPendingEvent*>(pending)->hash == hash;
 }

 // Try to remove a pending event from `pending_redispatches` with the target
 // hash.
 //
 // Returns true if the event is found and removed.
 static bool fl_keyboard_manager_remove_redispatched(FlKeyboardManager* self,
                                                     uint64_t hash) {
   guint result_index;
   gboolean found = g_ptr_array_find_with_equal_func1(
       self->pending_redispatches, static_cast<const uint64_t*>(&hash),
       compare_pending_by_hash, &result_index);
   if (found) {
     // The removed object is freed due to `pending_redispatches`'s free_func.
     g_ptr_array_remove_index_fast(self->pending_redispatches, result_index);
     return TRUE;
   } else {
     return FALSE;
   }
 }

 // The callback used by a responder after the event was dispatched.
 static void responder_handle_event_callback(bool handled,
                                             gpointer user_data_ptr) {
   g_return_if_fail(FL_IS_KEYBOARD_MANAGER_USER_DATA(user_data_ptr));
   FlKeyboardManagerUserData* user_data =
       FL_KEYBOARD_MANAGER_USER_DATA(user_data_ptr);
   FlKeyboardManager* self = user_data->manager;

   guint result_index = -1;
   gboolean found = g_ptr_array_find_with_equal_func1(
       self->pending_responds, &user_data->sequence_id,
       compare_pending_by_sequence_id, &result_index);
   g_return_if_fail(found);
   FlKeyboardPendingEvent* pending = FL_KEYBOARD_PENDING_EVENT(
       g_ptr_array_index(self->pending_responds, result_index));
   g_return_if_fail(pending != nullptr);
   g_return_if_fail(pending->unreplied > 0);
   pending->unreplied -= 1;
   pending->any_handled = pending->any_handled || handled;
   // All responders have replied.
   if (pending->unreplied == 0) {
     g_object_unref(user_data_ptr);
     gpointer removed =
         g_ptr_array_remove_index_fast(self->pending_responds, result_index);
     g_return_if_fail(removed == pending);
     bool should_redispatch =
         !pending->any_handled && (self->text_input_plugin == nullptr ||
                                   !fl_text_input_plugin_filter_keypress(
                                       self->text_input_plugin, pending->event));
     if (should_redispatch) {
       g_ptr_array_add(self->pending_redispatches, pending);
       self->redispatch_callback(pending->event->origin);
     } else {
       g_object_unref(pending);
     }
   }
 }

 FlKeyboardManager* fl_keyboard_manager_new(
     FlTextInputPlugin* text_input_plugin,
     FlKeyboardManagerRedispatcher redispatch_callback) {
   g_return_val_if_fail(text_input_plugin == nullptr ||
                            FL_IS_TEXT_INPUT_PLUGIN(text_input_plugin),
                        nullptr);
   g_return_val_if_fail(redispatch_callback != nullptr, nullptr);

   FlKeyboardManager* self = FL_KEYBOARD_MANAGER(
       g_object_new(fl_keyboard_manager_get_type(), nullptr));

   self->text_input_plugin = text_input_plugin;
   self->redispatch_callback = redispatch_callback;
   self->responder_list = g_ptr_array_new_with_free_func(g_object_unref);

   self->pending_responds = g_ptr_array_new();
   self->pending_redispatches = g_ptr_array_new_with_free_func(g_object_unref);

   self->last_sequence_id = 1;

   return self;
 }

 void fl_keyboard_manager_add_responder(FlKeyboardManager* self,
                                        FlKeyResponder* responder) {
   g_return_if_fail(FL_IS_KEYBOARD_MANAGER(self));
   g_return_if_fail(responder != nullptr);

   g_ptr_array_add(self->responder_list, responder);
 }

 // The loop body to dispatch an event to a responder.
 static void dispatch_to_responder(gpointer responder_data,
                                   gpointer foreach_data_ptr) {
   DispatchToResponderLoopContext* context =
       reinterpret_cast<DispatchToResponderLoopContext*>(foreach_data_ptr);
   FlKeyResponder* responder = FL_KEY_RESPONDER(responder_data);
   fl_key_responder_handle_event(responder, context->event,
                                 responder_handle_event_callback,
                                 context->user_data);
 }

 gboolean fl_keyboard_manager_handle_event(FlKeyboardManager* self,
                                           FlKeyEvent* event) {
   g_return_val_if_fail(FL_IS_KEYBOARD_MANAGER(self), FALSE);
   g_return_val_if_fail(event != nullptr, FALSE);

   uint64_t incoming_hash = fl_keyboard_manager_get_event_hash(event);
   if (fl_keyboard_manager_remove_redispatched(self, incoming_hash)) {
     return FALSE;
   }

   FlKeyboardPendingEvent* pending = fl_keyboard_pending_event_new(
       event, ++self->last_sequence_id, self->responder_list->len);

   g_ptr_array_add(self->pending_responds, pending);
   FlKeyboardManagerUserData* user_data =
       fl_keyboard_manager_user_data_new(self, pending->sequence_id);
   DispatchToResponderLoopContext data{
       .event = event,
       .user_data = user_data,
   };
   g_ptr_array_foreach(self->responder_list, dispatch_to_responder, &data);

   return TRUE;
 }

 gboolean fl_keyboard_manager_is_state_clear(FlKeyboardManager* self) {
   g_return_val_if_fail(FL_IS_KEYBOARD_MANAGER(self), FALSE);
   return self->pending_responds->len == 0 &&
          self->pending_redispatches->len == 0;
 }
	// 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_keyboard_manager.h"

	#include <cinttypes>

	/* Declare and define FlKeyboardPendingEvent */

	/**
	* FlKeyboardPendingEvent:
	* A record for events that have been received by the manager, but
	* dispatched to other objects, whose results have yet to return.
	*
	* This object is used by both the "pending_responds" list and the
	* "pending_redispatches" list.
	*/
	G_DECLARE_FINAL_TYPE(FlKeyboardPendingEvent,
	fl_keyboard_pending_event,
	FL,
	KEYBOARD_PENDING_EVENT,
	GObject);

	struct _FlKeyboardPendingEvent {
	GObject parent_instance;

	// The target event.
	//
	// This is freed by #FlKeyboardPendingEvent.
	FlKeyEvent* event;

	// Self-incrementing ID attached to an event sent to the framework.
	//
	// Used to identify pending responds.
	uint64_t sequence_id;
	// The number of responders that haven't replied.
	size_t unreplied;
	// Whether any replied responders reported true (handled).
	bool any_handled;

	// A value calculated out of critical event information that can be used
	// to identify redispatched events.
	uint64_t hash;
	};

	G_DEFINE_TYPE(FlKeyboardPendingEvent, fl_keyboard_pending_event, G_TYPE_OBJECT)

	static void fl_keyboard_pending_event_dispose(GObject* object) {
	// Redundant, but added so that we don't get a warning about unused function
	// for FL_IS_KEYBOARD_PENDING_EVENT.
	g_return_if_fail(FL_IS_KEYBOARD_PENDING_EVENT(object));

	FlKeyboardPendingEvent* self = FL_KEYBOARD_PENDING_EVENT(object);
	fl_key_event_dispose(self->event);
	G_OBJECT_CLASS(fl_keyboard_pending_event_parent_class)->dispose(object);
	}

	static void fl_keyboard_pending_event_class_init(
	FlKeyboardPendingEventClass* klass) {
	G_OBJECT_CLASS(klass)->dispose = fl_keyboard_pending_event_dispose;
	}

	static void fl_keyboard_pending_event_init(FlKeyboardPendingEvent* self) {}

	// Calculates a unique ID for a given FlKeyEvent object to use for
	// identification of responses from the framework.
	static uint64_t fl_keyboard_manager_get_event_hash(FlKeyEvent* event) {
	// Combine the event timestamp, the type of event, and the hardware keycode
	// (scan code) of the event to come up with a unique id for this event that
	// can be derived solely from the event data itself, so that we can identify
	// whether or not we have seen this event already.
	guint64 type =
	static_cast<uint64_t>(event->is_press ? GDK_KEY_PRESS : GDK_KEY_RELEASE);
	guint64 keycode = static_cast<uint64_t>(event->keycode);
	return (event->time & 0xffffffff) \| ((type & 0xffff) << 32) \|
	((keycode & 0xffff) << 48);
	}

	// Create a new FlKeyboardPendingEvent by providing the target event,
	// the sequence ID, and the number of responders that will reply.
	//
	// This will acquire the ownership of the event.
	FlKeyboardPendingEvent* fl_keyboard_pending_event_new(FlKeyEvent* event,
	uint64_t sequence_id,
	size_t to_reply) {
	FlKeyboardPendingEvent* self = FL_KEYBOARD_PENDING_EVENT(
	g_object_new(fl_keyboard_pending_event_get_type(), nullptr));

	self->event = event;
	self->sequence_id = sequence_id;
	self->unreplied = to_reply;
	self->any_handled = false;
	self->hash = fl_keyboard_manager_get_event_hash(event);
	return self;
	}

	/* Declare and define FlKeyboardManagerUserData */

	/**
	* FlKeyEmbedderUserData:
	* The user_data used when #FlKeyboardManagerUserData sends event to
	* responders.
	*/
	#define FL_TYPE_KEYBOARD_MANAGER_USER_DATA \
	fl_keyboard_manager_user_data_get_type()
	G_DECLARE_FINAL_TYPE(FlKeyboardManagerUserData,
	fl_keyboard_manager_user_data,
	FL,
	KEYBOARD_MANAGER_USER_DATA,
	GObject);

	struct _FlKeyboardManagerUserData {
	GObject parent_instance;

	// A weak reference to the owner manager.
	FlKeyboardManager* manager;
	uint64_t sequence_id;
	};

	namespace {

	// Context variables for the foreach call used to dispatch events to responders.
	typedef struct {
	FlKeyEvent* event;
	FlKeyboardManagerUserData* user_data;
	} DispatchToResponderLoopContext;

	} // namespace

	G_DEFINE_TYPE(FlKeyboardManagerUserData,
	fl_keyboard_manager_user_data,
	G_TYPE_OBJECT)

	static void fl_keyboard_manager_user_data_dispose(GObject* object) {
	g_return_if_fail(FL_IS_KEYBOARD_MANAGER_USER_DATA(object));
	FlKeyboardManagerUserData* self = FL_KEYBOARD_MANAGER_USER_DATA(object);
	if (self->manager != nullptr) {
	g_object_remove_weak_pointer(G_OBJECT(self->manager),
	reinterpret_cast<gpointer*>(&(self->manager)));
	self->manager = nullptr;
	}
	}

	static void fl_keyboard_manager_user_data_class_init(
	FlKeyboardManagerUserDataClass* klass) {
	G_OBJECT_CLASS(klass)->dispose = fl_keyboard_manager_user_data_dispose;
	}

	static void fl_keyboard_manager_user_data_init(
	FlKeyboardManagerUserData* self) {}

	// Creates a new FlKeyboardManagerUserData private class with all information.
	FlKeyboardManagerUserData* fl_keyboard_manager_user_data_new(
	FlKeyboardManager* manager,
	uint64_t sequence_id) {
	FlKeyboardManagerUserData* self = FL_KEYBOARD_MANAGER_USER_DATA(
	g_object_new(fl_keyboard_manager_user_data_get_type(), nullptr));

	self->manager = manager;
	// Add a weak pointer so we can know if the key event responder disappeared
	// while the framework was responding.
	g_object_add_weak_pointer(G_OBJECT(manager),
	reinterpret_cast<gpointer*>(&(self->manager)));
	self->sequence_id = sequence_id;
	return self;
	}

	/* Define FlKeyboardManager */

	struct _FlKeyboardManager {
	GObject parent_instance;

	// The callback that unhandled events should be redispatched through.
	FlKeyboardManagerRedispatcher redispatch_callback;

	// A text plugin.
	//
	// Released by the manager on dispose.
	FlTextInputPlugin* text_input_plugin;

	// An array of #FlKeyResponder. Elements are added with
	// #fl_keyboard_manager_add_responder immediately after initialization and are
	// automatically released on dispose.
	GPtrArray* responder_list;

	// An array of #FlKeyboardPendingEvent.
	//
	// Its elements are not unreferenced when removed. When FlKeyboardManager is
	// disposed, this array will be set with a free_func so that the elements are
	// unreferenced when removed.
	GPtrArray* pending_responds;

	// An array of #FlKeyboardPendingEvent.
	//
	// Its elements are unreferenced when removed.
	GPtrArray* pending_redispatches;

	// The last sequence ID used. Increased by 1 by every use.
	uint64_t last_sequence_id;
	};

	G_DEFINE_TYPE(FlKeyboardManager, fl_keyboard_manager, G_TYPE_OBJECT);

	static void fl_keyboard_manager_dispose(GObject* object);

	static void fl_keyboard_manager_class_init(FlKeyboardManagerClass* klass) {
	G_OBJECT_CLASS(klass)->dispose = fl_keyboard_manager_dispose;
	}

	static void fl_keyboard_manager_init(FlKeyboardManager* self) {}

	static void fl_keyboard_manager_dispose(GObject* object) {
	FlKeyboardManager* self = FL_KEYBOARD_MANAGER(object);

	if (self->text_input_plugin != nullptr) {
	g_clear_object(&self->text_input_plugin);
	}
	g_ptr_array_free(self->responder_list, TRUE);
	g_ptr_array_set_free_func(self->pending_responds, g_object_unref);
	g_ptr_array_free(self->pending_responds, TRUE);
	g_ptr_array_free(self->pending_redispatches, TRUE);

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

	/* Implement FlKeyboardManager */

	// This is an exact copy of g_ptr_array_find_with_equal_func. Somehow CI
	// reports that can not find symbol g_ptr_array_find_with_equal_func, despite
	// the fact that it runs well locally.
	gboolean g_ptr_array_find_with_equal_func1(GPtrArray* haystack,
	gconstpointer needle,
	GEqualFunc equal_func,
	guint* index_) {
	guint i;
	g_return_val_if_fail(haystack != NULL, FALSE);
	if (equal_func == NULL) {
	equal_func = g_direct_equal;
	}
	for (i = 0; i < haystack->len; i++) {
	if (equal_func(g_ptr_array_index(haystack, i), needle)) {
	if (index_ != NULL) {
	*index_ = i;
	}
	return TRUE;
	}
	}

	return FALSE;
	}

	// Compare a #FlKeyboardPendingEvent with the given sequence_id. The needle
	// should be a pointer to uint64_t sequence_id.
	static gboolean compare_pending_by_sequence_id(
	gconstpointer pending,
	gconstpointer needle_sequence_id) {
	uint64_t sequence_id = reinterpret_cast<const uint64_t>(needle_sequence_id);
	return static_cast<const FlKeyboardPendingEvent*>(pending)->sequence_id ==
	sequence_id;
	}

	// Compare a #FlKeyboardPendingEvent with the given hash. The #needle should be
	// a pointer to uint64_t hash.
	static gboolean compare_pending_by_hash(gconstpointer pending,
	gconstpointer needle_hash) {
	uint64_t hash = reinterpret_cast<const uint64_t>(needle_hash);
	return static_cast<const FlKeyboardPendingEvent*>(pending)->hash == hash;
	}

	// Try to remove a pending event from `pending_redispatches` with the target
	// hash.
	//
	// Returns true if the event is found and removed.
	static bool fl_keyboard_manager_remove_redispatched(FlKeyboardManager* self,
	uint64_t hash) {
	guint result_index;
	gboolean found = g_ptr_array_find_with_equal_func1(
	self->pending_redispatches, static_cast<const uint64_t*>(&hash),
	compare_pending_by_hash, &result_index);
	if (found) {
	// The removed object is freed due to `pending_redispatches`'s free_func.
	g_ptr_array_remove_index_fast(self->pending_redispatches, result_index);
	return TRUE;
	} else {
	return FALSE;
	}
	}

	// The callback used by a responder after the event was dispatched.
	static void responder_handle_event_callback(bool handled,
	gpointer user_data_ptr) {
	g_return_if_fail(FL_IS_KEYBOARD_MANAGER_USER_DATA(user_data_ptr));
	FlKeyboardManagerUserData* user_data =
	FL_KEYBOARD_MANAGER_USER_DATA(user_data_ptr);
	FlKeyboardManager* self = user_data->manager;

	guint result_index = -1;
	gboolean found = g_ptr_array_find_with_equal_func1(
	self->pending_responds, &user_data->sequence_id,
	compare_pending_by_sequence_id, &result_index);
	g_return_if_fail(found);
	FlKeyboardPendingEvent* pending = FL_KEYBOARD_PENDING_EVENT(
	g_ptr_array_index(self->pending_responds, result_index));
	g_return_if_fail(pending != nullptr);
	g_return_if_fail(pending->unreplied > 0);
	pending->unreplied -= 1;
	pending->any_handled = pending->any_handled \|\| handled;
	// All responders have replied.
	if (pending->unreplied == 0) {
	g_object_unref(user_data_ptr);
	gpointer removed =
	g_ptr_array_remove_index_fast(self->pending_responds, result_index);
	g_return_if_fail(removed == pending);
	bool should_redispatch =
	!pending->any_handled && (self->text_input_plugin == nullptr \|\|
	!fl_text_input_plugin_filter_keypress(
	self->text_input_plugin, pending->event));
	if (should_redispatch) {
	g_ptr_array_add(self->pending_redispatches, pending);
	self->redispatch_callback(pending->event->origin);
	} else {
	g_object_unref(pending);
	}
	}
	}

	FlKeyboardManager* fl_keyboard_manager_new(
	FlTextInputPlugin* text_input_plugin,
	FlKeyboardManagerRedispatcher redispatch_callback) {
	g_return_val_if_fail(text_input_plugin == nullptr \|\|
	FL_IS_TEXT_INPUT_PLUGIN(text_input_plugin),
	nullptr);
	g_return_val_if_fail(redispatch_callback != nullptr, nullptr);

	FlKeyboardManager* self = FL_KEYBOARD_MANAGER(
	g_object_new(fl_keyboard_manager_get_type(), nullptr));

	self->text_input_plugin = text_input_plugin;
	self->redispatch_callback = redispatch_callback;
	self->responder_list = g_ptr_array_new_with_free_func(g_object_unref);

	self->pending_responds = g_ptr_array_new();
	self->pending_redispatches = g_ptr_array_new_with_free_func(g_object_unref);

	self->last_sequence_id = 1;

	return self;
	}

	void fl_keyboard_manager_add_responder(FlKeyboardManager* self,
	FlKeyResponder* responder) {
	g_return_if_fail(FL_IS_KEYBOARD_MANAGER(self));
	g_return_if_fail(responder != nullptr);

	g_ptr_array_add(self->responder_list, responder);
	}

	// The loop body to dispatch an event to a responder.
	static void dispatch_to_responder(gpointer responder_data,
	gpointer foreach_data_ptr) {
	DispatchToResponderLoopContext* context =
	reinterpret_cast<DispatchToResponderLoopContext*>(foreach_data_ptr);
	FlKeyResponder* responder = FL_KEY_RESPONDER(responder_data);
	fl_key_responder_handle_event(responder, context->event,
	responder_handle_event_callback,
	context->user_data);
	}

	gboolean fl_keyboard_manager_handle_event(FlKeyboardManager* self,
	FlKeyEvent* event) {
	g_return_val_if_fail(FL_IS_KEYBOARD_MANAGER(self), FALSE);
	g_return_val_if_fail(event != nullptr, FALSE);

	uint64_t incoming_hash = fl_keyboard_manager_get_event_hash(event);
	if (fl_keyboard_manager_remove_redispatched(self, incoming_hash)) {
	return FALSE;
	}

	FlKeyboardPendingEvent* pending = fl_keyboard_pending_event_new(
	event, ++self->last_sequence_id, self->responder_list->len);

	g_ptr_array_add(self->pending_responds, pending);
	FlKeyboardManagerUserData* user_data =
	fl_keyboard_manager_user_data_new(self, pending->sequence_id);
	DispatchToResponderLoopContext data{
	.event = event,
	.user_data = user_data,
	};
	g_ptr_array_foreach(self->responder_list, dispatch_to_responder, &data);

	return TRUE;
	}

	gboolean fl_keyboard_manager_is_state_clear(FlKeyboardManager* self) {
	g_return_val_if_fail(FL_IS_KEYBOARD_MANAGER(self), FALSE);
	return self->pending_responds->len == 0 &&
	self->pending_redispatches->len == 0;
	}