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// Copyright (c) 2013 The Chromium 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 PPAPI_CPP_EXTENSIONS_EVENT_BASE_H_
#define PPAPI_CPP_EXTENSIONS_EVENT_BASE_H_
#include "ppapi/c/extensions/dev/ppb_ext_events_dev.h"
#include "ppapi/c/pp_macros.h"
#include "ppapi/c/pp_stdint.h"
#include "ppapi/c/pp_var.h"
#include "ppapi/cpp/extensions/from_var_converter.h"
#include "ppapi/cpp/instance_handle.h"
#include "ppapi/cpp/logging.h"
namespace pp {
namespace ext {
namespace internal {
// This file contains base classes for events. Usually you don't need to use
// them directly.
//
// For each event type, there is a corresponding event class derived from
// EventBase[0-3]. The event class defines a Listener interface and exposes the
// public methods of GenericEventBase.
//
// Take pp::ext::alarms::OnAlarmEvent_Dev as example, your code to listen to the
// event would look like this:
//
// class MyListener : public pp::ext::alarms::OnAlarmEvent_Dev {
// ...
// // The parameter is a non-const reference so you could directly modify it
// // if necessary.
// virtual void OnAlarm(Alarm_Dev& alarm) {
// ...handle the event...
// }
// };
//
// MyListener on_alarm_listener;
// // The listener is not owned by the event and must outlive it.
// pp::ext::alarms::OnAlarmEvent_Dev on_alarm(instance, &on_alarm_listener);
// on_alarm.StartListening();
// ...
// // It is guaranteed that |on_alarm_listener| won't get called after
// // |on_alarm| goes away. So this step is optional.
// on_alarm.StopListening();
class GenericEventBase {
public:
bool StartListening();
void StopListening();
bool IsListening() const { return listener_id_ != 0; }
uint32_t listener_id() const { return listener_id_; }
protected:
GenericEventBase(const InstanceHandle& instance,
const PP_Ext_EventListener& pp_listener);
~GenericEventBase();
InstanceHandle instance_;
uint32_t listener_id_;
const PP_Ext_EventListener pp_listener_;
private:
// Disallow copying and assignment.
GenericEventBase(const GenericEventBase&);
GenericEventBase& operator=(const GenericEventBase&);
};
// EventBase[0-3] are event base classes which can be instantiated with a
// pointer to a PP_Ext_EventListener creation function and the input parameter
// types of the listener callback.
//
// For example, EvenBase1<PP_Ext_Alarms_OnAlarm_Dev, Alarm_Dev> deals with
// the event type defined by the PP_Ext_Alarms_OnAlarm_Dev function pointer. And
// it defines a pure virtual method as the listener callback:
// virtual void Callback(Alarm_Dev&) = 0;
typedef PP_Ext_EventListener (*CreatePPEventListener0)(
void (*)(uint32_t, void*), void*);
template <const CreatePPEventListener0 kCreatePPEventListener0>
class EventBase0 : public GenericEventBase {
public:
explicit EventBase0(const InstanceHandle& instance)
: PP_ALLOW_THIS_IN_INITIALIZER_LIST(
GenericEventBase(instance,
kCreatePPEventListener0(&CallbackThunk, this))) {
}
virtual ~EventBase0() {}
private:
virtual void Callback() = 0;
static void CallbackThunk(uint32_t listener_id, void* user_data) {
EventBase0<kCreatePPEventListener0>* event_base =
static_cast<EventBase0<kCreatePPEventListener0>*>(user_data);
PP_DCHECK(listener_id == event_base->listener_id_);
// Suppress unused variable warnings.
static_cast<void>(listener_id);
event_base->Callback();
}
// Disallow copying and assignment.
EventBase0(const EventBase0<kCreatePPEventListener0>&);
EventBase0<kCreatePPEventListener0>& operator=(
const EventBase0<kCreatePPEventListener0>&);
};
typedef PP_Ext_EventListener (*CreatePPEventListener1)(
void (*)(uint32_t, void*, PP_Var), void*);
template <const CreatePPEventListener1 kCreatePPEventListener1, class A>
class EventBase1 : public GenericEventBase {
public:
explicit EventBase1(const InstanceHandle& instance)
: PP_ALLOW_THIS_IN_INITIALIZER_LIST(
GenericEventBase(instance,
kCreatePPEventListener1(&CallbackThunk, this))) {
}
virtual ~EventBase1() {}
private:
virtual void Callback(A&) = 0;
static void CallbackThunk(uint32_t listener_id,
void* user_data,
PP_Var var_a) {
EventBase1<kCreatePPEventListener1, A>* event_base =
static_cast<EventBase1<kCreatePPEventListener1, A>*>(user_data);
PP_DCHECK(listener_id == event_base->listener_id_);
// Suppress unused variable warnings.
static_cast<void>(listener_id);
FromVarConverter<A> a(var_a);
event_base->Callback(a.value());
}
// Disallow copying and assignment.
EventBase1(const EventBase1<kCreatePPEventListener1, A>&);
EventBase1<kCreatePPEventListener1, A>& operator=(
const EventBase1<kCreatePPEventListener1, A>&);
};
typedef PP_Ext_EventListener (*CreatePPEventListener2)(
void (*)(uint32_t, void*, PP_Var, PP_Var), void*);
template <const CreatePPEventListener2 kCreatePPEventListener2,
class A,
class B>
class EventBase2 : public GenericEventBase {
public:
explicit EventBase2(const InstanceHandle& instance)
: PP_ALLOW_THIS_IN_INITIALIZER_LIST(
GenericEventBase(instance,
kCreatePPEventListener2(&CallbackThunk, this))) {
}
virtual ~EventBase2() {}
private:
virtual void Callback(A&, B&) = 0;
static void CallbackThunk(uint32_t listener_id,
void* user_data,
PP_Var var_a,
PP_Var var_b) {
EventBase2<kCreatePPEventListener2, A, B>* event_base =
static_cast<EventBase2<kCreatePPEventListener2, A, B>*>(user_data);
PP_DCHECK(listener_id == event_base->listener_id_);
// Suppress unused variable warnings.
static_cast<void>(listener_id);
FromVarConverter<A> a(var_a);
FromVarConverter<B> b(var_b);
event_base->Callback(a.value(), b.value());
}
// Disallow copying and assignment.
EventBase2(const EventBase2<kCreatePPEventListener2, A, B>&);
EventBase2<kCreatePPEventListener2, A, B>& operator=(
const EventBase2<kCreatePPEventListener2, A, B>&);
};
typedef PP_Ext_EventListener (*CreatePPEventListener3)(
void (*)(uint32_t, void*, PP_Var, PP_Var, PP_Var), void*);
template <const CreatePPEventListener3 kCreatePPEventListener3,
class A,
class B,
class C>
class EventBase3 : public GenericEventBase {
public:
explicit EventBase3(const InstanceHandle& instance)
: PP_ALLOW_THIS_IN_INITIALIZER_LIST(
GenericEventBase(instance,
kCreatePPEventListener3(&CallbackThunk, this))) {
}
virtual ~EventBase3() {}
private:
virtual void Callback(A&, B&, C&) = 0;
static void CallbackThunk(uint32_t listener_id,
void* user_data,
PP_Var var_a,
PP_Var var_b,
PP_Var var_c) {
EventBase3<kCreatePPEventListener3, A, B, C>* event_base =
static_cast<EventBase3<kCreatePPEventListener3, A, B, C>*>(user_data);
PP_DCHECK(listener_id == event_base->listener_id_);
// Suppress unused variable warnings.
static_cast<void>(listener_id);
FromVarConverter<A> a(var_a);
FromVarConverter<B> b(var_b);
FromVarConverter<C> c(var_c);
event_base->Callback(a.value(), b.value(), c.value());
}
// Disallow copying and assignment.
EventBase3(const EventBase3<kCreatePPEventListener3, A, B, C>&);
EventBase3<kCreatePPEventListener3, A, B, C>& operator=(
const EventBase3<kCreatePPEventListener3, A, B, C>&);
};
} // namespace internal
} // namespace ext
} // namespace pp
#endif // PPAPI_CPP_EXTENSIONS_EVENT_BASE_H_
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