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// Copyright 2014 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.
#include "ui/events/platform/platform_event_source.h"
#include <algorithm>
#include "base/lazy_instance.h"
#include "base/threading/thread_local.h"
#include "ui/events/platform/platform_event_dispatcher.h"
#include "ui/events/platform/platform_event_observer.h"
#include "ui/events/platform/scoped_event_dispatcher.h"
namespace ui {
namespace {
// PlatformEventSource singleton is thread local so that different instances
// can be used on different threads (e.g. browser thread should be able to
// access PlatformEventSource owned by the UI Service's thread).
base::LazyInstance<base::ThreadLocalPointer<PlatformEventSource>>::Leaky
lazy_tls_ptr = LAZY_INSTANCE_INITIALIZER;
} // namespace
PlatformEventSource::PlatformEventSource()
: overridden_dispatcher_(NULL),
overridden_dispatcher_restored_(false) {
CHECK(!lazy_tls_ptr.Pointer()->Get())
<< "Only one platform event source can be created.";
lazy_tls_ptr.Pointer()->Set(this);
}
PlatformEventSource::~PlatformEventSource() {
CHECK_EQ(this, lazy_tls_ptr.Pointer()->Get());
lazy_tls_ptr.Pointer()->Set(nullptr);
}
PlatformEventSource* PlatformEventSource::GetInstance() {
return lazy_tls_ptr.Pointer()->Get();
}
void PlatformEventSource::AddPlatformEventDispatcher(
PlatformEventDispatcher* dispatcher) {
CHECK(dispatcher);
dispatchers_.AddObserver(dispatcher);
OnDispatcherListChanged();
}
void PlatformEventSource::RemovePlatformEventDispatcher(
PlatformEventDispatcher* dispatcher) {
dispatchers_.RemoveObserver(dispatcher);
OnDispatcherListChanged();
}
std::unique_ptr<ScopedEventDispatcher> PlatformEventSource::OverrideDispatcher(
PlatformEventDispatcher* dispatcher) {
CHECK(dispatcher);
overridden_dispatcher_restored_ = false;
return std::make_unique<ScopedEventDispatcher>(&overridden_dispatcher_,
dispatcher);
}
void PlatformEventSource::StopCurrentEventStream() {
}
void PlatformEventSource::AddPlatformEventObserver(
PlatformEventObserver* observer) {
CHECK(observer);
observers_.AddObserver(observer);
}
void PlatformEventSource::RemovePlatformEventObserver(
PlatformEventObserver* observer) {
observers_.RemoveObserver(observer);
}
uint32_t PlatformEventSource::DispatchEvent(PlatformEvent platform_event) {
uint32_t action = POST_DISPATCH_PERFORM_DEFAULT;
for (PlatformEventObserver& observer : observers_)
observer.WillProcessEvent(platform_event);
// Give the overridden dispatcher a chance to dispatch the event first.
if (overridden_dispatcher_)
action = overridden_dispatcher_->DispatchEvent(platform_event);
if (action & POST_DISPATCH_PERFORM_DEFAULT) {
for (PlatformEventDispatcher& dispatcher : dispatchers_) {
if (dispatcher.CanDispatchEvent(platform_event))
action = dispatcher.DispatchEvent(platform_event);
if (action & POST_DISPATCH_STOP_PROPAGATION)
break;
}
}
for (PlatformEventObserver& observer : observers_)
observer.DidProcessEvent(platform_event);
// If an overridden dispatcher has been destroyed, then the platform
// event-source should halt dispatching the current stream of events, and wait
// until the next message-loop iteration for dispatching events. This lets any
// nested message-loop to unwind correctly and any new dispatchers to receive
// the correct sequence of events.
if (overridden_dispatcher_restored_)
StopCurrentEventStream();
overridden_dispatcher_restored_ = false;
return action;
}
void PlatformEventSource::OnDispatcherListChanged() {
}
void PlatformEventSource::OnOverriddenDispatcherRestored() {
CHECK(overridden_dispatcher_);
overridden_dispatcher_restored_ = true;
}
} // namespace ui
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