Gamepad API: add support for connection events

content/browser/gamepad/gamepad_provider.cc

 // Copyright (c) 2012 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 <cmath>
 #include <set>
 #include <vector>
 
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/message_loop/message_loop.h"
 #include "base/message_loop/message_loop_proxy.h"
 #include "base/threading/thread.h"
 #include "base/threading/thread_restrictions.h"
 #include "content/browser/gamepad/gamepad_data_fetcher.h"
 #include "content/browser/gamepad/gamepad_platform_data_fetcher.h"
 #include "content/browser/gamepad/gamepad_provider.h"
+#include "content/browser/gamepad/gamepad_service.h"
 #include "content/common/gamepad_hardware_buffer.h"
 #include "content/common/gamepad_messages.h"
 #include "content/common/gamepad_user_gesture.h"
+#include "content/public/browser/browser_thread.h"
+
+using blink::WebGamepad;
+using blink::WebGamepads;
 
 namespace content {
 
 GamepadProvider::ClosureAndThread::ClosureAndThread(
     const base::Closure& c,
     const scoped_refptr<base::MessageLoopProxy>& m)
     : closure(c),
       message_loop(m) {
 }
 
 GamepadProvider::ClosureAndThread::~ClosureAndThread() {
 }
 
 GamepadProvider::GamepadProvider()
     : is_paused_(true),
       have_scheduled_do_poll_(false),
-      devices_changed_(true) {
+      devices_changed_(true),
+      ever_had_user_gesture_(false) {
   Initialize(scoped_ptr<GamepadDataFetcher>());
 }
 
 GamepadProvider::GamepadProvider(scoped_ptr<GamepadDataFetcher> fetcher)
     : is_paused_(true),
       have_scheduled_do_poll_(false),
-      devices_changed_(true) {
+      devices_changed_(true),
+      ever_had_user_gesture_(false) {
   Initialize(fetcher.Pass());
 }
 
 GamepadProvider::~GamepadProvider() {
   base::SystemMonitor* monitor = base::SystemMonitor::Get();
   if (monitor)
     monitor->RemoveDevicesChangedObserver(this);
 
   // Use Stop() to join the polling thread, as there may be pending callbacks
   // which dereference |polling_thread_|.
   polling_thread_->Stop();
   data_fetcher_.reset();
 }
 
 base::SharedMemoryHandle GamepadProvider::GetSharedMemoryHandleForProcess(
     base::ProcessHandle process) {
   base::SharedMemoryHandle renderer_handle;
   gamepad_shared_memory_.ShareToProcess(process, &renderer_handle);
   return renderer_handle;
 }
 
+void GamepadProvider::GetCurrentGamepadData(WebGamepads* data) {
+  const WebGamepads& pads = SharedMemoryAsHardwareBuffer()->buffer;
+  base::AutoLock lock(shared_memory_lock_);
+  *data = pads;
+}
+
 void GamepadProvider::Pause() {
   {
     base::AutoLock lock(is_paused_lock_);
     is_paused_ = true;
   }
   base::MessageLoop* polling_loop = polling_thread_->message_loop();
   polling_loop->PostTask(
       FROM_HERE,
       base::Bind(&GamepadProvider::SendPauseHint, Unretained(this), true));
 }
@@ skipping 28 matching lines @@
 
 void GamepadProvider::Initialize(scoped_ptr<GamepadDataFetcher> fetcher) {
   size_t data_size = sizeof(GamepadHardwareBuffer);
   base::SystemMonitor* monitor = base::SystemMonitor::Get();
   if (monitor)
     monitor->AddDevicesChangedObserver(this);
   bool res = gamepad_shared_memory_.CreateAndMapAnonymous(data_size);
   CHECK(res);
   GamepadHardwareBuffer* hwbuf = SharedMemoryAsHardwareBuffer();
   memset(hwbuf, 0, sizeof(GamepadHardwareBuffer));
+  pad_states_.reset(new PadState[WebGamepads::itemsLengthCap]);
 
   polling_thread_.reset(new base::Thread("Gamepad polling thread"));
 #if defined(OS_LINUX)
   // On Linux, the data fetcher needs to watch file descriptors, so the message
   // loop needs to be a libevent loop.
   const base::MessageLoop::Type kMessageLoopType = base::MessageLoop::TYPE_IO;
 #else
   // On Mac, the data fetcher uses IOKit which depends on CFRunLoop, so the
   // message loop needs to be a UI-type loop. On Windows it must be a UI loop
   // to properly pump the MessageWindow that captures device state.
@@ skipping 17 matching lines @@
     fetcher.reset(new GamepadPlatformDataFetcher);
   data_fetcher_ = fetcher.Pass();
 }
 
 void GamepadProvider::SendPauseHint(bool paused) {
   DCHECK(base::MessageLoop::current() == polling_thread_->message_loop());
   if (data_fetcher_)
     data_fetcher_->PauseHint(paused);
 }
 
+bool GamepadProvider::PadState::Match(const WebGamepad& pad) const {
+  return connected_ == pad.connected &&
+         axes_length_ == pad.axesLength &&
+         buttons_length_ == pad.buttonsLength &&
+         memcmp(id_, pad.id, arraysize(id_)) == 0 &&
+         memcmp(mapping_, pad.mapping, arraysize(mapping_)) == 0;
+}
+
+void GamepadProvider::PadState::SetPad(const WebGamepad& pad) {
+  DCHECK(pad.connected);
+  connected_ = true;
+  axes_length_ = pad.axesLength;
+  buttons_length_ = pad.buttonsLength;
+  memcpy(id_, pad.id, arraysize(id_));
+  memcpy(mapping_, pad.mapping, arraysize(mapping_));
+}
+
+void GamepadProvider::PadState::SetDisconnected() {
+  connected_ = false;
+  axes_length_ = 0;
+  buttons_length_ = 0;
+  memset(id_, 0, arraysize(id_));
+  memset(mapping_, 0, arraysize(mapping_));
+}
+
+void GamepadProvider::PadState::AsWebGamepad(WebGamepad* pad) {
+  pad->connected = connected_;
+  pad->axesLength = axes_length_;
+  pad->buttonsLength = buttons_length_;
+  memcpy(pad->id, id_, arraysize(id_));
+  memcpy(pad->mapping, mapping_, arraysize(mapping_));
+  memset(pad->axes, 0, arraysize(pad->axes));
+  memset(pad->buttons, 0, arraysize(pad->buttons));
+}
+
 void GamepadProvider::DoPoll() {
   DCHECK(base::MessageLoop::current() == polling_thread_->message_loop());
   DCHECK(have_scheduled_do_poll_);
   have_scheduled_do_poll_ = false;
 
   bool changed;
   GamepadHardwareBuffer* hwbuf = SharedMemoryAsHardwareBuffer();
 
   ANNOTATE_BENIGN_RACE_SIZED(
       &hwbuf->buffer,
-      sizeof(blink::WebGamepads),
+      sizeof(WebGamepads),
       "Racey reads are discarded");
 
   {
     base::AutoLock lock(devices_changed_lock_);
     changed = devices_changed_;
     devices_changed_ = false;
   }
 
-  // Acquire the SeqLock. There is only ever one writer to this data.
-  // See gamepad_hardware_buffer.h.
-  hwbuf->sequence.WriteBegin();
-  data_fetcher_->GetGamepadData(&hwbuf->buffer, changed);
-  hwbuf->sequence.WriteEnd();
+  {
+    base::AutoLock lock(shared_memory_lock_);
+
+    // Acquire the SeqLock. There is only ever one writer to this data.
+    // See gamepad_hardware_buffer.h.
+    hwbuf->sequence.WriteBegin();
+    data_fetcher_->GetGamepadData(&hwbuf->buffer, changed);
+    hwbuf->sequence.WriteEnd();
+  }
 
   CheckForUserGesture();
 
+  if (ever_had_user_gesture_) {
+    for (unsigned i = 0; i < WebGamepads::itemsLengthCap; ++i) {
+      WebGamepad& pad = hwbuf->buffer.items[i];
+      PadState& state = pad_states_.get()[i];
+      if (pad.connected && !state.connected()) {
+        OnGamepadConnectionChange(true, i, pad);
+      } else if (!pad.connected && state.connected()) {
+        OnGamepadConnectionChange(false, i, pad);
+      } else if (pad.connected && state.connected() && !state.Match(pad)) {
+        WebGamepad old_pad;
+        state.AsWebGamepad(&old_pad);
+        OnGamepadConnectionChange(false, i, old_pad);
+        OnGamepadConnectionChange(true, i, pad);
+      }
+    }
+  }
+
   // Schedule our next interval of polling.
   ScheduleDoPoll();
 }
 
 void GamepadProvider::ScheduleDoPoll() {
   DCHECK(base::MessageLoop::current() == polling_thread_->message_loop());
   if (have_scheduled_do_poll_)
     return;
 
   {
     base::AutoLock lock(is_paused_lock_);
     if (is_paused_)
       return;
   }
 
   base::MessageLoop::current()->PostDelayedTask(
       FROM_HERE,
       base::Bind(&GamepadProvider::DoPoll, Unretained(this)),
       base::TimeDelta::FromMilliseconds(kDesiredSamplingIntervalMs));
   have_scheduled_do_poll_ = true;
 }
 
+void GamepadProvider::OnGamepadConnectionChange(
+    bool connected, int index, const WebGamepad& pad) {
+  PadState& state = pad_states_.get()[index];
+  if (connected)
+    state.SetPad(pad);
+  else
+    state.SetDisconnected();
+
+  BrowserThread::PostTask(
+      BrowserThread::IO,
+      FROM_HERE,
+      base::Bind(&GamepadProvider::DispatchGamepadConnectionChange,
+                 base::Unretained(this),
+                 connected,
+                 index,
+                 pad));
+}
+
+void GamepadProvider::DispatchGamepadConnectionChange(
+    bool connected, int index, const WebGamepad& pad) {
+  if (connected)
+    GamepadService::GetInstance()->OnGamepadConnected(index, pad);
+  else
+    GamepadService::GetInstance()->OnGamepadDisconnected(index, pad);
+}
+
 GamepadHardwareBuffer* GamepadProvider::SharedMemoryAsHardwareBuffer() {
   void* mem = gamepad_shared_memory_.memory();
   CHECK(mem);
   return static_cast<GamepadHardwareBuffer*>(mem);
 }
 
 void GamepadProvider::CheckForUserGesture() {
   base::AutoLock lock(user_gesture_lock_);
-  if (user_gesture_observers_.empty())
-    return;  // Don't need to check if nobody is listening.
+  if (user_gesture_observers_.empty() && ever_had_user_gesture_)
+    return;
 
   if (GamepadsHaveUserGesture(SharedMemoryAsHardwareBuffer()->buffer)) {
+    ever_had_user_gesture_ = true;
     for (size_t i = 0; i < user_gesture_observers_.size(); i++) {
       user_gesture_observers_[i].message_loop->PostTask(FROM_HERE,
           user_gesture_observers_[i].closure);
     }
     user_gesture_observers_.clear();
   }
 }
 
 }  // namespace content