Expose Gamepad API instance for Cardboard button

device/vr/android/gvr/cardboard_gamepad_data_fetcher.cc

+// Copyright 2017 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 "device/vr/android/gvr/cardboard_gamepad_data_fetcher.h"
+
+#include "base/memory/ptr_util.h"
+#include "base/strings/utf_string_conversions.h"
+#include "device/gamepad/public/cpp/gamepads.h"
+#include "device/vr/android/gvr/cardboard_gamepad_data_provider.h"
+#include "device/vr/vr_types.h"
+
+namespace device {
+
+namespace {
+
+void CopyToUString(UChar* dest, size_t dest_length, base::string16 src) {
+  static_assert(sizeof(base::string16::value_type) == sizeof(UChar),
+                "Mismatched string16/WebUChar size.");
+
+  const size_t str_to_copy = std::min(src.size(), dest_length - 1);
+  memcpy(dest, src.data(), str_to_copy * sizeof(base::string16::value_type));
+  dest[str_to_copy] = 0;
+}
+
+}  // namespace
+
+CardboardGamepadDataFetcher::Factory::Factory(
+    CardboardGamepadDataProvider* data_provider,
+    unsigned int display_id)
+    : data_provider_(data_provider), display_id_(display_id) {
+  DVLOG(1) << __FUNCTION__ << "=" << this;
+}
+
+CardboardGamepadDataFetcher::Factory::~Factory() {
+  DVLOG(1) << __FUNCTION__ << "=" << this;
+}
+
+std::unique_ptr<GamepadDataFetcher>
+CardboardGamepadDataFetcher::Factory::CreateDataFetcher() {
+  return base::MakeUnique<CardboardGamepadDataFetcher>(data_provider_,
+                                                       display_id_);
+}
+
+GamepadSource CardboardGamepadDataFetcher::Factory::source() {
+  return GAMEPAD_SOURCE_CARDBOARD;
+}
+
+CardboardGamepadDataFetcher::CardboardGamepadDataFetcher(
+    CardboardGamepadDataProvider* data_provider,
+    unsigned int display_id)
+    : display_id_(display_id) {
+  // Called on UI thread.
+  DVLOG(1) << __FUNCTION__ << "=" << this;
+  data_provider->RegisterCardboardGamepadDataFetcher(this);
+}
+
+CardboardGamepadDataFetcher::~CardboardGamepadDataFetcher() {
+  DVLOG(1) << __FUNCTION__ << "=" << this;
+}
+
+GamepadSource CardboardGamepadDataFetcher::source() {
+  return GAMEPAD_SOURCE_CARDBOARD;
+}
+
+void CardboardGamepadDataFetcher::OnAddedToProvider() {
+  PauseHint(false);
+}
+
+void CardboardGamepadDataFetcher::SetGamepadData(CardboardGamepadData data) {
+  // Called from UI thread.
+  gamepad_data_ = data;
+}
+
+void CardboardGamepadDataFetcher::GetGamepadData(bool devices_changed_hint) {
+  // Called from gamepad polling thread.
+  PadState* state = GetPadState(0);
+  if (!state)
+    return;
+
+  CardboardGamepadData provided_data = gamepad_data_;
+
+  Gamepad& pad = state->data;
+  if (state->active_state == GAMEPAD_NEWLY_ACTIVE) {
+    // This is the first time we've seen this device, so do some one-time
+    // initialization
+    pad.connected = true;
+    CopyToUString(pad.id, Gamepad::kIdLengthCap,
+                  base::UTF8ToUTF16("Cardboard Controller"));

[bajones, 2017/05/19 22:38:40]

Nit: This sounds weird in this context. Maybe "Cardboard Button" or "Cardboard
Input" instead?

[billorr, 2017/05/22 20:11:09]

Done.

+    CopyToUString(pad.mapping, Gamepad::kMappingLengthCap,
+                  base::UTF8ToUTF16(""));
+    pad.buttons_length = 1;
+    pad.axes_length = 0;
+
+    pad.display_id = display_id_;
+
+    pad.hand = GamepadHand::kNone;
+  }
+
+  pad.timestamp = provided_data.timestamp;
+
+  bool pressed = provided_data.is_screen_touching;
+  pad.buttons[0].touched = pressed;
+  pad.buttons[0].pressed = pressed;
+  pad.buttons[0].value = pressed ? 1.0f : 0.0f;
+  pad.pose.not_null = false;
+}
+
+void CardboardGamepadDataFetcher::PauseHint(bool paused) {}
+
+}  // namespace device