Refactored gamepad polling to support dynamic sources

device/gamepad/gamepad_pad_state_provider.cc

-// Copyright (c) 2015 The Chromium Authors. All rights reserved.
+// Copyright 2016 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/gamepad/gamepad_data_fetcher.h"
-
-#include <stddef.h>
-#include <string.h>
+#include "device/gamepad/gamepad_pad_state_provider.h"
 
 #include <cmath>
 
-#include "base/logging.h"
-#include "build/build_config.h"
-
-namespace {
-
-#if !defined(OS_ANDROID)
-const float kMinAxisResetValue = 0.1f;
-#endif
-
-}  // namespace
-
-namespace device {
+#include "device/gamepad/gamepad_data_fetcher.h"
+#include "third_party/WebKit/public/platform/WebGamepads.h"
 
 using blink::WebGamepad;
 using blink::WebGamepads;
 
-#if !defined(OS_ANDROID)
-void GamepadDataFetcher::MapAndSanitizeGamepadData(PadState* pad_state,
-                                                   WebGamepad* pad) {
+namespace device {
+
+namespace {
+
+const float kMinAxisResetValue = 0.1f;
+
+}  // namespace
+
+GamepadPadStateProvider::GamepadPadStateProvider() {
+  pad_states_.reset(new PadState[WebGamepads::itemsLengthCap]);
+
+  for (unsigned i = 0; i < WebGamepads::itemsLengthCap; ++i)
+    ClearPadState(pad_states_.get()[i]);
+}
+
+GamepadPadStateProvider::~GamepadPadStateProvider() {}
+
+PadState* GamepadPadStateProvider::GetPadState(GamepadSource source,
+                                               int source_id) {
+  // Check to see if the device already has a reserved slot
+  PadState* empty_slot = nullptr;
+  for (size_t i = 0; i < WebGamepads::itemsLengthCap; ++i) {
+    PadState& state = pad_states_.get()[i];
+    if (state.source == source && state.source_id == source_id) {
+      // Retrieving the pad state marks this gamepad as active.
+      state.active_state = GAMEPAD_ACTIVE;
+      return &state;
+    }
+    if (!empty_slot && state.source == GAMEPAD_SOURCE_NONE)
+      empty_slot = &state;
+  }
+  if (empty_slot) {
+    empty_slot->source = source;
+    empty_slot->source_id = source_id;
+    empty_slot->active_state = GAMEPAD_NEWLY_ACTIVE;
+  }
+  return empty_slot;
+}
+
+void GamepadPadStateProvider::ClearPadState(PadState& state) {
+  memset(&state, 0, sizeof(PadState));
+}
+
+void GamepadPadStateProvider::InitializeDataFetcher(
+    GamepadDataFetcher* fetcher) {
+  fetcher->InitializeProvider(this);
+}
+
+void GamepadPadStateProvider::MapAndSanitizeGamepadData(PadState* pad_state,
+                                                        WebGamepad* pad,
+                                                        bool sanitize) {
   DCHECK(pad_state);
   DCHECK(pad);
 
   if (!pad_state->data.connected) {
     memset(pad, 0, sizeof(WebGamepad));
     return;
   }
 
   // Copy the current state to the output buffer, using the mapping
   // function, if there is one available.
   if (pad_state->mapper)
     pad_state->mapper(pad_state->data, pad);
   else
     *pad = pad_state->data;
 
+  pad->connected = true;
+
+  if (!sanitize)
+    return;
+
   // About sanitization: Gamepads may report input event if the user is not
   // interacting with it, due to hardware problems or environmental ones (pad
   // has something heavy leaning against an axis.) This may cause user gestures
   // to be detected erroniously, exposing gamepad information when the user had
   // no intention of doing so. To avoid this we require that each button or axis
   // report being at rest (zero) at least once before exposing its value to the
   // Gamepad API. This state is tracked by the axis_mask and button_mask
   // bitfields. If the bit for an axis or button is 0 it means the axis has
   // never reported being at rest, and the value will be forced to zero.
 
@@ skipping 19 matching lines @@
         if (!pad->buttons[button].pressed) {
           pad_state->button_mask |= 1 << button;
         } else {
           pad->buttons[button].pressed = false;
           pad->buttons[button].value = 0.0f;
         }
       }
     }
   }
 }
-#endif
 
-}  // namespace device
+}  // namespace device