Refactoring gamepad polling to support dynamically added sources

content/browser/gamepad/gamepad_data_fetcher.cc

 // Copyright (c) 2015 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 "content/browser/gamepad/gamepad_data_fetcher.h"
 
-#include <stddef.h>
-#include <string.h>
-
-#include "base/logging.h"
-#include "build/build_config.h"
-
-namespace {
-
-#if !defined(OS_ANDROID)
-const float kMinAxisResetValue = 0.1f;
-#endif
-
-}  // namespace
-
 namespace content {
 
-using blink::WebGamepad;
-using blink::WebGamepads;
+GamepadDataFetcher::GamepadDataFetcher() : provider_(nullptr) {
+}
 
-#if !defined(OS_ANDROID)
-void GamepadDataFetcher::MapAndSanitizeGamepadData(
-    PadState* pad_state, WebGamepad* pad) {
-  DCHECK(pad_state);
-  DCHECK(pad);
+void GamepadDataFetcher::InitializeProvider(GamepadProvider* provider) {
+  DCHECK(provider);
 
-  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;
-
-  // 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.
-
-  // We can skip axis sanitation if all available axes have been masked.
-  uint32_t full_axis_mask = (1 << pad->axesLength) - 1;
-  if (pad_state->axis_mask != full_axis_mask) {
-    for (size_t axis = 0; axis < pad->axesLength; ++axis) {
-      if (!(pad_state->axis_mask & 1 << axis)) {
-        if (fabs(pad->axes[axis]) < kMinAxisResetValue) {
-          pad_state->axis_mask |= 1 << axis;
-        } else {
-          pad->axes[axis] = 0.0f;
-        }
-      }
-    }
-  }
-
-  // We can skip button sanitation if all available buttons have been masked.
-  uint32_t full_button_mask = (1 << pad->buttonsLength) - 1;
-  if (pad_state->button_mask != full_button_mask) {
-    for (size_t button = 0; button < pad->buttonsLength; ++button) {
-      if (!(pad_state->button_mask & 1 << button)) {
-        if (!pad->buttons[button].pressed) {
-          pad_state->button_mask |= 1 << button;
-        } else {
-          pad->buttons[button].pressed = false;
-          pad->buttons[button].value = 0.0f;
-        }
-      }
-    }
-  }
+  provider_ = provider;
+  OnAddedToProvider();
 }
-#endif
 
 }  // namespace content