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Side by Side Diff: content/browser/gamepad/gamepad_data_fetcher.cc

Issue 1586663006: Refactoring gamepad polling to support dynamically added sources (Closed) Base URL: https://chromium.googlesource.com/chromium/src.git@master
Patch Set: Created 4 years, 11 months ago
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1 // Copyright (c) 2015 The Chromium Authors. All rights reserved. 1 // Copyright (c) 2015 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be 2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file. 3 // found in the LICENSE file.
4 4
5 #include "content/browser/gamepad/gamepad_data_fetcher.h" 5 #include "content/browser/gamepad/gamepad_data_fetcher.h"
6 6
7 #include <stddef.h>
8 #include <string.h>
9
10 #include "base/logging.h"
11 #include "build/build_config.h"
12
13 namespace {
14
15 #if !defined(OS_ANDROID)
16 const float kMinAxisResetValue = 0.1f;
17 #endif
18
19 } // namespace
20
21 namespace content { 7 namespace content {
22 8
23 using blink::WebGamepad; 9 GamepadDataFetcher::GamepadDataFetcher() : provider_(nullptr) {
24 using blink::WebGamepads; 10 }
25 11
26 #if !defined(OS_ANDROID) 12 void GamepadDataFetcher::InitializeProvider(GamepadProvider* provider) {
27 void GamepadDataFetcher::MapAndSanitizeGamepadData( 13 DCHECK(provider);
28 PadState* pad_state, WebGamepad* pad) {
29 DCHECK(pad_state);
30 DCHECK(pad);
31 14
32 if (!pad_state->data.connected) { 15 provider_ = provider;
33 memset(pad, 0, sizeof(WebGamepad)); 16 OnAddedToProvider();
34 return;
35 }
36
37 // Copy the current state to the output buffer, using the mapping
38 // function, if there is one available.
39 if (pad_state->mapper)
40 pad_state->mapper(pad_state->data, pad);
41 else
42 *pad = pad_state->data;
43
44 // About sanitization: Gamepads may report input event if the user is not
45 // interacting with it, due to hardware problems or environmental ones (pad
46 // has something heavy leaning against an axis.) This may cause user gestures
47 // to be detected erroniously, exposing gamepad information when the user had
48 // no intention of doing so. To avoid this we require that each button or axis
49 // report being at rest (zero) at least once before exposing its value to the
50 // Gamepad API. This state is tracked by the axis_mask and button_mask
51 // bitfields. If the bit for an axis or button is 0 it means the axis has
52 // never reported being at rest, and the value will be forced to zero.
53
54 // We can skip axis sanitation if all available axes have been masked.
55 uint32_t full_axis_mask = (1 << pad->axesLength) - 1;
56 if (pad_state->axis_mask != full_axis_mask) {
57 for (size_t axis = 0; axis < pad->axesLength; ++axis) {
58 if (!(pad_state->axis_mask & 1 << axis)) {
59 if (fabs(pad->axes[axis]) < kMinAxisResetValue) {
60 pad_state->axis_mask |= 1 << axis;
61 } else {
62 pad->axes[axis] = 0.0f;
63 }
64 }
65 }
66 }
67
68 // We can skip button sanitation if all available buttons have been masked.
69 uint32_t full_button_mask = (1 << pad->buttonsLength) - 1;
70 if (pad_state->button_mask != full_button_mask) {
71 for (size_t button = 0; button < pad->buttonsLength; ++button) {
72 if (!(pad_state->button_mask & 1 << button)) {
73 if (!pad->buttons[button].pressed) {
74 pad_state->button_mask |= 1 << button;
75 } else {
76 pad->buttons[button].pressed = false;
77 pad->buttons[button].value = 0.0f;
78 }
79 }
80 }
81 }
82 } 17 }
83 #endif
84 18
85 } // namespace content 19 } // namespace content
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