ozone: evdev: Add gamepad support

ui/events/ozone/gamepad/webgamepad_constants.h

+// Copyright (c) 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.
+
+#ifndef UI_EVENTS_OZONE_GAMEPAD_WEBGAMEPAD_CONSTANTS_H_
+#define UI_EVENTS_OZONE_GAMEPAD_WEBGAMEPAD_CONSTANTS_H_
+
+#include <stdint.h>
+
+namespace ui {
+
+// We care about three type of gamepad events.
+enum class GamepadEventType { BUTTON, AXIS, FRAME };
+
+// This WebGamepadButtonType matches the index of gamepad button defined in w3c
+// standard gamepad.
+enum WebGamepadButtonType {
+  WG_BUTTON_A = 0,
+  WG_BUTTON_B = 1,
+  WG_BUTTON_X = 2,
+  WG_BUTTON_Y = 3,
+  WG_BUTTON_L1 = 4,
+  WG_BUTTON_R1 = 5,
+  WG_BUTTON_L2 = 6,
+  WG_BUTTON_R2 = 7,
+  WG_BUTTON_SELECT = 8,
+  WG_BUTTON_START = 9,
+  WG_BUTTON_THUMBL = 10,
+  WG_BUTTON_THUMBR = 11,
+  WG_BUTTON_DPAD_UP = 12,
+  WG_BUTTON_DPAD_DOWN = 13,
+  WG_BUTTON_DPAD_LEFT = 14,
+  WG_BUTTON_DPAD_RIGHT = 15,
+  WG_BUTTON_MODE = 16
+};
+
+// This WebGamepadAbsType matches the index of gamepad abs defined in w3c
+// standard gamepad.
+enum WebGamepadAbsType {
+  WG_ABS_X = 0,
+  WG_ABS_Y = 1,
+  WG_ABS_Z = 2,
+  WG_ABS_RZ = 3
+};
+
+constexpr uint16_t kWebGamepadBtnCnt = 17;

[scottmg, 2017/05/01 18:20:53]

Can you make these values in their respective enumerations instead?

[jkwang, 2017/05/01 22:21:57]

Done.

+constexpr uint16_t kWebGamepadAbsCnt = 4;
+
+// Following constants are used to normalize abs values to web gamepad standard.
+constexpr double kWebGamepadTriggerMin = 0.0;
+constexpr double kWebGamepadTriggerMax = 1.0;
+constexpr double kWebGamepadJoystickMin = -1.0;
+constexpr double kWebGamepadJoystickMax = 1.0;
+
+}  // namespace ui
+
+#endif  // UI_EVENTS_OZONE_EVDEV_WEBGAMEPAD_CONSTANTS_H_