Gamepad API support for chrome on android

content/public/android/java/src/org/chromium/content/browser/GamepadList.java

+// Copyright 2014 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.
+
+package org.chromium.content.browser;
+
+import android.content.Context;
+import android.hardware.input.InputManager;
+import android.hardware.input.InputManager.InputDeviceListener;
+import android.view.InputDevice;
+import android.view.InputEvent;
+import android.view.KeyEvent;
+import android.view.MotionEvent;
+
+import org.chromium.base.CalledByNative;
+import org.chromium.base.JNINamespace;
+
+/*
+ * Class to manage connected gamepad devices list.
+ */
+@JNINamespace("content")
+class GamepadList implements InputDeviceListener {
+    private static final int MAX_GAMEPADS = 4;
+    private GamepadDevice[] mGamepadDevices = new GamepadDevice[MAX_GAMEPADS];
+    protected boolean mHaveDevicesBeenInteractedWith = false;
+    private boolean IS_GAMEPAD_ACCESSED = false;

[kbalazs, 2014/02/20 00:48:24]

Shouldn't be named with initials since it's not a constant :)

[SaurabhK, 2014/02/26 14:14:26]

On 2014/02/20 00:48:24, kbalazs wrote:

Done.

+    private InputManager inputManager;

[xwang, 2014/02/25 10:26:58]

inputManager -> mInputManager?

[SaurabhK, 2014/02/26 14:14:26]

On 2014/02/25 10:26:58, xwang wrote:

Done.

+    // Native pointer to C++ GamepadReader object which will be set by CreateJavaObject().
+    private long mNativeGamepadReader = 0;
+
+    private GamepadList(Context context) {
+
+        inputManager =  (InputManager) context.getSystemService(Context.INPUT_SERVICE);
+        // Get list of all the attached input devices.
+        int[] deviceIds = inputManager.getInputDeviceIds();
+
+        for (int i = 0; i < deviceIds.length; i++) {
+            InputDevice inputDevice = InputDevice.getDevice(deviceIds[i]);
+            // Check for gamepad device
+            if (isGamepadDevice(inputDevice)) {
+                // Register a new gamepad device.
+                registerGamepad(inputDevice);
+            }
+        }
+        // Register an input device listener.
+        inputManager.registerInputDeviceListener(this, null);
+    }
+
+    private static GamepadList gamepadList = null;

[xwang, 2014/02/25 10:26:58]

gamepadList -> sGamepadList

[SaurabhK, 2014/02/26 14:14:26]

On 2014/02/25 10:26:58, xwang wrote:

Done.

+
+    // Override InputDeviceListener methods
+    @Override
+    public void onInputDeviceChanged(int deviceId) {
+    }
+
+    @Override
+    public void onInputDeviceRemoved(int deviceId) {
+        unregisterGamepad(deviceId);
+    }
+
+    @Override
+    public void onInputDeviceAdded(int deviceId) {
+        InputDevice inputDevice = InputDevice.getDevice(deviceId);
+        if (isGamepadDevice(inputDevice))
+            registerGamepad(inputDevice);
+    }
+
+    public static GamepadList createInstance(Context context) {
+        if (gamepadList != null) {
+            return gamepadList;
+        } else {
+            gamepadList = new GamepadList(context);
+            return gamepadList;
+        }
+    }
+
+    private boolean haveDevicesBeenInteractedWith() { return mHaveDevicesBeenInteractedWith; }

[xwang, 2014/02/25 10:26:58]

Is it necessary to add a private function to access
mHaveDevicesBeenInteractedWith?
I feel it's straightforward to use it directly.

[SaurabhK, 2014/02/26 14:14:26]

On 2014/02/25 10:26:58, xwang wrote:

Removed it.
It was earlier getting used when i was passing it to Native. Now it is not
needed.

+
+    private int getDeviceCount() {
+        int count = 0;
+        for (int i = 0; i < getCount(); ++i) {
+            if (getDevice(i) != null) {
+                count++;
+            }
+        }
+        return count;
+    }
+
+    private String getDeviceName(int index) {
+        return getDevice(index).getName();
+    }
+
+    private long getDeviceTimestamp(int index) {
+        return getDevice(index).getTimestamp();
+    }
+
+    private float[] getDeviceAxes(int index) {
+        return getDevice(index).getAxes();
+    }
+
+    private float[] getDeviceButtons(int index) {
+        return getDevice(index).getButtons();
+    }
+
+    private boolean isDeviceConnected(int index) {
+        if (index < MAX_GAMEPADS && getDevice(index) != null) {
+            return true;
+        }
+        return false;
+    }
+
+    private boolean isKnownGamepadLayout(int index) {
+        return getDevice(index).isKnownGamepadLayout();
+    }
+
+    public GamepadDevice getDeviceById(int deviceId) {
+        for (int i = 0; i < getCount(); ++i) {
+            GamepadDevice gamepad = mGamepadDevices[i];
+            if (gamepad != null && gamepad.getId() == deviceId) {
+                return gamepad;
+            }
+        }
+        return null;
+    }
+
+    public GamepadDevice getDevice(int index) {
+        // Maximum 4 Gamepads can be connected at a time starting at index zero.
+        assert index >= 0 && index <= getCount() - 1;
+        return mGamepadDevices[index];
+    }
+
+    public int getCount() {

[kbalazs, 2014/02/20 00:48:24]

This doesn't look very useful to me, I would just use the constant directly.

[SaurabhK, 2014/02/26 14:14:26]

On 2014/02/20 00:48:24, kbalazs wrote:

Done.

+        return MAX_GAMEPADS;
+    }
+
+    public boolean updateForEvent(KeyEvent event) {
+        GamepadDevice gamepad = getGamepadForEvent(event);
+        if (gamepad != null) {
+            mHaveDevicesBeenInteractedWith = true;

[kbalazs, 2014/02/20 00:48:24]

I think it's not strictly necessary to maintain this. The renderer side shared
memory reader (GamepadSharedMemoryReader) checks this to prevent fingerprinting.

+            return gamepad.updateForEvent(event);
+        }
+        return false;
+    }
+
+    public boolean updateForEvent(MotionEvent event) {
+        GamepadDevice gamepad = getGamepadForEvent(event);
+        if (gamepad != null) {
+            mHaveDevicesBeenInteractedWith = true;
+            return gamepad.updateForEvent(event);
+        }
+        return false;
+    }
+
+    public void onPause() {
+        inputManager.unregisterInputDeviceListener(this);
+    }
+
+    public void onResume() {
+        // Re-initialize gamepad list.
+        // Check if any registered gamepad is disconnected when webview was in pause state.

[kbalazs, 2014/02/20 00:48:24]

Can you word it more generally? This feature is not just for the webview so we
shouldn't refer to it exclusively.

[SaurabhK, 2014/02/26 14:14:26]

On 2014/02/20 00:48:24, kbalazs wrote:

Removing onPause and onResume as it is already getting discussed in another CL.

+        for (int i = 0; i < getCount(); ++i) {

[kbalazs, 2014/02/20 00:48:24]

Isn't it enough to null out the array and enumerate again? You could move it to
a common method in this case and call it from the constructor. Or you want to
keep the original index for devices we already saw?

+            if (mGamepadDevices[i] != null) {
+                InputDevice device = InputDevice.getDevice(mGamepadDevices[i].getId());
+                if (device == null) {
+                    // Remove disconnected gamepad.
+                    mGamepadDevices[i] = null;
+                }
+            }
+        }
+        // Check if any new gamepad is connected when webview was in pause state.
+        int[] deviceIds = inputManager.getInputDeviceIds();
+        for (int i = 0; i < deviceIds.length; ++i) {
+            InputDevice device = InputDevice.getDevice(deviceIds[i]);
+            if (isGamepadDevice(device)) {
+                GamepadDevice gamepad = getDeviceById(deviceIds[i]);
+                if (gamepad == null) {
+                    // Found unregistered gamepad, could be a new device connected when
+                    // webview was in puase state or disconnected and re-connected same device.
+                    registerGamepad(device);
+                }
+            }
+        }
+        inputManager.registerInputDeviceListener(this, null);
+    }
+
+    protected int getNextAvailableIndex() {
+        // When multiple gamepads are connected to a user agent, indices must be assigned on a
+        // first-come first-serve basis, starting at zero. If a gamepad is disconnected, previously
+        // assigned indices must not be reassigned to gamepads that continue to be connected.
+        // However, if a gamepad is disconnected, and subsequently the same or a different
+        // gamepad is then connected, index entries must be reused.
+
+        for (int i = 0; i < getCount(); ++i) {
+            if (getDevice(i) == null) {
+                return i;
+            }
+        }
+        // Reached maximum gamepads limit.
+        return -1;
+    }
+
+    protected boolean registerGamepad(InputDevice inputDevice) {
+        int index = getNextAvailableIndex();
+        if (index == -1) {
+            return false; // invalid index
+        }
+
+        GamepadDevice gamepad = new GamepadDevice(index, inputDevice);
+        mGamepadDevices[index] = gamepad;
+        return true;
+    }
+
+    protected void unregisterGamepad(int deviceId) {
+        GamepadDevice gamepadDevice = getDeviceById(deviceId);
+        if (gamepadDevice == null) {
+            return; // Not a registered device.
+        }
+        int index = gamepadDevice.getIndex();
+        mGamepadDevices[index] = null;
+    }
+
+    private boolean isGamepadDevice(InputDevice inputDevice) {
+        int sources = inputDevice.getSources();
+            if ((sources & InputDevice.SOURCE_JOYSTICK) == InputDevice.SOURCE_JOYSTICK ) {

[kbalazs, 2014/02/20 00:48:24]

Shouln't it be '(sources & InputDevice.SOURCE_JOYSTICK) != 0'?

I'm not sure but the documentation says an input device can have multiple inputs
and probably we want it to be true for everything that provides joystick input.

+                //Found gamepad device
+                return true;
+            }
+        return false;
+    }
+
+    private GamepadDevice getGamepadForEvent(InputEvent event) {
+        int deviceId = event.getDeviceId();
+        GamepadDevice gamepad = getDeviceById(deviceId);
+        return gamepad;
+    }
+
+    public boolean isGamepadAccessed() {
+        return IS_GAMEPAD_ACCESSED;
+    }
+
+    public boolean isGamepadEvent(MotionEvent event) {
+        if ((event.getSource() & InputDevice.SOURCE_JOYSTICK) == InputDevice.SOURCE_JOYSTICK) {

[kbalazs, 2014/02/20 00:48:24]

Ditto about the condition.

+            return true;
+        }
+        return false;
+    }
+
+    // Returns true if event's keycode corresponds to a gamepad key.
+    // Specific handling for dpad keys is required because
+    // KeyEvent.isGamepadButton doesn't consider dpad keys.
+    public boolean isGamepadEvent(KeyEvent event) {
+        int keyCode = event.getKeyCode();
+        switch (keyCode) {
+            case KeyEvent.KEYCODE_DPAD_UP:
+            case KeyEvent.KEYCODE_DPAD_DOWN:
+            case KeyEvent.KEYCODE_DPAD_LEFT:
+            case KeyEvent.KEYCODE_DPAD_RIGHT:
+                return true;
+            default:
+                return KeyEvent.isGamepadButton(keyCode);
+        }
+    }
+
+    @CalledByNative
+    private void getGamepadData() {
+        int devicecount = getDeviceCount();
+        if (devicecount == 0 || !haveDevicesBeenInteractedWith())
+            nativeUpdateDeviceCount(mNativeGamepadReader, 0);
+        else
+            nativeUpdateDeviceCount(mNativeGamepadReader, devicecount);
+            for (int i = 0; i < MAX_GAMEPADS; i++) {
+                if (isDeviceConnected(i))
+                    nativeSetGamepadData(mNativeGamepadReader, i, true, getDeviceName(i),
+                                         getDeviceTimestamp(i), getDeviceAxes(i),
+                                         getDeviceButtons(i));
+                else
+                    nativeSetGamepadData(mNativeGamepadReader, i, false, null, 0, null, null);
+            }
+    }
+
+    @CalledByNative
+    public static GamepadList getInstance(long nativeGamepadReader) {
+        if (gamepadList != null) {
+            gamepadList.mNativeGamepadReader = nativeGamepadReader;
+            return gamepadList;
+        } else {
+            return null;
+        }
+    }
+
+    @CalledByNative
+    private void notifyForGamepadsAccess(boolean isaccesspaused) {
+        IS_GAMEPAD_ACCESSED = !isaccesspaused;
+    }
+
+    private native void nativeSetGamepadData(long nativeGamepadsReader,
+                                             int index,
+                                             boolean connected,
+                                             String devicename,
+                                             long timestamp,
+                                             float[] axes,
+                                             float[] buttons);
+
+    private native void nativeUpdateDeviceCount(long nativeGamepadsReader, int devicecount);
+
+}