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;
+import org.chromium.base.ThreadUtils;
+
+/*
+ * 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];

[Ted C, 2014/04/04 18:52:18]

for readability, try to order the params like:

static finals
statics
finals
other members

Blank lines can sometimes help separate them as well.

[SaurabhK, 2014/04/11 14:41:42]

On 2014/04/04 18:52:18, Ted C wrote:

Done.

+    private boolean mIsGamepadAccessed = false;

[Ted C, 2014/04/04 18:52:18]

false is the default, so it's not needed

[SaurabhK, 2014/04/11 14:41:42]

On 2014/04/04 18:52:18, Ted C wrote:

Removed

+    private final Object mLock = new Object();
+    private InputManager mInputManager;
+    private int mAttachedToWindowCounter;
+
+    private GamepadList() {}
+
+    private void initializeDevices() {
+        // Get list of all the attached input devices.
+        int[] deviceIds = mInputManager.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);
+            }
+        }
+    }
+
+    private static GamepadList sGamepadList = null;

[Ted C, 2014/04/04 18:52:18]

move this up with the other params.

[SaurabhK, 2014/04/11 14:41:42]

On 2014/04/04 18:52:18, Ted C wrote:

Done.

+
+    /**
+    * Notifies the GamepadList that a {@link ContentView} is attached to a window and it should
+    * prepare itself for gamepad input. It must be called before {@link onGenericMotionEvent} and
+    * {@link dispatchKeyEvent}.
+    */
+    public static void onAttachedToWindow(Context context) {
+        assert ThreadUtils.runningOnUiThread();
+        createInstance();
+        sGamepadList.attachedToWindow(context);
+    }
+
+    private void attachedToWindow(Context context) {
+        if (mAttachedToWindowCounter++ == 0) {
+            mInputManager =  (InputManager) context.getSystemService(Context.INPUT_SERVICE);
+            synchronized (mLock) {
+                initializeDevices();
+            }
+            // Register an input device listener.
+            mInputManager.registerInputDeviceListener(this, null);
+        }
+    }
+
+    /**
+    * Notifies the GamepadList that a {@link ContentView} is detached from it's window.
+    */
+    public static void onDetachedFromWindow() {
+        assert ThreadUtils.runningOnUiThread();
+        sGamepadList.detachedFromWindow();
+    }
+
+    private void detachedFromWindow() {
+        if (--mAttachedToWindowCounter == 0) {
+            synchronized (mLock) {
+                for (int i = 0; i < MAX_GAMEPADS; ++i) {
+                    mGamepadDevices[i] = null;
+                }
+            }
+            mInputManager.unregisterInputDeviceListener(this);
+            mInputManager = null;
+        }
+    }
+
+    // ------------------------------------------------------------
+
+    // Override InputDeviceListener methods
+    @Override
+    public void onInputDeviceChanged(int deviceId) {
+    }
+
+    @Override
+    public void onInputDeviceRemoved(int deviceId) {
+        synchronized (mLock) {
+            unregisterGamepad(deviceId);
+        }
+    }
+
+    @Override
+    public void onInputDeviceAdded(int deviceId) {
+        InputDevice inputDevice = InputDevice.getDevice(deviceId);
+        if (!isGamepadDevice(inputDevice)) return;
+        synchronized (mLock) {
+            registerGamepad(inputDevice);
+        }
+    }
+
+    // ------------------------------------------------------------
+
+    private static void createInstance() {
+        if (sGamepadList == null) {
+            sGamepadList = new GamepadList();
+        }
+    }
+
+    private int getDeviceCount() {
+        int count = 0;
+        for (int i = 0; i < MAX_GAMEPADS; ++i) {

[Ted C, 2014/04/04 18:52:18]

i++

[SaurabhK, 2014/04/11 14:41:42]

On 2014/04/04 18:52:18, Ted C wrote:

Done.

+            if (getDevice(i) != null) {
+                count++;
+            }
+        }
+        return count;
+    }
+
+    private boolean isDeviceConnected(int index) {
+        if (index < MAX_GAMEPADS && getDevice(index) != null) {
+            return true;
+        }
+        return false;
+    }
+
+    private GamepadDevice getDeviceById(int deviceId) {
+        for (int i = 0; i < MAX_GAMEPADS; ++i) {

[Ted C, 2014/04/04 18:52:18]

i++

[SaurabhK, 2014/04/11 14:41:42]

On 2014/04/04 18:52:18, Ted C wrote:

Done.

+            GamepadDevice gamepad = mGamepadDevices[i];
+            if (gamepad != null && gamepad.getId() == deviceId) {
+                return gamepad;
+            }
+        }
+        return null;
+    }
+
+    private GamepadDevice getDevice(int index) {
+        // Maximum 4 Gamepads can be connected at a time starting at index zero.
+        assert index >= 0 && index < MAX_GAMEPADS;
+        return mGamepadDevices[index];
+    }
+
+    /**
+    * Handles key events from the gamepad devices.
+    * @return True if the event has been consumed.
+    */
+    public static boolean dispatchKeyEvent(KeyEvent event) {
+        if (!isGamepadEvent(event)) return false;
+        return sGamepadList.updateForEvent(event);
+    }
+
+    private static boolean updateForEvent(KeyEvent event) {

[Ted C, 2014/04/04 18:52:18]

Based on the calling site, I don't think these should be marked as static.

Also per my naming suggestion in the other file, I would call this
handleKeyEvent and handleMotionEvent

[SaurabhK, 2014/04/11 14:41:42]

On 2014/04/04 18:52:18, Ted C wrote:

Keeping non-static now.

+        synchronized (sGamepadList.mLock) {
+            if (!sGamepadList.mIsGamepadAccessed) return false;
+            GamepadDevice gamepad = sGamepadList.getGamepadForEvent(event);
+            if (gamepad == null) return false;
+            return gamepad.updateForEvent(event);
+        }
+    }
+
+    /**
+    * Handles motion events from the gamepad devices.
+    * @return True if the event has been consumed.
+    */
+    public static boolean onGenericMotionEvent(MotionEvent event) {
+        if (!isGamepadEvent(event)) return false;
+        return sGamepadList.updateForEvent(event);
+    }
+
+    private static boolean updateForEvent(MotionEvent event) {
+        synchronized (sGamepadList.mLock) {
+            if (!sGamepadList.mIsGamepadAccessed) return false;
+            GamepadDevice gamepad = sGamepadList.getGamepadForEvent(event);
+            if (gamepad == null) return false;
+            return gamepad.updateForEvent(event);
+        }
+    }
+
+    private 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 < MAX_GAMEPADS; ++i) {
+            if (getDevice(i) == null) {
+                return i;
+            }
+        }
+        // Reached maximum gamepads limit.
+        return -1;
+    }
+
+    private 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;
+    }
+
+    private void unregisterGamepad(int deviceId) {
+        GamepadDevice gamepadDevice = getDeviceById(deviceId);
+        if (gamepadDevice == null) return; // Not a registered device.
+        int index = gamepadDevice.getIndex();
+        mGamepadDevices[index] = null;
+    }
+
+    private static boolean isGamepadDevice(InputDevice inputDevice) {
+        return ((inputDevice.getSources() & InputDevice.SOURCE_JOYSTICK) ==
+                 InputDevice.SOURCE_JOYSTICK);

[Ted C, 2014/04/04 18:52:18]

should be indented 8

[SaurabhK, 2014/04/11 14:41:42]

On 2014/04/04 18:52:18, Ted C wrote:

Done.

+    }
+
+    private GamepadDevice getGamepadForEvent(InputEvent event) {
+        int deviceId = event.getDeviceId();
+        GamepadDevice gamepad = getDeviceById(deviceId);
+        return gamepad;
+    }
+
+    /**
+    * @return True if the motion event corresponds to a gamepad event.
+    */
+    public static boolean isGamepadEvent(MotionEvent event) {
+

[Ted C, 2014/04/04 18:52:18]

remove blank line

[SaurabhK, 2014/04/11 14:41:42]

On 2014/04/04 18:52:18, Ted C wrote:

Done.

+        return ((event.getSource() & InputDevice.SOURCE_JOYSTICK) == InputDevice.SOURCE_JOYSTICK);
+    }
+
+    /**
+    * @return 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 static 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
+    static void getGamepadData(long gamepads) {
+        assert sGamepadList != null;
+        sGamepadList.grabGamepadData(gamepads);
+    }
+
+    private void grabGamepadData(long gamepads) {
+        synchronized (mLock) {
+            for (int i = 0; i < MAX_GAMEPADS; i++) {
+                final GamepadDevice device = getDevice(i);
+                if (device != null) {
+                    device.mapButtonsAndAxes();
+                    nativeSetGamepadData(gamepads, i, device.getMapping(), true,
+                                         device.getName(), device.getTimestamp(), device.getAxes(),
+                                         device.getButtons());
+                }
+                else
+                    nativeSetGamepadData(gamepads, i, null, false, null, 0, null, null);
+            }
+        }
+    }
+
+    @CalledByNative
+    static void notifyForGamepadsAccess(boolean isAccessPaused) {
+        assert sGamepadList != null;
+        sGamepadList.isGamepadAccessed(!isAccessPaused);
+    }
+
+    private void isGamepadAccessed(boolean isGamepadAccessed) {
+        synchronized (mLock) {
+            mIsGamepadAccessed = isGamepadAccessed;
+            if (isGamepadAccessed) {
+                for (int i = 0; i < MAX_GAMEPADS; i++) {
+                    GamepadDevice gamepadDevice = getDevice(i);
+                    if (gamepadDevice == null) continue;
+                    gamepadDevice.clearData();
+                }
+            }
+        }
+    }
+
+    private native void nativeSetGamepadData(long gamepads,
+                                             int index,
+                                             String mapping,
+                                             boolean connected,
+                                             String devicename,
+                                             long timestamp,
+                                             float[] axes,
+                                             float[] buttons);
+
+}