Gamepad API support for chrome on android

content/public/android/java/src/org/chromium/content/browser/GamepadDevice.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.os.SystemClock;
+import android.view.InputDevice;
+import android.view.InputDevice.MotionRange;
+import android.view.KeyEvent;
+import android.view.MotionEvent;
+
+import java.util.Iterator;
+import java.util.LinkedHashMap;
+
+/*
+ * Class to manage information related to each connected gamepad device.
+ */
+
+class GamepadDevice {
+    // An id for the gamepad.
+    protected int mDeviceId;
+    // The index of the gamepad in the Navigator.
+    protected int mDeviceIndex;
+    // An identification string for the gamepad.
+    protected String mDeviceName;
+    // Last time the data for this gamepad was updated.
+    protected long mTimestamp;
+
+    // Array of values for all axes of the gamepad.
+    // All axis values must be linearly normalized to the range [-1.0 .. 1.0].
+    // As appropriate, -1.0 should correspond to "up" or "left", and 1.0
+    // should correspond to "down" or "right".
+    protected float[] mAxisValues;
+    // Array of axes ids.
+    private int[] mAxes;
+
+    protected GamepadMappings.GamepadType mGamepadType;
+
+    // List of keycodes that can be sent by a standard gamepad. Standard gamepad can have
+    // buttons as per the spec:
+    // https://dvcs.w3.org/hg/gamepad/raw-file/default/gamepad.html#remapping
+    // Need to maintain this list to get input device capabilities. We query
+    // input devices with this list and device returns list mentioning which
+    // Keycodes out of these can be sent by a gamepad device.
+    private static final int[] standardGamepadKeyCodes = {

[bajones, 2014/02/28 23:56:11]

This is more-or-less a duplicate of the StandardButtons class in
GamepadMappings. Is there a reasonable way to combine them to reduce
duplication?

[SaurabhK, 2014/03/11 17:39:27]

On 2014/02/28 23:56:11, bajones wrote:

I have to maintain the list of keycode because I need to pass it to InputDevice
to get the list of supported Keycodes that can be produced by a connected
device.
Whereas I am using class StandardButtons to map the buttons to standard gamepad
button array format.

These Keycodes in standardGamepadKeyCodes have values that do not follow any
order. All i can do is explicitly add and subtract from these values at the time
of mapping to standard format in the mapper function, but it does not look like
a nice approach to me.

Please advice if i should go ahead with this approach.

+        KeyEvent.KEYCODE_BUTTON_A, // Button 0
+        KeyEvent.KEYCODE_BUTTON_B, // Button 1
+        KeyEvent.KEYCODE_BUTTON_X, // Button 2
+        KeyEvent.KEYCODE_BUTTON_Y, // Button 3
+        KeyEvent.KEYCODE_BUTTON_L1, // Button 4
+        KeyEvent.KEYCODE_BUTTON_R1, // Button 5
+        KeyEvent.KEYCODE_BUTTON_L2, // Button 6
+        KeyEvent.KEYCODE_BUTTON_R2, // Button 7
+        KeyEvent.KEYCODE_BUTTON_SELECT, // Button 8
+        KeyEvent.KEYCODE_BUTTON_START, // Button 9
+        KeyEvent.KEYCODE_BUTTON_THUMBL, // Button 10
+        KeyEvent.KEYCODE_BUTTON_THUMBR, // Button 11
+        KeyEvent.KEYCODE_DPAD_UP, // Button 12
+        KeyEvent.KEYCODE_DPAD_DOWN, // Button 13
+        KeyEvent.KEYCODE_DPAD_LEFT, // Button 14
+        KeyEvent.KEYCODE_DPAD_RIGHT, // Button 15
+        KeyEvent.KEYCODE_BUTTON_MODE, // Button 16??
+    };
+
+    // Hash map of supported keycodes and their current value linearly
+    // normalized to the range [0.0 .. 1.0].
+    // 0.0 must mean fully unpressed, and 1.0 must mean fully pressed.
+    protected LinkedHashMap<Integer, Float> mKeyCodeValueMap = new LinkedHashMap<Integer, Float>();
+
+    GamepadDevice(int index, InputDevice inputDevice) {
+        mDeviceIndex = index;
+        mDeviceId = inputDevice.getId();
+        mDeviceName = inputDevice.getName();
+        mTimestamp = SystemClock.uptimeMillis();
+        // Get the total number of axes supported by gamepad.
+        int totalAxes = 0;
+        for (MotionRange range : inputDevice.getMotionRanges()) {
+            if ((range.getSource() & InputDevice.SOURCE_CLASS_JOYSTICK) != 0) {
+                totalAxes++;
+            }
+        }
+        // Get axis ids and initialize axes values.
+        mAxes = new int[totalAxes];
+        mAxisValues = new float[totalAxes];
+        int i = 0;
+        for (MotionRange range : inputDevice.getMotionRanges()) {
+            if ((range.getSource() & InputDevice.SOURCE_CLASS_JOYSTICK) != 0) {
+                mAxes[i] = range.getAxis();
+                mAxisValues[i] = 0.0f;
+                i++;
+            }
+        }
+        // Update supported buttons list.
+        boolean[] deviceKeys = inputDevice.hasKeys(standardGamepadKeyCodes);
+        for (int j = 0; j < standardGamepadKeyCodes.length; ++j) {
+            if (deviceKeys[j]) {
+                mKeyCodeValueMap.put(standardGamepadKeyCodes[j], 0.0f);
+            }
+        }
+
+        // When the user agent recognizes the attached inputDevice, it is recommended
+        // that it be remapped to a canonical ordering when possible. Devices
+        // that are not recognized should still be exposed in their raw form.
+        setGamepadType();
+    }
+
+    GamepadDevice() {}
+
+    protected void setGamepadType() {

[bajones, 2014/02/28 23:56:11]

I'd rather this logic occur in the GamepadMappings. That way as new gamepads are
added and mapped only a single files needs to be touched.

[SaurabhK, 2014/03/11 17:39:27]

On 2014/02/28 23:56:11, bajones wrote:

Done.

+        if (isKnownShieldGamepad()) {
+            mGamepadType = GamepadMappings.GamepadType.Shield;
+        } else if (isKnownXBoxGamepad()) {
+            mGamepadType = GamepadMappings.GamepadType.XBox360;
+        } else {
+            // TODO: Add support for mapping other common gamepads to the standard gamepads.
+            mGamepadType = GamepadMappings.GamepadType.Unknown;
+        }
+    }
+
+    private boolean isKnownShieldGamepad() {
+        if (mDeviceName.contains("NVIDIA") && mDeviceName.contains("Controller")) {

[bajones, 2014/02/28 23:56:11]

This feels imprecise. If NVIDIA ever makes another controller this may start
registering incorrectly. Is there a way to detect vendor/product IDs like the
desktop code does, or a similar device-specific value? If the device name is the
most precise identifier we have I'd prefer to do an exact string match against
the full name instead.

[SaurabhK, 2014/03/11 17:39:27]

On 2014/02/28 23:56:11, bajones wrote:

Done.

+            // Known shield gamepad should have mRawShieldAxes and mRawShieldButtons.
+            if (mAxisValues.length == GamepadMappings.mRawShieldAxes &&
+                        mKeyCodeValueMap.size() == GamepadMappings.mRawShieldButtons) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    private boolean isKnownXBoxGamepad() {
+        if (mDeviceName.contains("Microsoft") && mDeviceName.contains("X-Box") &&
+            mDeviceName.contains("360") && mDeviceName.contains("pad")) {
+            // Known XBox gamepad should have mRawXBoxAxes and mRawXBoxButtons.
+            if (mAxisValues.length == GamepadMappings.mRawXBoxAxes &&
+                mKeyCodeValueMap.size() == GamepadMappings.mRawXBoxButtons) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    public int getId() { return mDeviceId; }
+
+    public String getName() { return mDeviceName; }
+
+    public int getIndex() { return mDeviceIndex; }
+
+    public long getTimestamp() { return mTimestamp; }
+
+    public float[] getAxes() {
+        if ( mGamepadType != GamepadMappings.GamepadType.Unknown) {
+            return GamepadMappings.mapToStandardGamepadAxes(mAxisValues, mGamepadType);
+        }
+        return mAxisValues;
+    }
+
+    public float[] getButtons() {
+        int size = mKeyCodeValueMap.size();
+        float[] values = new float[size];
+        int i = 0;
+        Iterator itr = mKeyCodeValueMap.values().iterator();
+        while (itr.hasNext()) {
+            values[i++] = (Float)itr.next();
+        }
+        if ( mGamepadType != GamepadMappings.GamepadType.Unknown) {
+            return GamepadMappings.mapToStandardGamepadButtons(values, mAxisValues, mGamepadType);
+        }
+        return values;
+    }
+
+    public boolean updateForEvent(KeyEvent event) {
+        mTimestamp = SystemClock.uptimeMillis();
+        // Ignore event if it is not for standard gamepad key.
+        int keyCode = event.getKeyCode();
+        if (mKeyCodeValueMap.get(keyCode) == null) {
+            return true;
+        }
+        // Button value 0.0 must mean fully unpressed, and 1.0 must mean fully pressed.
+        if (event.getAction() == KeyEvent.ACTION_DOWN) {
+            mKeyCodeValueMap.put(keyCode, 1.0f);
+        } else if (event.getAction() == KeyEvent.ACTION_UP) {
+            mKeyCodeValueMap.put(keyCode, 0.0f);
+        }
+
+        return true;
+    }
+
+    public boolean updateForEvent(MotionEvent event) {
+        mTimestamp = SystemClock.uptimeMillis();
+        // Update axes values.
+        for (int i = 0; i < mAxes.length; ++i) {
+            mAxisValues[i] = event.getAxisValue(mAxes[i]);
+        }
+        return true;
+    }
+
+    public boolean isKnownGamepadLayout() {
+        return mGamepadType != GamepadMappings.GamepadType.Unknown;
+    }
+}