Gamepad API support for chrome on android

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

Index: content/public/android/java/src/org/chromium/content/browser/GamepadMappings.java
diff --git a/content/public/android/java/src/org/chromium/content/browser/GamepadMappings.java b/content/public/android/java/src/org/chromium/content/browser/GamepadMappings.java
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+// 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;
+
+/*
+ * Class to manage mapping information related to each supported gamepad controller device.
+ */
+
+class GamepadMappings {
+
+    // Standard gamepad buttons.
+    public static class StandardButtons {
+        public static final int BUTTON_A = 0;
+        public static final int BUTTON_B = 1;
+        public static final int BUTTON_X = 2;
+        public static final int BUTTON_Y = 3;
+        public static final int LEFT_TRIGGER = 4;
+        public static final int RIGHT_TRIGGER = 5;
+        public static final int BOTTOM_LEFT_TRIGGER = 6;
+        public static final int BOTTOM_RIGHT_TRIGGER = 7;
+        public static final int SELECT = 8;
+        public static final int START = 9;
+        public static final int LEFT_THUMB = 10;
+        public static final int RIGHT_THUMB = 11;
+        public static final int DPAD_UP = 12;
+        public static final int DPAD_DOWN = 13;
+        public static final int DPAD_LEFT = 14;
+        public static final int DPAD_RIGHT = 15;
+        public static final int MODE = 16;
+        public static final int MAX_BUTTONS = 17;
+    }
+
+    // Standard gamepad axes.
+    public static class StandardAxes {
+        public static final int AXIS_0 = 0;
+        public static final int AXIS_1 = 1;
+        public static final int AXIS_2 = 2;
+        public static final int AXIS_3 = 3;
+        public static final int MAX_AXES = 4;
+    }
+
+    // Following values should be changed if the gamepad layout changes
+    // or frameworks exposes different axes / buttons for a particular gamepad.
+    // mRawShieldAxes is the total raw axes on known shield gamepad.
+    protected static final int mRawShieldAxes = 10;
+    // mRawShieldButtons is the total raw buttons on known shield gamepad.
+    protected static final int mRawShieldButtons = 10;
+    // mRawXBoxAxes is the total raw axes on known XBox gamepad.
+    protected static final int mRawXBoxAxes = 10;
+    // mRawXBoxButtons is the total raw buttons on known XBox gamepad.
+    protected static final int mRawXBoxButtons = 9;
+
+    public static boolean mapToStandardGamepad(float[] mappedAxis, float[] mappedButtons,
+                                               float[] rawAxes, float[] rawButtons,
+                                               String deviceName) {
+        boolean isMapped = true;
+        if (deviceName.contains("NVIDIA Corporation NVIDIA Controller") &&
+            rawAxes.length == mRawShieldAxes && rawButtons.length == mRawShieldButtons) {
+            mapShieldGamepad(mappedButtons, rawButtons, mappedAxis, rawAxes);
+        }
+        else if (deviceName.contains("Microsoft X-Box 360 pad") &&
+                 rawAxes.length == mRawXBoxAxes && rawButtons.length == mRawXBoxButtons) {
+            mapXBox360Gamepad(mappedButtons, rawButtons, mappedAxis, rawAxes);
+        }
+        else {
+            isMapped = false;
+        }
+        return isMapped;
+    }
+
+    private static float negativeAxisValueAsButton(float input) {
+        return (input < -0.5f) ? 1.f : 0.f;
+    }
+
+    private static float positiveAxisValueAsButton(float input) {
+        return (input > 0.5f) ? 1.f : 0.f;
+    }
+
+    /**
+     * Method for mapping Nvidia gamepad axis and button values
+     * to standard gamepad button and axes values.
+     */
+    private static void mapShieldGamepad(float[] mappedButtons, float[] rawButtons,
+                                         float[] mappedAxis, float[] rawAxes) {
+        // First four buttons on Nvidia gamepad appear in correct order so no mapping is required.
+        mappedButtons[StandardButtons.BUTTON_A] = rawButtons[0];
+        mappedButtons[StandardButtons.BUTTON_B] = rawButtons[1];
+        mappedButtons[StandardButtons.BUTTON_X] = rawButtons[2];
+        mappedButtons[StandardButtons.BUTTON_Y] = rawButtons[3];
+        // Third axis on Nvidia gamepad acts as a bottom left trigger button.
+        mappedButtons[StandardButtons.BOTTOM_LEFT_TRIGGER] = rawAxes[2];
+        mappedButtons[StandardButtons.LEFT_TRIGGER] = rawButtons[4];
+        mappedButtons[StandardButtons.RIGHT_TRIGGER] = rawButtons[5];
+        mappedButtons[StandardButtons.SELECT] = rawButtons[6];
+        mappedButtons[StandardButtons.START] = rawButtons[7];
+        mappedButtons[StandardButtons.LEFT_THUMB] = rawButtons[8];
+        mappedButtons[StandardButtons.RIGHT_THUMB] = rawButtons[9];
+        // Seventh axis on Nvidia gamepad acts as a bottom right trigger button.
+        mappedButtons[StandardButtons.BOTTOM_RIGHT_TRIGGER] = rawAxes[6];
+        // Ninth axis on Nvidia gamepad acts as directional pad right and left button.
+        // Positive axis value indicates dpad right.
+        // Negative value indicates dpad left.
+        mappedButtons[StandardButtons.DPAD_RIGHT] = positiveAxisValueAsButton(rawAxes[8]);
+        mappedButtons[StandardButtons.DPAD_LEFT] = negativeAxisValueAsButton(rawAxes[8]);
+        // Tenth axis on Nvidia gamepad acts as directional pad up and down button.
+        // Positive axis value indicates dpad down.
+        // Negative value indicates dpad up.
+        mappedButtons[StandardButtons.DPAD_DOWN] = positiveAxisValueAsButton(rawAxes[9]);
+        mappedButtons[StandardButtons.DPAD_UP] = negativeAxisValueAsButton(rawAxes[9]);
+        // Other standard buttons are either not present on the gamepad or not exposed to an
+        // application.
+        mappedButtons[StandardButtons.MODE] = 0.0f;
+
+        // Standard gamepad can have only four axes.
+        mappedAxis[StandardAxes.AXIS_0] = rawAxes[0];
+        mappedAxis[StandardAxes.AXIS_1] = rawAxes[1];
+        mappedAxis[StandardAxes.AXIS_2] = rawAxes[4];
+        mappedAxis[StandardAxes.AXIS_3] = rawAxes[5];
+    }
+
+    /**
+     * Method for mapping Microsoft XBox 360 gamepad axis and button values
+     * to standard gamepad button and axes values.
+     */
+    private static void mapXBox360Gamepad(float[] mappedButtons, float[] rawButtons,
+                                          float[] mappedAxis, float[] rawAxes) {
+        // First four buttons on Microsoft XBox 360 gamepad appear in correct order so no mapping
+        // is required.
+        mappedButtons[StandardButtons.BUTTON_A] = rawButtons[0];
+        mappedButtons[StandardButtons.BUTTON_B] = rawButtons[1];
+        mappedButtons[StandardButtons.BUTTON_X] = rawButtons[2];
+        mappedButtons[StandardButtons.BUTTON_Y] = rawButtons[3];
+        // Third axis on Microsoft XBox 360 gamepad acts as a left bottom shoulder button.
+        mappedButtons[StandardButtons.BOTTOM_LEFT_TRIGGER] = rawAxes[2];
+        mappedButtons[StandardButtons.LEFT_TRIGGER] = rawButtons[4];
+        mappedButtons[StandardButtons.RIGHT_TRIGGER] = rawButtons[5];
+        mappedButtons[StandardButtons.START] = rawButtons[6];
+        mappedButtons[StandardButtons.LEFT_THUMB] = rawButtons[7];
+        mappedButtons[StandardButtons.RIGHT_THUMB] = rawButtons[8];
+        // Seventh axis on Microsoft XBox 360 gamepad acts as a right bottom shoulder button.
+        mappedButtons[StandardButtons.BOTTOM_RIGHT_TRIGGER] = rawAxes[6];
+        // Ninth axis on Microsoft XBox 360 gamepad acts as directional pad right and left button.
+        // Positive axis value indicates dpad right.
+        // Negative value indicates dpad left.
+        mappedButtons[StandardButtons.DPAD_RIGHT] = positiveAxisValueAsButton(rawAxes[8]);
+        mappedButtons[StandardButtons.DPAD_LEFT] = negativeAxisValueAsButton(rawAxes[8]);
+        // Tenth axis on Microsoft XBox 360 gamepad acts as directional pad up and down button.
+        // Positive axis value indicates dpad down.
+        // Negative value indicates dpad up.
+        mappedButtons[StandardButtons.DPAD_DOWN] = positiveAxisValueAsButton(rawAxes[9]);
+        mappedButtons[StandardButtons.DPAD_UP] = negativeAxisValueAsButton(rawAxes[9]);
+        // Other standard buttons are either not present on the gamepad or not exposed to an
+        // application.
+        mappedButtons[StandardButtons.SELECT] = 0.0f;
+        mappedButtons[StandardButtons.MODE] = 0.0f;
+
+        // Standard gamepad can have only four axes.
+        mappedAxis[StandardAxes.AXIS_0] = rawAxes[0];
+        mappedAxis[StandardAxes.AXIS_1] = rawAxes[1];
+        mappedAxis[StandardAxes.AXIS_2] = rawAxes[4];
+        mappedAxis[StandardAxes.AXIS_3] = rawAxes[5];
+    }
+
+}