Gamepad API support for chrome on android

content/public/android/java/src/org/chromium/content/browser/GamepadMappings.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 org.chromium.content.browser.input.CanonicalAxisIndex;
+import org.chromium.content.browser.input.CanonicalButtonIndex;
+
+/*
+ * Class to manage mapping information related to each supported gamepad controller device.
+ */
+
+class GamepadMappings {

[kbalazs, 2014/03/26 19:24:53]

I would slightly prefer an abstract class implemented per device.

+    // 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[CanonicalButtonIndex.BUTTON_PRIMARY] = rawButtons[0];

[kbalazs, 2014/03/26 19:24:53]

I would also prefer if we could use the symbolic constants from the api (like
AXIS_FOO and KEYCODE_BUTTON_BAR). To me it looks clearer and easier to add new
devices. Not a very big deal though, I'm ok if you keep it that way.

+        mappedButtons[CanonicalButtonIndex.BUTTON_SECONDARY] = rawButtons[1];
+        mappedButtons[CanonicalButtonIndex.BUTTON_TERTIARY] = rawButtons[2];
+        mappedButtons[CanonicalButtonIndex.BUTTON_QUATERNARY] = rawButtons[3];
+        // Third axis on Nvidia gamepad acts as a bottom left trigger button.
+        mappedButtons[CanonicalButtonIndex.BUTTON_LEFT_TRIGGER] = rawAxes[2];
+        mappedButtons[CanonicalButtonIndex.BUTTON_LEFT_SHOULDER] = rawButtons[4];
+        mappedButtons[CanonicalButtonIndex.BUTTON_RIGHT_SHOULDER] = rawButtons[5];
+        mappedButtons[CanonicalButtonIndex.BUTTON_BACK_SELECT] = rawButtons[6];
+        mappedButtons[CanonicalButtonIndex.BUTTON_START] = rawButtons[7];
+        mappedButtons[CanonicalButtonIndex.BUTTON_LEFT_THUMBSTICK] = rawButtons[8];
+        mappedButtons[CanonicalButtonIndex.BUTTON_RIGHT_THUMBSTICK] = rawButtons[9];
+        // Seventh axis on Nvidia gamepad acts as a bottom right trigger button.
+        mappedButtons[CanonicalButtonIndex.BUTTON_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[CanonicalButtonIndex.BUTTON_DPAD_RIGHT] =
+                            positiveAxisValueAsButton(rawAxes[8]);
+        mappedButtons[CanonicalButtonIndex.BUTTON_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[CanonicalButtonIndex.BUTTON_DPAD_DOWN] =
+                            positiveAxisValueAsButton(rawAxes[9]);
+        mappedButtons[CanonicalButtonIndex.BUTTON_DPAD_UP] = negativeAxisValueAsButton(rawAxes[9]);
+        // Other standard buttons are either not present on the gamepad or not exposed to an
+        // application.
+        mappedButtons[CanonicalButtonIndex.BUTTON_META] = 0.0f;
+
+        // Standard gamepad can have only four axes.
+        mappedAxis[CanonicalAxisIndex.AXIS_LEFT_STICK_X] = rawAxes[0];
+        mappedAxis[CanonicalAxisIndex.AXIS_LEFT_STICK_Y] = rawAxes[1];
+        mappedAxis[CanonicalAxisIndex.AXIS_RIGHT_STICK_X] = rawAxes[4];
+        mappedAxis[CanonicalAxisIndex.AXIS_RIGHT_STICK_Y] = 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[CanonicalButtonIndex.BUTTON_PRIMARY] = rawButtons[0];
+        mappedButtons[CanonicalButtonIndex.BUTTON_SECONDARY] = rawButtons[1];
+        mappedButtons[CanonicalButtonIndex.BUTTON_TERTIARY] = rawButtons[2];
+        mappedButtons[CanonicalButtonIndex.BUTTON_QUATERNARY] = rawButtons[3];
+        // Third axis on Microsoft XBox 360 gamepad acts as a left bottom shoulder button.
+        mappedButtons[CanonicalButtonIndex.BUTTON_LEFT_TRIGGER] = rawAxes[2];
+        mappedButtons[CanonicalButtonIndex.BUTTON_LEFT_SHOULDER] = rawButtons[4];
+        mappedButtons[CanonicalButtonIndex.BUTTON_RIGHT_SHOULDER] = rawButtons[5];
+        mappedButtons[CanonicalButtonIndex.BUTTON_START] = rawButtons[6];
+        mappedButtons[CanonicalButtonIndex.BUTTON_LEFT_THUMBSTICK] = rawButtons[7];
+        mappedButtons[CanonicalButtonIndex.BUTTON_RIGHT_THUMBSTICK] = rawButtons[8];
+        // Seventh axis on Microsoft XBox 360 gamepad acts as a right bottom shoulder button.
+        mappedButtons[CanonicalButtonIndex.BUTTON_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[CanonicalButtonIndex.BUTTON_DPAD_RIGHT] =
+                            positiveAxisValueAsButton(rawAxes[8]);
+        mappedButtons[CanonicalButtonIndex.BUTTON_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[CanonicalButtonIndex.BUTTON_DPAD_DOWN] =
+                            positiveAxisValueAsButton(rawAxes[9]);
+        mappedButtons[CanonicalButtonIndex.BUTTON_DPAD_UP] = negativeAxisValueAsButton(rawAxes[9]);
+        // Other standard buttons are either not present on the gamepad or not exposed to an
+        // application.
+        mappedButtons[CanonicalButtonIndex.BUTTON_BACK_SELECT] = 0.0f;
+        mappedButtons[CanonicalButtonIndex.BUTTON_META] = 0.0f;
+
+        // Standard gamepad can have only four axes.
+        mappedAxis[CanonicalAxisIndex.AXIS_LEFT_STICK_X] = rawAxes[0];
+        mappedAxis[CanonicalAxisIndex.AXIS_LEFT_STICK_Y] = rawAxes[1];
+        mappedAxis[CanonicalAxisIndex.AXIS_RIGHT_STICK_X] = rawAxes[4];
+        mappedAxis[CanonicalAxisIndex.AXIS_RIGHT_STICK_Y] = rawAxes[5];
+    }
+
+}