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
new file mode 100644
index 0000000000000000000000000000000000000000..0949c6262a0360e5566543db5ad0215f343554eb
--- /dev/null
+++ b/content/public/android/java/src/org/chromium/content/browser/GamepadMappings.java
@@ -0,0 +1,143 @@
+// 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 {

[jdduke (slow), 2014/04/04 15:10:17]

Actually... I'm looking at the other platform code, and I'm wondering why we're
doing the standard mappings in Java.  Is there any reason we can't pass the raw
values to native, populate the WebGamepad, and use the same mapping approach as
every other platform?
(https://code.google.com/p/chromium/codesearch#chromium/src/content/browser/ga...)

As far as I can tell, the logic should be more or less exactly the same, right?
We'll just add a |gamepad_standard_mappings_android.cc|.  Sorry to dump more
work on your plate, but having all mappings done in a consistent way across
platforms should make this a bit easier to maintain.  Then we no longer need the
Java template mappings for canonical axis/button values.

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

On 2014/04/04 15:10:17, jdduke wrote:

In the current patch-set I have incorporated all other review comments expect
moving mapping to native.
Me and kbalazs have provided our reasons for keeping mapping in Java in our
previous comments.
If your opinion differs then please provide your feedback on it.

+    // 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;

[jdduke (slow), 2014/04/04 15:10:17]

protected -> private

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

On 2014/04/04 15:10:17, jdduke wrote:

I have removed this check, it looks to me that checking the device name is
suffiecient to determine a device.

+    // 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;

[jdduke (slow), 2014/04/04 15:10:17]

Let's remove the |isMapped| variable.  Instead, have each successful condition
return true after mapping.  Then remove the final |else| branch, and just return
false at the end of the function.

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

On 2014/04/04 15:10:17, jdduke wrote:

Done.

+        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];
+        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];
+    }
+
+}