Gamepad API support for chrome on android

content/public/android/java/src/org/chromium/content/browser/input/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.input;
+
+import android.view.KeyEvent;
+
+/**
+ * Class to manage mapping information related to each supported gamepad controller device.
+ */
+class GamepadMappings {
+    public static boolean mapToStandardGamepad(float[] mappedAxis, float[] mappedButtons,
+            float[] rawAxes, float[] rawButtons, String deviceName) {
+        if (deviceName.contains("NVIDIA Corporation NVIDIA Controller")) {
+            mapShieldGamepad(mappedButtons, rawButtons, mappedAxis, rawAxes);
+            return true;
+        } else if (deviceName.contains("Microsoft X-Box 360 pad")) {
+            mapXBox360Gamepad(mappedButtons, rawButtons, mappedAxis, rawAxes);
+            return true;
+        }
+
+        mapUnkownGamepad(mappedButtons, rawButtons, mappedAxis, rawAxes);
+        return false;
+    }
+
+    private static void mapCommonButtons(float[] mappedButtons, float[] rawButtons) {
+        mappedButtons[CanonicalButtonIndex.BUTTON_PRIMARY] = rawButtons[KeyEvent.KEYCODE_BUTTON_A];
+        mappedButtons[CanonicalButtonIndex.BUTTON_SECONDARY] =
+                rawButtons[KeyEvent.KEYCODE_BUTTON_B];
+        mappedButtons[CanonicalButtonIndex.BUTTON_TERTIARY] =
+                rawButtons[KeyEvent.KEYCODE_BUTTON_X];
+        mappedButtons[CanonicalButtonIndex.BUTTON_QUATERNARY] =
+                rawButtons[KeyEvent.KEYCODE_BUTTON_Y];
+        mappedButtons[CanonicalButtonIndex.BUTTON_LEFT_SHOULDER] =
+                rawButtons[KeyEvent.KEYCODE_BUTTON_L1];
+        mappedButtons[CanonicalButtonIndex.BUTTON_RIGHT_SHOULDER] =
+                rawButtons[KeyEvent.KEYCODE_BUTTON_R1];
+        mappedButtons[CanonicalButtonIndex.BUTTON_BACK_SELECT] =
+                rawButtons[KeyEvent.KEYCODE_BUTTON_SELECT];
+        mappedButtons[CanonicalButtonIndex.BUTTON_START] =
+                rawButtons[KeyEvent.KEYCODE_BUTTON_START];
+        mappedButtons[CanonicalButtonIndex.BUTTON_LEFT_THUMBSTICK] =
+                rawButtons[KeyEvent.KEYCODE_BUTTON_THUMBL];
+        mappedButtons[CanonicalButtonIndex.BUTTON_RIGHT_THUMBSTICK] =
+                rawButtons[KeyEvent.KEYCODE_BUTTON_THUMBR];
+        mappedButtons[CanonicalButtonIndex.BUTTON_META] = rawButtons[KeyEvent.KEYCODE_BUTTON_MODE];
+    }
+
+    private static void mapDpadButtonsToAxes(float[] mappedButtons, float[] rawAxes) {
+        // Negative value indicates dpad up.
+        mappedButtons[CanonicalButtonIndex.BUTTON_DPAD_UP] = negativeAxisValueAsButton(rawAxes[9]);
+        // Positive axis value indicates dpad down.
+        mappedButtons[CanonicalButtonIndex.BUTTON_DPAD_DOWN] =
+                positiveAxisValueAsButton(rawAxes[9]);
+        // Positive axis value indicates dpad right.
+        mappedButtons[CanonicalButtonIndex.BUTTON_DPAD_RIGHT] =
+                positiveAxisValueAsButton(rawAxes[8]);
+        // Negative value indicates dpad left.
+        mappedButtons[CanonicalButtonIndex.BUTTON_DPAD_LEFT] =
+                negativeAxisValueAsButton(rawAxes[8]);
+    }
+
+    private static void mapAxes(float[] mappedAxis, float[] rawAxes) {
+        // 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];
+    }
+
+    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) {
+        mapCommonButtons(mappedButtons, rawButtons);
+
+        mappedButtons[CanonicalButtonIndex.BUTTON_LEFT_TRIGGER] = rawAxes[2]; // or rawAxes[3];

[Ted C, 2014/04/16 23:36:53]

I'm confused of what the comment // or rawAxes[3] means.  Is that actionable?

[SaurabhK, 2014/04/18 14:51:57]

On 2014/04/16 23:36:53, Ted C wrote:

No there is no action.
Actually the axes value for left trigger button is duplicated at index 2,3 and
for right trigger button it is duplicated at index 6,7.
So I just added comment with intention to state that any of these 2 indices can
be used to map to button value.
I think I should remove it as it can create confusion.

[kbalazs, 2014/04/18 15:21:20]

I agree :)

+        mappedButtons[CanonicalButtonIndex.BUTTON_RIGHT_TRIGGER] = rawAxes[6]; // or rawAxes[7];
+
+        mapDpadButtonsToAxes(mappedButtons, rawAxes);
+        mapAxes(mappedAxis, rawAxes);
+    }
+
+    /**
+     * 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) {
+        mapCommonButtons(mappedButtons, rawButtons);
+
+        mappedButtons[CanonicalButtonIndex.BUTTON_LEFT_TRIGGER] = rawAxes[2]; // or rawAxes[3];
+        mappedButtons[CanonicalButtonIndex.BUTTON_RIGHT_TRIGGER] = rawAxes[6]; // or rawAxes[7];
+
+        mapDpadButtonsToAxes(mappedButtons, rawAxes);
+        mapAxes(mappedAxis, rawAxes);
+    }
+
+    /**
+     * Method for mapping Unkown gamepad axis and button values
+     * to standard gamepad button and axes values.
+     */
+    private static void mapUnkownGamepad(float[] mappedButtons, float[] rawButtons,
+            float[] mappedAxis, float[] rawAxes) {
+        mapCommonButtons(mappedButtons, rawButtons);
+
+        mappedButtons[CanonicalButtonIndex.BUTTON_LEFT_TRIGGER] =
+                rawButtons[KeyEvent.KEYCODE_BUTTON_L2];
+        mappedButtons[CanonicalButtonIndex.BUTTON_RIGHT_TRIGGER] =
+                rawButtons[KeyEvent.KEYCODE_BUTTON_R2];
+
+        mappedButtons[CanonicalButtonIndex.BUTTON_DPAD_UP] = rawButtons[KeyEvent.KEYCODE_DPAD_UP];
+        mappedButtons[CanonicalButtonIndex.BUTTON_DPAD_DOWN] =
+                rawButtons[KeyEvent.KEYCODE_DPAD_DOWN];
+        mappedButtons[CanonicalButtonIndex.BUTTON_DPAD_RIGHT] =
+                rawButtons[KeyEvent.KEYCODE_DPAD_RIGHT];
+        mappedButtons[CanonicalButtonIndex.BUTTON_DPAD_LEFT] =
+                rawButtons[KeyEvent.KEYCODE_DPAD_LEFT];
+
+        mapAxes(mappedAxis, rawAxes);
+    }
+
+}