Gamepad API for Android

content/public/android/java/src/org/chromium/content/browser/input/GamepadDataMapper.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.util.SparseArray;
+import android.view.KeyEvent;
+import android.view.MotionEvent;
+
+import org.chromium.base.JNINamespace;
+import org.chromium.content.browser.input.gamepad_mapping.CanonicalAxisIndex;
+import org.chromium.content.browser.input.gamepad_mapping.CanonicalButtonIndex;
+
+/**
+ * Device specific input data converter for Gamepad API.
+ * Implemented per device by subclasses.
+ */
+@JNINamespace("content")
+abstract class GamepadDataMapper {
+    protected static final String PS3_SIXAXIS_DEVICE_NAME = "Sony PLAYSTATION(R)3 Controller";
+
+    public abstract WebGamepadData map(SparseArray<Float> axes, SparseArray<Boolean> buttons);

[Ted C, 2014/03/07 20:18:09]

per my comment about object creation in the other file, you might want to have
this take a data object and write over it or have this class own one that will
get reused.

Either way a a comment on this would be good.

[kbalazs, 2014/03/12 00:17:36]

Done, I hold the object in the mapper now.

+
+    // Factory method.
+    public static GamepadDataMapper createDataMapper(String deviceName) {
+        if (deviceName.equals(PS3_SIXAXIS_DEVICE_NAME))
+            return new PS3SixAxisGamepadDataMapper();
+
+        return new GenericGamepadDataMapper(deviceName);
+    }
+
+    protected static float axisValue(Float f) { return f == null ? 0 : f.floatValue(); }
+    protected static float buttonValue(Boolean b) { return (b == null || !b) ? 0 : 1; }
+
+    protected static WebGamepadData createWebGamepadData() {
+        WebGamepadData data = new WebGamepadData();
+        data.axes = new float[CanonicalAxisIndex.NUM_CANONICAL_AXES];
+        data.buttons = new float[CanonicalButtonIndex.NUM_CANONICAL_BUTTONS];
+        return data;
+    }
+
+    protected static void mapCommonXYAxes(WebGamepadData data, SparseArray<Float> axes) {
+        Float x = (Float) axes.get(MotionEvent.AXIS_X);

[Ted C, 2014/03/07 20:18:09]

get on a typed SparseArray should mean that you don't need to have these casts
anywhere.

Same for all the following functions.

[kbalazs, 2014/03/07 22:40:22]

Right, but unfortunately there is no such thing as SparseFloatArray (and
SparseArray is not generic). I can use a HashMap<int, float> although I'm not
sure that would be more efficient.

[Ted C, 2014/03/08 01:06:00]

My previous comment was that calling .get() on a SparseArray<Float> is a 
templated function that doesn't require you to cast the return value.

In the above cases, it can just be written:

Float x = axes.get(MotionEvent.AXIS_X);
Float y = axes.get(MotionEvent.AXIS_Y);

With that being said, I think you have to forgo the niceness of SparseArray
for the floats due to the GC issue.  I totally agree it's annoying, but
we've done as much as we can to no allocate anything per frame where ever
possible.

+        Float y = (Float) axes.get(MotionEvent.AXIS_Y);
+        data.axes[CanonicalAxisIndex.AXIS_LEFT_STICK_X] = axisValue(x);
+        data.axes[CanonicalAxisIndex.AXIS_LEFT_STICK_Y] = axisValue(y);
+    }
+
+    protected static void mapCommonTriggerAxes(WebGamepadData data, SparseArray<Float> axes) {
+        Float lTrigger = (Float) axes.get(MotionEvent.AXIS_LTRIGGER);
+        Float rTrigger = (Float) axes.get(MotionEvent.AXIS_RTRIGGER);
+        data.buttons[CanonicalButtonIndex.BUTTON_LEFT_SHOULDER] = axisValue(lTrigger);
+        data.buttons[CanonicalButtonIndex.BUTTON_RIGHT_SHOULDER] = axisValue(rTrigger);
+    }
+
+    protected static void mapCommonTriggerButtons(
+            WebGamepadData data, SparseArray<Boolean> buttons) {
+        Boolean l1 = (Boolean) buttons.get(KeyEvent.KEYCODE_BUTTON_L1);
+        Boolean r1 = (Boolean) buttons.get(KeyEvent.KEYCODE_BUTTON_R1);
+        data.buttons[CanonicalButtonIndex.BUTTON_LEFT_TRIGGER] = buttonValue(l1);
+        data.buttons[CanonicalButtonIndex.BUTTON_RIGHT_TRIGGER] = buttonValue(r1);
+    }
+
+    protected static void mapCommonThumbstickButtons(
+            WebGamepadData data, SparseArray<Boolean> buttons) {
+        Boolean thumbL = (Boolean) buttons.get(KeyEvent.KEYCODE_BUTTON_THUMBL);
+        Boolean thumbR = (Boolean) buttons.get(KeyEvent.KEYCODE_BUTTON_THUMBR);
+        data.buttons[CanonicalButtonIndex.BUTTON_LEFT_THUMBSTICK] = buttonValue(thumbL);
+        data.buttons[CanonicalButtonIndex.BUTTON_RIGHT_THUMBSTICK] = buttonValue(thumbR);
+    }
+
+    protected static void mapCommonStartSelectButtons(
+            WebGamepadData data, SparseArray<Boolean> buttons) {
+        Boolean select = (Boolean) buttons.get(KeyEvent.KEYCODE_BUTTON_SELECT);
+        Boolean start = (Boolean) buttons.get(KeyEvent.KEYCODE_BUTTON_START);
+        data.buttons[CanonicalButtonIndex.BUTTON_BACK_SELECT] = buttonValue(select);
+        data.buttons[CanonicalButtonIndex.BUTTON_START] = buttonValue(start);
+    }
+
+    protected static void mapCommonDpadButtons(
+            WebGamepadData data, SparseArray<Boolean> buttons) {
+        Boolean dpadDown = (Boolean) buttons.get(KeyEvent.KEYCODE_DPAD_DOWN);
+        Boolean dpadUp = (Boolean) buttons.get(KeyEvent.KEYCODE_DPAD_UP);
+        Boolean dpadLeft = (Boolean) buttons.get(KeyEvent.KEYCODE_DPAD_LEFT);
+        Boolean dpadRight = (Boolean) buttons.get(KeyEvent.KEYCODE_DPAD_RIGHT);
+        data.buttons[CanonicalButtonIndex.BUTTON_DPAD_DOWN] = buttonValue(dpadDown);
+        data.buttons[CanonicalButtonIndex.BUTTON_DPAD_UP] = buttonValue(dpadUp);
+        data.buttons[CanonicalButtonIndex.BUTTON_DPAD_LEFT] = buttonValue(dpadLeft);
+        data.buttons[CanonicalButtonIndex.BUTTON_DPAD_RIGHT] = buttonValue(dpadRight);
+    }
+
+    protected static void mapCommonXYABButtons(
+            WebGamepadData data, SparseArray<Boolean> buttons) {
+        Boolean bA = (Boolean) buttons.get(KeyEvent.KEYCODE_BUTTON_A);
+        Boolean bB = (Boolean) buttons.get(KeyEvent.KEYCODE_BUTTON_B);
+        Boolean bX = (Boolean) buttons.get(KeyEvent.KEYCODE_BUTTON_X);
+        Boolean bY = (Boolean) buttons.get(KeyEvent.KEYCODE_BUTTON_Y);
+        data.buttons[CanonicalButtonIndex.BUTTON_PRIMARY] = buttonValue(bA);
+        data.buttons[CanonicalButtonIndex.BUTTON_SECONDARY] = buttonValue(bB);
+        data.buttons[CanonicalButtonIndex.BUTTON_TERTIARY] = buttonValue(bX);
+        data.buttons[CanonicalButtonIndex.BUTTON_QUATERNARY] = buttonValue(bY);
+    }
+}
+
+// This is a last resort if we find a device that we don't know about.
+// The Android API is general enough that this can be better than nothing
+// but we should not really rely on this.
+class GenericGamepadDataMapper extends GamepadDataMapper {
+    private final String mDeviceName;
+
+    GenericGamepadDataMapper(String deviceName) {
+        mDeviceName = deviceName;
+    }
+
+    // Find something for right stick x and y. If there is even more axes, map them to
+    // non-canonical positions.
+    private static void mapRightAndExtraSticks(WebGamepadData data, SparseArray<Float> axes) {
+        int position = CanonicalAxisIndex.AXIS_RIGHT_STICK_X;
+        // position + 1 is AXIS_RIGHT_STICK_Y.
+        Float x = (Float) axes.get(MotionEvent.AXIS_RX);
+        Float y = (Float) axes.get(MotionEvent.AXIS_RY);
+        if (x != null || y != null) {
+            data.axes[position++] = axisValue(x);
+            data.axes[position++] = axisValue(y);
+        }
+        x = (Float) axes.get(MotionEvent.AXIS_Z);
+        y = (Float) axes.get(MotionEvent.AXIS_RZ);
+        if (x != null || y != null) {
+            data.axes[position++] = axisValue(x);
+            data.axes[position++] = axisValue(y);
+        }
+        x = (Float) axes.get(MotionEvent.AXIS_HAT_X);
+        y = (Float) axes.get(MotionEvent.AXIS_HAT_Y);
+        if (x != null || y != null) {
+            data.axes[position++] = axisValue(x);
+            data.axes[position++] = axisValue(y);
+        }

[Ted C, 2014/03/07 20:18:09]

This doesn't verify axes size is large enough.  Might be good to have some
assertion in this file that the value you expect doesn't change in native and
not get updated here.

And looking at it, this looks like it's only initialized to size 4, so this
would out of bounds fail if all these values were present.  I think some sanity
checking on bounds is definitely something we should do here.

[kbalazs, 2014/03/07 22:40:22]

Right, I overlooked it.

[kbalazs, 2014/03/12 00:17:36]

Done.

+    }
+
+    public WebGamepadData map(SparseArray<Float> axes, SparseArray<Boolean> buttons) {
+        WebGamepadData data = createWebGamepadData();
+        data.id = mDeviceName + " (STANDARD_GAMEPAD)";
+        data.mapping = "standard";
+        mapCommonXYAxes(data, axes);
+        mapRightAndExtraSticks(data, axes);
+        mapCommonTriggerAxes(data, axes);
+        mapCommonXYABButtons(data, buttons);
+        mapCommonTriggerButtons(data, buttons);
+        mapCommonThumbstickButtons(data, buttons);
+        mapCommonStartSelectButtons(data, buttons);
+        mapCommonDpadButtons(data, buttons);
+
+        // TODO(b.kelemen): meta is missing.
+
+        return data;
+    }
+}
+
+class PS3SixAxisGamepadDataMapper extends GamepadDataMapper {
+    public WebGamepadData map(SparseArray<Float> axes, SparseArray<Boolean> buttons) {
+        WebGamepadData data = createWebGamepadData();
+        data.id = PS3_SIXAXIS_DEVICE_NAME + " (STANDARD_GAMEPAD)";

[Ted C, 2014/03/07 20:18:09]

I would make " (STANDARD_GAMEPAD)" and "standard" constants as well.

[kbalazs, 2014/03/12 00:17:36]

Done.

+        data.mapping = "standard";
+
+        mapCommonXYAxes(data, axes);
+
+        Float z = (Float) axes.get(MotionEvent.AXIS_Z);
+        Float rz = (Float) axes.get(MotionEvent.AXIS_RZ);
+        data.axes[CanonicalAxisIndex.AXIS_RIGHT_STICK_X] = axisValue(z);
+        data.axes[CanonicalAxisIndex.AXIS_RIGHT_STICK_Y] = axisValue(rz);
+
+        mapCommonTriggerAxes(data, axes);
+
+        Boolean bA = (Boolean) buttons.get(KeyEvent.KEYCODE_BUTTON_A);
+        Boolean bB = (Boolean) buttons.get(KeyEvent.KEYCODE_BUTTON_B);
+        Boolean bX = (Boolean) buttons.get(KeyEvent.KEYCODE_BUTTON_X);
+        Boolean bY = (Boolean) buttons.get(KeyEvent.KEYCODE_BUTTON_Y);
+        data.buttons[CanonicalButtonIndex.BUTTON_PRIMARY] = buttonValue(bX);
+        data.buttons[CanonicalButtonIndex.BUTTON_SECONDARY] = buttonValue(bY);
+        data.buttons[CanonicalButtonIndex.BUTTON_TERTIARY] = buttonValue(bA);
+        data.buttons[CanonicalButtonIndex.BUTTON_QUATERNARY] = buttonValue(bB);
+
+        mapCommonTriggerButtons(data, buttons);
+        mapCommonThumbstickButtons(data, buttons);
+        mapCommonStartSelectButtons(data, buttons);
+        mapCommonDpadButtons(data, buttons);
+
+        // TODO(b.kelemen): PS button is missing. Looks like it is swallowed by Android
+        // but probably there is a way to configure otherwise and in this case we should
+        // handle it.
+
+        return data;
+    }
+}
+
+// TODO(b.kelemen): add more implementations. It would be nice to support at least those that are
+// supported on Linux.