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GamepadController.java

/*
 * Copyright 2014 Google Inc. All rights reserved.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.google.fpl.gamecontroller;

import android.view.KeyEvent;
import android.view.MotionEvent;

/**
 * Handles input events from game pad controllers (includes joystick and button inputs).
 */
public class GamepadController {

// The buttons on the game pad.
    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 BUTTON_COUNT = 4;

// The axes for joystick movement.
    public static final int AXIS_X = 0;
    public static final int AXIS_Y = 1;
    public static final int AXIS_COUNT = 2;

// Game pads usually have 2 joysticks.
    public static final int JOYSTICK_1 = 0;
    public static final int JOYSTICK_2 = 1;
    public static final int JOYSTICK_COUNT = 2;

// Keep track of button states for the current and previous frames.
    protected static final int FRAME_INDEX_CURRENT = 0;
    protected static final int FRAME_INDEX_PREVIOUS = 1;
    protected static final int FRAME_INDEX_COUNT = 2;

// Positions of the two joysticks.
    private final float mJoystickPositions[][];
    // The button states for the current and previous frames.
    private final boolean mButtonState[][];
    // The device that we are tuned to.
    private int mDeviceId = -1;

public GamepadController() {
        mButtonState = new boolean[BUTTON_COUNT][FRAME_INDEX_COUNT];
        mJoystickPositions = new float[JOYSTICK_COUNT][AXIS_COUNT];
        resetState();
    }

/**
     * Returns the controller to its default state.
     *
     * The histories for all joystick movements and button presses is also reset.
     */
    private void resetState() {
        for (int button = 0; button < BUTTON_COUNT; ++button) {
            for (int frame = 0; frame < FRAME_INDEX_COUNT; ++frame) {
                mButtonState[button][frame] = false;
            }
        }
        for (int joystick = 0; joystick < JOYSTICK_COUNT; ++joystick) {
            for (int axis = 0; axis < AXIS_COUNT; ++axis) {
                mJoystickPositions[joystick][axis] = 0.0f;
            }
        }
    }

/**
     * @return The id of the associated controller device, or -1 if not assigned a device.
     */
    public int getDeviceId() {
        return mDeviceId;
    }
    /**
     * Sets the physical device id for this controller.
     *
     * @param newId The physical device id, or -1 to indicate no assigned physical device.
     */
    public void setDeviceId(int newId) {
        if (newId != mDeviceId) {
            mDeviceId = newId;
            if (newId != -1) {
                // Reset our button and axis state when a new physical device is attached.
                resetState();
            }
        }
    }
    /**
     * @return true if this controller is assigned a physical device id.
     */
    public boolean isActive() {
        return mDeviceId != -1;
    }

/**
     * Returns the position of a joystick along a single axis.
     *
     * @param joystickIndex One of: JOYSTICK_1 or JOYSTICK_2.
     * @param axis One of: AXIS_X or AXIS_Y.
     * @return A value in the range -1 to 1, inclusive, where 0 represents the joystick's
     *          center position.
     */
    public float getJoystickPosition(int joystickIndex, int axis) {
        return mJoystickPositions[joystickIndex][axis];
    }

/**
     * Returns true if the given button is currently pressed.
     *
     * @param buttonId One of: BUTTON_A, BUTTON_B, BUTTON_X, or BUTTON_Y.
     * @return true if the given button is currently pressed.
     */
    public boolean isButtonDown(int buttonId) {
        return mButtonState[buttonId][FRAME_INDEX_CURRENT];
    }

/**
     * Returns true if a button is down now, but wasn't last frame.
     *
     * @param buttonId One of: BUTTON_A, BUTTON_B, BUTTON_X, or BUTTON_Y.
     * @return true if a button is down now, but wasn't last frame.
     */
    public boolean wasButtonPressed(int buttonId) {
        // Returns true if it's down now, but wasn't last frame.
        return mButtonState[buttonId][FRAME_INDEX_CURRENT]
                && !mButtonState[buttonId][FRAME_INDEX_PREVIOUS];
    }

/**
     * Returns true if it's up now, but wasn't last frame.
     *
     * @param buttonId One of: BUTTON_A, BUTTON_B, BUTTON_X, or BUTTON_Y.
     * @return true if it's up now, but wasn't last frame.
     */
    public boolean wasButtonReleased(int buttonId) {
        return !mButtonState[buttonId][FRAME_INDEX_CURRENT]
                && mButtonState[buttonId][FRAME_INDEX_PREVIOUS];
    }

/**
     * Tells the controller to start tracking events for the next frame.
     */
    public void advanceFrame() {
        // Copy the current button state to the previous frame.
        // We can't just toggle between both buffers because the buttons only update
        // when an event occurs (press or release), and not every frame.
        for (int i = 0; i < BUTTON_COUNT; i++) {
            mButtonState[i][FRAME_INDEX_PREVIOUS] = mButtonState[i][FRAME_INDEX_CURRENT];
        }
    }

/**
     * Updates the tracked state values of this controller in response to a motion input event.
     */
    public void handleMotionEvent(MotionEvent motionEvent) {
        mJoystickPositions[JOYSTICK_1][AXIS_X] = motionEvent.getAxisValue(MotionEvent.AXIS_X);
        mJoystickPositions[JOYSTICK_1][AXIS_Y] = motionEvent.getAxisValue(MotionEvent.AXIS_Y);

// The X and Y axes of the second joystick on a controller are mapped to the
        // MotionEvent AXIS_Z and AXIS_RZ values, respectively.
        mJoystickPositions[JOYSTICK_2][AXIS_X] = motionEvent.getAxisValue(MotionEvent.AXIS_Z);
        mJoystickPositions[JOYSTICK_2][AXIS_Y] = motionEvent.getAxisValue(MotionEvent.AXIS_RZ);
    }

/**
     * Updates the tracked state values of this controller in response to a key input event.
     */
    public void handleKeyEvent(KeyEvent keyEvent) {
        boolean keyIsDown = keyEvent.getAction() == KeyEvent.ACTION_DOWN;

if (keyEvent.getKeyCode() == KeyEvent.KEYCODE_BUTTON_A) {
            mButtonState[BUTTON_A][FRAME_INDEX_CURRENT] = keyIsDown;
        } else if (keyEvent.getKeyCode() == KeyEvent.KEYCODE_BUTTON_B) {
            mButtonState[BUTTON_B][FRAME_INDEX_CURRENT] = keyIsDown;
        } else if (keyEvent.getKeyCode() == KeyEvent.KEYCODE_BUTTON_X) {
            mButtonState[BUTTON_X][FRAME_INDEX_CURRENT] = keyIsDown;
        } else if (keyEvent.getKeyCode() == KeyEvent.KEYCODE_BUTTON_Y) {
            mButtonState[BUTTON_Y][FRAME_INDEX_CURRENT] = keyIsDown;
        }
    }
}