Android Open Source - smartcar Joystick View

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Back to project page smartcar.

License

The source code is released under:

GNU General Public License

Java Source Code

/** This class handles the joystick appearance.
 * Original code by Zerokol//from  www.ja v a  2 s  .  c  o m
 * https://github.com/zerokol
 * Changes by Team Balmung (simeon & dimi)
 */

package se.chalmers.balmung.smartcar;

import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;

public class JoystickView extends View implements Runnable {
  // Constants
  private final double RAD = 57.2957795;
  public final static long DEFAULT_LOOP_INTERVAL = 80; // default:100 ms
  public final static int FRONT = 3;
  public final static int FRONT_RIGHT = 4;
  public final static int RIGHT = 5;
  public final static int RIGHT_BOTTOM = 6;
  public final static int BOTTOM = 7;
  public final static int BOTTOM_LEFT = 8;
  public final static int LEFT = 1;
  public final static int LEFT_FRONT = 2;

  // Variables
  private OnJoystickMoveListener onJoystickMoveListener; // Listener
  private Thread thread = new Thread(this);
  private long loopInterval = DEFAULT_LOOP_INTERVAL;
  private int xPosition = 0; // Touch x position
  private int yPosition = 0; // Touch y position
  private double centerX = 0; // Center view x position
  private double centerY = 0; // Center view y position
  private Paint mainCircle;
  private Paint button;
  private int joystickRadius;
  private int buttonRadius;
  private int lastAngle = 0;
  private int lastPower = 0;
  public static int threadsRunning = 0;
  public JoystickView(Context context) {
    super(context);
  }

  public JoystickView(Context context, AttributeSet attrs) {
    super(context, attrs);
    initJoystickView();
  }

  public JoystickView(Context context, AttributeSet attrs, int defaultStyle) {
    super(context, attrs, defaultStyle);
    initJoystickView();
  }

  protected void initJoystickView() {
    mainCircle = new Paint(Paint.ANTI_ALIAS_FLAG);
    mainCircle.setColor(Color.WHITE);
    mainCircle.setStyle(Paint.Style.FILL_AND_STROKE);
    mainCircle.setAlpha(40);
    
    button = new Paint(Paint.ANTI_ALIAS_FLAG);
    button.setColor(Color.GRAY);
    button.setStyle(Paint.Style.FILL);
    button.setAlpha(60);
  }

  @Override
  protected void onFinishInflate() {
  }

  @Override
  protected void onMeasure(int widthMeasureSpec, int heightMeasureSpec) {
    // setting the measured values to resize the view to a certain width and
    // height
    int d = Math.min(measure(widthMeasureSpec), measure(heightMeasureSpec));

    setMeasuredDimension(d, d);

    // before measure, get the center of view
    xPosition = (int) getWidth() / 2;
    yPosition = (int) getWidth() / 2;

    buttonRadius = (int) (d / 2 * 0.25);
    joystickRadius = (int) (d / 2 * 0.65);
  }

  private int measure(int measureSpec) {
    int result = 0;

    // Decode the measurement specifications.
    int specMode = MeasureSpec.getMode(measureSpec);
    int specSize = MeasureSpec.getSize(measureSpec);

    if (specMode == MeasureSpec.UNSPECIFIED) {
      // Return a default size of 200 if no bounds are specified.
      result = 200;
    } else {
      // As you want to fill the available space
      // always return the full available bounds.
      result = specSize;
    }
    return result;
  }

  @Override
  protected void onDraw(Canvas canvas) {
    // super.onDraw(canvas);
    centerX = (getWidth()) / 2;
    centerY = (getHeight()) / 2;

    // painting the main circle
    canvas.drawCircle((int) centerX, (int) centerY, joystickRadius,
        mainCircle);

    // painting the move button
    canvas.drawCircle(xPosition, yPosition, buttonRadius, button);
  }

  @Override
  public boolean onTouchEvent(MotionEvent event) {
    xPosition = (int) event.getX();
    yPosition = (int) event.getY();
    double abs = Math.sqrt((xPosition - centerX) * (xPosition - centerX)
        + (yPosition - centerY) * (yPosition - centerY));
    if (abs > joystickRadius) {
      xPosition = (int) ((xPosition - centerX) * joystickRadius / abs + centerX);
      yPosition = (int) ((yPosition - centerY) * joystickRadius / abs + centerY);
    }
    invalidate();
    if (event.getAction() == MotionEvent.ACTION_UP) {
      xPosition = (int) centerX;
      yPosition = (int) centerY;
      thread.interrupt();
      threadsRunning--;
      onJoystickMoveListener.onValueChanged(getAngle(), getPower(),
          getDirection());
    }
    if (onJoystickMoveListener != null
        && event.getAction() == MotionEvent.ACTION_DOWN) {
      if (thread != null && thread.isAlive()) {
        thread.interrupt();
        threadsRunning--;
      }
      thread = new Thread(this);
      thread.start();
      threadsRunning++;
      onJoystickMoveListener.onValueChanged(getAngle(), getPower(),
          getDirection());
    }
    return true;
  }

  private int getAngle() {
    if (xPosition > centerX) {
      if (yPosition < centerY) {
        return lastAngle = (int) (Math.atan((yPosition - centerY)
            / (xPosition - centerX))
            * RAD + 90);
      } else if (yPosition > centerY) {
        return lastAngle = (int) (Math.atan((yPosition - centerY)
            / (xPosition - centerX)) * RAD) + 90;
      } else {
        return lastAngle = 90;
      }
    } else if (xPosition < centerX) {
      if (yPosition < centerY) {
        return lastAngle = (int) (Math.atan((yPosition - centerY)
            / (xPosition - centerX))
            * RAD - 90);
      } else if (yPosition > centerY) {
        return lastAngle = (int) (Math.atan((yPosition - centerY)
            / (xPosition - centerX)) * RAD) - 90;
      } else {
        return lastAngle = -90;
      }
    } else {
      if (yPosition <= centerY) {
        return lastAngle = 0;
      } else {
        if (lastAngle < 0) {
          return lastAngle = -180;
        } else {
          return lastAngle = 180;
        }
      }
    }
  }

  private int getPower() {
    return (int) (100 * Math.sqrt((xPosition - centerX)
        * (xPosition - centerX) + (yPosition - centerY)
        * (yPosition - centerY)) / joystickRadius);
  }

  private int getDirection() {
    if (lastPower == 0 && lastAngle == 0) {
      return 0;
    }
    int a = 0;
    if (lastAngle <= 0) {
      a = (lastAngle * -1) + 90;
    } else if (lastAngle > 0) {
      if (lastAngle <= 90) {
        a = 90 - lastAngle;
      } else {
        a = 360 - (lastAngle - 90);
      }
    }

    int direction = (int) (((a + 22) / 45) + 1);

    if (direction > 8) {
      direction = 1;
    }
    return direction;
  }

  public void setOnJoystickMoveListener(OnJoystickMoveListener listener,
      long repeatInterval) {
    this.onJoystickMoveListener = listener;
    this.loopInterval = repeatInterval;
  }

  public static interface OnJoystickMoveListener {
    public void onValueChanged(int angle, int power, int direction);
  }

  @Override
  public void run() {
    while (!Thread.interrupted()) {
      post(new Runnable() {
        public void run() {
          onJoystickMoveListener.onValueChanged(getAngle(),
              getPower(), getDirection());
        }
      });
      try {
        Thread.sleep(loopInterval);
      } catch (InterruptedException e) {
        break;
      }
    }
  }
}

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