Question

我正在学习Android编程。所以我设法实现了一个简单的应用程序，如果您倾斜手机，可以在屏幕上滚动球。但是现在它很简单：如果滚动＆gt; 0然后xpos ++ else xpos-- end和ypos相同。

所以我想计算一个更准确的方向，而且我希望球越快，手机倾斜的速度越快。

因此，如果我知道滚转方向和俯仰方向的倾斜度，我该如何计算球的方向和速度？

Answer 1

以下是：

   package benyamephrem.tiltball;

import android.graphics.Point;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.util.Log;
import android.view.Menu;
import android.view.MenuItem;
import java.util.Timer;
import java.util.TimerTask;
import android.app.Activity;
import android.os.Handler;
import android.view.Display;
import android.view.Window;
import android.view.WindowManager.LayoutParams;
import android.widget.FrameLayout;
import android.hardware.Sensor;
import android.hardware.SensorEvent;
import android.hardware.SensorManager;
import android.content.Context;
import android.content.res.Configuration;
import android.hardware.SensorEventListener;
import android.widget.Toast;


public class TiltBall extends ActionBarActivity {

    BallView mBallView = null;
    Handler RedrawHandler = new Handler(); //so redraw occurs in main thread
    Timer mTmr = null;
    TimerTask mTsk = null;
    int mScrWidth, mScrHeight;
    android.graphics.PointF mBallPos, mBallSpd;




    @Override
    protected void onCreate(Bundle savedInstanceState) {
        requestWindowFeature(Window.FEATURE_NO_TITLE); //hide title bar
    //set app to full screen and keep screen on
        getWindow().setFlags(0xFFFFFFFF, LayoutParams.FLAG_FULLSCREEN | LayoutParams.FLAG_KEEP_SCREEN_ON);
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_tilt_ball);
    //create pointer to main screen
        final FrameLayout mainView = (android.widget.FrameLayout) findViewById(R.id.main_view);

     //get screen dimensions
        Display display = getWindowManager().getDefaultDisplay();
        mScrWidth = display.getWidth();
        mScrHeight = display.getHeight();
        mBallPos = new android.graphics.PointF();
        mBallSpd = new android.graphics.PointF();




    //create variables for ball position and speed
        mBallPos.x = mScrWidth / 2;
        mBallPos.y = mScrHeight / 5;
        mBallSpd.x = 0;
        mBallSpd.y = 0;

        //create initial ball
        mBallView = new BallView(this, mBallPos.x, mBallPos.y, 75);

        mainView.addView(mBallView); //add ball to main screen
        mBallView.invalidate(); //call onDraw in BallView

    //listener for accelerometer, use anonymous class for simplicity
        ((SensorManager) getSystemService(Context.SENSOR_SERVICE)).registerListener(
                new SensorEventListener() {
                    @Override
                    public void onSensorChanged(SensorEvent event) {
                        //set ball speed based on phone tilt (ignore Z axis)


 //***Change speed here by multiplying event values by bigger numbers***
                        mBallSpd.x = -event.values[0] * (30/10);
                        mBallSpd.y = event.values[1] * (30/10);
                        //timer event will redraw ball
                    }

                    @Override
                    public void onAccuracyChanged(Sensor sensor, int accuracy) {
                    } //ignore
                },
                ((SensorManager) getSystemService(Context.SENSOR_SERVICE))
                        .getSensorList(Sensor.TYPE_ACCELEROMETER).get(0),
                SensorManager.SENSOR_DELAY_NORMAL);

        //listener for touch event
        mainView.setOnTouchListener(new android.view.View.OnTouchListener() {
            public boolean onTouch(android.view.View v, android.view.MotionEvent e) {
                //set ball position based on screen touch
                mBallPos.x = e.getX();
                mBallPos.y = e.getY();
                //timer event will redraw ball
                return true;
            }
        });
    } //OnCreate

    //listener for menu button on phone
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        menu.add("Exit"); //only one menu item
        return super.onCreateOptionsMenu(menu);
    }

    //listener for menu item clicked
    @Override
    public boolean onOptionsItemSelected(MenuItem item) {
        // Handle item selection
        if (item.getTitle() == "Exit") //user clicked Exit
            finish(); //will call onPause
        return super.onOptionsItemSelected(item);
    }

    //For state flow see http://developer.android.com/reference/android/app/Activity.html
    @Override
    public void onPause() //app moved to background, stop background threads
    {
        mTmr.cancel(); //kill\release timer (our only background thread)
        mTmr = null;
        mTsk = null;
        super.onPause();
    }


    @Override
    public void onResume() //app moved to foreground (also occurs at app startup)
    {
        //create timer to move ball to new position
        mTmr = new Timer();
        mTsk = new TimerTask() {
            public void run() {

                //if debugging with external device,
//  a log cat viewer will be needed on the device
                Log.d("TiltBall", "Timer Hit - " + mBallPos.x + ":" + mBallPos.y);


//move ball based on current speed
                mBallPos.x += mBallSpd.x;
                mBallPos.y += mBallSpd.y;

                //if ball goes off screen, reposition to opposite side of screen
                if (mBallPos.x > mScrWidth) mBallPos.x = 0;
                if (mBallPos.y > mScrHeight) mBallPos.y = 0;
                if (mBallPos.x < 0) mBallPos.x = mScrWidth;
                if (mBallPos.y < 0) mBallPos.y = mScrHeight;

                //update ball class instance
                mBallView.x = mBallPos.x;
                mBallView.y = mBallPos.y;
//redraw ball. Must run in background thread to prevent thread lock.
                RedrawHandler.post(new Runnable() {
                    public void run() {
                        mBallView.invalidate();
                    }
                });
            }
        }; // TimerTask

        mTmr.schedule(mTsk, 10, 10); //start timer
        super.onResume();
    } // onResume


    @Override
    public void onDestroy() //main thread stopped
    {
        super.onDestroy();
        //wait for threads to exit before clearing app
        System.runFinalizersOnExit(true);
        //remove app from memory
        android.os.Process.killProcess(android.os.Process.myPid());
    }

    //listener for config change.
    //This is called when user tilts phone enough to trigger landscape view
    // we want our app to stay in portrait view, so bypass event
    @Override
    public void onConfigurationChanged(Configuration newConfig)
    {
        super.onConfigurationChanged(newConfig);
    }

} //TiltBallActivity

这是BallView类;

import android.content.Context;

import android.graphics.Canvas;
import android.graphics.Paint;
import android.view.View;

public class BallView extends View {

    public float x;
    public float y;
    private final int r;
    private final Paint mPaint = new Paint(Paint.ANTI_ALIAS_FLAG);


    //construct new ball object
    public BallView(Context context, float x, float y, int r) {
        super(context);
        //color hex is [transparncy][red][green][blue]
        mPaint.setColor(0xFF1325E0);  //not transparent. color is blue
        this.x = x;
        this.y = y;
        this.r = r;  //radius
    }

    //qcalled by invalidate()
    @Override
    protected void onDraw(Canvas canvas) {
        super.onDraw(canvas);
        canvas.drawCircle(x, y, r, mPaint);
    }

    public int getRadius(){
        return r;
    }
}

这不是我的代码，但是我忘记了它的来源，所以无论谁做了它。我正在将它用于我正在进行的当前项目。

如何计算滚转和俯仰（倾斜）的方向和速度？

1 个答案: