Android如何实现360度摇杆

这篇文章给大家分享的是有关Android如何实现360度摇杆的内容。小编觉得挺实用的，因此分享给大家做个参考，一起跟随小编过来看看吧。

新建一个类。举例为MySurfaceView

package com.example.blt;import android.annotation.SuppressLint;import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.graphics.PixelFormat;import android.graphics.PorterDuff.Mode;import android.util.AttributeSet;import android.view.MotionEvent;import android.view.SurfaceHolder;import android.view.SurfaceView;import android.view.SurfaceHolder.Callback;public class MySurfaceView extends SurfaceView implements Callback {        private SurfaceHolder sfh;        private Canvas canvas;        private Paint paint;        private int coordinate;        // 固定摇杆背景圆形的半径        private int RockerCircleR, SmallRockerCircleR;        // 摇杆的X,Y坐标以及摇杆的半径        private float SmallRockerCircleX, SmallRockerCircleY;        private RudderListener listener = null; // 事件回调接口        public MySurfaceView(Context context) {                super(context);        }        public MySurfaceView(Context context, AttributeSet as) {                super(context, as);                this.setKeepScreenOn(true);                sfh = getHolder();                sfh.addCallback(this);                paint = new Paint();                paint.setColor(Color.GREEN);                paint.setAntiAlias(true);// 抗锯齿                setFocusable(true);                setFocusableInTouchMode(true);                setZOrderOnTop(true);                sfh.setFormat(PixelFormat.TRANSPARENT);// 设置背景透明        }        public void surfaceCreated(SurfaceHolder holder) {                // 获得控件最小值                int little = this.getWidth() < this.getHeight() ? this.getWidth()                                : this.getHeight();                // 根据屏幕大小绘制                SmallRockerCircleX = SmallRockerCircleY = coordinate = little / 2;                // 固定摇杆背景圆形的半径                RockerCircleR = (int) (little * 0.35);                // 摇杆的半径                SmallRockerCircleR = (int) (little * 0.15);                draw();        }        /***         * 得到两点之间的弧度         */        public double getRad(float px1, float py1, float px2, float py2) {                // 得到两点X的距离                float x = px2 - px1;                // 得到两点Y的距离                float y = py1 - py2;                // 算出斜边长                float xie = (float) Math.sqrt(Math.pow(x, 2) + Math.pow(y, 2));                // 得到这个角度的余弦值（通过三角函数中的定理 ：邻边/斜边=角度余弦值）                float cosAngle = x / xie;                // 通过反余弦定理获取到其角度的弧度                float rad = (float) Math.acos(cosAngle);                // 注意：当触屏的位置Y坐标<摇杆的Y坐标我们要取反值-0~-180                if (py2 < py1) {                        rad = -rad;                }                return rad;        }        @SuppressLint("ClickableViewAccessibility")        @Override        public boolean onTouchEvent(MotionEvent event) {                if (event.getAction() == MotionEvent.ACTION_DOWN                                || event.getAction() == MotionEvent.ACTION_MOVE) {                        // 当触屏区域不在活动范围内                        if (Math.sqrt(Math.pow((coordinate - (int) event.getX()), 2)                                        + Math.pow((coordinate - (int) event.getY()), 2)) >= RockerCircleR) {                                // 得到摇杆与触屏点所形成的角度                                double tempRad = getRad(coordinate, coordinate, event.getX(),                                                event.getY());                                // 保证内部小圆运动的长度限制                                getXY(coordinate, coordinate, RockerCircleR, tempRad);                        } else {// 如果小球中心点小于活动区域则随着用户触屏点移动即可                                SmallRockerCircleX = (int) event.getX();                                SmallRockerCircleY = (int) event.getY();                        }                } else if (event.getAction() == MotionEvent.ACTION_UP) {                        // 当释放按键时摇杆要恢复摇杆的位置为初始位置                        SmallRockerCircleX = coordinate;                        SmallRockerCircleY = coordinate;                }                draw();                if (listener != null) {                        listener.onSteeringWheelChanged((SmallRockerCircleX - coordinate)                                        / RockerCircleR, (coordinate - SmallRockerCircleY)                                        / RockerCircleR);                }                return true;        }        /**         *          * @param R         *            圆周运动的旋转点         * @param centerX         *            旋转点X         * @param centerY         *            旋转点Y         * @param rad         *            旋转的弧度         */        public void getXY(float centerX, float centerY, float R, double rad) {                // 获取圆周运动的X坐标                SmallRockerCircleX = (float) (R * Math.cos(rad)) + centerX;                // 获取圆周运动的Y坐标                SmallRockerCircleY = (float) (R * Math.sin(rad)) + centerY;        }        public void draw() {                try {                        canvas = sfh.lockCanvas();                        // canvas.drawColor(Color.WHITE);                        canvas.drawColor(Color.TRANSPARENT, Mode.CLEAR);// 清除屏幕                        // 设置透明度                        paint.setColor(Color.CYAN);                        // 绘制摇杆背景                        canvas.drawCircle(coordinate, coordinate, RockerCircleR, paint);                        paint.setColor(Color.RED);                        // 绘制摇杆                        canvas.drawCircle(SmallRockerCircleX, SmallRockerCircleY,                                        SmallRockerCircleR, paint);                } catch (Exception e) {                        // TODO: handle exception                } finally {                        try {                                if (canvas != null)                                        sfh.unlockCanvasAndPost(canvas);                        } catch (Exception e2) {                        }                }        }        public void surfaceChanged(SurfaceHolder holder, int format, int width,                        int height) {        }        public void surfaceDestroyed(SurfaceHolder holder) {        }        // 设置回调接口        public void setRudderListener(RudderListener rockerListener) {                listener = rockerListener;        }        // 回调接口        public interface RudderListener {                void onSteeringWheelChanged(float cross, float longitudinal);        }}

主窗体中

package com.example.blt;import android.app.Activity;import android.content.Intent;import android.os.Bundle;import android.util.Log;import android.view.Menu;import android.view.MenuItem;import android.view.View;import android.view.View.OnClickListener;import android.widget.Button;import android.widget.TextView;public class ControlActivity extends Activity {        @Override        protected void onCreate(Bundle savedInstanceState) {                super.onCreate(savedInstanceState);                setContentView(R.layout.activity_control);                MySurfaceView temp = (MySurfaceView) findViewById(R.id.rudder);                temp.setRudderListener(new MySurfaceView.RudderListener() {                        @Override                        public void onSteeringWheelChanged(float cross, float longitudinal) {                                // TODO Auto-generated method stub                                Log.v("change", "c" + cross + "l" + longitudinal);                                ((TextView) findViewById(R.id.textView2)).setText("c:" + cross                                                + "l:" + longitudinal);                        }                });                ((Button) findViewById(R.id.button2))                                .setOnClickListener(new OnClickListener() {                                        @Override                                        public void onClick(View v) {                                                // TODO Auto-generated method stub                                                                                        }                                });        }        @Override        public boolean onCreateOptionsMenu(Menu menu) {                // Inflate the menu; this adds items to the action bar if it is present.                // getMenuInflater().inflate(R.menu.control, menu);                return false;        }        @Override        public boolean onOptionsItemSelected(MenuItem item) {                // Handle action bar item clicks here. The action bar will                // automatically handle clicks on the Home/Up button, so long                // as you specify a parent activity in AndroidManifest.xml.                int id = item.getItemId();                if (id == R.id.action_settings) {                        return true;                }                return super.onOptionsItemSelected(item);        }}

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