这段时间研究Android自定义控件，遂想起游戏里的摇杆的实现挺有意思，于是来自己写一套熟悉熟悉，关于SurfaceView的特性网上也有很多，故不赘述，反正绘图用起来挺爽就是了，永远的告别了JAVA GUI手动实现双缓冲的时代了……
Android相关内容:
import com.game.graphics.utils.MathUtils;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.PixelFormat;
import android.graphics.Point;
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 Rudder extends SurfaceView implements Runnable,Callback{
private SurfaceHolder mHolder;
private boolean isStop = false;
private Thread mThread;
private Paint mPaint;
private Point mRockerPosition; //摇杆位置
private Point mCtrlPoint = new Point(80,80);//摇杆起始位置
private int mRudderRadius = 20;//摇杆半径
private int mWheelRadius = 60;//摇杆活动范围半径
private RudderListener listener = null; //事件回调接口
public static final int ACTION_RUDDER = 1 , ACTION_ATTACK = 2; // 1：摇杆事件 2：按钮事件（未实现）
public Rudder(Context context) {
super(context);
}
public Rudder(Context context, AttributeSet as) {
super(context, as);
this.setKeepScreenOn(true);
mHolder = getHolder();
mHolder.addCallback(this);
mThread = new Thread(this);
mPaint = new Paint();
mPaint.setColor(Color.GREEN);
mPaint.setAntiAlias(true);//抗锯齿
mRockerPosition = new Point(mCtrlPoint);
setFocusable(true);
setFocusableInTouchMode(true);
setZOrderOnTop(true);
mHolder.setFormat(PixelFormat.TRANSPARENT);//设置背景透明
}
//设置回调接口
public void setRudderListener(RudderListener rockerListener) {
listener = rockerListener;
}
@Override
public void run() {
Canvas canvas = null;
while(!isStop) {
try {
canvas = mHolder.lockCanvas();
canvas.drawColor(Color.TRANSPARENT,Mode.CLEAR);//清除屏幕
mPaint.setColor(Color.CYAN);
canvas.drawCircle(mCtrlPoint.x, mCtrlPoint.y, mWheelRadius, mPaint);//绘制范围
mPaint.setColor(Color.RED);
canvas.drawCircle(mRockerPosition.x, mRockerPosition.y, mRudderRadius, mPaint);//绘制摇杆
} catch (Exception e) {
e.printStackTrace();
} finally {
if(canvas != null) {
mHolder.unlockCanvasAndPost(canvas);
}
}
try {
Thread.sleep(30);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}
@Override
public void surfaceChanged(SurfaceHolder holder, int format, int width,
int height) {
}
@Override
public void surfaceCreated(SurfaceHolder holder) {
mThread.start();
}
@Override
public void surfaceDestroyed(SurfaceHolder holder) {
isStop = true;
}
@Override
public boolean onTouchEvent(MotionEvent event) {
int len = MathUtils.getLength(mCtrlPoint.x, mCtrlPoint.y, event.getX(), event.getY());
if(event.getAction() == MotionEvent.ACTION_DOWN) {
//如果屏幕接触点不在摇杆挥动范围内,则不处理
if(len >mWheelRadius) {
return true;
}
}
if(event.getAction() == MotionEvent.ACTION_MOVE){
if(len <= mWheelRadius) {
//如果手指在摇杆活动范围内，则摇杆处于手指触摸位置
mRockerPosition.set((int)event.getX(), (int)event.getY());
}else{
//设置摇杆位置，使其处于手指触摸方向的 摇杆活动范围边缘
mRockerPosition = MathUtils.getBorderPoint(mCtrlPoint,
new Point((int)event.getX(), (int)event.getY()), mWheelRadius);
}
if(listener != null) {
float radian = MathUtils.getRadian(mCtrlPoint, new Point((int)event.getX(), (int)event.getY()));
listener.onSteeringWheelChanged(ACTION_RUDDER,Rudder.this.getAngleCouvert(radian));
}
}
//如果手指离开屏幕，则摇杆返回初始位置
if(event.getAction() == MotionEvent.ACTION_UP) {
mRockerPosition = new Point(mCtrlPoint);
}
return true;
}
//获取摇杆偏移角度 0-360°
private int getAngleCouvert(float radian) {
int tmp = (int)Math.round(radian/Math.PI*180);
if(tmp < 0) {
return -tmp;
}else{
return 180 + (180 - tmp);
}
}
//回调接口
public interface RudderListener {
void onSteeringWheelChanged(int action,int angle);
}
}
import android.graphics.Point;
public class MathUtils {
//获取两点间直线距离
public static int getLength(float x1,float y1,float x2,float y2) {
return (int)Math.sqrt(Math.pow(x1-x2, 2) + Math.pow(y1-y2, 2));
}
/**
* 获取线段上某个点的坐标，长度为a.x - cutRadius
* @param a 点A
* @param b 点B
* @param cutRadius 截断距离
* @return 截断点
*/
public static Point getBorderPoint(Point a, Point b,int cutRadius) {
float radian = getRadian(a, b);
return new Point(a.x + (int)(cutRadius * Math.cos(radian)), a.x + (int)(cutRadius * Math.sin(radian)));
}
//获取水平线夹角弧度
public static float getRadian (Point a, Point b) {
float lenA = b.x-a.x;
float lenB = b.y-a.y;
float lenC = (float)Math.sqrt(lenA*lenA+lenB*lenB);
float ang = (float)Math.acos(lenA/lenC);
ang = ang * (b.y < a.y ? -1 : 1);
return ang;
}
}
<?xml version="1.0" encoding="utf-8"?>
<FrameLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:orientation="vertical"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<ImageView
android:layout_width="fill_parent"
android:layout_height="fill_parent"
android:scaleType="fitXY"
android:src="@drawable/xx"/>
<RelativeLayout
android:id="@+id/ctrls"
android:layout_width="fill_parent"
android:layout_height="fill_parent">
<com.game.demo.views.Rudder
android:id="@+id/rudder"
android:layout_width="480dip"
android:layout_height="160dip"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"/>
</RelativeLayout>
</FrameLayout>
setContentView(R.layout.main);
Rudder rudder = (Rudder) findViewById(R.id.rudder);
rudder.setRudderListener(new RudderListener() {
@Override
public void onSteeringWheelChanged(int action, int angle) {
if(action == Rudder.ACTION_RUDDER) {
//TODO:事件实现
}
}
});