這篇文章給大家分享的是有關Android如何實現360度搖桿的內容。小編覺得挺實用的，因此分享給大家做個參考，一起跟隨小編過來看看吧。
新建一個類。舉例為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;
// 固定搖桿背景圓形的半徑
private int RockerCircleR, SmallRockerCircleR;
// 搖桿的X,Y坐標以及搖桿的半徑
private float SmallRockerCircleX, SmallRockerCircleY;
private RudderListener listener = null; // 事件回調接口
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);// 抗鋸齒
setFocusable(true);
setFocusableInTouchMode(true);
setZOrderOnTop(true);
sfh.setFormat(PixelFormat.TRANSPARENT);// 設置背景透明
}
public void surfaceCreated(SurfaceHolder holder) {
// 獲得控件最小值
int little = this.getWidth() < this.getHeight() ? this.getWidth()
: this.getHeight();
// 根據屏幕大小繪制
SmallRockerCircleX = SmallRockerCircleY = coordinate = little / 2;
// 固定搖桿背景圓形的半徑
RockerCircleR = (int) (little * 0.35);
// 搖桿的半徑
SmallRockerCircleR = (int) (little * 0.15);
draw();
}
/***
* 得到兩點之間的弧度
*/
public double getRad(float px1, float py1, float px2, float py2) {
// 得到兩點X的距離
float x = px2 - px1;
// 得到兩點Y的距離
float y = py1 - py2;
// 算出斜邊長
float xie = (float) Math.sqrt(Math.pow(x, 2) + Math.pow(y, 2));
// 得到這個角度的余弦值（通過三角函數中的定理 ：鄰邊/斜邊=角度余弦值）
float cosAngle = x / xie;
// 通過反余弦定理獲取到其角度的弧度
float rad = (float) Math.acos(cosAngle);
// 注意：當觸屏的位置Y坐標<搖桿的Y坐標我們要取反值-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) {
// 當觸屏區域不在活動范圍內
if (Math.sqrt(Math.pow((coordinate - (int) event.getX()), 2)
+ Math.pow((coordinate - (int) event.getY()), 2)) >= RockerCircleR) {
// 得到搖桿與觸屏點所形成的角度
double tempRad = getRad(coordinate, coordinate, event.getX(),
event.getY());
// 保證內部小圓運動的長度限制
getXY(coordinate, coordinate, RockerCircleR, tempRad);
} else {// 如果小球中心點小于活動區域則隨著用戶觸屏點移動即可
SmallRockerCircleX = (int) event.getX();
SmallRockerCircleY = (int) event.getY();
}
} else if (event.getAction() == MotionEvent.ACTION_UP) {
// 當釋放按鍵時搖桿要恢復搖桿的位置為初始位置
SmallRockerCircleX = coordinate;
SmallRockerCircleY = coordinate;
}
draw();
if (listener != null) {
listener.onSteeringWheelChanged((SmallRockerCircleX - coordinate)
/ RockerCircleR, (coordinate - SmallRockerCircleY)
/ RockerCircleR);
}
return true;
}
/**
*
* @param R
* 圓周運動的旋轉點
* @param centerX
* 旋轉點X
* @param centerY
* 旋轉點Y
* @param rad
* 旋轉的弧度
*/
public void getXY(float centerX, float centerY, float R, double rad) {
// 獲取圓周運動的X坐標
SmallRockerCircleX = (float) (R * Math.cos(rad)) + centerX;
// 獲取圓周運動的Y坐標
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
// 設置透明度
paint.setColor(Color.CYAN);
// 繪制搖桿背景
canvas.drawCircle(coordinate, coordinate, RockerCircleR, paint);
paint.setColor(Color.RED);
// 繪制搖桿
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) {
}
// 設置回調接口
public void setRudderListener(RudderListener rockerListener) {
listener = rockerListener;
}
// 回調接口
public interface RudderListener {
void onSteeringWheelChanged(float cross, float longitudinal);
}
}主窗體中
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);
}
}----------------------主窗體XML
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android" xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent" android:layout_height="match_parent" android:background="#ffffff" android:paddingBottom="@dimen/activity_vertical_margin" android:paddingLeft="@dimen/activity_horizontal_margin" android:paddingRight="@dimen/activity_horizontal_margin" android:paddingTop="@dimen/activity_vertical_margin" > <GridLayout android:layout_width="match_parent" android:layout_height="match_parent" android:layout_alignParentLeft="true" android:layout_alignParentTop="true" android:columnCount="3" > <com.example.blt.MySurfaceView android:id="@+id/rudder" android:layout_width="150dp" android:layout_height="150dp" android:layout_column="0" android:layout_gravity="left|bottom" /> <TextView android:id="@+id/textView2" android:layout_column="1" android:layout_gravity="left|top" android:text="TextView" /> <TableLayout android:layout_column="2" android:layout_gravity="bottom" android:layout_row="0" > <TableRow android:id="@+id/tableRow1" android:layout_width="wrap_content" android:layout_height="wrap_content" > <TextView android:id="@+id/axis_x" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="TextView" /> </TableRow> <TableRow android:id="@+id/tableRow2" android:layout_width="wrap_content" android:layout_height="wrap_content" > <Button android:id="@+id/button2" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="自動" /> <Button android:id="@+id/button3" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Button" /> </TableRow> <TableRow android:id="@+id/tableRow3" android:layout_width="wrap_content" android:layout_height="wrap_content" > <Button android:id="@+id/button1" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Button" /> <Button android:id="@+id/button4" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Button" /> </TableRow> <TableRow android:id="@+id/tableRow4" android:layout_width="wrap_content" android:layout_height="wrap_content" > <Button android:id="@+id/button5" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Button" /> <Button android:id="@+id/button6" android:layout_width="wrap_content" android:layout_height="wrap_content" android:text="Button" /> </TableRow> </TableLayout> </GridLayout> </RelativeLayout>
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