Android提高应用篇之模拟信号示波器（转）

本文结合SurfaceView实现一个Android版的手机模拟信号示波器(PS：以前也讲过J2ME版的手机示波器)。最近物联网炒得很火，作为手机软件开发者，如何在不修改手机硬件电路的前提下实现与第三方传感器结合呢？麦克风就是一个很好的ADC接口，通过麦克风与第三方传感器结合，再在软件里对模拟信号做相应的处理，就可以提供更丰富的传感化应用。

本文程序使用8000hz的采样率，对X轴方向绘图的实时性要求较高，如果不降低X轴的分辨率，程序的实时性较差，因此程序对X轴数据缩小区间为8倍～16倍。由于采用16位采样，因此Y轴数据的高度相对于手机屏幕来说也偏大，程序也对Y轴数据做缩小，区间为1倍～10倍。在SurfaceView的OnTouchListener方法里加入了波形基线的位置调节，直接在SurfaceView控件上触摸即可控制整体波形偏上或偏下显示。

main.xml源码如下：

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<?xml version="1.0" encoding="utf-8"?>  
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"  
    android:orientation="vertical" android:layout_width="fill_parent"  
    android:layout_height="fill_parent">  
    <LinearLayout android:id="@+id/LinearLayout01"  
        android:layout_height="wrap_content" android:layout_width="fill_parent"  
        android:orientation="horizontal">  
        <Button android:layout_height="wrap_content" android:id="@+id/btnStart"  
            android:text="开始" android:layout_width="80dip"></Button>  
        <Button android:layout_height="wrap_content" android:text="停止"  
            android:id="@+id/btnExit" android:layout_width="80dip"></Button>  
        <ZoomControls android:layout_width="wrap_content"  
            android:layout_height="wrap_content" android:id="@+id/zctlX"></ZoomControls>  
        <ZoomControls android:layout_width="wrap_content"  
            android:layout_height="wrap_content" android:id="@+id/zctlY"></ZoomControls>  
    </LinearLayout>  
    <SurfaceView android:id="@+id/SurfaceView01"  
        android:layout_height="fill_parent" android:layout_width="fill_parent"></SurfaceView>  
</LinearLayout>  
<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
 android:orientation="vertical" android:layout_width="fill_parent"
 android:layout_height="fill_parent">
 <LinearLayout android:id="@+id/LinearLayout01"
  android:layout_height="wrap_content" android:layout_width="fill_parent"
  android:orientation="horizontal">
  <Button android:layout_height="wrap_content" android:id="@+id/btnStart"
   android:text="开始" android:layout_width="80dip"></Button>
  <Button android:layout_height="wrap_content" android:text="停止"
   android:id="@+id/btnExit" android:layout_width="80dip"></Button>
  <ZoomControls android:layout_width="wrap_content"
   android:layout_height="wrap_content" android:id="@+id/zctlX"></ZoomControls>
  <ZoomControls android:layout_width="wrap_content"
   android:layout_height="wrap_content" android:id="@+id/zctlY"></ZoomControls>
 </LinearLayout>
 <SurfaceView android:id="@+id/SurfaceView01"
  android:layout_height="fill_parent" android:layout_width="fill_parent"></SurfaceView>
</LinearLayout>

ClsOscilloscope.java是实现示波器的类库，包含AudioRecord操作线程和SurfaceView绘图线程的实现，两个线程同步操作，代码如下：

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package com.testOscilloscope;   
import java.util.ArrayList;   
import android.graphics.Canvas;   
import android.graphics.Color;   
import android.graphics.Paint;   
import android.graphics.Rect;   
import android.media.AudioRecord;   
import android.view.SurfaceView;   
public class ClsOscilloscope {   
    private ArrayList<short[]> inBuf = new ArrayList<short[]>();   
    private boolean isRecording = false;// 线程控制标记   
    /**  
     * X轴缩小的比例  
     */  
    public int rateX = 4;   
    /**  
     * Y轴缩小的比例  
     */  
    public int rateY = 4;   
    /**  
     * Y轴基线  
     */  
    public int baseLine = 0;   
    /**  
     * 初始化  
     */  
    public void initOscilloscope(int rateX, int rateY, int baseLine) {   
        this.rateX = rateX;   
        this.rateY = rateY;   
        this.baseLine = baseLine;   
    }   
    /**  
     * 开始  
     *   
     * @param recBufSize  
     *            AudioRecord的MinBufferSize  
     */  
    public void Start(AudioRecord audioRecord, int recBufSize, SurfaceView sfv,   
            Paint mPaint) {   
        isRecording = true;   
        new RecordThread(audioRecord, recBufSize).start();// 开始录制线程   
        new DrawThread(sfv, mPaint).start();// 开始绘制线程   
    }   
    /**  
     * 停止  
     */  
    public void Stop() {   
        isRecording = false;   
        inBuf.clear();// 清除   
    }   
    /**  
     * 负责从MIC保存数据到inBuf  
     *   
     * @author GV  
     *   
     */  
    class RecordThread extends Thread {   
        private int recBufSize;   
        private AudioRecord audioRecord;   
        public RecordThread(AudioRecord audioRecord, int recBufSize) {   
            this.audioRecord = audioRecord;   
            this.recBufSize = recBufSize;   
        }   
        public void run() {   
            try {   
                short[] buffer = new short[recBufSize];   
                audioRecord.startRecording();// 开始录制   
                while (isRecording) {   
                    // 从MIC保存数据到缓冲区   
                    int bufferReadResult = audioRecord.read(buffer, 0,   
                            recBufSize);   
                    short[] tmpBuf = new short[bufferReadResult / rateX];   
                    for (int i = 0, ii = 0; i < tmpBuf.length; i++, ii = i   
                            * rateX) {   
                        tmpBuf[i] = buffer[ii];   
                    }   
                    synchronized (inBuf) {//   
                        inBuf.add(tmpBuf);// 添加数据   
                    }   
                }   
                audioRecord.stop();   
            } catch (Throwable t) {   
            }   
        }   
    };   
    /**  
     * 负责绘制inBuf中的数据  
     *   
     * @author GV  
     *   
     */  
    class DrawThread extends Thread {   
        private int oldX = 0;// 上次绘制的X坐标   
        private int oldY = 0;// 上次绘制的Y坐标   
        private SurfaceView sfv;// 画板   
        private int X_index = 0;// 当前画图所在屏幕X轴的坐标   
        private Paint mPaint;// 画笔   
        public DrawThread(SurfaceView sfv, Paint mPaint) {   
            this.sfv = sfv;   
            this.mPaint = mPaint;   
        }   
        public void run() {   
            while (isRecording) {   
                ArrayList<short[]> buf = new ArrayList<short[]>();   
                synchronized (inBuf) {   
                    if (inBuf.size() == 0)   
                        continue;   
                    buf = (ArrayList<short[]>) inBuf.clone();// 保存   
                    inBuf.clear();// 清除   
                }   
                for (int i = 0; i < buf.size(); i++) {   
                    short[] tmpBuf = buf.get(i);   
                    SimpleDraw(X_index, tmpBuf, rateY, baseLine);// 把缓冲区数据画出来   
                    X_index = X_index + tmpBuf.length;   
                    if (X_index > sfv.getWidth()) {   
                        X_index = 0;   
                    }   
                }   
            }   
        }   
        /**  
         * 绘制指定区域  
         *   
         * @param start  
         *            X轴开始的位置(全屏)  
         * @param buffer  
         *            缓冲区  
         * @param rate  
         *            Y轴数据缩小的比例  
         * @param baseLine  
         *            Y轴基线  
         */  
        void SimpleDraw(int start, short[] buffer, int rate, int baseLine) {   
            if (start == 0)   
                oldX = 0;   
            Canvas canvas = sfv.getHolder().lockCanvas(   
                    new Rect(start, 0, start + buffer.length, sfv.getHeight()));// 关键:获取画布   
            canvas.drawColor(Color.BLACK);// 清除背景   
            int y;   
            for (int i = 0; i < buffer.length; i++) {// 有多少画多少   
                int x = i + start;   
                y = buffer[i] / rate + baseLine;// 调节缩小比例，调节基准线   
                canvas.drawLine(oldX, oldY, x, y, mPaint);   
                oldX = x;   
                oldY = y;   
            }   
            sfv.getHolder().unlockCanvasAndPost(canvas);// 解锁画布，提交画好的图像   
        }   
    }   
}

package com.testOscilloscope;
import java.util.ArrayList;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.graphics.Rect;
import android.media.AudioRecord;
import android.view.SurfaceView;
public class ClsOscilloscope {
 private ArrayList<short[]> inBuf = new ArrayList<short[]>();
 private boolean isRecording = false;// 线程控制标记
 /**
  * X轴缩小的比例
  */
 public int rateX = 4;
 /**
  * Y轴缩小的比例
  */
 public int rateY = 4;
 /**
  * Y轴基线
  */
 public int baseLine = 0;
 /**
  * 初始化
  */
 public void initOscilloscope(int rateX, int rateY, int baseLine) {
  this.rateX = rateX;
  this.rateY = rateY;
  this.baseLine = baseLine;
 }
 /**
  * 开始
  * 
  * @param recBufSize
  *            AudioRecord的MinBufferSize
  */
 public void Start(AudioRecord audioRecord, int recBufSize, SurfaceView sfv,
   Paint mPaint) {
  isRecording = true;
  new RecordThread(audioRecord, recBufSize).start();// 开始录制线程
  new DrawThread(sfv, mPaint).start();// 开始绘制线程
 }
 /**
  * 停止
  */
 public void Stop() {
  isRecording = false;
  inBuf.clear();// 清除
 }
 /**
  * 负责从MIC保存数据到inBuf
  * 
  * @author GV
  * 
  */
 class RecordThread extends Thread {
  private int recBufSize;
  private AudioRecord audioRecord;
  public RecordThread(AudioRecord audioRecord, int recBufSize) {
   this.audioRecord = audioRecord;
   this.recBufSize = recBufSize;
  }
  public void run() {
   try {
    short[] buffer = new short[recBufSize];
    audioRecord.startRecording();// 开始录制
    while (isRecording) {
     // 从MIC保存数据到缓冲区
     int bufferReadResult = audioRecord.read(buffer, 0,
       recBufSize);
     short[] tmpBuf = new short[bufferReadResult / rateX];
     for (int i = 0, ii = 0; i < tmpBuf.length; i++, ii = i
       * rateX) {
      tmpBuf[i] = buffer[ii];
     }
     synchronized (inBuf) {//
      inBuf.add(tmpBuf);// 添加数据
     }
    }
    audioRecord.stop();
   } catch (Throwable t) {
   }
  }
 };
 /**
  * 负责绘制inBuf中的数据
  * 
  * @author GV
  * 
  */
 class DrawThread extends Thread {
  private int oldX = 0;// 上次绘制的X坐标
  private int oldY = 0;// 上次绘制的Y坐标
  private SurfaceView sfv;// 画板
  private int X_index = 0;// 当前画图所在屏幕X轴的坐标
  private Paint mPaint;// 画笔
  public DrawThread(SurfaceView sfv, Paint mPaint) {
   this.sfv = sfv;
   this.mPaint = mPaint;
  }
  public void run() {
   while (isRecording) {
    ArrayList<short[]> buf = new ArrayList<short[]>();
    synchronized (inBuf) {
     if (inBuf.size() == 0)
      continue;
     buf = (ArrayList<short[]>) inBuf.clone();// 保存
     inBuf.clear();// 清除
    }
    for (int i = 0; i < buf.size(); i++) {
     short[] tmpBuf = buf.get(i);
     SimpleDraw(X_index, tmpBuf, rateY, baseLine);// 把缓冲区数据画出来
     X_index = X_index + tmpBuf.length;
     if (X_index > sfv.getWidth()) {
      X_index = 0;
     }
    }
   }
  }
  /**
   * 绘制指定区域
   * 
   * @param start
   *            X轴开始的位置(全屏)
   * @param buffer
   *            缓冲区
   * @param rate
   *            Y轴数据缩小的比例
   * @param baseLine
   *            Y轴基线
   */
  void SimpleDraw(int start, short[] buffer, int rate, int baseLine) {
   if (start == 0)
    oldX = 0;
   Canvas canvas = sfv.getHolder().lockCanvas(
     new Rect(start, 0, start + buffer.length, sfv.getHeight()));// 关键:获取画布
   canvas.drawColor(Color.BLACK);// 清除背景
   int y;
   for (int i = 0; i < buffer.length; i++) {// 有多少画多少
    int x = i + start;
    y = buffer[i] / rate + baseLine;// 调节缩小比例，调节基准线
    canvas.drawLine(oldX, oldY, x, y, mPaint);
    oldX = x;
    oldY = y;
   }
   sfv.getHolder().unlockCanvasAndPost(canvas);// 解锁画布，提交画好的图像
  }
 }
}

testOscilloscope.java是主程序，控制UI和ClsOscilloscope，代码如下：

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package com.testOscilloscope;   
import android.app.Activity;   
import android.graphics.Color;   
import android.graphics.Paint;   
import android.media.AudioFormat;   
import android.media.AudioRecord;   
import android.media.MediaRecorder;   
import android.os.Bundle;   
import android.view.MotionEvent;   
import android.view.SurfaceView;   
import android.view.View;   
import android.view.View.OnTouchListener;   
import android.widget.Button;   
import android.widget.ZoomControls;   
public class testOscilloscope extends Activity {   
    /** Called when the activity is first created. */  
    Button btnStart,btnExit;   
    SurfaceView sfv;   
    ZoomControls zctlX,zctlY;   
       
    ClsOscilloscope clsOscilloscope=new ClsOscilloscope();   
       
    static final int frequency = 8000;//分辨率   
    static final int channelConfiguration = AudioFormat.CHANNEL_CONFIGURATION_MONO;   
    static final int audioEncoding = AudioFormat.ENCODING_PCM_16BIT;   
    static final int xMax = 16;//X轴缩小比例最大值,X轴数据量巨大，容易产生刷新延时   
    static final int xMin = 8;//X轴缩小比例最小值   
    static final int yMax = 10;//Y轴缩小比例最大值   
    static final int yMin = 1;//Y轴缩小比例最小值   
       
    int recBufSize;//录音最小buffer大小   
    AudioRecord audioRecord;   
    Paint mPaint;   
    @Override  
    public void onCreate(Bundle savedInstanceState) {   
        super.onCreate(savedInstanceState);   
        setContentView(R.layout.main);   
        //录音组件   
        recBufSize = AudioRecord.getMinBufferSize(frequency,   
                channelConfiguration, audioEncoding);   
        audioRecord = new AudioRecord(MediaRecorder.AudioSource.MIC, frequency,   
                channelConfiguration, audioEncoding, recBufSize);   
        //按键   
        btnStart = (Button) this.findViewById(R.id.btnStart);   
        btnStart.setOnClickListener(new ClickEvent());   
        btnExit = (Button) this.findViewById(R.id.btnExit);   
        btnExit.setOnClickListener(new ClickEvent());   
        //画板和画笔   
        sfv = (SurfaceView) this.findViewById(R.id.SurfaceView01);    
        sfv.setOnTouchListener(new TouchEvent());   
        mPaint = new Paint();     
        mPaint.setColor(Color.GREEN);// 画笔为绿色     
        mPaint.setStrokeWidth(1);// 设置画笔粗细    
        //示波器类库   
        clsOscilloscope.initOscilloscope(xMax/2, yMax/2, sfv.getHeight()/2);   
           
        //缩放控件，X轴的数据缩小的比率高些   
        zctlX = (ZoomControls)this.findViewById(R.id.zctlX);   
        zctlX.setOnZoomInClickListener(new View.OnClickListener() {   
            @Override  
            public void onClick(View v) {   
                if(clsOscilloscope.rateX>xMin)   
                    clsOscilloscope.rateX--;   
                setTitle("X轴缩小"+String.valueOf(clsOscilloscope.rateX)+"倍"  
                        +","+"Y轴缩小"+String.valueOf(clsOscilloscope.rateY)+"倍");   
            }   
        });   
        zctlX.setOnZoomOutClickListener(new View.OnClickListener() {   
            @Override  
            public void onClick(View v) {   
                if(clsOscilloscope.rateX<xMax)   
                    clsOscilloscope.rateX++;       
                setTitle("X轴缩小"+String.valueOf(clsOscilloscope.rateX)+"倍"  
                        +","+"Y轴缩小"+String.valueOf(clsOscilloscope.rateY)+"倍");   
            }   
        });   
        zctlY = (ZoomControls)this.findViewById(R.id.zctlY);   
        zctlY.setOnZoomInClickListener(new View.OnClickListener() {   
            @Override  
            public void onClick(View v) {   
                if(clsOscilloscope.rateY>yMin)   
                    clsOscilloscope.rateY--;   
                setTitle("X轴缩小"+String.valueOf(clsOscilloscope.rateX)+"倍"  
                        +","+"Y轴缩小"+String.valueOf(clsOscilloscope.rateY)+"倍");   
            }   
        });   
           
        zctlY.setOnZoomOutClickListener(new View.OnClickListener() {   
            @Override  
            public void onClick(View v) {   
                if(clsOscilloscope.rateY<yMax)   
                    clsOscilloscope.rateY++;       
                setTitle("X轴缩小"+String.valueOf(clsOscilloscope.rateX)+"倍"  
                        +","+"Y轴缩小"+String.valueOf(clsOscilloscope.rateY)+"倍");   
            }   
        });   
    }   
    @Override  
    protected void onDestroy() {   
        super.onDestroy();   
        android.os.Process.killProcess(android.os.Process.myPid());   
    }   
       
    /**  
     * 按键事件处理  
     * @author GV  
     *  
     */  
    class ClickEvent implements View.OnClickListener {   
        @Override  
        public void onClick(View v) {   
            if (v == btnStart) {   
                clsOscilloscope.baseLine=sfv.getHeight()/2;   
                clsOscilloscope.Start(audioRecord,recBufSize,sfv,mPaint);   
            } else if (v == btnExit) {   
                clsOscilloscope.Stop();   
            }   
        }   
    }   
    /**  
     * 触摸屏动态设置波形图基线  
     * @author GV  
     *  
     */  
    class TouchEvent implements OnTouchListener{   
        @Override  
        public boolean onTouch(View v, MotionEvent event) {   
            clsOscilloscope.baseLine=(int)event.getY();   
            return true;   
        }   
           
    }   
}

http://ee.ofweek.com/2010-12/ART-8300-2807-28433357.html