Android 模拟信号示波器示例代码

2019-12-12 05:35:18

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上次简单地介绍了AudioRecord和AudioTrack的使用，这次就结合SurfaceView实现一个Android版的手机模拟信号示波器。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。

先来看看本文程序运行的效果图(屏幕录像速度较慢，真机实际运行起来会更加流畅)：

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：

XML/HTML代码

<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 android:layout_height="wrap_content" android:text="停止"              android:id="@+id/btnExit" android:layout_width="80dip">         <zoomcontrols android:layout_width="wrap_content"              android:layout_height="wrap_content" android:id="@+id/zctlX">         <zoomcontrols android:layout_width="wrap_content"              android:layout_height="wrap_content" android:id="@+id/zctlY">          <surfaceview android:id="@+id/SurfaceView01"          android:layout_height="fill_parent" android:layout_width="fill_parent">

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：

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 inBuf = new ArrayList();     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 buf = new ArrayList();                 synchronized (inBuf) {                     if (inBuf.size() == 0)                         continue;                     buf = (ArrayList) 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：

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;         }              } }

以上就是对Android 实现模拟系信号示波器的示例详解，后续继续补充相关知识，谢谢大家对本站的支持！

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