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Android提高應(yīng)用篇之模擬信號示波器
摘要: 本文結(jié)合SurfaceView實(shí)現(xiàn)一個Android版的手機(jī)模擬信號示波器(PS:以前也講過J2ME版的手機(jī)示波器)。最近物聯(lián)網(wǎng)炒得很火,作為手機(jī)軟件開發(fā)者,如何在不修改手機(jī)硬件電路的前提下實(shí)現(xiàn)與第三方傳感器結(jié)合呢?
Abstract:
Key words :

本文結(jié)合SurfaceView實(shí)現(xiàn)一個Android版的手機(jī)模擬信號示波器(PS:以前也講過J2ME版的手機(jī)示波器)。最近物聯(lián)網(wǎng)炒得很火,作為手機(jī)軟件開發(fā)者,如何在不修改手機(jī)硬件電路的前提下實(shí)現(xiàn)與第三方傳感器結(jié)合呢?麥克風(fēng)就是一個很好的ADC接口,通過麥克風(fēng)與第三方傳感器結(jié)合,再在軟件里對模擬信號做相應(yīng)的處理,就可以提供更豐富的傳感化應(yīng)用。

先來看看本文程序運(yùn)行的效果圖(屏幕錄像速度較慢,真機(jī)實(shí)際運(yùn)行起來會更加流暢):

 

       本文程序使用8000hz的采樣率,對X軸方向繪圖的實(shí)時性要求較高,如果不降低X軸的分辨率,程序的實(shí)時性較差,因此程序?qū)軸數(shù)據(jù)縮小區(qū)間為8倍~16倍。由于采用16位采樣,因此Y軸數(shù)據(jù)的高度相對于手機(jī)屏幕來說也偏大,程序也對Y軸數(shù)據(jù)做縮小,區(qū)間為1倍~10倍。在SurfaceView的OnTouchListener方法里加入了波形基線的位置調(diào)節(jié),直接在SurfaceView控件上觸摸即可控制整體波形偏上或偏下顯示。

main.xml源碼如下:

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    android:orientation="vertical" android:layout_width="fill_parent" 
    android:layout_height="fill_parent"> 
            android:layout_height="wrap_content" android:layout_width="fill_parent" 
        android:orientation="horizontal"> 
        
        
                    android:layout_height="wrap_content" android:id="@+id/zctlX"> 
                    android:layout_height="wrap_content" android:id="@+id/zctlY"> 
     
            android:layout_height="fill_parent" android:layout_width="fill_parent"> 
 

 android:orientation="vertical" android:layout_width="fill_parent"
 android:layout_height="fill_parent">
   android:layout_height="wrap_content" android:layout_width="fill_parent"
  android:orientation="horizontal">
  
  
     android:layout_height="wrap_content" android:id="@+id/zctlX">
     android:layout_height="wrap_content" android:id="@+id/zctlY">
 
   android:layout_height="fill_parent" android:layout_width="fill_parent">

 

ClsOscilloscope.java是實(shí)現(xiàn)示波器的類庫,包含AudioRecord操作線程和SurfaceView繪圖線程的實(shí)現(xiàn),兩個線程同步操作,代碼如下:

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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 inBuf = new ArrayList();  
    private boolean isRecording = false;// 線程控制標(biāo)記  
    /** 
     * X軸縮小的比例 
     */ 
    public int rateX = 4;  
    /** 
     * Y軸縮小的比例 
     */ 
    public int rateY = 4;  
    /** 
     * Y軸基線 
     */ 
    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;  
    }  
    /** 
     * 開始 
     *  
     * @param recBufSize 
     *            AudioRecord的MinBufferSize 
     */ 
    public void Start(AudioRecord audioRecord, int recBufSize, SurfaceView sfv,  
            Paint mPaint) {  
        isRecording = true;  
        new RecordThread(audioRecord, recBufSize).start();// 開始錄制線程  
        new DrawThread(sfv, mPaint).start();// 開始繪制線程  
    }  
    /** 
     * 停止 
     */ 
    public void Stop() {  
        isRecording = false;  
        inBuf.clear();// 清除  
    }  
    /** 
     * 負(fù)責(zé)從MIC保存數(shù)據(jù)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();// 開始錄制  
                while (isRecording) {  
                    // 從MIC保存數(shù)據(jù)到緩沖區(qū)  
                    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);// 添加數(shù)據(jù)  
                    }  
                }  
                audioRecord.stop();  
            } catch (Throwable t) {  
            }  
        }  
    };  
    /** 
     * 負(fù)責(zé)繪制inBuf中的數(shù)據(jù) 
     *  
     * @author GV 
     *  
     */ 
    class DrawThread extends Thread {  
        private int oldX = 0;// 上次繪制的X坐標(biāo)  
        private int oldY = 0;// 上次繪制的Y坐標(biāo)  
        private SurfaceView sfv;// 畫板  
        private int X_index = 0;// 當(dāng)前畫圖所在屏幕X軸的坐標(biāo)  
        private Paint mPaint;// 畫筆  
        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);// 把緩沖區(qū)數(shù)據(jù)畫出來  
                    X_index = X_index + tmpBuf.length;  
                    if (X_index > sfv.getWidth()) {  
                        X_index = 0;  
                    }  
                }  
            }  
        }  
        /** 
         * 繪制指定區(qū)域 
         *  
         * @param start 
         *            X軸開始的位置(全屏) 
         * @param buffer 
         *            緩沖區(qū) 
         * @param rate 
         *            Y軸數(shù)據(jù)縮小的比例 
         * @param baseLine 
         *            Y軸基線 
         */ 
        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()));// 關(guān)鍵:獲取畫布  
            canvas.drawColor(Color.BLACK);// 清除背景  
            int y;  
            for (int i = 0; i < buffer.length; i++) {// 有多少畫多少  
                int x = i + start;  
                y = buffer[i] / rate + baseLine;// 調(diào)節(jié)縮小比例,調(diào)節(jié)基準(zhǔn)線  
                canvas.drawLine(oldX, oldY, x, y, mPaint);  
                oldX = x;  
                oldY = y;  
            }  
            sfv.getHolder().unlockCanvasAndPost(canvas);// 解鎖畫布,提交畫好的圖像  
        }  
    }  

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 inBuf = new ArrayList();
 private boolean isRecording = false;// 線程控制標(biāo)記
 /**
  * X軸縮小的比例
  */
 public int rateX = 4;
 /**
  * Y軸縮小的比例
  */
 public int rateY = 4;
 /**
  * Y軸基線
  */
 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;
 }
 /**
  * 開始
  *
  * @param recBufSize
  *            AudioRecord的MinBufferSize
  */
 public void Start(AudioRecord audioRecord, int recBufSize, SurfaceView sfv,
   Paint mPaint) {
  isRecording = true;
  new RecordThread(audioRecord, recBufSize).start();// 開始錄制線程
  new DrawThread(sfv, mPaint).start();// 開始繪制線程
 }
 /**
  * 停止
  */
 public void Stop() {
  isRecording = false;
  inBuf.clear();// 清除
 }
 /**
  * 負(fù)責(zé)從MIC保存數(shù)據(jù)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();// 開始錄制
    while (isRecording) {
     // 從MIC保存數(shù)據(jù)到緩沖區(qū)
     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);// 添加數(shù)據(jù)
     }
    }
    audioRecord.stop();
   } catch (Throwable t) {
   }
  }
 };
 /**
  * 負(fù)責(zé)繪制inBuf中的數(shù)據(jù)
  *
  * @author GV
  *
  */
 class DrawThread extends Thread {
  private int oldX = 0;// 上次繪制的X坐標(biāo)
  private int oldY = 0;// 上次繪制的Y坐標(biāo)
  private SurfaceView sfv;// 畫板
  private int X_index = 0;// 當(dāng)前畫圖所在屏幕X軸的坐標(biāo)
  private Paint mPaint;// 畫筆
  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);// 把緩沖區(qū)數(shù)據(jù)畫出來
     X_index = X_index + tmpBuf.length;
     if (X_index > sfv.getWidth()) {
      X_index = 0;
     }
    }
   }
  }
  /**
   * 繪制指定區(qū)域
   *
   * @param start
   *            X軸開始的位置(全屏)
   * @param buffer
   *            緩沖區(qū)
   * @param rate
   *            Y軸數(shù)據(jù)縮小的比例
   * @param baseLine
   *            Y軸基線
   */
  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()));// 關(guān)鍵:獲取畫布
   canvas.drawColor(Color.BLACK);// 清除背景
   int y;
   for (int i = 0; i < buffer.length; i++) {// 有多少畫多少
    int x = i + start;
    y = buffer[i] / rate + baseLine;// 調(diào)節(jié)縮小比例,調(diào)節(jié)基準(zhǔn)線
    canvas.drawLine(oldX, oldY, x, y, mPaint);
    oldX = x;
    oldY = y;
   }
   sfv.getHolder().unlockCanvasAndPost(canvas);// 解鎖畫布,提交畫好的圖像
  }
 }
}
 

testOscilloscope.java是主程序,控制UI和ClsOscilloscope,代碼如下:

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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軸縮小比例最大值,X軸數(shù)據(jù)量巨大,容易產(chǎn)生刷新延時  
    static final int xMin = 8;//X軸縮小比例最小值  
    static final int yMax = 10;//Y軸縮小比例最大值  
    static final int yMin = 1;//Y軸縮小比例最小值  
      
    int recBufSize;//錄音最小buffer大小  
    AudioRecord audioRecord;  
    Paint mPaint;  
    @Override 
    public void onCreate(Bundle savedInstanceState) {  
        super.onCreate(savedInstanceState);  
        setContentView(R.layout.main);  
        //錄音組件  
        recBufSize = AudioRecord.getMinBufferSize(frequency,  
                channelConfiguration, audioEncoding);  
        audioRecord = new AudioRecord(MediaRecorder.AudioSource.MIC, frequency,  
                channelConfiguration, audioEncoding, recBufSize);  
        //按鍵  
        btnStart = (Button) this.findViewById(R.id.btnStart);  
        btnStart.setOnClickListener(new ClickEvent());  
        btnExit = (Button) this.findViewById(R.id.btnExit);  
        btnExit.setOnClickListener(new ClickEvent());  
        //畫板和畫筆  
        sfv = (SurfaceView) this.findViewById(R.id.SurfaceView01);   
        sfv.setOnTouchListener(new TouchEvent());  
        mPaint = new Paint();    
        mPaint.setColor(Color.GREEN);// 畫筆為綠色    
        mPaint.setStrokeWidth(1);// 設(shè)置畫筆粗細(xì)   
        //示波器類庫  
        clsOscilloscope.initOscilloscope(xMax/2, yMax/2, sfv.getHeight()/2);  
          
        //縮放控件,X軸的數(shù)據(jù)縮小的比率高些  
        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軸縮小"+String.valueOf(clsOscilloscope.rateX)+"倍" 
                        +","+"Y軸縮小"+String.valueOf(clsOscilloscope.rateY)+"倍");  
            }  
        });  
        zctlX.setOnZoomOutClickListener(new View.OnClickListener() {  
            @Override 
            public void onClick(View v) {  
                if(clsOscilloscope.rateX                    clsOscilloscope.rateX++;      
                setTitle("X軸縮小"+String.valueOf(clsOscilloscope.rateX)+"倍" 
                        +","+"Y軸縮小"+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軸縮小"+String.valueOf(clsOscilloscope.rateX)+"倍" 
                        +","+"Y軸縮小"+String.valueOf(clsOscilloscope.rateY)+"倍");  
            }  
        });  
          
        zctlY.setOnZoomOutClickListener(new View.OnClickListener() {  
            @Override 
            public void onClick(View v) {  
                if(clsOscilloscope.rateY                    clsOscilloscope.rateY++;      
                setTitle("X軸縮小"+String.valueOf(clsOscilloscope.rateX)+"倍" 
                        +","+"Y軸縮小"+String.valueOf(clsOscilloscope.rateY)+"倍");  
            }  
        });  
    }  
    @Override 
    protected void onDestroy() {  
        super.onDestroy();  
        android.os.Process.killProcess(android.os.Process.myPid());  
    }  
      
    /** 
     * 按鍵事件處理 
     * @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();  
            }  
        }  
    }  
    /** 
     * 觸摸屏動態(tài)設(shè)置波形圖基線 
     * @author GV 
     * 
     */ 
    class TouchEvent implements OnTouchListener{  
        @Override 
        public boolean onTouch(View v, MotionEvent event) {  
            clsOscilloscope.baseLine=(int)event.getY();  
            return true;  
        }  
          
    }  

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