Android提高應用篇之模擬信號示波器

2017-11-26 12:40:46

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關鍵詞： Android手機,模擬信號示波器

本文結合SurfaceView實現一個Android版的手機模擬信號示波器(PS：以前也講過J2ME版的手機示波器)。最近物聯網炒得很火，作為手機軟件開發者，如何在不修改手機硬件電路的前提下實現與第三方傳感器結合呢？麥克風就是一個很好的ADC接口，通過麥克風與第三方傳感器結合，再在軟件里對模擬信號做相應的處理，就可以提供更豐富的傳感化應用。

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

本文程序使用8000hz的采樣率，對X軸方向繪圖的實時性要求較高，如果不降低X軸的分辨率，程序的實時性較差，因此程序對X軸數據縮小區間為8倍～16倍。由于采用16位采樣，因此Y軸數據的高度相對于手機屏幕來說也偏大，程序也對Y軸數據做縮小，區間為1倍～10倍。在SurfaceView的OnTouchListener方法里加入了波形基線的位置調節，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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<?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="開始" 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="開始" 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是實現示波器的類庫，包含AudioRecord操作線程和SurfaceView繪圖線程的實現，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<short[]> inBuf = new ArrayList<short[]>();
    private boolean isRecording = false;// 線程控制標記
    /**
     * 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
    }
    /**
     * 負責從MIC保存數據到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保存數據到緩沖區
                    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);// 添加數據
                    }
                }
                audioRecord.stop();
            } catch (Throwable t) {
            }
        }
    };
    /**
     * 負責繪制inBuf中的數據
     *
     * @author GV
     *
     */

    class DrawThread extends Thread {
        private int oldX = 0;// 上次繪制的X坐標
        private int oldY = 0;// 上次繪制的Y坐標
        private SurfaceView sfv;// 畫板
        private int X_index = 0;// 當前畫圖所在屏幕X軸的坐標
        private Paint mPaint;// 畫筆
        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);// 把緩沖區數據畫出來
                    X_index = X_index + tmpBuf.length;
                    if (X_index > sfv.getWidth()) {
                        X_index = 0;
                    }
                }
            }
        }
        /**
         * 繪制指定區域
         *
         * @param start
         *            X軸開始的位置(全屏)
         * @param buffer
         *            緩沖區
         * @param rate
         *            Y軸數據縮小的比例
         * @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;// 調節縮小比例，調節基準線
                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<short[]> inBuf = new ArrayList<short[]>();
private boolean isRecording = false;// 線程控制標記
/**
* 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
}
/**
* 負責從MIC保存數據到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保存數據到緩沖區
     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);// 添加數據
     }
    }
    audioRecord.stop();
   } catch (Throwable t) {
   }
  }
};
/**
* 負責繪制inBuf中的數據
*
* @author GV
*
*/
class DrawThread extends Thread {
  private int oldX = 0;// 上次繪制的X坐標
  private int oldY = 0;// 上次繪制的Y坐標
  private SurfaceView sfv;// 畫板
  private int X_index = 0;// 當前畫圖所在屏幕X軸的坐標
  private Paint mPaint;// 畫筆
  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);// 把緩沖區數據畫出來
     X_index = X_index + tmpBuf.length;
     if (X_index > sfv.getWidth()) {
      X_index = 0;
     }
    }
   }
  }

  /**
   * 繪制指定區域
   *
   * @param start
   *            X軸開始的位置(全屏)
   * @param buffer
   *            緩沖區
   * @param rate
   *            Y軸數據縮小的比例
   * @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;// 調節縮小比例，調節基準線
    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軸數據量巨大，容易產生刷新延時
    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);// 設置畫筆粗細
        //示波器類庫
        clsOscilloscope.initOscilloscope(xMax/2, yMax/2, sfv.getHeight()/2);

        //縮放控件，X軸的數據縮小的比率高些
        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<xMax)
                    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<yMax)
                    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();
            }
        }
    }
    /**
     * 觸摸屏動態設置波形圖基線
     * @author GV
     *
     */
    class TouchEvent implements OnTouchListener{
        @Override
        public boolean onTouch(View v, MotionEvent event) {
            clsOscilloscope.baseLine=(int)event.getY();
            return true;
        }

    }
}

(審核編輯: 智匯小新)

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