android开发培训模拟信号示波器

android开发培训模拟信号示波器上次简单地介绍了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：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 voidStop() { 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(BundlesavedInstanceState){super.onCreate(savedInstanceState);setContentView(yout.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(newView.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(newView.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(newView.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(newView.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; } } }。