前面简单地介绍了android程序开发中audiorecord和audiotrack的使用，这次再结合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(屏幕录像截图的速度较慢，真机实际运行起来会很流畅)：
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：
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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> |
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 } }} |
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; } }} |
希望本文实例对于读者进行android项目开发能起到一定的借鉴与帮助作用。
