前面簡單地介紹了android程序開發中audiorecord和audiotrack的使用，這次再結合surfaceview實現一個android版的手機模擬信號示波器。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(屏幕錄像截圖的速度較慢，真機實際運行起來會很流暢)：
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> |
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 } }} |
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; } }} |
希望本文實例對于讀者進行android項目開發能起到一定的借鑒與幫助作用。
