引用：http://www.oschina.net/code/snippet_54100_1423
SurfaceView 由于可以直接从内存或者DMA等硬件接口取得图像数据，因此是个非常重要的绘图容器，网上介绍 SurfaceView的用法有很多，写法也层出不同，例如继承SurfaceView类，或者继承SurfaceHolder.Callback类等，这个可以根据功能实际需要自己选择，我这里就直接在普通的用户界面调用SurfaceHolder的lockCanvas和 unlockCanvasAndPost。
对比下面的第二、三两图，三图用.lockCanvas(null)，而二图用.lockCanvas(new Rect(oldX, 0, oldX + length, getWindowManager().getDefaultDisplay().getHeight()))，对比一下两个效果，由于二图是按指定Rect绘画，所以效率会比三图的全控件绘画高些，并且在清屏之后 (canvas.drawColor(Color.BLACK))不会留有上次绘画的残留。
对比下面的第二、三两图，三图用.lockCanvas(null)，而二图用.lockCanvas(new Rect(oldX, 0, oldX + length, getWindowManager().getDefaultDisplay().getHeight()))，对比一下两个效果，由于二图是按指定Rect绘画，所以效率会比三图的全控件绘画高些，并且在清屏之后 (canvas.drawColor(Color.BLACK))不会留有上次绘画的残留。
代码片段(5)
[图片] 程序运行的截图
[图片] 1.gif
[图片] 2.gif
[代码] main.xml
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<?xml version="1.0" encoding="utf-8"?> |
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<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" |
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android:layout_width="fill_parent" android:layout_height="fill_parent" |
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android:orientation="vertical"> |
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<LinearLayout android:id="@+id/LinearLayout01" |
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android:layout_width="wrap_content" android:layout_height="wrap_content"> |
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<Button android:id="@+id/Button01" android:layout_width="wrap_content" |
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android:layout_height="wrap_content" android:text="简单绘画"></Button> |
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<Button android:id="@+id/Button02" android:layout_width="wrap_content" |
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android:layout_height="wrap_content" android:text="定时器绘画"></Button> |
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</LinearLayout> |
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<SurfaceView android:id="@+id/SurfaceView01" |
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android:layout_width="fill_parent" android:layout_height="fill_parent"></SurfaceView> |
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</LinearLayout> |
[代码] TestSurfaceView.java
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package com.testSurfaceView; |
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import java.util.Timer; |
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import java.util.TimerTask; |
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import android.app.Activity; |
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import android.graphics.Canvas; |
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import android.graphics.Color; |
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import android.graphics.Paint; |
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import android.graphics.Rect; |
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import android.os.Bundle; |
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import android.util.Log; |
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import android.view.SurfaceHolder; |
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import android.view.SurfaceView; |
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import android.view.View; |
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import android.widget.Button; |
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public class TestSurfaceView extends Activity { |
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/** Called when the activity is first created. */ |
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Button btnSimpleDraw, btnTimerDraw; |
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SurfaceView sfv; |
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SurfaceHolder sfh; |
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private Timer mTimer; |
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private MyTimerTask mTimerTask; |
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int Y_axis[],//保存正弦波的Y轴上的点 |
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centerY,//中心线 |
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oldX,oldY,//上一个XY点 |
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currentX;//当前绘制到的X轴上的点 |
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@Override |
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public void onCreate(Bundle savedInstanceState) { |
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super.onCreate(savedInstanceState); |
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setContentView(R.layout.main); |
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btnSimpleDraw = (Button) this.findViewById(R.id.Button01); |
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btnTimerDraw = (Button) this.findViewById(R.id.Button02); |
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btnSimpleDraw.setOnClickListener(new ClickEvent()); |
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btnTimerDraw.setOnClickListener(new ClickEvent()); |
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sfv = (SurfaceView) this.findViewById(R.id.SurfaceView01); |
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sfh = sfv.getHolder(); |
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//动态绘制正弦波的定时器 |
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mTimer = new Timer(); |
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mTimerTask = new MyTimerTask(); |
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// 初始化y轴数据 |
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centerY = (getWindowManager().getDefaultDisplay().getHeight() - sfv |
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.getTop()) / 2; |
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Y_axis = new int[getWindowManager().getDefaultDisplay().getWidth()]; |
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for (int i = 1; i < Y_axis.length; i++) {// 计算正弦波 |
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Y_axis[i - 1] = centerY |
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- (int) (100 * Math.sin(i * 2 * Math.PI / 180)); |
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} |
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} |
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class ClickEvent implements View.OnClickListener { |
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@Override |
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public void onClick(View v) { |
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if (v == btnSimpleDraw) { |
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SimpleDraw(Y_axis.length-1);//直接绘制正弦波 |
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|
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} else if (v == btnTimerDraw) { |
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oldY = centerY; |
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mTimer.schedule(mTimerTask, 0, 5);//动态绘制正弦波 |
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} |
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} |
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} |
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class MyTimerTask extends TimerTask { |
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@Override |
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public void run() { |
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SimpleDraw(currentX); |
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currentX++;//往前进 |
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if (currentX == Y_axis.length - 1) {//如果到了终点，则清屏重来 |
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ClearDraw(); |
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currentX = 0; |
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oldY = centerY; |
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} |
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} |
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} |
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|
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/** |
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* 绘制指定区域 |
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*/ |
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void SimpleDraw(int length) { |
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if (length == 0) |
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oldX = 0; |
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Canvas canvas = sfh.lockCanvas(new Rect(oldX, 0, oldX + length, |
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getWindowManager().getDefaultDisplay().getHeight()));// 关键:获取画布 |
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Log.i("Canvas:", |
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String.valueOf(oldX) + "," + String.valueOf(oldX + length)); |
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Paint mPaint = new Paint(); |
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mPaint.setColor(Color.GREEN);// 画笔为绿色 |
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mPaint.setStrokeWidth(2);// 设置画笔粗细 |
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int y; |
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for (int i = oldX + 1; i < length; i++) {// 绘画正弦波 |
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y = Y_axis[i - 1]; |
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canvas.drawLine(oldX, oldY, i, y, mPaint); |
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oldX = i; |
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oldY = y; |
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} |
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sfh.unlockCanvasAndPost(canvas);// 解锁画布，提交画好的图像 |
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} |
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void ClearDraw() { |
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Canvas canvas = sfh.lockCanvas(null); |
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canvas.drawColor(Color.BLACK);// 清除画布 |
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sfh.unlockCanvasAndPost(canvas); |
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} |
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} |
