上一篇文章介绍了mediaplayer相关内容,这次用两篇文章来介绍surfaceview的用法。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。
先来看看程序运行的截图:
截图1主要演示了直接把正弦波绘画在surfaceview上
对比上面的左右两图,右图用.lockcanvas(null),而左图用.lockcanvas(new rect(oldx, 0, oldx + length,getwindowmanager().getdefaultdisplay().getheight())),对比一下两个效果,由于左图是按指定rect绘画,所以效率会比右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。
接下来贴出main.xml的源码:
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<linearlayout xmlns:android= "http://schemas.android.com/apk/res/android"
android:layout_width= "fill_parent" android:layout_height= "fill_parent"
android:orientation= "vertical" >
<linearlayout android:id= "@+id/linearlayout01"
android:layout_width= "wrap_content" android:layout_height= "wrap_content" >
<button android:id= "@+id/button01" android:layout_width= "wrap_content"
android:layout_height= "wrap_content" android:text= "简单绘画" >
<button android:id= "@+id/button02" android:layout_width= "wrap_content"
android:layout_height= "wrap_content" android:text= "定时器绘画" >
<surfaceview android:id= "@+id/surfaceview01"
android:layout_width= "fill_parent" android:layout_height= "fill_parent" >
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接下来贴出程序源码:
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package com.testsurfaceview;
import java.util.timer;
import java.util.timertask;
import android.app.activity;
import android.graphics.canvas;
import android.graphics.color;
import android.graphics.paint;
import android.graphics.rect;
import android.os.bundle;
import android.util.log;
import android.view.surfaceholder;
import android.view.surfaceview;
import android.view.view;
import android.widget.button;
public class testsurfaceview extends activity {
/** called when the activity is first created. */
button btnsimpledraw, btntimerdraw;
surfaceview sfv;
surfaceholder sfh;
private timer mtimer;
private mytimertask mtimertask;
int y_axis[], //保存正弦波的y轴上的点
centery, //中心线
oldx,oldy, //上一个xy点
currentx; //当前绘制到的x轴上的点
@override
public void oncreate(bundle savedinstancestate) {
super .oncreate(savedinstancestate);
setcontentview(r.layout.main);
btnsimpledraw = (button) this .findviewbyid(r.id.button01);
btntimerdraw = (button) this .findviewbyid(r.id.button02);
btnsimpledraw.setonclicklistener( new clickevent());
btntimerdraw.setonclicklistener( new clickevent());
sfv = (surfaceview) this .findviewbyid(r.id.surfaceview01);
sfh = sfv.getholder();
//动态绘制正弦波的定时器
mtimer = new timer();
mtimertask = new mytimertask();
// 初始化y轴数据
centery = (getwindowmanager().getdefaultdisplay().getheight() - sfv
.gettop()) / 2 ;
y_axis = new int [getwindowmanager().getdefaultdisplay().getwidth()];
for ( int i = 1 ; i < y_axis.length; i++) { // 计算正弦波
y_axis[i - 1 ] = centery
- ( int ) ( 100 * math.sin(i * 2 * math.pi / 180 ));
}
}
class clickevent implements view.onclicklistener {
@override
public void onclick(view v) {
if (v == btnsimpledraw) {
simpledraw(y_axis.length- 1 ); //直接绘制正弦波
} else if (v == btntimerdraw) {
oldy = centery;
mtimer.schedule(mtimertask, 0 , 5 ); //动态绘制正弦波
}
}
}
class mytimertask extends timertask {
@override
public void run() {
simpledraw(currentx);
currentx++; //往前进
if (currentx == y_axis.length - 1 ) { //如果到了终点,则清屏重来
cleardraw();
currentx = 0 ;
oldy = centery;
}
}
}
/*
* 绘制指定区域
*/
void simpledraw( int length) {
if (length == 0 )
oldx = 0 ;
canvas canvas = sfh.lockcanvas( new rect(oldx, 0 , oldx + length,
getwindowmanager().getdefaultdisplay().getheight())); // 关键:获取画布
log.i( "canvas:" ,
string.valueof(oldx) + "," + string.valueof(oldx + length));
paint mpaint = new paint();
mpaint.setcolor(color.green); // 画笔为绿色
mpaint.setstrokewidth( 2 ); // 设置画笔粗细
int y;
for ( int i = oldx + 1 ; i < length; i++) { // 绘画正弦波
y = y_axis[i - 1 ];
canvas.drawline(oldx, oldy, i, y, mpaint);
oldx = i;
oldy = y;
}
sfh.unlockcanvasandpost(canvas); // 解锁画布,提交画好的图像
}
void cleardraw() {
canvas canvas = sfh.lockcanvas( null );
canvas.drawcolor(color.black); // 清除画布
sfh.unlockcanvasandpost(canvas);
}
}
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以上就是本文的全部内容,希望对大家学习android软件编程有所帮助。