前文简单介绍了android中surfaceview的基本使用,本文就来介绍一下surfaceview与多线程的混搭。surfaceview与多线程混搭,是为了防止动画闪烁而实现的一种多线程应用。android的多线程用法与java的多线程用法完全一样,本文不做多线程方面的介绍了。直接讲解surfaceview与多线程的混合使用,即开一条线程专门读取图片,另外一条线程专门绘图。
本文程序运行截图如下,左边是开单个线程读取并绘图,右边是开两个线程,一个专门读取图片,一个专门绘图:
对比一下可以看出,右边动画的帧速明显比左边的快,左右两者都没使用thread.sleep()。为什么要开两个线程一个读一个画,而不去开两个线程像左边那样都“边读边画”呢?因为surfaceview每次绘图都会锁定canvas,也就是说同一片区域这次没画完下次就不能画,因此要提高动画播放的效率,就得开一条线程专门画图,开另外一条线程做预处理的工作。
main.xml的源码如下:
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<?xml version= "1.0" encoding= "utf-8" ?>
<linearlayout xmlns:android= "http://schemas.android.com/apk/res/android"
android: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= "单个独立线程" ></button>
<button android:id= "@+id/button02" android:layout_width= "wrap_content"
android:layout_height= "wrap_content" android:text= "两个独立线程" ></button>
</linearlayout>
<surfaceview android:id= "@+id/surfaceview01"
android:layout_width= "fill_parent" android:layout_height= "fill_parent" ></surfaceview>
</linearlayout>
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java程序的源码如下:
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package com.testsurfaceview;
import java.lang.reflect.field;
import java.util.arraylist;
import android.app.activity;
import android.graphics.bitmap;
import android.graphics.bitmapfactory;
import android.graphics.canvas;
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 btnsinglethread, btndoublethread;
surfaceview sfv;
surfaceholder sfh;
arraylist<integer> imglist = new arraylist<integer>();
int imgwidth, imgheight;
bitmap bitmap; //独立线程读取,独立线程绘图
@override
public void oncreate(bundle savedinstancestate) {
super .oncreate(savedinstancestate);
setcontentview(r.layout.main);
btnsinglethread = (button) this .findviewbyid(r.id.button01);
btndoublethread = (button) this .findviewbyid(r.id.button02);
btnsinglethread.setonclicklistener( new clickevent());
btndoublethread.setonclicklistener( new clickevent());
sfv = (surfaceview) this .findviewbyid(r.id.surfaceview01);
sfh = sfv.getholder();
sfh.addcallback( new mycallback()); // 自动运行surfacecreated以及surfacechanged
}
class clickevent implements view.onclicklistener {
@override
public void onclick(view v) {
if (v == btnsinglethread) {
new load_drawimage( 0 , 0 ).start(); //开一条线程读取并绘图
} else if (v == btndoublethread) {
new loadimage().start(); //开一条线程读取
new drawimage(imgwidth + 10 , 0 ).start(); //开一条线程绘图
}
}
}
class mycallback implements surfaceholder.callback {
@override
public void surfacechanged(surfaceholder holder, int format, int width,
int height) {
log.i( "surface:" , "change" );
}
@override
public void surfacecreated(surfaceholder holder) {
log.i( "surface:" , "create" );
// 用反射机制来获取资源中的图片id和尺寸
field[] fields = r.drawable. class .getdeclaredfields();
for (field field : fields) {
if (! "icon" .equals(field.getname())) // 除了icon之外的图片
{
int index = 0 ;
try {
index = field.getint(r.drawable. class );
} catch (illegalargumentexception e) {
// todo auto-generated catch block
e.printstacktrace();
} catch (illegalaccessexception e) {
// todo auto-generated catch block
e.printstacktrace();
}
// 保存图片id
imglist.add(index);
}
}
// 取得图像大小
bitmap bmimg = bitmapfactory.decoderesource(getresources(),
imglist.get( 0 ));
imgwidth = bmimg.getwidth();
imgheight = bmimg.getheight();
}
@override
public void surfacedestroyed(surfaceholder holder) {
log.i( "surface:" , "destroy" );
}
}
/*
* 读取并显示图片的线程
*/
class load_drawimage extends thread {
int x, y;
int imgindex = 0;
public load_drawimage(int x, int y) {
this.x = x;
this.y = y;
}
public void run() {
while (true) {
canvas c = sfh.lockcanvas(new rect(this.x, this.y, this.x
+ imgwidth, this.y + imgheight));
bitmap bmimg = bitmapfactory.decoderesource(getresources(),
imglist.get(imgindex));
c.drawbitmap(bmimg, this.x, this.y, new paint());
imgindex++;
if (imgindex == imglist.size())
imgindex = 0;
sfh.unlockcanvasandpost(c);// 更新屏幕显示内容
}
}
};
/*
* 只负责绘图的线程
*/
class drawimage extends thread {
int x, y;
public drawimage(int x, int y) {
this.x = x;
this.y = y;
}
public void run() {
while (true) {
if (bitmap != null) {//如果图像有效
canvas c = sfh.lockcanvas(new rect(this.x, this.y, this.x
+ imgwidth, this.y + imgheight));
c.drawbitmap(bitmap, this.x, this.y, new paint());
sfh.unlockcanvasandpost(c);// 更新屏幕显示内容
}
}
}
};
/*
* 只负责读取图片的线程
*/
class loadimage extends thread {
int imgindex = 0 ;
public void run() {
while ( true ) {
bitmap = bitmapfactory.decoderesource(getresources(),
imglist.get(imgindex));
imgindex++;
if (imgindex == imglist.size()) //如果到尽头则重新读取
imgindex = 0 ;
}
}
};
}
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希望本文所述示例能对大家进行android的surfaceview与多线程的混搭编程有所帮助。