Android开发--SurfaceView的基本用法

来源：互联网发布：销售管理数据流程图编辑：程序博客网时间：2024/05/16 13:00

在Android中可以利用View来绘制一些图形，图片，但当我们开发游戏或视频时，View就不再适用，这时必须使用SurfaceView来代替View。SurfaceView相比View可以实现多线程绘图和双缓冲技术，可以使得我们的动画更加流畅。接下来简单记录一下Surface的基本用法：

首先我们应该继承SurfaceView的类，并实现SurfaceHolder.Callback，这个接口是用来管理SurfaceView的生命周期，一共有三个方法：

             1）surfaceCreated: SurfaceView对象被创建时触发；
             2）surfaceChanged: SurfaceView的大小发生变化时触发；
             3）surfaceDestroyed: SurfaceView对象被销毁时触发；

我们在初始化方法中得到SurfaceHolder的对象，并通过该对象的addCallback方法添加这个接口进来

        private void init() {holder = getHolder();holder.addCallback(this);paint = new Paint();paint.setColor(Color.BLUE);paint.setStyle(Paint.Style.STROKE);}

接下来创建我们的异步线程来进行绘图操作

private Thread myThread = new Thread(new Runnable() {@Overridepublic void run() {// TODO Auto-generated method stubwhile (isLived) {if (num <= 20) {num++;} else {num = 2;}canvas = holder.lockCanvas();if (canvas != null) {canvas.drawColor(Color.BLACK);//清屏canvas.drawCircle(100, 100, num, paint);holder.unlockCanvasAndPost(canvas);}try {Thread.sleep(1000);} catch (Exception e) {// TODO: handle exception}}}});

通过lockCanvas方法我们可以得到一个加锁的Canvas，当Canvas在进行绘图时，或被锁起来。注：如果当前Canvas正在被绘制，将会返回一个null值。接下来我们绘制一个空心的圆，半径不断增加。绘制完成后将锁打开。

然后我们在Callback接口方法中在create方法中设置标志isLived为true，然后开启线程，在destory方法中设置isLived为false

@Overridepublic void surfaceChanged(SurfaceHolder holder, int format, int width,int height) {// TODO Auto-generated method stub}@Overridepublic void surfaceCreated(SurfaceHolder holder) {// TODO Auto-generated method stubisLived = true;myThread.start();Log.w(TAG, "surfaceCreated");}@Overridepublic void surfaceDestroyed(SurfaceHolder holder) {// TODO Auto-generated method stubisLived = false;Log.w(TAG, "surfaceDestroyed");}

附上整个类的源码

package com.example.test;import android.content.Context;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.util.AttributeSet;import android.util.Log;import android.view.SurfaceHolder;import android.view.SurfaceView;public class MySurfaceView extends SurfaceView implementsSurfaceHolder.Callback {private static final String TAG = "MySurfaceView";private SurfaceHolder holder;private boolean isLived;private Paint paint;private Canvas canvas;private int num;private Thread myThread = new Thread(new Runnable() {@Overridepublic void run() {// TODO Auto-generated method stubwhile (isLived) {if (num <= 20) {num++;} else {num = 2;}canvas = holder.lockCanvas();if (canvas != null) {canvas.drawColor(Color.BLACK);canvas.drawCircle(100, 100, num, paint);holder.unlockCanvasAndPost(canvas);}try {Thread.sleep(1000);} catch (Exception e) {// TODO: handle exception}}}});public MySurfaceView(Context context, AttributeSet attrs, int defStyle) {super(context, attrs, defStyle);// TODO Auto-generated constructor stubinit();}public MySurfaceView(Context context, AttributeSet attrs) {super(context, attrs);// TODO Auto-generated constructor stubinit();}public MySurfaceView(Context context) {super(context);init();// TODO Auto-generated constructor stub}private void init() {holder = getHolder();holder.addCallback(this);paint = new Paint();paint.setColor(Color.BLUE);paint.setStyle(Paint.Style.STROKE);}@Overridepublic void surfaceChanged(SurfaceHolder holder, int format, int width,int height) {// TODO Auto-generated method stub}@Overridepublic void surfaceCreated(SurfaceHolder holder) {// TODO Auto-generated method stubisLived = true;myThread.start();Log.w(TAG, "surfaceCreated");}@Overridepublic void surfaceDestroyed(SurfaceHolder holder) {// TODO Auto-generated method stubisLived = false;Log.w(TAG, "surfaceDestroyed");}}

0 0