Android中SurfaceView的使用示例

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SurfaceView在游戏开发中有着举足轻重的地位,它对于画面的控制有着更大的自由度(不像View要用handler来更新,关于View的).

SurfaceView,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,这次我就用两篇文章来介绍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.

下面是个简单的示例,力求把流程清楚展示,其他的可简则简。

程序效果:用线程画一个蓝色的长方形。

wps_clip_image-19158_thumb[1]

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。

创建新的项目

1.在Eclipse IDE中创建一个新的项目并把填入必须的信息。 File->New->Android Project

创建完项目结构如下:

wps_clip_image-19161_thumb[1]

2.创建新项目后的第一步是要在AndroidManifest.xml文件中进行配置

<?xml version="1.0" encoding="utf-8"?>

<manifest xmlns:android="http://schemas.android.com/apk/res/android"

package="iigrowing.android.network.surfaceview"

android:versionCode="1"

android:versionName="1.0" >

<uses-sdk android:minSdkVersion="9" />

<application

android:icon="@drawable/ic_launcher"

android:label="@string/app_name" >

<activity

android:label="@string/app_name"

android:name=".SurfaceViewActivity" >

<intent-filter >

<action android:name="android.intent.action.MAIN" />

<category android:name="android.intent.category.LAUNCHER" />

</intent-filter>

</activity>

</application>

<uses-permission android:name="android.permission.INTERNET" />

<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />

</manifest>

main.xml的源码:

<?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="简单绘画" >

</Button>

<Button

android:id="@+id/Button02"

android:layout_width="wrap_content"

android:layout_height="wrap_content"

android:text="定时器绘画" >

</Button>

</LinearLayout>

<SurfaceView

android:id="@+id/SurfaceView01"

android:layout_width="fill_parent"

android:layout_height="fill_parent" >

</SurfaceView>

</LinearLayout>

SurfaceViewActivity.java

/*

* Copyright (C) 2013 carema authors

* @author shao

* @date 2013.9.26

* @blog http://www.iigrowing.cn/

* 本程序是一个android客户端软件演示程序

*

*/

package iigrowing.android.network.surfaceview;

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.graphics.RectF;

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 SurfaceViewActivity 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;

}

// 绘制一个矩形

Paint mPaint2 = new Paint();  

        mPaint2.setColor(Color.BLUE);  

        canvas.drawRect(new RectF(40,60,180,280), mPaint2);  

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);

}

}

注意一下 for (int i = oldX + 1; i < length; i++) {// 绘画正弦波 这句,在.lockCanvas()指定Rect内减少循环画线的次数,可以提高绘图效率。

源代码 下载地址



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