android开发笔记之browser 获取view对象的缩略图

       在android 的浏览器(browser)中，有一个可以查看上一个，下一个网页，而这个功能的核心是网页缩略图的功能。这二天，我在看浏览器(browser)的源码时，觉得这个功能其实完全能独立出来，并且扩展到对所有的View的都可以获取缩略图。

样例效果图：

详细代码：

（1）CaptureScreeUtil.java

package com.example.testcapturescreen;import android.graphics.Bitmap;import android.graphics.Canvas;import android.graphics.Color;import android.graphics.Paint;import android.util.Log;import android.view.View;class CaptureScreeUtil{private static final String TAG = "TestCaptureScreen";public static Bitmap capture(int width,int height,View view) {// TODO Auto-generated method stubLog.i(TAG,"capture");Bitmap bitmap = Bitmap.createBitmap(width, height,Bitmap.Config.RGB_565);bitmap.eraseColor(Color.WHITE);Canvas canvas = new Canvas(bitmap);final int left = view.getScrollX();final int top = view.getScrollY();int state = canvas.save();canvas.translate(-left, -top);float scale = width / (float) view.getWidth();canvas.scale(scale, scale, left, top);view.draw(canvas);canvas.restoreToCount(state);        // manually anti-alias the edges for the tilt    Paint sAlphaPaint = new Paint();          //sAlphaPaint.setXfermode(new PorterDuffXfermode(Mode.CLEAR));    sAlphaPaint.setColor(Color.TRANSPARENT);canvas.drawRect(0, 0, 1, height, sAlphaPaint);canvas.drawRect(width - 1, 0, width,height, sAlphaPaint);canvas.drawRect(0, 0, width, 1, sAlphaPaint);canvas.drawRect(0, height - 1, width,height, sAlphaPaint);canvas.setBitmap(null);return bitmap;       }}

（2）MainActivity.java

package com.example.testcapturescreen;import android.os.Bundle;import android.view.View;import android.view.View.OnClickListener;import android.webkit.WebView;import android.widget.ImageView;import android.widget.RelativeLayout;import android.widget.TextView;import android.app.Activity;import android.graphics.Bitmap;public class MainActivity extends Activity {private TextView myTextView = null;private WebView myWebView = null;private ImageView myImageView = null;private ImageView myImageView_2 = null;private RelativeLayout rl = null;private Bitmap mCapture = null;    private int mCaptureWidth = 150;    private int mCaptureHeight = 150;        @Override    protected void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.activity_main);        init();    }private void init() {// TODO Auto-generated method stubmyImageView = (ImageView)findViewById(R.id.myImageView);myImageView_2 = (ImageView)findViewById(R.id.myImageView_2);rl = (RelativeLayout)findViewById(R.id.rl);myWebView = (WebView)findViewById(R.id.myWebView);myWebView.loadUrl("http://www.baidu.com"); myWebView.getSettings().setJavaScriptEnabled(true);  myTextView = (TextView)findViewById(R.id.myTextView);myTextView.setOnClickListener(new OnClickListener() {@Overridepublic void onClick(View arg0) {// TODO Auto-generated method stubmCapture = CaptureScreeUtil.capture(mCaptureWidth,mCaptureHeight,myWebView);updateUI(); }});}private void updateUI() {// TODO Auto-generated method stubmyImageView.setImageBitmap(mCapture);myImageView_2.setImageBitmap(CaptureScreeUtil.capture(mCaptureWidth,mCaptureHeight,rl));}}

（3）activity_main.xml

<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"    xmlns:tools="http://schemas.android.com/tools"    android:id="@+id/rl"    android:layout_width="match_parent"    android:layout_height="match_parent"    android:paddingBottom="@dimen/activity_vertical_margin"    android:paddingLeft="@dimen/activity_horizontal_margin"    android:paddingRight="@dimen/activity_horizontal_margin"    android:paddingTop="@dimen/activity_vertical_margin"    tools:context=".MainActivity" >    <TextView        android:id="@+id/myTextView"        android:layout_width="wrap_content"        android:layout_height="wrap_content"        android:paddingBottom="@dimen/activity_vertical_margin"        android:text="点击我--测试网页的缩略图功能" />       <WebViewandroid:id="@+id/myWebView"android:layout_below="@id/myTextView"android:layout_width="match_parent"        android:layout_height="150dp"       />      <ImageViewandroid:id="@+id/myImageView"android:layout_below="@id/myWebView"android:layout_width="wrap_content"        android:layout_height="wrap_content"               />      <ImageViewandroid:id="@+id/myImageView_2"android:layout_below="@id/myWebView"android:layout_toRightOf="@id/myImageView"android:layout_width="wrap_content"        android:layout_height="wrap_content"               /> </RelativeLayout>

（4）androidmanifest.xml

<?xml version="1.0" encoding="utf-8"?><manifest xmlns:android="http://schemas.android.com/apk/res/android"    package="com.example.testcapturescreen"    android:versionCode="1"    android:versionName="1.0" >    <uses-sdk        android:minSdkVersion="8"        android:targetSdkVersion="18" />    <uses-permission android:name="android.permission.INTERNET" />    <uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />    <application        android:allowBackup="true"        android:icon="@drawable/ic_launcher"        android:label="@string/app_name"        android:theme="@style/AppTheme" >        <activity            android:name="com.example.testcapturescreen.MainActivity"            android:label="@string/app_name" >            <intent-filter>                <action android:name="android.intent.action.MAIN" />                <category android:name="android.intent.category.LAUNCHER" />            </intent-filter>        </activity>    </application></manifest>

代码下载：

http://download.csdn.net/detail/hfreeman2008/7808975