安卓UI相关问题，页卡下标Matrix矩阵无法初始化

http://blog.csdn.net/zdfghj123/article/details/51547781

具体写在了自己的博客里，希望有大牛看到帮我解答一下吧~

具体达成上面这种效果，页面滑动，下标会改变，但是网络代码给出的matrix初始化下标的方法，下标一直是顶格在最左边的

再附上自己的其余代码

XML文件如下

 <RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="#ffffff" >

    <LinearLayout
        android:id="@+id/ll_tital"
        android:layout_width="match_parent"
        android:layout_height="60dp"
        android:layout_alignParentTop="true"
        android:background="@drawable/tab_bg"
        android:orientation="horizontal" >

        <Button
            android:id="@+id/btn_index"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:background="#00ffffff"
            android:text="首页"
            android:textColor="#fff" />

        <Button
            android:id="@+id/btn_classify"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:background="#00ffffff"
            android:text="分类"
            android:textColor="#fff" />

        <Button
            android:id="@+id/btn_rank"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:background="#00ffffff"
            android:text="排行"
            android:textColor="#fff" />

        <Button
            android:id="@+id/btn_manage"
            android:layout_width="0dp"
            android:layout_height="match_parent"
            android:layout_weight="1"
            android:background="#00ffffff"
            android:text="管理"
            android:textColor="#fff" />
    </LinearLayout>

    <ImageView
        android:id="@+id/move_bar"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignBottom="@+id/ll_tital"
        android:background="@drawable/switch_btn_on" />

    <android.support.v4.view.ViewPager
        android:id="@+id/id_viewpager"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:layout_below="@id/ll_tital" >
    </android.support.v4.view.ViewPager>

</RelativeLayout>

然后是主Activity

 package com.game.gamemarket;

import java.util.ArrayList;
import java.util.List;

import com.download.manager.MyDownloadManager;
import com.frag.classifyfragment.ClassifyFragment;
import com.frag.indexfragment.IndexFragment;
import com.frag.managefragment.ManageFragment;
import com.frag.rankfragment.RankFragment;
import com.game.search.SearchGameInfo;

import android.content.Intent;
import android.graphics.BitmapFactory;
import android.graphics.Matrix;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentActivity;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.util.DisplayMetrics;
import android.view.View;
import android.view.View.OnClickListener;
import android.view.Window;
import android.view.animation.Animation;
import android.view.animation.TranslateAnimation;
import android.widget.Button;
import android.widget.ImageButton;
import android.widget.ImageView;
import android.widget.TextView;

/**
 * 整体主框架
 */
public class MainActivity extends FragmentActivity implements OnClickListener {

    // 跟随标题一起移动的
    private ImageView moveBarImg;
    // 导航的四个按钮
    private Button indexBtn;
    private Button classifyBtn;
    private Button rankBtn;
    private Button manageBtn;

    // 标题搜索栏按钮
    private TextView searchGameTitle;
    // 二维码扫描按钮
    private ImageButton quickMarkBtn;
    // 下载管理界面按钮
    private ImageButton dowmloadManagerBtn;

    // 作为页面容器的ViewPager
    private ViewPager mViewPager;

    // Fragment页面的集合
    private List<Fragment> fragmentList;

    // 四个Fragment界面
    private IndexFragment indexFragment;
    private ClassifyFragment classifyFragment;
    private RankFragment rankFragment;
    private ManageFragment manageFragment;

    private MyPagerAdapter myPagerAdapter;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        requestWindowFeature(Window.FEATURE_CUSTOM_TITLE);
        setContentView(R.layout.activity_main);
        // 设置Titlebar
        getWindow().setFeatureInt(Window.FEATURE_CUSTOM_TITLE, R.layout.titlebar);

        // 初始化数据
        init();
    }

    private void init() {
        indexBtn = (Button) findViewById(R.id.btn_index);
        classifyBtn = (Button) findViewById(R.id.btn_classify);
        rankBtn = (Button) findViewById(R.id.btn_rank);
        manageBtn = (Button) findViewById(R.id.btn_manage);

        searchGameTitle = (TextView) findViewById(R.id.title_search_text);
        quickMarkBtn = (ImageButton) findViewById(R.id.title_scan);
        dowmloadManagerBtn = (ImageButton) findViewById(R.id.title_download);

        // 初始化移动下标图片
        InitImageView();

        indexBtn.setOnClickListener(this);
        classifyBtn.setOnClickListener(this);
        rankBtn.setOnClickListener(this);
        manageBtn.setOnClickListener(this);
        searchGameTitle.setOnClickListener(this);
        quickMarkBtn.setOnClickListener(this);
        dowmloadManagerBtn.setOnClickListener(this);

        mViewPager = (ViewPager) findViewById(R.id.id_viewpager);

        fragmentList = new ArrayList<Fragment>();
        indexFragment = new IndexFragment();
        classifyFragment = new ClassifyFragment();
        rankFragment = new RankFragment();
        manageFragment = new ManageFragment();

        fragmentList.add(indexFragment);
        fragmentList.add(classifyFragment);
        fragmentList.add(rankFragment);
        fragmentList.add(manageFragment);

        myPagerAdapter = new MyPagerAdapter(getSupportFragmentManager(), fragmentList);
        mViewPager.setAdapter(myPagerAdapter);
        // 给ViewPager设置滑动改变监听
        mViewPager.setOnPageChangeListener(new MyOnPageChangeListener());
    }

    @Override
    public void onClick(View v) {
        Intent intent = null;
        switch (v.getId()) {
        case R.id.btn_index:
            changeView(0);
            break;
        case R.id.btn_classify:
            changeView(1);
            break;
        case R.id.btn_rank:
            changeView(2);
            break;
        case R.id.btn_manage:
            changeView(3);
            break;
        case R.id.title_search_text:// 进入搜索界面
            intent = new Intent(this, SearchGameInfo.class);
            startActivity(intent);
            break;
        case R.id.title_scan:// 进入二维码搜索

            break;
        case R.id.title_download:// 进入下载管理
            intent = new Intent(this, MyDownloadManager.class);
            startActivity(intent);
            break;
        }
    }

    // 手动设置ViewPager要显示的视图
    private void changeView(int desTab) {
        mViewPager.setCurrentItem(desTab, true);
    }

    private int offset = 0;// 动画图片偏移量
    private int bmpW;// 动画图片宽度
    private int currIndex = 0;// 当前页卡编号

    /**
     * 初始化动画，这个就是页卡滑动时，下面的横线也滑动的效果，在这里需要计算一些数据
     */
    private void InitImageView() {
        moveBarImg = (ImageView) findViewById(R.id.move_bar);
        // 获取图片宽度
        bmpW = BitmapFactory.decodeResource(getResources(), R.drawable.switch_btn_on).getWidth();
        DisplayMetrics dm = new DisplayMetrics();
        getWindowManager().getDefaultDisplay().getMetrics(dm);
        int screenW = dm.widthPixels;// 获取分辨率宽度
        offset = (screenW / 4 - bmpW) / 2;// 计算偏移量
//      Matrix matrix = new Matrix();
//      matrix.postTranslate(offset, 0);
//      System.out.println(offset + "=====================================");
//
//      System.out.println(matrix);
//      moveBarImg.setImageMatrix(matrix);// 设置动画初始位置
        moveBarImg.setX(offset);
//       Animation animation = new TranslateAnimation(offset, offset, 0, 0);
//       moveBarImg.startAnimation(animation);

    }

    public class MyOnPageChangeListener implements OnPageChangeListener {

        int one = offset * 2 + bmpW;// 页卡1 -> 页卡2 偏移量
        int two = one * 2;// 页卡1 -> 页卡3 偏移量

        public void onPageScrollStateChanged(int arg0) {
        }

        public void onPageScrolled(int arg0, float arg1, int arg2) {
        }

        public void onPageSelected(int arg0) {
            System.out.println("==============" + arg0 + "==============");
            Animation animation = new TranslateAnimation(one * currIndex, one * arg0, 0, 0);// 显然这个比较简洁，只有一行代码。
            currIndex = arg0;
            animation.setFillAfter(true);// True:图片停在动画结束位置
            animation.setDuration(300);
            moveBarImg.startAnimation(animation);
        }
    }
}