ViewPager指示器实现

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先看效果图
这里写图片描述
public class MainActivity extends Activity {    // ViewPager是google SDk中自带的一个附加包的一个类，可以用来实现屏幕间的切换。    // android-support-v4.jar    private ViewPager mPager;//页卡内容    private List<View> listViews; // Tab页面列表    private ImageView cursor;// 动画图片    private TextView t1, t2, t3;// 页卡头标    private int offset = 0;// 动画图片偏移量    private int currIndex = 0;// 当前页卡编号    private int bmpW;// 动画图片宽度    @Override    public void onCreate(Bundle savedInstanceState) {        super.onCreate(savedInstanceState);        setContentView(R.layout.main);        InitImageView();        InitTextView();        InitViewPager();    }    /**     * 初始化头标     */    private void InitTextView() {        t1 = (TextView) findViewById(R.id.text1);        t2 = (TextView) findViewById(R.id.text2);        t3 = (TextView) findViewById(R.id.text3);        t1.setOnClickListener(new MyOnClickListener(0));        t2.setOnClickListener(new MyOnClickListener(1));        t3.setOnClickListener(new MyOnClickListener(2));    }    /**     * 初始化ViewPager     */    private void InitViewPager() {        mPager = (ViewPager) findViewById(R.id.vPager);        listViews = new ArrayList<View>();        LayoutInflater mInflater = getLayoutInflater();        listViews.add(mInflater.inflate(R.layout.lay1, null));        listViews.add(mInflater.inflate(R.layout.lay2, null));        listViews.add(mInflater.inflate(R.layout.lay3, null));        mPager.setAdapter(new MyPagerAdapter(listViews));        mPager.setCurrentItem(0);        mPager.setOnPageChangeListener(new MyOnPageChangeListener());    }    /**     * 初始化动画     */    private void InitImageView() {        cursor = (ImageView) findViewById(R.id.cursor);        bmpW = BitmapFactory.decodeResource(getResources(), R.drawable.a)                .getWidth();// 获取图片宽度        DisplayMetrics dm = new DisplayMetrics();        getWindowManager().getDefaultDisplay().getMetrics(dm);        int screenW = dm.widthPixels;// 获取分辨率宽度        offset = (screenW / 3 - bmpW) / 2;// 计算偏移量        Matrix matrix = new Matrix();        matrix.postTranslate(offset, 0);        cursor.setImageMatrix(matrix);// 设置动画初始位置    }    /**     * ViewPager适配器     */    public class MyPagerAdapter extends PagerAdapter {        public List<View> mListViews;        public MyPagerAdapter(List<View> mListViews) {            this.mListViews = mListViews;        }        @Override        public void destroyItem(View arg0, int arg1, Object arg2) {            ((ViewPager) arg0).removeView(mListViews.get(arg1));        }        @Override        public void finishUpdate(View arg0) {        }        @Override        public int getCount() {            return mListViews.size();        }        @Override        public Object instantiateItem(View arg0, int arg1) {            ((ViewPager) arg0).addView(mListViews.get(arg1), 0);            return mListViews.get(arg1);        }        @Override        public boolean isViewFromObject(View arg0, Object arg1) {            return arg0 == (arg1);        }        @Override        public void restoreState(Parcelable arg0, ClassLoader arg1) {        }        @Override        public Parcelable saveState() {            return null;        }        @Override        public void startUpdate(View arg0) {        }    }    /**     * 头标点击监听     */    public class MyOnClickListener implements View.OnClickListener {        private int index = 0;        public MyOnClickListener(int i) {            index = i;        }        @Override        public void onClick(View v) {            mPager.setCurrentItem(index);        }    };    /**     * 页卡切换监听     */    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        @Override        public void onPageSelected(int arg0) {            Animation animation = null;            switch (arg0) {            case 0:                if (currIndex == 1) {                    animation = new TranslateAnimation(one, 0, 0, 0);                } else if (currIndex == 2) {                    animation = new TranslateAnimation(two, 0, 0, 0);                }                break;            case 1:                if (currIndex == 0) {                    animation = new TranslateAnimation(offset, one, 0, 0);                } else if (currIndex == 2) {                    animation = new TranslateAnimation(two, one, 0, 0);                }                break;            case 2:                if (currIndex == 0) {                    animation = new TranslateAnimation(offset, two, 0, 0);                } else if (currIndex == 1) {                    animation = new TranslateAnimation(one, two, 0, 0);                }                break;            }            currIndex = arg0;            animation.setFillAfter(true);// True:图片停在动画结束位置            animation.setDuration(300);            cursor.startAnimation(animation);        }        @Override        public void onPageScrolled(int arg0, float arg1, int arg2) {        }        @Override        public void onPageScrollStateChanged(int arg0) {        }    }}
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