android 使用自定义控件制作 类似天猫广告条滑动效果

package com.example.ex_templete;
import android.os.Bundle;
import android.support.v4.app.Fragment;
import android.support.v4.app.FragmentManager;
import android.support.v4.app.FragmentPagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v4.view.ViewPager.OnPageChangeListener;
import android.util.Log;
import android.view.LayoutInflater;
import android.view.View;
import android.view.ViewGroup;
public class BannerFragment extends Fragment
{
    private static final int COUNT_BANNER = 100000;
    private ViewPager mPager;
    // 定义广告图片
    private int[] mDrawerRes = new int[]
    { R.drawable.banner01, R.drawable.banner02, R.drawable.banner03,
            R.drawable.banner04, R.drawable.banner05 };
    // 保存当前ViewPager手动滑动状态
    private BannerIndicater mIndicater;
    class BannerAdapter extends FragmentPagerAdapter
    {
        public BannerAdapter(FragmentManager fm)
        {// FragmentPagerAdapter要求传入一个FragmentManager的对象
            super(fm);
        }
        @Override
        public Fragment getItem(int position)
        {// 将mDrawerRes集合中的五张图片加入到FragmentPagerAdapter中
            ImageFragment fragment = new ImageFragment();
            int index = position % mDrawerRes.length;
            fragment.changeImg(mDrawerRes[index], index);
            return fragment;
        }
        @Override
        public int getCount()
        {
            return COUNT_BANNER;//当前有100000张pager页面模拟无尽模式
        }
    }
    @Override
    public View onCreateView(LayoutInflater inflater, ViewGroup container,
            Bundle savedInstanceState)
    {
        View layout = inflater.inflate(R.layout.fragment_banner, container,
                false);
        initViewPager(layout);// 初始化ViewPager（广告）
        initIndicater(layout);// 初始化指示器（可以滚动的圆点）
        return layout;
    }
    private void initIndicater(View layout)
    {//BannerIndicater是自定义控件
        mIndicater = (BannerIndicater) layout.findViewById(R.id.indicater);
    }
                                                                                                                    
    private void initViewPager(View layout)
    {
        mPager = (ViewPager) layout.findViewById(R.id.pager);
        FragmentManager fm = getChildFragmentManager();
        mPager.setAdapter(new BannerAdapter(fm));
        mPager.setOnPageChangeListener(new BannerPagerChangeListener());
        // 从第50000张pager开始 就可以左右都能滑动了，给用户的感觉是无尽的
        mPager.setCurrentItem(COUNT_BANNER / 2);
    }
    class BannerPagerChangeListener implements OnPageChangeListener
    {
        @Override
        public void onPageScrollStateChanged(int state)
        {
            switch (state)
            {
                case ViewPager.SCROLL_STATE_IDLE:
                    Log.e("PagerChange", "ScrollState : arg0" + "空闲");
                    break;
                case ViewPager.SCROLL_STATE_DRAGGING:
                    Log.e("PagerChange", "ScrollState : arg0" + "拖拽");
                    break;
                case ViewPager.SCROLL_STATE_SETTLING:
                    Log.e("PagerChange", "ScrollState : arg0" + "固定");
                    break;
                default:
                    break;
            }
        }
        @Override
        public void onPageScrolled(int persion, float positionOffset,
                int positionOffsetPixels)
        {
            Log.e("PagerChange", "Scrolled : 滑动百分比" + positionOffset
                    + " 滑动像素: " + positionOffsetPixels);
            mIndicater.changeFrontPlace(persion, positionOffset);
        }
        @Override
        public void onPageSelected(int postion)
        {
            Log.e("PagerChange", "Selected : postion" + postion);
            // changeInidcatorImg(postion % mImgIndicatorIDs.length);
        }
    }
                                                                                                                    
}

package com.example.ex_templete;
import android.content.Context;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.util.AttributeSet;
import android.widget.ImageView;
public class BannerIndicater extends ImageView
{
    private static final int R = 5;
    private static final int Y = 32;
    private static final int X = 20;
    private static final int POINT_DISTENCE = R*3;
    private float mFrontX = X;
    private float mFrontY = Y;
    private Paint mBgPaint;
    private Paint mFrontPaint;
                                                                                                   
    private float persionOffset;
    private int persion;
    public BannerIndicater(Context context){
        super(context);
        //如果只重写这个方法 那么这个自定义控件只能在setViewContent(new BannerIndicater());
    }
                                                                                                   
    public BannerIndicater(Context context, AttributeSet attrs)
    {//自定义控件必须有一个 有参的构造方法，如果想在layout.xml文件中直接写入的话就要重写这个方法
        super(context, attrs);
        initPaint();
    }
    @Override
    protected void onDraw(Canvas canvas)
    {
        super.onDraw(canvas);
        for (int i = 0; i < 5; i++)
        {
            canvas.drawCircle(X + i * POINT_DISTENCE, Y, R, mBgPaint);
        }
                                                                                                       
        canvas.drawCircle(mFrontX+ (persion+persionOffset)*POINT_DISTENCE, mFrontY, R, mFrontPaint);
    }
                                                                                                   
    public void changeFrontPlace(int persion,float persionOffset)
    {
        this.persionOffset = persionOffset;
        this.persion = persion % 5;
    }
    private void initPaint()
    {
        mFrontPaint = new Paint();
        mFrontPaint.setColor(Color.RED);
        mBgPaint = new Paint();
        mBgPaint.setColor(Color.YELLOW);
        mBgPaint.setAntiAlias(true);
        mBgPaint.setStyle(Paint.Style.STROKE);
        mBgPaint.setStrokeWidth(2);
    }
}

<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"
    tools:context=".BannerFragment" >
    <android.support.v4.view.ViewPager
        android:id="@+id/pager"
        android:layout_width="match_parent"
        android:layout_height="140dp"
        android:background="#C0C0C0" >
    </android.support.v4.view.ViewPager>
                                                                                           
                                                                                           
    <!-- 在布局中使用自定义控件 -->
    <com.example.ex_templete.BannerIndicater
        android:id="@+id/indicater"
        android:layout_width="100dp"
        android:layout_height="40dp"
        android:layout_alignBottom="@+id/pager"
        android:layout_alignParentRight="true"
        android:background="#80000000" />
</RelativeLayout>