viewpager欢迎页面底部点的滑动效果

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"

    android:layout_height="match_parent">
    <androidx.viewpager.widget.ViewPager
        android:id="@+id/vp_guide"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
    </androidx.viewpager.widget.ViewPager>



    <RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="30dip">

        <LinearLayout
            android:id="@+id/ll_guide_points"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal">
        </LinearLayout>

        <View
            android:id="@+id/v_guide_redpoint"
            android:layout_width="10px"
            android:layout_height="10px"
       android:background="@drawable/shap"/>

    </RelativeLayout>

</RelativeLayout>

public class MyAdapter extends PagerAdapter {
    private List<ImageView> mGuids;

    public MyAdapter(Context ctx, List<ImageView> guids) {
        this.mGuids = guids;
    }

    @Override
    public int getCount() {
        return mGuids.size();// 返回数据的个数
    }

    @Override
    public boolean isViewFromObject(View arg0, Object arg1) {
        return arg0 == arg1;// 过滤和缓存的作用
    }

    @Override
    public void destroyItem(ViewGroup container, int position, Object object) {
        container.removeView((View) object);//从viewpager中移除掉
    }

    @Override
    public Object instantiateItem(ViewGroup container, int position) {
        // container viewpaper
        //获取View
        View child = mGuids.get(position);
        // 添加View
        container.addView(child);
        return child;
    }
}

public class MainActivity extends AppCompatActivity {
    private ViewPager mVp_Guide;
    private View mGuideRedPoint;
    private LinearLayout mLlGuidePoints;
    private int[] mPics = new int[]{R.drawable.lunch1, R.drawable.lunch2, R.drawable.lunch3, R.drawable.lunch4};
    private View v_point;
    private int disPoints;
    private int currentItem;
    private MyAdapter adapter;
    private List<ImageView> guids;
    private int width;
    @Override
    protected void onCreate(@Nullable Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);


//            UIUtils.init(getApplicationContext());
        WindowManager windowManager = (WindowManager) getApplicationContext().getSystemService(Context.WINDOW_SERVICE);
        //获取屏幕的宽度
        Point size = new Point();
        windowManager.getDefaultDisplay().getSize(size);
       width = size.x;
            initView();
            initData();
            initEvent();

        }

        private void initView() {
            mVp_Guide = (ViewPager) findViewById(R.id.vp_guide);
            mGuideRedPoint = findViewById(R.id.v_guide_redpoint);
            mLlGuidePoints = (LinearLayout) findViewById(R.id.ll_guide_points);
        }

        private void initData() {
            // viewpaper adapter适配器
            guids = new ArrayList<ImageView>();

            //创建viewpager的适配器
            for (int i = 0; i < mPics.length; i++) {
                ImageView iv_temp = new ImageView(getApplicationContext());
                iv_temp.setBackgroundResource(mPics[i]);

                //添加界面的数据
                guids.add(iv_temp);

                //灰色的点在LinearLayout中绘制：
                //获取点
               v_point = new View(getApplicationContext());
                v_point.setBackgroundResource(R.drawable.shap2);//灰点背景色
                //设置灰色点的显示大小
                LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(10, 10);
                //设置点与点的距离,第一个点除外
                if (i != 0)
                    params.leftMargin = 47;
                v_point.setLayoutParams(params);

                mLlGuidePoints.addView(v_point);
            }

            // 创建viewpager的适配器
            adapter = new MyAdapter(getApplicationContext(), guids);
            // 设置适配器
            mVp_Guide.setAdapter(adapter);
        }

        private void initEvent() {
            //监听界面绘制完成
            mGuideRedPoint.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver.OnGlobalLayoutListener() {
                @Override
                public void onGlobalLayout() {
                    //取消注册界面而产生的回调接口
                    mGuideRedPoint.getViewTreeObserver().removeGlobalOnLayoutListener(this);
                    //计算点于点之间的距离
                    disPoints = (mLlGuidePoints.getChildAt(1).getLeft() - mLlGuidePoints.getChildAt(0).getLeft());
                }
            });

            //滑动事件监听滑动距离，点更随滑动。
            mVp_Guide.setOnPageChangeListener(new ViewPager.OnPageChangeListener() {
                @Override
                public void onPageSelected(int position) {
               /* //当前viewpager显示的页码
                //如果viewpager滑动到第三页码（最后一页），显示进入的button
                if (position == guids.size() - 1) {
                    bt_startExp.setVisibility(View.VISIBLE);//设置按钮的显示
                } else {
                    //隐藏该按钮
                    bt_startExp.setVisibility(View.GONE);
                }*/
                    currentItem = position;
                }

                /**
                 *页面滑动调用，拿到滑动距离设置视图的滑动状态
                 * @param position 当前页面位置
                 * @param positionOffset 移动的比例值
                 * @param positionOffsetPixels 便宜的像素
                 */
                @Override
                public void onPageScrolled(int position, float positionOffset, int positionOffsetPixels) {
                    //计算红点的左边距
                    float leftMargin = disPoints * (position + positionOffset);
                    //设置红点的左边距
                    RelativeLayout.LayoutParams layoutParams = (RelativeLayout.LayoutParams) mGuideRedPoint.getLayoutParams();
                    //对folat类型进行四舍五入，
                    layoutParams.leftMargin = Math.round(leftMargin);
                    //设置位置
                    mGuideRedPoint.setLayoutParams(layoutParams);
                }

                @Override
                public void onPageScrollStateChanged(int state) {
                }
            });

            //给页面设置触摸事件
            mVp_Guide.setOnTouchListener(new View.OnTouchListener() {
                float startX;
                float endX;

                @Override
                public boolean onTouch(View v, MotionEvent event) {
                    switch (event.getAction()) {
                        case MotionEvent.ACTION_DOWN:
                            startX = event.getX();
                            break;
                        case MotionEvent.ACTION_UP:
                            endX = event.getX();

                            //首先要确定的是，是否到了最后一页，然后判断是否向左滑动，并且滑动距离是否符合，我这里的判断距离是屏幕宽度的4分之一（这里可以适当控制）
                            if (currentItem == (guids.size() - 1) && startX - endX >= (width / 4)) {
                                Toast.makeText( MainActivity.this, "跳转", Toast.LENGTH_SHORT ).show();
                                //进入主页
//                                Intent intent = new Intent(MainActivity.this, Main2Activity.class);
//                                startActivity(intent);
//                                //这部分代码是切换Activity时的动画，看起来就不会很生硬
//                                overridePendingTransition(android.R.anim.slide_in_left, android.R.anim.slide_out_right);
//                                finish();
                            }
                            break;
                    }
                    return false;
                }
            });
        }

        @Override
        public boolean onKeyDown(int keyCode, KeyEvent event) {
            return true;
        }


    }

<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="oval">


        <corners android:radius="10dp"/>
        <solid android:color="#e7e7e7"/>
        <size android:width="10px"
            android:height="10px"/>




</shape>

<shape xmlns:android="http://schemas.android.com/apk/res/android"
    android:shape="oval">
    <corners android:radius="10dp"/>
    <solid android:color="#FF393939"/>
    <size android:width="10px"
        android:height="10px"/>


</shape>