android引导页中的小圆点随手势滑动demo

直接上代码，首先是布局文件：

xml version="1.0" encoding="utf-8"?>
xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="match_parent"
    android:layout_height="match_parent" >

            android:id="@+id/vp_guide"
        android:layout_width="match_parent"
        android:layout_height="match_parent" />

            android:id="@+id/btn_start"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="60dp"
        android:padding="5dp"
        android:text="立即进入"
        android:visibility="invisible"/>

            android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="20dp" >

                    android:id="@+id/ll_point_group"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:orientation="horizontal" >
        

                    android:id="@+id/view_blue_point"
            android:layout_width="10dp"
            android:layout_height="10dp"
            android:background="@mipmap/activity_point_h" />
    

操作代码：

package com.company.augus.guidepointdemo;

import android.os.Bundle;
import android.support.v4.view.PagerAdapter;
import android.support.v4.view.ViewPager;
import android.support.v7.app.AppCompatActivity;
import android.view.View;
import android.view.ViewGroup;
import android.view.ViewTreeObserver;
import android.view.Window;
import android.widget.Button;
import android.widget.ImageView;
import android.widget.LinearLayout;
import android.widget.RelativeLayout;
import android.widget.Toast;

import java.util.ArrayList;

public class MainActivity extends AppCompatActivity {
    private static final int[] mImageIds = new int[] { R.mipmap.activity_one,R.mipmap.activity_two, R.mipmap.activity_three};

    private ViewPager vpGuide;
    private ArrayList mImageViewList;

    private LinearLayout llPointGroup;// 引导圆点的父控件

    private int mPointWidth;// 圆点间的距离

    private View viewBluePoint;// 蓝点

    private Button btnStart;// 进入

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);

        requestWindowFeature(Window.FEATURE_NO_TITLE);
        setContentView(R.layout.activity_main);

        vpGuide = (ViewPager) findViewById(R.id.vp_guide);
        llPointGroup = (LinearLayout) findViewById(R.id.ll_point_group);
        viewBluePoint = findViewById(R.id.view_blue_point);
        btnStart = (Button) findViewById(R.id.btn_start);

        btnStart.setOnClickListener(new View.OnClickListener() {

            @Override
            public void onClick(View v) {
                Toast.makeText(MainActivity.this,"enter",Toast.LENGTH_SHORT).show();
            }
        });

        initViews();
        vpGuide.setAdapter(new GuideAdapter());

        vpGuide.setOnPageChangeListener(new GuidePageListener());
    }

    /**
     * 初始化界面
     */
    private void initViews() {
        mImageViewList = new ArrayList();

        // 初始化引导页的3个页面
        for (int i = 0; i < mImageIds.length; i++) {
            ImageView image = new ImageView(this);
            image.setBackgroundResource(mImageIds[i]);// 设置引导页背景
            mImageViewList.add(image);
        }

        // 初始化引导页的灰色圆点
        for (int i = 0; i < mImageIds.length; i++) {
            View point = new View(this);
            point.setBackgroundResource(R.mipmap.activity_point_n);// 设置引导页默认圆点

            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(18, 18);
            if (i > 0) {
                params.leftMargin = 10;// 设置圆点间隔
            }

            point.setLayoutParams(params);// 设置圆点的大小

            llPointGroup.addView(point);// 将圆点添加给线性布局
        }

        // 获取视图树, 对layout结束事件进行监听
        llPointGroup.getViewTreeObserver().addOnGlobalLayoutListener(
                new ViewTreeObserver.OnGlobalLayoutListener() {

                    // 当layout执行结束后回调此方法
                    @Override
                    public void onGlobalLayout() {

                        llPointGroup.getViewTreeObserver().removeGlobalOnLayoutListener(this);
                        mPointWidth = llPointGroup.getChildAt(1).getLeft()-llPointGroup.getChildAt(0).getLeft();
                        System.out.println("圆点距离:" + mPointWidth);
                    }
                });
    }

    /**
     * ViewPager数据适配器
     *
     */
    class GuideAdapter extends PagerAdapter {

        @Override
        public int getCount() {
            return mImageIds.length;
        }

        @Override
        public boolean isViewFromObject(View arg0, Object arg1) {
            return arg0 == arg1;
        }

        @Override
        public Object instantiateItem(ViewGroup container, int position) {
            container.addView(mImageViewList.get(position));
            return mImageViewList.get(position);
        }

        @Override
        public void destroyItem(ViewGroup container, int position, Object object) {
            container.removeView((View) object);
        }
    }

    /**
     * viewpager的滑动监听
     */
    class GuidePageListener implements ViewPager.OnPageChangeListener {

        // 滑动事件
        @Override
        public void onPageScrolled(int position, float positionOffset,
                                   int positionOffsetPixels) {
            // System.out.println("当前位置:" + position + ";百分比:" + positionOffset
            // + ";移动距离:" + positionOffsetPixels);
            int len = (int) (mPointWidth * positionOffset) + position * mPointWidth;
            RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams) viewBluePoint.getLayoutParams();// 获取当前蓝点的布局参数
            params.leftMargin = len;// 设置左边距
            viewBluePoint.setLayoutParams(params);// 重新给蓝点设置布局参数
        }

        // 某个页面被选中
        @Override
        public void onPageSelected(int position) {
            if (position == mImageIds.length - 1) {// 最后一个页面
                btnStart.setVisibility(View.VISIBLE);// 显示立即进入的按钮
            } else {
                btnStart.setVisibility(View.INVISIBLE);
            }
        }

        // 滑动状态发生变化
        @Override
        public void onPageScrollStateChanged(int state) {

        }

    }

}