Android从圆点导航的两个案例（ViewPager）

Posted 2020-08-22

案例一效果：

布局文件：

<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_view_pager"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.jogger.demo.ViewPagerActivity">

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

    <LinearLayout
        android:id="@+id/ll_container"
        android:layout_width="match_parent"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_marginBottom="40dp"
        android:gravity="center"
        android:orientation="horizontal"></LinearLayout>

</RelativeLayout>

Activity：

public class ViewPagerActivity extends FragmentActivity {

    private ViewPager vp_guide;
    private List<ImageView> mImgList;//导航图集合
    private LinearLayout ll_container;//小圆点容器
    private int mCurrentIndex = 0;//当前小圆点的位置
    private int[] imgArray = {R.drawable.guidance1, R.drawable.guidance2, R.drawable.guidance3, R
            .drawable.guidance4};

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_view_pager);
        vp_guide = (ViewPager) findViewById(R.id.vp_guide);
        ll_container = (LinearLayout) findViewById(R.id.ll_container);
        mImgList = new ArrayList<>();
        for (int i = 0; i < imgArray.length; i++) {
            ImageView imageView = new ImageView(this);//获取4个圆点
            imageView.setImageResource(imgArray[i]);
            mImgList.add(imageView);
            ImageView dot = new ImageView(this);
            if (i == mCurrentIndex) {
                dot.setImageResource(R.drawable.page_now);//设置当前页的圆点
            } else {
                dot.setImageResource(R.drawable.page);//其余页的圆点
            }
            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LinearLayout
                    .LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
            if (i > 0) {
                params.leftMargin = 10;//设置圆点边距
            }
            dot.setLayoutParams(params);
            ll_container.addView(dot);//将圆点添加到容器中
        }
        vp_guide.setAdapter(new MyAdapter(mImgList));
        //添加监听
        vp_guide.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int
                    positionOffsetPixels) {

            }

            @Override
            public void onPageSelected(int position) {
                //根据监听的页面改变当前页对应的小圆点
                mCurrentIndex = position;
                for (int i = 0; i < ll_container.getChildCount(); i++) {
                    ImageView imageView = (ImageView) ll_container.getChildAt(i);
                    if (i == position) {
                        imageView.setImageResource(R.drawable.page_now);
                    } else {
                        imageView.setImageResource(R.drawable.page);
                    }
                }
            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });
    }

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

        public MyAdapter(List<ImageView> viewList) {
            mViewList = viewList;
        }

        @Override
        public ImageView instantiateItem(ViewGroup container, int position) {
            ImageView view = mViewList.get(position);
            container.addView(view);
            return view;
        }

        @Override
        public int getCount() {
            return mViewList.size();
        }

        @Override
        public boolean isViewFromObject(View view, Object object) {
            return view == object;
        }

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

案例二效果：

布局文件：

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout
    xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:id="@+id/activity_view_pager"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context="com.jogger.demo.ViewPagerActivity">

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

    <RelativeLayout
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_alignParentBottom="true"
        android:layout_centerHorizontal="true"
        android:layout_marginBottom="40dp">

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

        <ImageView
            android:id="@+id/iv_dot_now"
            android:layout_width="wrap_content"
            android:layout_height="wrap_content"
            android:src="@drawable/page_now"/>
    </RelativeLayout>

</RelativeLayout>

Activity：

public class ViewPagerActivity extends FragmentActivity {

    private ViewPager vp_guide;
    private List<ImageView> mImgList;//导航图集合
    private LinearLayout ll_container;//小圆点容器
    private int mCurrentIndex = 0;//当前小圆点的位置
    private int mDotDis;//小圆点的距离
    private ImageView iv_dot_now;//当前圆点
    private int[] imgArray = {R.drawable.guidance1, R.drawable.guidance2, R.drawable.guidance3, R
            .drawable.guidance4};

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_view_pager);
        vp_guide = (ViewPager) findViewById(R.id.vp_guide);
        ll_container = (LinearLayout) findViewById(R.id.ll_container);
        iv_dot_now = (ImageView) findViewById(R.id.iv_dot_now);
        mImgList = new ArrayList<>();
        for (int i = 0; i < imgArray.length; i++) {
            ImageView imageView = new ImageView(this);//获取4个圆点
            imageView.setImageResource(imgArray[i]);
            mImgList.add(imageView);
            ImageView dot = new ImageView(this);
            dot.setImageResource(R.drawable.page);
            LinearLayout.LayoutParams params = new LinearLayout.LayoutParams(LinearLayout
                    .LayoutParams.WRAP_CONTENT, LinearLayout.LayoutParams.WRAP_CONTENT);
            if (i > 0) {
                params.leftMargin = 10;//设置圆点边距
            }
            dot.setLayoutParams(params);
            ll_container.addView(dot);//将圆点添加到容器中
        }
        vp_guide.setAdapter(new MyAdapter(mImgList));
        //添加监听
        vp_guide.addOnPageChangeListener(new ViewPager.OnPageChangeListener() {
            @Override
            public void onPageScrolled(int position, float positionOffset, int
                    positionOffsetPixels) {
                // 滚动过程中
                // 红色小圆点的移动距离=移动百分比*两个圆点的间距
                // 更新小红点距离
                int dis = (int) (mDotDis * positionOffset) + position * mDotDis;//
                // 因为移动完一个界面后，百分比会归0，所以要加上移动过的单位position*mPointDis
                //获取小圆点的布局属性，更新左边距
                RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams) iv_dot_now
                        .getLayoutParams();
                params.leftMargin = dis;// 修改左边距
                // 重新设置布局参数
                iv_dot_now.setLayoutParams(params);
            }

            @Override
            public void onPageSelected(int position) {

            }

            @Override
            public void onPageScrollStateChanged(int state) {

            }
        });
        // 监听layout方法结束的事件，位置确定之后获取圆点间距
        // 视图树
        iv_dot_now.getViewTreeObserver().addOnGlobalLayoutListener(new ViewTreeObserver
                .OnGlobalLayoutListener() {

            @Override
            public void onGlobalLayout() {
                //视图树移除监听
                iv_dot_now.getViewTreeObserver().removeOnGlobalLayoutListener(this);
                //计算得到小圆点距离
                mDotDis = ll_container.getChildAt(1).getLeft() - ll_container.getChildAt(0)
                        .getLeft();
            }
        });
    }

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

        public MyAdapter(List<ImageView> viewList) {
            mViewList = viewList;
        }

        @Override
        public ImageView instantiateItem(ViewGroup container, int position) {
            ImageView view = mViewList.get(position);
            container.addView(view);
            return view;
        }

        @Override
        public int getCount() {
            return mViewList.size();
        }

        @Override
        public boolean isViewFromObject(View view, Object object) {
            return view == object;
        }

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