Android ViewPager无限循环实现底部小圆点动态滑动

这篇文章主要介绍了Android ViewPager无限循环实现底部小圆点动态滑动的相关资料,需要的朋友可以参考下

页面拖动到最后一页 再向下滑动回复到 第一页，第一页向前滑动回到 最后一页

同时，底部红色小圆点随着页面的滑动距离比例随时改变位置



布局：

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<?xmlversion="1.0"encoding="utf-8"?>
<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"
android:paddingBottom="@dimen/activity_vertical_margin"
android:paddingLeft="@dimen/activity_horizontal_margin"
android:paddingRight="@dimen/activity_horizontal_margin"
android:paddingTop="@dimen/activity_vertical_margin"
tools:context="com.lian.viewpagertest.MainActivity">

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

<TextView
android:id="@+id/tv"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:text="内容"
android:textSize="25sp"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
/>

<RelativeLayout
android:id="@+id/rl_bottom"
android:layout_width="wrap_content"
android:layout_height="wrap_content"
android:layout_alignParentBottom="true"
android:layout_centerHorizontal="true"
android:layout_marginBottom="45dip">

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

<View
android:id="@+id/v_redpoint"
android:layout_width="10dip"
android:layout_height="10dip"
android:background="@drawable/red_circle"/>
</RelativeLayout>
</RelativeLayout>

其中red_circle是用shape绘制的红色小圆点

最后的LinearLayout实际上是灰色小圆点的容器，在代码中根据数据的长度动态确定数目

代码：

packagecom.lian.viewpagertest;

importandroid.os.Bundle;
importandroid.support.v4.view.PagerAdapter;
importandroid.support.v4.view.ViewPager;
importandroid.support.v7.app.AppCompatActivity;
importandroid.util.Log;
importandroid.view.View;
importandroid.view.ViewGroup;
importandroid.view.ViewTreeObserver;
importandroid.widget.ImageView;
importandroid.widget.LinearLayout;
importandroid.widget.RelativeLayout;
importandroid.widget.TextView;

importjava.util.ArrayList;
importjava.util.List;

publicclass MainActivity extendsAppCompatActivity {

privateViewPager mViewPager;
privateTextView mTextView;
privateLinearLayout mLinearLayout;
privateView mView;
privateList<ImageView> mDataList;
privateint diatance;

@Override
protectedvoid onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
initView();
initData();
initEvent();
}

/**
* 初始化数据
*/

privatevoid initData() {
int[] sorce = newint[]{R.drawable.a,R.drawable.b,R.drawable.c,R.drawable.d,R.drawable.e};

mDataList = newArrayList<ImageView>();

for(inti = 0;i < sorce.length;i ++){
ImageView img = newImageView(getApplicationContext());
img.setImageResource(sorce[i]);
mDataList.add(img);

//添加底部灰点
View v = newView(getApplicationContext());
v.setBackgroundResource(R.drawable.gray_circle);
//指定其大小
LinearLayout.LayoutParams params = newLinearLayout.LayoutParams(20,20);
if(i != 0)
params.leftMargin = 20;
v.setLayoutParams(params);
mLinearLayout.addView(v);
}

mViewPager.setAdapter(newMyAdapter());

//设置每次加载时第一页在MAX_VALUE / 2 - Extra 页，造成用户无限轮播的错觉
intstartPage = Integer.MAX_VALUE / 2;
intextra = startPage % mDataList.size();
startPage = startPage - extra;
mViewPager.setCurrentItem(startPage);
}

/**
* ViewPager的容器
*/

publicclass MyAdapter extendsPagerAdapter{

@Override
publicint getCount() {
//告诉容器我们的数据长度为Integer.MAX_VALUE，这样就可以一直滚动
returnInteger.MAX_VALUE;
}

@Override
publicboolean isViewFromObject(View view, Object object) {
returnview == object;
}

@Override
publicObject instantiateItem(ViewGroup container, intposition) {
//若position超过mDataList.size()，会发生越界异常，所以这里每次超过size又从0开始计算位置
position = position % mDataList.size();

ImageView img = mDataList.get(position);
container.addView(img);

returnimg;
}

@Override
publicvoid destroyItem(ViewGroup container, intposition, Object object) {

position = position % mDataList.size();

container.removeView((View)object);

// super.destroyItem(container, position, object);
}
}

privatevoid initEvent() {

/**
* 当底部红色小圆点加载完成时测出两个小灰点的距离，便于计算后面小红点动态移动的距离
*/
mView.getViewTreeObserver().addOnGlobalLayoutListener(newViewTreeObserver.OnGlobalLayoutListener() {
@Override
publicvoid onGlobalLayout() {
diatance = mLinearLayout.getChildAt(1).getLeft() - mLinearLayout.getChildAt(0).getLeft();
Log.d("两点间距",diatance + "测出来了");
}
});

mViewPager.setOnPageChangeListener(newViewPager.OnPageChangeListener() {
@Override
publicvoid onPageScrolled(intposition, floatpositionOffset, intpositionOffsetPixels) {

//测出页面滚动时小红点移动的距离，并通过setLayoutParams(params)不断更新其位置
position = position % mDataList.size();
floatleftMargin = diatance * (position + positionOffset);
RelativeLayout.LayoutParams params = (RelativeLayout.LayoutParams) mView.getLayoutParams();
params.leftMargin = Math.round(leftMargin);
mView.setLayoutParams(params);
Log.d("红点在这",leftMargin + "");
}

@Override
publicvoid onPageSelected(intposition) {

}

@Override
publicvoid onPageScrollStateChanged(intstate) {

}
});
}

privatevoid initView() {

setContentView(R.layout.activity_main);

mViewPager = (ViewPager) findViewById(R.id.viewpager);

mTextView = (TextView) findViewById(R.id.tv);

mLinearLayout = (LinearLayout) findViewById(R.id.ll_points);

mView = findViewById(R.id.v_redpoint);
}
}

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