Android吸顶效果并有着ViewPager左右切换功能

import android.content.context
import android.util.attributeset
import android.view.view
import androidx.core.view.nestedscrollingparent2
import androidx.core.widget.nestedscrollview
/**
 * @author: shuhuai
 * @desc:
 * @date: 2024/11/20
 * @version:
 * @remark
 */
class coordinatorscrollview : nestedscrollview, nestedscrollingparent2 {
    private var maxscrolly = 0
    constructor(context: context?) : super(context!!)
    constructor(context: context?, attrs: attributeset?) : super(
        context!!,
        attrs
    )
    constructor(
        context: context?,
        attrs: attributeset?,
        defstyleattr: int
    ) : super(context!!, attrs, defstyleattr)
    override fun onstartnestedscroll(
        child: view,
        target: view,
        axes: int,
        type: int
    ): boolean {
        return true
    }
    /**
     * 设置最大滑动距离
     *
     * @param maxscrolly 最大滑动距离
     */
    fun setmaxscrolly(maxscrolly: int) {
        this.maxscrolly = maxscrolly
    }
    /**
     * @param target   触发嵌套滑动的view
     * @param dx       表示 view 本次 x 方向的滚动的总距离
     * @param dy       表示 view 本次 y 方向的滚动的总距离
     * @param consumed 表示父布局消费的水平和垂直距离
     * @param type     触发滑动事件的类型
     */
    override fun onnestedprescroll(
        target: view,
        dx: int,
        dy: int,
        consumed: intarray,
        type: int
    ) {
        if (dy > 0 && scrolly < maxscrolly) {
            scrollby(0, dy)
            consumed[1] = dy
        }
    }
}

<?xml version="1.0" encoding="utf-8"?>
<linearlayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:orientation="vertical"
    tools:context=".mainactivity">
    <!--titlebar-->
    <linearlayout
        android:id="@+id/titlebar"
        android:layout_width="match_parent"
        android:layout_height="45dp"
        android:gravity="center_vertical"
        android:orientation="horizontal"
        android:paddingleft="18dp"
        android:paddingright="18dp">
        <edittext
            android:layout_width="0dp"
            android:layout_height="35dp"
            android:layout_marginend="12dp"
            android:layout_marginright="12dp"
            android:layout_weight="1"
            android:background="@drawable/edit_style"
            android:paddingleft="12dp"
            android:paddingright="12dp" />
        <textview
            android:layout_width="wrap_content"
            android:layout_height="35dp"
            android:background="@drawable/button_style"
            android:gravity="center"
            android:paddingleft="15dp"
            android:paddingright="15dp"
            android:text="搜索"
            android:textcolor="#333333"
            android:textstyle="bold" />
    </linearlayout>
    <!--coordinatorscrollview-->
    <com.cyn.mt.coordinatorscrollview
        android:id="@+id/coordinatorscrollview"
        android:layout_width="match_parent"
        android:layout_height="match_parent">
        <linearlayout
            android:layout_width="match_parent"
            android:layout_height="wrap_content"
            android:orientation="vertical">
            <!--相当于分析图中头部的linearlayout，模拟动态添加的情况-->
            <linearlayout
                android:id="@+id/titlelinerlayout"
                android:layout_width="match_parent"
                android:layout_height="wrap_content"
                android:orientation="vertical" />
            <!--相当于分析图中红色标记处tablayout-->
            <com.google.android.material.tabs.tablayout
                android:id="@+id/tablayout"
                android:layout_width="match_parent"
                android:layout_height="wrap_content" />
            <!--相当于分析图中绿色标记处viewpager，代码中动态设置高度-->
            <androidx.viewpager.widget.viewpager
                android:id="@+id/viewpager"
                android:layout_width="match_parent"
                android:layout_height="wrap_content" />
        </linearlayout>
    </com.cyn.mt.coordinatorscrollview>
</linearlayout>

class mainactivity : appcompatactivity() {
    //屏幕宽
    var screenwidth = 0
    //屏幕高
    var screenheight = 0
    //tablayout的文本和图片
    private val tabtextdata = arrayof("常用药品", "夜间送药", "隐形眼镜", "成人用品", "医疗器械", "全部商家")
    private val tabicondata = arrayof(
        r.mipmap.tab_icon,
        r.mipmap.tab_icon,
        r.mipmap.tab_icon,
        r.mipmap.tab_icon,
        r.mipmap.tab_icon,
        r.mipmap.tab_icon
    )
    private var fragmentdata = mutablelistof<fragment>()
    override fun oncreate(savedinstancestate: bundle?) {
        super.oncreate(savedinstancestate)
        setcontentview(r.layout.activity_main)
        initview()
        initdata()
    }
    private fun initview() {
        //获取屏幕宽高
        val resources: resources = this.resources
        val dm: displaymetrics = resources.displaymetrics
        screenwidth = dm.widthpixels
        screenheight = dm.heightpixels
        //状态栏沉浸
        statusbarutil.immersive(this)
        //titlebar填充
        statusbarutil.setpaddingsmart(this, titlebar)
        //状态栏字体颜色设置为黑色
        statusbarutil.darkmode(this)
        //动态设置viewpager高度
        coordinatorscrollview.post {
            val layoutparams = viewpager.layoutparams
            layoutparams.width = screenwidth
            layoutparams.height = coordinatorscrollview.height - tablayout.height
            viewpager.layoutparams = layoutparams
        }
    }
    private fun initdata() {
        //我模拟在头部动态添加三个布局，就用图片代替了，要设置的图片高度都是我提前算好的，根据屏幕的比例来计算的
        val titleview1 = gettitleview(screenwidth * 0.42f, r.mipmap.title1)
        val titleview2 = gettitleview(screenwidth * 0.262f, r.mipmap.title2)
        titlelinerlayout.addview(titleview1)
        titlelinerlayout.addview(titleview2)
        //设置最大滑动距离
        titlelinerlayout.post {
            coordinatorscrollview.setmaxscrolly(titlelinerlayout.height)
        }
        //用于请求网络后动态添加子布局
        handler().postdelayed({
            val titleview3 = gettitleview(screenwidth * 0.589f, r.mipmap.title3)
            titlelinerlayout.addview(titleview3)
            //再次设置最大滑动距离
            titlelinerlayout.post {
                coordinatorscrollview.setmaxscrolly(titlelinerlayout.height)
            }
        }, 200)
        //添加tablayout
        for (i in tabtextdata.indices) {
            tablayout.addtab(tablayout.newtab())
            tablayout.gettabat(i)!!.settext(tabtextdata[i]).seticon(tabicondata[i])
            //添加fragment
            fragmentdata.add(testfragment.newinstance(tabtextdata[i]))
        }
        //fragment viewpager
        viewpager.adapter = viewpageradapter(supportfragmentmanager, fragmentdata)
        //tablayout关联viewpager
        tablayout.setupwithviewpager(viewpager)
        //设置tablayout数据
        for (i in tabtextdata.indices) {
            tablayout.gettabat(i)!!.settext(tabtextdata[i]).seticon(tabicondata[i])
        }
    }
    /**
     * 获取一个title布局
     * 我这里就用三张图片模拟的
     *
     * @height 要设置的图片高度
     */
    private fun gettitleview(height: float, res: int): view {
        val inflate = from(this).inflate(r.layout.title_layout, null, false)
        val layoutparams = inflate.titleimage.layoutparams
        layoutparams.width = screenwidth
        layoutparams.height = height.toint()
        inflate.titleimage.setimageresource(res)
        return inflate
    }
}