悬停view的使用

首先是布局资源

 

activity_main.xml

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 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">



    <com.example.stickview.MyScrollView
        android:id="@+id/scroll"
        android:layout_width="match_parent"
        android:layout_height="wrap_content">
        <LinearLayout
            android:layout_width="match_parent"
            android:layout_height="match_parent"
            android:orientation="vertical">
    <TextView
        android:layout_width="match_parent"
        android:layout_height="200dp"
        android:background="#ffff00"
        />
    <TextView
        android:id="@+id/t2"
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:background="@color/colorAccent"
        android:text="我是全局悬浮view"
/>

    <TextView
        android:layout_width="match_parent"
        android:layout_height="600dp"
        android:background="@color/colorPrimaryDark"
        />
        </LinearLayout>
    </com.example.stickview.MyScrollView>
    <TextView
        android:id="@+id/t1"
        android:layout_width="match_parent"
        android:layout_height="100dp"
        android:background="@color/colorAccent"
        android:text="我是假全局悬浮view"
        android:visibility="gone"
        />
</RelativeLayout>





MainActivity代码

package com.example.stickview;

import androidx.appcompat.app.AppCompatActivity;

import android.os.Bundle;
import android.widget.TextView;

public class MainActivity extends AppCompatActivity {

    MyScrollView scroll;
    TextView t1,t2;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        scroll = (MyScrollView)findViewById(R.id.scroll);
        t1 = (TextView)findViewById(R.id.t1);
        t2 = (TextView)findViewById(R.id.t2);
        scroll.setView(t1,t2);
    }
}

自定义ScrollView代码

package com.example.stickview;

import android.content.Context;
import android.util.AttributeSet;
import android.view.View;
import android.widget.ScrollView;
import android.widget.TextView;


public class MyScrollView extends ScrollView {

    private static StopCall stopCall;
    Context ctx;
    TextView t1,t2;
    //ScrollView向上滑动到顶部的距离
    private int upH;

    public MyScrollView(Context context) {

        super(context);

    }

    public MyScrollView(Context context, AttributeSet attrs) {
        super(context, attrs);
        this.ctx = context;
        //赋值：300很重要，这个值是顶部2上面的高度，也就是本例中图片的高度
        upH = dpToPx(ctx,200);//单位是dp
    }

    public MyScrollView(Context context, AttributeSet attrs, int defStyleAttr) {
        super(context, attrs, defStyleAttr);

    }


    public static void setCallback(StopCall c){
        stopCall =c ;
    }


    @Override protected void onScrollChanged(int l, int t, int oldl, int oldt)
    {
        super.onScrollChanged(l, t, oldl, oldt);
        if(t>upH) {
            stopSlide(true);
        }
        else{
           stopSlide(false);
        }

        }

/**
 * 接口实现，可不可就
 */
        public void stopSlide(boolean isStop){
            if (isStop) {
                t1.setVisibility(View.VISIBLE);
                t2.setVisibility(View.GONE);
            } else {
                t2.setVisibility(View.VISIBLE);
                t1.setVisibility(View.GONE);
            }
        }


        public interface StopCall {

            public void stopSlide(boolean isStop);
        }


        public static int dpToPx(Context context,float dpValue) {//dp转换为px
            float scale=context.getResources().getDisplayMetrics().density;//获得当前屏幕密度
            return (int)(dpValue*scale+0.5f);
        }


        public void setView(TextView t1,TextView t2)
        {
            this.t1 = t1;
            this.t2 = t2;
        }
    }