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; } }