给Android 原生的SeekBar控件添加一个指示器标签；记录一下

按下时弹出popupwindow，进度条更新时刷新pw，松开时关闭pw；

public class SeekBarPopUtils {

    private static PopupWindow popWin = null;
    private static ConstraintLayout clPopPar = null;
    private static TextView tvPopTxt = null;

    public static void showPop(int progress,View seekBar){
        popWin = new PopupWindow();
        View mPopView = LayoutInflater.from(BaseApp.Companion.getAppContext()).inflate(R.layout.item_popup_win,null,false);
        clPopPar = mPopView.findViewById(R.id.cl_pop_par);
        tvPopTxt = mPopView.findViewById(R.id.tv_pop_txt);
        popWin.setContentView(mPopView);
        popWin.setHeight(dp2px(30));
        popWin.setWidth(seekBar.getWidth());
        popWin.showAsDropDown(seekBar,0,-(dp2px(30) + popWin.getHeight()));
        move(progress,seekBar);
    }


    public static void move(int progress,View seekBar){
        if (clPopPar != null){
            int tvPopWidth = dp2px(40);
            ConstraintLayout.LayoutParams params  = new ConstraintLayout.LayoutParams(
                    tvPopWidth, dp2px(30)
            );
            params.startToStart = clPopPar.getId();
            params.setMarginStart((seekBar.getWidth() - tvPopWidth)/100 * progress + tvPopWidth/3);
            tvPopTxt.setLayoutParams(params);

            tvPopTxt.setText(progress"");
        }
    }

    private static int dp2px(int dpVal){
        return (int) TypedValue.applyDimension(
                TypedValue.COMPLEX_UNIT_DIP,
                (float) dpVal,
                BaseApp.Companion.getAppContext().getResources().getDisplayMetrics()
        );
    }

    public static void dismiss(){
        popWin.dismiss();
        popWin = null;
        clPopPar = null;
        tvPopTxt = null;
    }
}

布局：

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout
    android:id="@+id/cl_pop_par"
    xmlns:android="http://schemas.android.com/apk/res/android"
    android:layout_width="30dp"
    android:layout_height="40dp"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools">

    <TextView
        android:id="@+id/tv_pop_txt"
        android:layout_width="30dp"
        android:layout_height="40dp"
        android:gravity="center"
        android:paddingBottom="10px"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintBottom_toBottomOf="parent"
        android:textSize="14sp"
        android:background="@mipmap/popup_center_seekbar_qipao"
        android:textColor="#fff"
        tools:text = "55" />

</androidx.constraintlayout.widget.ConstraintLayout>

使用：

mSeekbar.setOnSeekBarChangeListener(object: SeekBar.OnSeekBarChangeListener{
            override fun onProgressChanged(seekBar: SeekBar?, progress: Int, fromUser: Boolean) {
              SeekBarPopUtils.move(progress,seekBar!!)
            }

            override fun onStartTrackingTouch(seekBar: SeekBar?) {
                SeekBarPopUtils.showPop(seekBar!!)
            }

            override fun onStopTrackingTouch(seekBar: SeekBar?) {
                SeekBarPopUtils.dismiss()
            }
        })