我如何才能迫使将清除按钮添加到EditText成为片段？

Question

我希望你能帮助我。 我正在尝试实现一个edittext，当您键入内容时，将出现一个按钮（x）以清除该edittext。我希望在editext为空时禁用此（x）按钮。我能够实现用于清除edittext的按钮，但是当edittext为空时，我无法使按钮消失。有人可以帮忙吗？

compileSdkVersion 28
ext.kotlin_version ='1.3.21'
classpath'com.android.tools.build:gradle:3.3.2'

import android.graphics.drawable.Drawable
import android.os.Bundle
import android.support.v4.app.Fragment
import android.support.v4.content.ContextCompat
import android.text.Editable
import android.text.TextWatcher
import android.view.LayoutInflater
import android.view.MotionEvent

import android.view.View
import android.view.ViewGroup
import android.widget.EditText
import br.com.adrianofpinheiro.testesantander.R
import br.com.adrianofpinheiro.testesantander.utils.PhoneNumberFormatType
import br.com.adrianofpinheiro.testesantander.utils.PhoneNumberFormatter

import kotlinx.android.synthetic.main.fragment_contato.*
import kotlinx.android.synthetic.main.fragment_contato.view.*
import java.lang.ref.WeakReference


// TODO: Rename parameter arguments, choose names that match
// the fragment initialization parameters, e.g. ARG_ITEM_NUMBER
private const val ARG_PARAM1 = "param1"
private const val ARG_PARAM2 = "param2"

/**
 * A simple [Fragment] subclass.
 * Activities that contain this fragment must implement the
 * [ContatoFragment.OnFragmentInteractionListener] interface
 * to handle interaction events.
 * Use the [ContatoFragment.newInstance] factory method to
 * create an instance of this fragment.
 *
 */
class ContatoFragment : Fragment() {


    val COMPOUND_DRAWABLE_RIGHT_INDEX = 2

    override fun onCreateView(
        inflater: LayoutInflater, container: ViewGroup?,
        savedInstanceState: Bundle?
    ): View? {
        val view: View = inflater.inflate(R.layout.fragment_contato, container, false)

        addRightCancelDrawable(view.findViewById(R.id.etNome))
        addRightCancelDrawable(view.findViewById(R.id.etEmail))
        addRightCancelDrawable(view.findViewById(R.id.etTelefone))


        val nome = view.findViewById<EditText>(R.id.etNome)
        nome.onRightDrawableClicked {
            it.text.clear()
        }

        val email = view.findViewById<EditText>(R.id.etEmail)
        email?.onRightDrawableClicked {
            it.text.clear()
        }

        val telefone = view.findViewById<EditText>(R.id.etTelefone)
        telefone?.onRightDrawableClicked {
            it.text.clear()
        }


        view.btnEnviar.setOnClickListener {
            if (!etNome.text.isNullOrEmpty() && !etEmail.text.isNullOrEmpty() && !etTelefone.text.isNullOrEmpty()) {
                criarFragmentContato()
            } else {
                etNome.error = getString(R.string.msg_error_form_nome)
                etEmail.error = getString(R.string.msg_error_form_email)
                etTelefone.error = getString(R.string.msg_error_form_telefone)
            }
        }

        //Mask Phone
        val editText: EditText = view.findViewById(R.id.etTelefone)
        val country = PhoneNumberFormatType.PT_BR
        val phoneFormatter = PhoneNumberFormatter(WeakReference(editText), country)
        editText.addTextChangedListener(phoneFormatter)

        return view
    }

    fun criarFragmentContato() {
        val trasaction = fragmentManager?.beginTransaction()
        val fragment = ContatoEnviadoFragment()
        trasaction?.replace(R.id.fragment_container, fragment)
        trasaction?.addToBackStack(null)
        trasaction?.commit()
    }

    private fun addRightCancelDrawable(editText: EditText) {
        val cancel = ContextCompat.getDrawable(requireContext(), R.drawable.ic_cancel_gray_24dp)
        cancel?.setBounds(0, 0, cancel.intrinsicWidth, cancel.intrinsicHeight)
        editText.setCompoundDrawables(null, null, cancel, null)
    }


    fun EditText.makeClearableEditText(
        onIsNotEmpty: (() -> Unit)?,
        onClear: (() -> Unit)?,
        clearDrawable: Drawable
    ) {
        val updateRightDrawable = {
            this.setCompoundDrawables(
                null, null,
                if (text.isNotEmpty()) clearDrawable else null,
                null
            )
        }
        updateRightDrawable()

        this.addTextChangedListener(object : TextWatcher {
            override fun afterTextChanged(p0: Editable?) {
                if (text.isNotEmpty()) {
                    onIsNotEmpty?.invoke()

                }
                updateRightDrawable()
            }

            override fun beforeTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {
            }

            override fun onTextChanged(p0: CharSequence?, p1: Int, p2: Int, p3: Int) {
            }
        })

        this.onRightDrawableClicked {
            this.text.clear()
            this.setCompoundDrawables(null, null, null, null)
            onClear?.invoke()
            this.requestFocus()
        }
    }

    fun EditText.makeClearableEditText(onIsNotEmpty: (() -> Unit)?, onCleared: (() -> Unit)?) {
        compoundDrawables[COMPOUND_DRAWABLE_RIGHT_INDEX]?.let { clearDrawable ->
            makeClearableEditText(onIsNotEmpty, onCleared, clearDrawable)
        }
    }

    fun EditText.onRightDrawableClicked(onClicked: (view: EditText) -> Unit) {
        this.setOnTouchListener { v, event ->
            var hasConsumed = false
            if (v is EditText) {
                if (event.x >= v.width - v.totalPaddingRight) {
                    if (event.action == MotionEvent.ACTION_UP) {
                        onClicked(this)
                    }
                    hasConsumed = true
                }
            }
            hasConsumed
        }
    }

}