Android自定义EditText右侧带图片控件

package scut.userlogin;

import android.content.Context;
import android.util.AttributeSet;
import android.view.MotionEvent;
import android.view.View;
import android.widget.EditText;

/**
 * Created by yany on 2016/7/23.
 */
public class EditText_PassWordDisplay extends EditText implements View.OnTouchListener {

 //需要实现下面的几个构造函数，不然有可能加载不了这个EditText控件
 public EditText_PassWordDisplay(Context context) {
 super(context);
 init();
 }

 public EditText_PassWordDisplay(Context context, AttributeSet attrs, int defStyle) {
 super(context, attrs, defStyle);
 init();
 }

 public EditText_PassWordDisplay(Context context, AttributeSet attrs) {
 super(context, attrs);
 init();
 }

 //初始化控件，绑定监听器
 public void init(){
 setOnTouchListener(this);
 }

 @Override
 public boolean onTouch(View v, MotionEvent event) {
 //如果不是按下操作，就不做处理，如果是按下操作但是没有图片，也不做处理
 if (event.getAction() == MotionEvent.ACTION_UP && this.getCompoundDrawables()[2] != null) {
  //检测点击区域的X坐标是否在图片范围内
  if (event.getX() > this.getWidth()
   - this.getPaddingRight()
   - this.getCompoundDrawables()[2].getIntrinsicWidth()) {

  //在此做图片的点击处理
  System.out.println("点击区域");
  MessageShow.ShowToast(getContext(), "点击了图片");

  }
  return false;
 }
 return false;
 }
}

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout xmlns:android="http://schemas.android.com/apk/res/android"
 xmlns:tools="http://schemas.android.com/tools"
 android:layout_width="match_parent"
 android:layout_height="match_parent"
 android:paddingBottom="@dimen/activity_vertical_margin"
 android:paddingLeft="@dimen/activity_horizontal_margin"
 android:paddingRight="@dimen/activity_horizontal_margin"
 android:paddingTop="@dimen/activity_vertical_margin"
 tools:context="scut.userlogin.RegisterActivity3">

 <scut.userlogin.EditText_PassWordDisplay
 android:layout_width="match_parent"
 android:layout_height="wrap_content"
 android:id="@+id/EditText_PasswordRegisterInput"
 android:inputType="textPassword"
 android:hint="请输入登录密码"
 android:drawableRight="@mipmap/ic_launcher"
 android:layout_marginTop="50dp" />

</RelativeLayout>

 private EditText_PassWordDisplay et_PasswordRegisterInput;
 @Override
 protected void onCreate(Bundle savedInstanceState) {
 super.onCreate(savedInstanceState);
 setContentView(R.layout.activity_register3);
 init();
 }

 private void init(){
 et_PasswordRegisterInput = (EditText_PassWordDisplay) findViewById(R.id.EditText_PasswordRegisterInput);

 }