Programmatically set Select Handler color of TextView/EditText

textViews.kt

package com.squareup.util.android

import android.graphics.PorterDuff
import android.widget.TextView
import androidx.annotation.ColorInt
import androidx.core.content.ContextCompat
import timber.log.Timber

/**
 * This uses light-graylisted Android APIs.
 * Verified that it works in devices running APIs 21 and 28
 */
fun TextView.setSelectHandleColor(@ColorInt color: Int) {
  try {
    // Retrieve a reference to this text field's android.widget.Editor
    val editor = getEditor()

    handles.forEach {
      // Retrieve the field pointing to the drawable currently being used for the select handle
      val resourceField = TextView::class.java.getDeclaredField(it.resourceFieldName)
      resourceField.isAccessible = true

      // Retrieve the drawable resource from that field
      val drawableId = resourceField.getInt(this)
      val drawable = ContextCompat.getDrawable(context, drawableId)

      // Apply a filter on that drawable with the desired colour
      drawable?.setColorFilter(color, PorterDuff.Mode.SRC_IN)

      // Override the drawable being used by the Editor with our coloured drawable
      val selectHandleField = editor.javaClass.getDeclaredField(it.selectHandleFieldName)
      selectHandleField.isAccessible = true
      selectHandleField.set(editor, drawable)
    }
  } catch (e: Exception) {
    // This would be expectable if, in the future, the fields accessed via reflection go from being
    // light graylisted to dark graylisted or blacklisted.
    // Nothing we can do about it, other than not crash :)
    Timber.w(e) 
  }
}

private class HandleDescriptor(
  val resourceFieldName: String,
  val selectHandleFieldName: String
)

private val handles = arrayOf(
    HandleDescriptor(
        resourceFieldName = "mTextSelectHandleRes",
        selectHandleFieldName = "mSelectHandleCenter"),
    HandleDescriptor(
        resourceFieldName = "mTextSelectHandleLeftRes",
        selectHandleFieldName = "mSelectHandleLeft"),
    HandleDescriptor(
        resourceFieldName = "mTextSelectHandleRightRes",
        selectHandleFieldName = "mSelectHandleRight")
)

private fun TextView.getEditor() : Any {
  val editorField = TextView::class.java.getDeclaredField("mEditor")
  editorField.isAccessible = true
  return editorField.get(this)
}