toggle undo/redo menu button visibility as required

Author: tibbi

app/src/main/kotlin/com/simplemobiletools/notes/activities/MainActivity.kt

@@ -46,6 +46,8 @@ class MainActivity : SimpleActivity(), ViewPager.OnPageChangeListener {
     private var wasInit = false
     private var storedEnableLineWrap = true
     private var showSaveButton = false
+    private var showUndoButton = false
+    private var showRedoButton = false
     private var saveNoteButton: MenuItem? = null
 
     override fun onCreate(savedInstanceState: Bundle?) {
@@ -105,6 +107,11 @@ class MainActivity : SimpleActivity(), ViewPager.OnPageChangeListener {
 
     override fun onCreateOptionsMenu(menu: Menu): Boolean {
         menuInflater.inflate(R.menu.menu, menu)
+        menu.apply {
+            findItem(R.id.undo).isVisible = showUndoButton
+            findItem(R.id.redo).isVisible = showRedoButton
+        }
+
         return true
     }
 
@@ -573,13 +580,28 @@ class MainActivity : SimpleActivity(), ViewPager.OnPageChangeListener {
         config.currentNoteId = mCurrentNote.id
     }
 
-    fun currentNoteTextChanged(newText: String) {
+    fun currentNoteTextChanged(newText: String, showUndo: Boolean, showRedo: Boolean) {
+        var shouldRecreateMenu = false
+        if (showUndo != showUndoButton) {
+            showUndoButton = showUndo
+            shouldRecreateMenu = true
+        }
+
+        if (showRedo != showRedoButton) {
+            showRedoButton = showRedo
+            shouldRecreateMenu = true
+        }
+
         if (!config.autosaveNotes) {
             showSaveButton = newText != mCurrentNote.value
             if (showSaveButton != saveNoteButton?.isVisible) {
-                invalidateOptionsMenu()
+                shouldRecreateMenu = true
             }
         }
+
+        if (shouldRecreateMenu) {
+            invalidateOptionsMenu()
+        }
     }
 
     private fun checkWhatsNewDialog() {

app/src/main/kotlin/com/simplemobiletools/notes/fragments/NoteFragment.kt

@@ -1,5 +1,6 @@
 package com.simplemobiletools.notes.fragments
 
+import android.annotation.SuppressLint
 import android.graphics.Typeface
 import android.os.Bundle
 import android.support.v4.app.Fragment
@@ -115,7 +116,7 @@ class NoteFragment : Fragment() {
         if (menuVisible && noteId != 0) {
             val currentText = getCurrentNoteViewText()
             if (currentText != null) {
-                (activity as MainActivity).currentNoteTextChanged(currentText)
+                (activity as MainActivity).currentNoteTextChanged(currentText, isUndoAvailable(), isRedoAvailable())
             }
         }
     }
@@ -158,6 +159,7 @@ class NoteFragment : Fragment() {
 
     fun getCurrentNoteViewText() = view.notes_view?.text?.toString()
 
+    @SuppressLint("RtlHardcoded")
     private fun getTextGravity() = when (context!!.config.gravity) {
         GRAVITY_CENTER -> Gravity.CENTER_HORIZONTAL
         GRAVITY_RIGHT -> Gravity.RIGHT
@@ -237,7 +239,7 @@ class NoteFragment : Fragment() {
         override fun afterTextChanged(editable: Editable) {
             val text = editable.toString()
             setWordCounter(text)
-            (activity as MainActivity).currentNoteTextChanged(text)
+            (activity as MainActivity).currentNoteTextChanged(text, isUndoAvailable(), isRedoAvailable())
         }
     }
 }