fix(note-editor): restore instance state

Now Note Editor is a fragment, it no longer receives
`android:viewHierarchyState`. This is now handled by the Activity

But, we did not need to handle this manually.
Recreating the fields, with the same `id` value restores the text

----

This fix does not handle the loss of focus for dynamic elements

During testing, this lack of focus coming back from 'Drawing'
was jarring. In Production this will have minimal impact
as the user will have lost context by the time the activity is
restored (a user will not have 'Don't keep activities' on).

Fixes 17521

AnkiDroid/src/main/java/com/ichi2/anki/noteeditor/FieldState.kt

@@ -19,7 +19,6 @@ package com.ichi2.anki.noteeditor
 import android.content.Context
 import android.os.Bundle
 import android.view.View
-import androidx.core.os.BundleCompat
 import com.ichi2.anki.FieldEditLine
 import com.ichi2.anki.NoteEditor
 import com.ichi2.anki.R
@@ -37,19 +36,20 @@ import kotlin.math.min
 class FieldState private constructor(
     private val editor: NoteEditor,
 ) {
-    private var savedFieldData: List<View.BaseSavedState>? = null
+    private var customViewIds: List<Int>? = null
 
     fun loadFieldEditLines(type: FieldChangeType): List<FieldEditLine> {
-        val fieldEditLines: List<FieldEditLine>
-        if (type.type == Type.INIT && savedFieldData != null) {
-            fieldEditLines = recreateFieldsFromState()
-            savedFieldData = null
-        } else {
-            fieldEditLines = createFields(type)
-        }
-        for (l in fieldEditLines) {
-            l.id = View.generateViewId()
-        }
+        val fieldEditLines: List<FieldEditLine> =
+            if (type.type == Type.INIT && customViewIds != null) {
+                recreateFields(customViewIds!!)
+            } else {
+                createFields(type).also { fields ->
+                    for (field in fields) {
+                        field.id = View.generateViewId()
+                    }
+                }
+            }
+
         if (type.type == Type.CLEAR_KEEP_STICKY) {
             // we use the UI values here as the model will post-processing steps (newline -> br).
             val currentFieldStrings = editor.currentFieldStrings
@@ -69,18 +69,12 @@ class FieldState private constructor(
         return fieldEditLines
     }
 
-    private fun recreateFieldsFromState(): List<FieldEditLine> {
-        val editLines: MutableList<FieldEditLine> = ArrayList(savedFieldData!!.size)
-        for (state in savedFieldData!!) {
-            val editLineView = FieldEditLine(editor.requireContext())
-            if (editLineView.id == 0) {
-                editLineView.id = View.generateViewId()
-            }
-            editLineView.loadState(state)
-            editLines.add(editLineView)
-        }
-        return editLines
-    }
+    /**
+     * Given a list of [viewIds]: create the fields, assign the IDs and let Android
+     * restore the state via [FieldEditLine.onRestoreInstanceState]
+     */
+    private fun recreateFields(viewIds: List<Int>): List<FieldEditLine> =
+        viewIds.map { id -> FieldEditLine(editor.requireContext()).also { field -> field.id = id } }
 
     private fun createFields(type: FieldChangeType): List<FieldEditLine> {
         val fields = getFields(type)
@@ -105,28 +99,7 @@ class FieldState private constructor(
     }
 
     fun setInstanceState(savedInstanceState: Bundle?) {
-        if (savedInstanceState == null) {
-            return
-        }
-        if (!savedInstanceState.containsKey("customViewIds") || !savedInstanceState.containsKey("android:viewHierarchyState")) {
-            return
-        }
-        val customViewIds = savedInstanceState.getIntegerArrayList("customViewIds")
-        val viewHierarchyState = savedInstanceState.getBundle("android:viewHierarchyState")
-        if (customViewIds == null || viewHierarchyState == null) {
-            return
-        }
-        val views =
-            BundleCompat.getSparseParcelableArray(
-                viewHierarchyState,
-                "android:views",
-                View.BaseSavedState::class.java,
-            ) ?: return
-        val important: MutableList<View.BaseSavedState> = ArrayList(customViewIds.size)
-        for (i in customViewIds) {
-            important.add(views[i!!] as View.BaseSavedState)
-        }
-        savedFieldData = important
+        customViewIds = savedInstanceState?.getIntegerArrayList("customViewIds")
     }
 
     /** How fields should be changed when the UI is rebuilt  */