From 5b2c99d5a650db8392e00a4a56a0b09f4f0e6ffe Mon Sep 17 00:00:00 2001
From: Daniel Schaal <daniel@schaal.email>
Date: Wed, 14 Jul 2021 14:13:44 +0200
Subject: Refactor DividerItemDecoration

---
 .../schaal/ocreader/view/DividerItemDecoration.kt  | 53 +++++++++++-----------
 1 file changed, 26 insertions(+), 27 deletions(-)

diff --git a/app/src/main/java/email/schaal/ocreader/view/DividerItemDecoration.kt b/app/src/main/java/email/schaal/ocreader/view/DividerItemDecoration.kt
index 4a93869b..30547c02 100644
--- a/app/src/main/java/email/schaal/ocreader/view/DividerItemDecoration.kt
+++ b/app/src/main/java/email/schaal/ocreader/view/DividerItemDecoration.kt
@@ -32,9 +32,12 @@ import androidx.recyclerview.widget.RecyclerView.ItemDecoration
 import email.schaal.ocreader.R
 
 class DividerItemDecoration(context: Context, @DimenRes insetRes: Int) : ItemDecoration() {
-    private val mDivider: Drawable?
+    private val mDivider: Drawable? = context.obtainStyledAttributes(intArrayOf(android.R.attr.listDivider)).use {
+            it.getDrawable(0)
+        }
     private val inset: Int = context.resources.getDimensionPixelSize(insetRes)
-    private var size = 0
+    private val size = mDivider?.intrinsicHeight ?: 0
+    private val dividerRect = Rect(0, 0, 0, 0)
 
     override fun getItemOffsets(outRect: Rect, view: View, parent: RecyclerView,
                                 state: RecyclerView.State) {
@@ -45,34 +48,30 @@ class DividerItemDecoration(context: Context, @DimenRes insetRes: Int) : ItemDec
         outRect.top = size
     }
 
-    private val dividerRect = Rect(0, 0, 0, 0)
     override fun onDraw(c: Canvas, parent: RecyclerView, state: RecyclerView.State) {
         if (mDivider == null) return
-        val layoutManager = parent.layoutManager
-        check(!(layoutManager !is LinearLayoutManager ||
-                layoutManager.orientation != RecyclerView.VERTICAL)) { "DividerItemDecoration can only be used with a vertical LinearLayoutManager." }
-        val childCount = parent.childCount
-        val paddingLeft = parent.paddingLeft
-        val paddingLeftInset = paddingLeft + inset
-        dividerRect.right = parent.width - parent.paddingRight
-        loop@ for (i in 0 until childCount) {
-            val child = parent.getChildAt(i)
-            when (layoutManager.getItemViewType(child)) {
-                R.id.viewtype_item -> if (i == childCount - 1 || i == childCount - 2 && layoutManager.getItemViewType(parent.getChildAt(i + 1)) != R.id.viewtype_item) dividerRect.left = paddingLeft else dividerRect.left = paddingLeftInset
-                R.id.viewtype_empty, R.id.viewtype_loadmore -> dividerRect.left = paddingLeft
-                R.id.viewtype_error -> continue@loop
-            }
-            dividerRect.top = child.bottom + (child.layoutParams as RecyclerView.LayoutParams).bottomMargin
-            dividerRect.bottom = dividerRect.top + size
-            mDivider.bounds = dividerRect
-            mDivider.draw(c)
-        }
-    }
 
-    init {
-        mDivider = context.obtainStyledAttributes(intArrayOf(android.R.attr.listDivider)).use {
-            it.getDrawable(0)
+        parent.layoutManager?.let { layoutManager ->
+            val childCount = parent.childCount
+            val paddingLeft = parent.paddingLeft
+            val paddingLeftInset = paddingLeft + inset
+            dividerRect.right = parent.width - parent.paddingRight
+            loop@ for (i in 0 until childCount) {
+                val child = parent.getChildAt(i)
+                when (layoutManager.getItemViewType(child)) {
+                    R.id.viewtype_item -> if (i == childCount - 1 || i == childCount - 2 && layoutManager.getItemViewType(
+                            parent.getChildAt(i + 1)
+                        ) != R.id.viewtype_item
+                    ) dividerRect.left = paddingLeft else dividerRect.left = paddingLeftInset
+                    R.id.viewtype_empty, R.id.viewtype_loadmore -> dividerRect.left = paddingLeft
+                    R.id.viewtype_error -> continue@loop
+                }
+                dividerRect.top =
+                    child.bottom + (child.layoutParams as RecyclerView.LayoutParams).bottomMargin
+                dividerRect.bottom = dividerRect.top + size
+                mDivider.bounds = dividerRect
+                mDivider.draw(c)
+            }
         }
-        if (mDivider != null) size = mDivider.intrinsicHeight
     }
 }
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