From be19d0a9cf3cc74a6ba057ba199fa0c6a95d4223 Mon Sep 17 00:00:00 2001
From: maxmoney21m <maxmoney@nostrplebs.com>
Date: Fri, 10 Mar 2023 10:55:59 +0800
Subject: [PATCH] Add persistent lazy list state composable

---
 .../amethyst/ui/screen/LazyListState.kt       | 34 +++++++++++++++++++
 1 file changed, 34 insertions(+)
 create mode 100644 app/src/main/java/com/vitorpamplona/amethyst/ui/screen/LazyListState.kt

diff --git a/app/src/main/java/com/vitorpamplona/amethyst/ui/screen/LazyListState.kt b/app/src/main/java/com/vitorpamplona/amethyst/ui/screen/LazyListState.kt
new file mode 100644
index 000000000..e6eb0c39e
--- /dev/null
+++ b/app/src/main/java/com/vitorpamplona/amethyst/ui/screen/LazyListState.kt
@@ -0,0 +1,34 @@
+package com.vitorpamplona.amethyst.ui.screen
+
+import androidx.compose.foundation.lazy.LazyListState
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.DisposableEffect
+import androidx.compose.runtime.saveable.rememberSaveable
+
+private val savedScrollStates = mutableMapOf<String, ScrollState>()
+private data class ScrollState(val index: Int, val scrollOffset: Int)
+
+@Composable
+fun rememberForeverLazyListState(
+    key: String,
+    initialFirstVisibleItemIndex: Int = 0,
+    initialFirstVisibleItemScrollOffset: Int = 0
+): LazyListState {
+    val scrollState = rememberSaveable(saver = LazyListState.Saver) {
+        val savedValue = savedScrollStates[key]
+        val savedIndex = savedValue?.index ?: initialFirstVisibleItemIndex
+        val savedOffset = savedValue?.scrollOffset ?: initialFirstVisibleItemScrollOffset
+        LazyListState(
+            savedIndex,
+            savedOffset
+        )
+    }
+    DisposableEffect(Unit) {
+        onDispose {
+            val lastIndex = scrollState.firstVisibleItemIndex
+            val lastOffset = scrollState.firstVisibleItemScrollOffset
+            savedScrollStates[key] = ScrollState(lastIndex, lastOffset)
+        }
+    }
+    return scrollState
+}