From fe8301830ebc9680b79298ad5d57a3c417f450c2 Mon Sep 17 00:00:00 2001
From: Esmaeel Moustafa <esmaeel.moustafa@thermondo.de>
Date: Fri, 5 Jul 2024 09:26:35 +0200
Subject: [PATCH] scrolls to the top of the screen

Fixes scroll to the top by

- using the device actual screen height instead of a hardcoded value
---
 .../zeapp/zeui/LazyListScrollDirections.kt    |  5 ++++
 .../zeapp/zeui/ZeFloatingScroller.kt          | 16 +++++++++---
 .../berlindroid/zeapp/zeui/ZeNavigationPad.kt | 25 ++++++++++---------
 3 files changed, 30 insertions(+), 16 deletions(-)
 create mode 100644 zeapp/android/src/main/java/de/berlindroid/zeapp/zeui/LazyListScrollDirections.kt

diff --git a/zeapp/android/src/main/java/de/berlindroid/zeapp/zeui/LazyListScrollDirections.kt b/zeapp/android/src/main/java/de/berlindroid/zeapp/zeui/LazyListScrollDirections.kt
new file mode 100644
index 00000000..f9c61c43
--- /dev/null
+++ b/zeapp/android/src/main/java/de/berlindroid/zeapp/zeui/LazyListScrollDirections.kt
@@ -0,0 +1,5 @@
+package de.berlindroid.zeapp.zeui
+
+enum class LazyListScrollDirections {
+    UP, DOWN
+}
diff --git a/zeapp/android/src/main/java/de/berlindroid/zeapp/zeui/ZeFloatingScroller.kt b/zeapp/android/src/main/java/de/berlindroid/zeapp/zeui/ZeFloatingScroller.kt
index 25df397f..328c892f 100644
--- a/zeapp/android/src/main/java/de/berlindroid/zeapp/zeui/ZeFloatingScroller.kt
+++ b/zeapp/android/src/main/java/de/berlindroid/zeapp/zeui/ZeFloatingScroller.kt
@@ -1,7 +1,6 @@
 package de.berlindroid.zeapp.zeui
 
 import androidx.compose.foundation.border
-import androidx.compose.foundation.gestures.animateScrollBy
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.lazy.LazyListState
 import androidx.compose.foundation.shape.RoundedCornerShape
@@ -21,9 +20,13 @@ import androidx.compose.material3.Text as ZeText
 fun ZeFloatingScroller(
     coroutineScope: CoroutineScope,
     lazyListState: LazyListState,
-    scrollLength: Float,
-    text: String,
+    direction: LazyListScrollDirections,
 ) {
+    val text = when (direction) {
+        LazyListScrollDirections.UP -> "↑"
+        LazyListScrollDirections.DOWN -> "↓"
+    }
+
     FloatingActionButton(
         containerColor = ZeBlack,
         modifier = Modifier
@@ -35,7 +38,12 @@ fun ZeFloatingScroller(
             ),
         onClick = {
             coroutineScope.launch {
-                lazyListState.animateScrollBy(scrollLength)
+                when (direction) {
+                    LazyListScrollDirections.UP -> lazyListState.animateScrollToItem(0)
+                    LazyListScrollDirections.DOWN -> lazyListState.animateScrollToItem(
+                        lazyListState.layoutInfo.totalItemsCount - 1,
+                    )
+                }
             }
         },
     ) {
diff --git a/zeapp/android/src/main/java/de/berlindroid/zeapp/zeui/ZeNavigationPad.kt b/zeapp/android/src/main/java/de/berlindroid/zeapp/zeui/ZeNavigationPad.kt
index 7dc8a6a2..3f1b0703 100644
--- a/zeapp/android/src/main/java/de/berlindroid/zeapp/zeui/ZeNavigationPad.kt
+++ b/zeapp/android/src/main/java/de/berlindroid/zeapp/zeui/ZeNavigationPad.kt
@@ -20,12 +20,10 @@ fun ZeNavigationPad(
     lazyListState: LazyListState,
 ) {
     val coroutineScope = rememberCoroutineScope()
-    val scrollLength = 425f
-    val topReached by remember { derivedStateOf { lazyListState.layoutInfo.visibleItemsInfo.firstOrNull()?.offset == 0 } }
-    val bottomReached by remember {
+
+    val topReached by remember {
         derivedStateOf {
-            lazyListState.layoutInfo.visibleItemsInfo
-                .lastOrNull()?.index == lazyListState.layoutInfo.totalItemsCount - 1
+            lazyListState.firstVisibleItemIndex == 0 && lazyListState.firstVisibleItemScrollOffset == 0
         }
     }
 
@@ -35,12 +33,15 @@ fun ZeNavigationPad(
             .padding(24.dp),
         horizontalAlignment = Alignment.End,
     ) {
-        if (!topReached) {
-            ZeFloatingScroller(coroutineScope, lazyListState, -scrollLength, "↑")
-        }
-        Spacer(modifier = Modifier.size(10.dp))
-        if (!bottomReached) {
-            ZeFloatingScroller(coroutineScope, lazyListState, scrollLength, "↓")
-        }
+        ZeFloatingScroller(
+            coroutineScope = coroutineScope,
+            lazyListState = lazyListState,
+            direction = if (topReached) {
+                LazyListScrollDirections.DOWN
+            } else {
+                LazyListScrollDirections.UP
+            },
+        )
+        Spacer(modifier = Modifier.size(16.dp))
     }
 }