android: Button to jump to bottom of log view

This adds a button that can jump to the bottom of the log view.
If the user scrolls up we now disable the auto scroll down and show the
down button. When the down button is clicked the auto scroll resumes and
the button is removed.

android/app/src/main/java/org/musicpd/ui/LogScreen.kt

@@ -1,36 +1,79 @@
 package org.musicpd.ui
 
-import androidx.compose.foundation.layout.Column
+import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.items
 import androidx.compose.foundation.lazy.rememberLazyListState
+import androidx.compose.material.icons.Icons
+import androidx.compose.material.icons.filled.VerticalAlignBottom
+import androidx.compose.material3.FloatingActionButton
+import androidx.compose.material3.Icon
 import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
-import androidx.compose.runtime.State
+import androidx.compose.runtime.LaunchedEffect
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.runtime.snapshotFlow
+import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.text.font.FontFamily
+import androidx.compose.ui.tooling.preview.Preview
 import androidx.compose.ui.unit.dp
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.Dispatchers
 import kotlinx.coroutines.launch
 
 @Composable
-fun LogView(messages: State<List<String>>) {
+fun LogView(messages: List<String>) {
-    val state = rememberLazyListState()
+    val lazyListState = rememberLazyListState()
 
-    Column(Modifier.fillMaxSize()) {
+    var userScrolled = remember { mutableStateOf(false) }
+
+    LaunchedEffect(lazyListState) {
+        snapshotFlow { lazyListState.isScrollInProgress }
+            .collect {
+                if (it) {
+                    userScrolled.value = true
+                }
+            }
+    }
+
+    Box(Modifier.fillMaxSize()) {
         LazyColumn(
             Modifier.padding(4.dp),
-            state
+            lazyListState
         ) {
-            items(messages.value) { message ->
+            items(messages) { message ->
                 Text(text = message, fontFamily = FontFamily.Monospace)
             }
             CoroutineScope(Dispatchers.Main).launch {
-                state.scrollToItem(messages.value.count(), 0)
+                lazyListState.scrollToItem(messages.count(), 0)
+            }
+        }
+
+        if (lazyListState.canScrollForward) {
+            FloatingActionButton(
+                onClick = {
+                    userScrolled.value = false
+                    CoroutineScope(Dispatchers.Main).launch {
+                        lazyListState.scrollToItem(messages.count(), 0)
+                    }
+                },
+                modifier = Modifier.padding(16.dp).align(Alignment.BottomEnd)
+            ) {
+                Icon(Icons.Filled.VerticalAlignBottom, "Scroll to bottom icon")
             }
         }
     }
-}
+}
+
+@Preview
+@Composable
+fun LogViewPreview() {
+    val data = listOf("test",
+        "test2",
+        "test3")
+    LogView(data)
+}

android/app/src/main/java/org/musicpd/ui/MainScreen.kt

@@ -69,7 +69,7 @@ fun MPDApp(
                 StatusScreen(settingsViewModel)
             }
             composable(NavigationItem.Logs.route) {
-                LogView(settingsViewModel.getLogs().collectAsStateWithLifecycle())
+                LogView(settingsViewModel.getLogs().collectAsStateWithLifecycle().value)
             }
             composable(NavigationItem.Settings.route) {
                 MPDSettings(settingsViewModel)