android/ui: auto-resize tailnet name to fit space

Updates tailscale/corp#18202

Signed-off-by: Percy Wegmann <percy@tailscale.com>

android/src/main/java/com/tailscale/ipn/ui/theme/Theme.kt

@@ -21,6 +21,7 @@ import androidx.compose.runtime.Composable
 import androidx.compose.runtime.DisposableEffect
 import androidx.compose.ui.graphics.Color
 import androidx.compose.ui.text.TextStyle
+import androidx.compose.ui.unit.TextUnit
 import androidx.compose.ui.unit.sp
 import com.google.accompanist.systemuicontroller.rememberSystemUiController
 
@@ -245,3 +246,6 @@ val ColorScheme.searchBarColors: TextFieldColors
 
 val TextStyle.short: TextStyle
   get() = copy(lineHeight = 20.sp)
+
+val Typography.minTextSize: TextUnit
+  get() = 10.sp

android/src/main/java/com/tailscale/ipn/ui/util/AutoResizingText.kt

@@ -0,0 +1,78 @@
+// Copyright (c) Tailscale Inc & AUTHORS
+// SPDX-License-Identifier: BSD-3-Clause
+
+package com.tailscale.ipn.ui.util
+
+import androidx.compose.material3.LocalTextStyle
+import androidx.compose.material3.Text
+import androidx.compose.runtime.Composable
+import androidx.compose.runtime.mutableStateOf
+import androidx.compose.runtime.remember
+import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.drawWithContent
+import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.text.TextLayoutResult
+import androidx.compose.ui.text.TextStyle
+import androidx.compose.ui.text.font.FontFamily
+import androidx.compose.ui.text.font.FontStyle
+import androidx.compose.ui.text.font.FontWeight
+import androidx.compose.ui.text.style.TextAlign
+import androidx.compose.ui.text.style.TextDecoration
+import androidx.compose.ui.text.style.TextOverflow
+import androidx.compose.ui.unit.TextUnit
+
+// AutoResizingText automatically resizes text up to the specified minFontSize in order to avoid
+// overflowing. It is based on https://stackoverflow.com/a/66090448 licensed under CC BY-SA 4.0.
+@Composable
+fun AutoResizingText(
+    text: String,
+    minFontSize: TextUnit,
+    modifier: Modifier = Modifier,
+    color: Color = Color.Unspecified,
+    fontSize: TextUnit = TextUnit.Unspecified,
+    fontStyle: FontStyle? = null,
+    fontWeight: FontWeight? = null,
+    fontFamily: FontFamily? = null,
+    letterSpacing: TextUnit = TextUnit.Unspecified,
+    textDecoration: TextDecoration? = null,
+    textAlign: TextAlign? = null,
+    lineHeight: TextUnit = TextUnit.Unspecified,
+    overflow: TextOverflow = TextOverflow.Clip,
+    maxLines: Int = 1,
+    onTextLayout: ((TextLayoutResult) -> Unit)? = null,
+    style: TextStyle = LocalTextStyle.current
+) {
+  var textStyle = remember { mutableStateOf(style) }
+  var textOverflow = remember { mutableStateOf(TextOverflow.Clip) }
+  var readyToDraw = remember { mutableStateOf(false) }
+
+  Text(
+      text = text,
+      modifier = modifier.drawWithContent { if (readyToDraw.value) drawContent() },
+      color = color,
+      fontSize = fontSize,
+      fontStyle = fontStyle,
+      fontWeight = fontWeight,
+      fontFamily = fontFamily,
+      letterSpacing = letterSpacing,
+      textDecoration = textDecoration,
+      textAlign = textAlign,
+      lineHeight = lineHeight,
+      overflow = textOverflow.value,
+      maxLines = maxLines,
+      softWrap = false,
+      style = textStyle.value,
+      onTextLayout = { result ->
+        if (result.didOverflowWidth) {
+          var newSize = textStyle.value.fontSize * 0.9
+          if (newSize < minFontSize) {
+            newSize = minFontSize
+            textOverflow.value = overflow
+          }
+          textStyle.value = textStyle.value.copy(fontSize = newSize)
+        } else {
+          readyToDraw.value = true
+        }
+        onTextLayout?.let { it(result) }
+      })
+}

android/src/main/java/com/tailscale/ipn/ui/view/MainView.kt

@@ -69,11 +69,13 @@ import com.tailscale.ipn.ui.model.Permissions
 import com.tailscale.ipn.ui.model.Tailcfg
 import com.tailscale.ipn.ui.theme.disabled
 import com.tailscale.ipn.ui.theme.listItem
+import com.tailscale.ipn.ui.theme.minTextSize
 import com.tailscale.ipn.ui.theme.primaryListItem
 import com.tailscale.ipn.ui.theme.searchBarColors
 import com.tailscale.ipn.ui.theme.secondaryButton
 import com.tailscale.ipn.ui.theme.short
 import com.tailscale.ipn.ui.theme.surfaceContainerListItem
+import com.tailscale.ipn.ui.util.AutoResizingText
 import com.tailscale.ipn.ui.util.Lists
 import com.tailscale.ipn.ui.util.LoadingIndicator
 import com.tailscale.ipn.ui.util.PeerSet
@@ -112,11 +114,11 @@ fun MainView(navigation: MainViewNavigation, viewModel: MainViewModel = viewMode
                 },
                 headlineContent = {
                   user?.NetworkProfile?.DomainName?.let { domain ->
-                    Text(
+                    AutoResizingText(
                         text = domain,
-                        maxLines = 1,
+                        style = MaterialTheme.typography.titleMedium.short,
-                        overflow = TextOverflow.Ellipsis,
+                        minFontSize = MaterialTheme.typography.minTextSize,
-                        style = MaterialTheme.typography.titleMedium.short)
+                        overflow = TextOverflow.Ellipsis)
                   }
                 },
                 supportingContent = {

android/src/main/java/com/tailscale/ipn/ui/view/UserView.kt

@@ -11,9 +11,12 @@ import androidx.compose.material3.Text
 import androidx.compose.runtime.Composable
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.res.stringResource
+import androidx.compose.ui.text.style.TextOverflow
 import com.tailscale.ipn.R
 import com.tailscale.ipn.ui.model.IpnLocal
+import com.tailscale.ipn.ui.theme.minTextSize
 import com.tailscale.ipn.ui.theme.short
+import com.tailscale.ipn.ui.util.AutoResizingText
 
 // Used to decorate UserViews.
 // NONE indicates no decoration
@@ -39,14 +42,18 @@ fun UserView(
           modifier = Modifier.clickable { onClick() },
           leadingContent = { Avatar(profile = profile, size = 36) },
           headlineContent = {
-            Text(
+            AutoResizingText(
                 text = profile.UserProfile.DisplayName,
-                style = MaterialTheme.typography.titleMedium.short)
+                style = MaterialTheme.typography.titleMedium.short,
+                minFontSize = MaterialTheme.typography.minTextSize,
+                overflow = TextOverflow.Ellipsis)
           },
           supportingContent = {
-            Text(
+            AutoResizingText(
                 text = profile.NetworkProfile?.DomainName ?: "",
-                style = MaterialTheme.typography.bodyMedium.short)
+                style = MaterialTheme.typography.bodyMedium.short,
+                minFontSize = MaterialTheme.typography.minTextSize,
+                overflow = TextOverflow.Ellipsis)
           },
           trailingContent = {
             when (actionState) {