feat(ui): smooth screen transitions and list entrances

app/src/main/java/com/example/research/ui/about/AboutScreen.kt

@@ -1,19 +1,25 @@
 package com.example.research.ui.about
 
 import androidx.compose.animation.animateColorAsState
+import androidx.compose.animation.core.animateFloatAsState
+import androidx.compose.animation.core.tween
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.ExperimentalLayoutApi
 import androidx.compose.foundation.layout.FlowRow
 import androidx.compose.foundation.layout.Row
+import androidx.compose.foundation.layout.Spacer
 import androidx.compose.foundation.layout.fillMaxSize
 import androidx.compose.foundation.layout.fillMaxWidth
+import androidx.compose.foundation.layout.height
+import androidx.compose.foundation.layout.heightIn
 import androidx.compose.foundation.layout.padding
 import androidx.compose.foundation.lazy.LazyColumn
 import androidx.compose.foundation.lazy.items
 import androidx.compose.foundation.rememberScrollState
 import androidx.compose.foundation.verticalScroll
-import androidx.compose.material3.AlertDialog
+import androidx.compose.material3.AlertDialogDefaults
+import androidx.compose.material3.BasicAlertDialog
 import androidx.compose.material3.ExperimentalMaterial3Api
 import androidx.compose.material3.Icon
 import androidx.compose.material3.IconButton
@@ -25,13 +31,17 @@ import androidx.compose.material3.TextButton
 import androidx.compose.material3.TopAppBar
 import androidx.compose.material3.TopAppBarDefaults
 import androidx.compose.runtime.Composable
+import androidx.compose.runtime.LaunchedEffect
 import androidx.compose.runtime.getValue
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.produceState
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.setValue
+import androidx.compose.runtime.snapshotFlow
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.graphics.graphicsLayer
+import androidx.compose.ui.platform.LocalConfiguration
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.platform.LocalUriHandler
 import androidx.compose.ui.platform.testTag
@@ -45,6 +55,7 @@ import com.example.research.R
 import com.example.research.common.ui.components.OutlinedChoiceButton
 import com.example.research.ui.theme.AppWindowInsets
 import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.withContext
 
 @OptIn(ExperimentalMaterial3Api::class, ExperimentalLayoutApi::class)
@@ -112,6 +123,7 @@ fun AboutScreen(
                 contentType = { "about_library" },
             ) { library ->
                 AboutLibraryRow(
+                    modifier = Modifier.animateItem(fadeInSpec = tween(150)),
                     library = library,
                     licenses = librariesData?.licenses.orEmpty(),
                     expanded = expandedLibraryId == library.uniqueId,
@@ -176,6 +188,7 @@ private fun AboutHeader(versionName: String) {
 @OptIn(ExperimentalLayoutApi::class)
 @Composable
 private fun AboutLibraryRow(
+    modifier: Modifier = Modifier,
     library: AboutLibrary,
     licenses: Map<String, AboutLicense>,
     expanded: Boolean,
@@ -196,7 +209,7 @@ private fun AboutLibraryRow(
     )
 
     Surface(
-        modifier = Modifier
+        modifier = modifier
             .fillMaxWidth()
             .testTag("about_library_row")
             .semantics { testTagsAsResourceId = true },
@@ -301,32 +314,79 @@ private fun AboutLibraryRow(
     }
 }
 
+@OptIn(ExperimentalMaterial3Api::class)
 @Composable
 private fun LicenseDialog(
     license: AboutLicense,
     onDismiss: () -> Unit,
     onOpenWebsite: (String) -> Unit,
 ) {
-    AlertDialog(
-        onDismissRequest = onDismiss,
-        title = { Text(license.name) },
-        text = {
+    var open by remember { mutableStateOf(false) }
+    var wasOpen by remember { mutableStateOf(false) }
+    LaunchedEffect(Unit) { open = true }
+    val scale by animateFloatAsState(
+        targetValue = if (open) 1f else 0.92f,
+        animationSpec = tween(180),
+        label = "licenseDialogScale",
+    )
+    val alpha by animateFloatAsState(
+        targetValue = if (open) 1f else 0f,
+        animationSpec = tween(180),
+        label = "licenseDialogAlpha",
+    )
+    LaunchedEffect(open) {
+        if (open) {
+            wasOpen = true
+        } else if (wasOpen) {
+            snapshotFlow { alpha }.first { it == 0f }
+            onDismiss()
+        }
+    }
+
+    BasicAlertDialog(
+        onDismissRequest = { open = false },
+        modifier = Modifier.graphicsLayer {
+            scaleX = scale
+            scaleY = scale
+            this.alpha = alpha
+        }
+    ) {
+        val maxHeight = LocalConfiguration.current.screenHeightDp.dp - 96.dp
+        Surface(
+            shape = AlertDialogDefaults.shape,
+            color = AlertDialogDefaults.containerColor,
+            tonalElevation = AlertDialogDefaults.TonalElevation,
+        ) {
+            Column(modifier = Modifier.padding(24.dp).heightIn(max = maxHeight)) {
+                Text(
+                    text = license.name,
+                    style = MaterialTheme.typography.headlineSmall,
+                    color = MaterialTheme.colorScheme.onSurface
+                )
+                Spacer(modifier = Modifier.height(16.dp))
                 Text(
                     text = license.content ?: stringResource(R.string.license_text_unavailable),
-                modifier = Modifier.verticalScroll(rememberScrollState())
+                    style = MaterialTheme.typography.bodyMedium,
+                    color = MaterialTheme.colorScheme.onSurfaceVariant,
+                    modifier = Modifier
+                        .weight(1f, fill = false)
+                        .verticalScroll(rememberScrollState())
                 )
-        },
-        confirmButton = {
-            TextButton(onClick = onDismiss) {
-                Text(stringResource(R.string.action_close))
-            }
-        },
-        dismissButton = {
+                Spacer(modifier = Modifier.height(24.dp))
+                Row(
+                    modifier = Modifier.fillMaxWidth(),
+                    horizontalArrangement = Arrangement.spacedBy(8.dp, Alignment.End)
+                ) {
                     license.url?.takeIf(String::isNotBlank)?.let { url ->
                         TextButton(onClick = { onOpenWebsite(url) }) {
                             Text(stringResource(R.string.website))
                         }
                     }
+                    TextButton(onClick = { open = false }) {
+                        Text(stringResource(R.string.action_close))
+                    }
+                }
+            }
+        }
     }
-    )
 }

app/src/main/java/com/example/research/ui/main/components/SearchResultsList.kt

@@ -1,5 +1,6 @@
 package com.example.research.ui.main.components
 
+import androidx.compose.animation.core.tween
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.*
 import androidx.compose.foundation.lazy.*
@@ -45,6 +46,13 @@ fun SearchResultsList(
             contentType = results.itemContentType { "search_result" }
         ) { index ->
             results[index]?.let { entry ->
+                Box(
+                    modifier = Modifier.animateItem(
+                        fadeInSpec = if (index < 8) tween(150) else null,
+                        placementSpec = null,
+                        fadeOutSpec = null
+                    )
+                ) {
                     SearchResultItem(
                         entry = entry,
                         resultIndex = index,
@@ -53,6 +61,7 @@ fun SearchResultsList(
                     )
                 }
             }
+        }
 
         when (results.loadState.append) {
             is LoadState.Error -> {

app/src/main/java/com/example/research/ui/navigation/AppNavigation.kt

@@ -1,6 +1,13 @@
 package com.example.research.ui.navigation
 
 import androidx.activity.compose.BackHandler
+import androidx.compose.animation.AnimatedContent
+import androidx.compose.animation.fadeIn
+import androidx.compose.animation.fadeOut
+import androidx.compose.animation.slideInHorizontally
+import androidx.compose.animation.slideOutHorizontally
+import androidx.compose.animation.togetherWith
+import androidx.compose.animation.core.tween
 import androidx.compose.material3.adaptive.ExperimentalMaterial3AdaptiveApi
 import androidx.compose.material3.adaptive.currentWindowAdaptiveInfoV2
 import androidx.compose.runtime.*
@@ -92,7 +99,21 @@ fun AppNavigation(
         shouldShowSettings -> Screen.Settings
         else -> currentScreen
     }
-    when (effectiveScreen) {
+    AnimatedContent(
+        targetState = effectiveScreen,
+        transitionSpec = {
+            val forward = initialState.ordinal < targetState.ordinal
+            (
+                fadeIn(tween(180)) +
+                    slideInHorizontally(tween(180)) { if (forward) it / 3 else -it / 3 }
+                ).togetherWith(
+                fadeOut(tween(180)) +
+                    slideOutHorizontally(tween(180)) { if (forward) -it / 3 else it / 3 }
+            )
+        },
+        label = "screenTransition",
+    ) { screen ->
+        when (screen) {
         Screen.Home -> {
             MainRoute(
                 searchViewModel = searchViewModel,
@@ -143,4 +164,5 @@ fun AppNavigation(
             )
         }
         }
+    }
 }

app/src/main/java/com/example/research/ui/settings/SettingsScreen.kt

@@ -3,6 +3,11 @@ package com.example.research.ui.settings
 import android.net.Uri
 import androidx.activity.compose.rememberLauncherForActivityResult
 import androidx.activity.result.contract.ActivityResultContracts
+import androidx.compose.animation.AnimatedVisibility
+import androidx.compose.animation.expandVertically
+import androidx.compose.animation.fadeIn
+import androidx.compose.animation.fadeOut
+import androidx.compose.animation.shrinkVertically
 import androidx.compose.foundation.clickable
 import androidx.compose.foundation.layout.Arrangement
 import androidx.compose.foundation.layout.Column
@@ -266,7 +271,11 @@ private fun CollapsibleSettingsSection(
                 testTag = testTag
             )
 
-            if (isExpanded) {
+            AnimatedVisibility(
+                visible = isExpanded,
+                enter = expandVertically() + fadeIn(),
+                exit = shrinkVertically() + fadeOut(),
+            ) {
                 Column(
                     modifier = Modifier
                         .fillMaxWidth()

app/src/main/java/com/example/research/ui/settings/components/DictionaryManagement.kt

@@ -1,6 +1,9 @@
 package com.example.research.ui.settings.components
 
+import androidx.compose.animation.core.animateFloatAsState
+import androidx.compose.animation.core.tween
 import androidx.compose.foundation.layout.Arrangement
+import androidx.compose.foundation.layout.Box
 import androidx.compose.foundation.layout.Column
 import androidx.compose.foundation.layout.fillMaxWidth
 import androidx.compose.foundation.layout.padding
@@ -15,8 +18,10 @@ import androidx.compose.runtime.key
 import androidx.compose.runtime.mutableStateOf
 import androidx.compose.runtime.remember
 import androidx.compose.runtime.rememberUpdatedState
+import androidx.compose.runtime.setValue
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
+import androidx.compose.ui.draw.alpha
 import androidx.compose.ui.hapticfeedback.HapticFeedbackType
 import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.platform.LocalFocusManager
@@ -260,12 +265,27 @@ private fun DictionaryListSection(
     modifier: Modifier = Modifier,
     isDeleteBlocked: () -> Boolean = { false }
 ) {
+    var appearedPaths by remember { mutableStateOf(emptySet<String>()) }
+    LaunchedEffect(dictionaries) {
+        val visiblePaths = dictionaries.mapTo(mutableSetOf(), Dictionary::path)
+        appearedPaths = appearedPaths intersect visiblePaths
+    }
     Column(
         modifier = modifier,
         verticalArrangement = Arrangement.spacedBy(4.dp)
     ) {
         dictionaries.forEach { dictionary ->
             key(dictionary.path) {
+                val hasAppeared = dictionary.path in appearedPaths
+                val rowAlpha by animateFloatAsState(
+                    targetValue = if (hasAppeared) 1f else 0f,
+                    animationSpec = tween(150),
+                    label = "dictionaryRowAppear",
+                )
+                LaunchedEffect(dictionary.path) {
+                    appearedPaths = appearedPaths + dictionary.path
+                }
+                Box(modifier = Modifier.alpha(rowAlpha)) {
                     DictionaryListItem(
                         dictionary = dictionary,
                         onToggle = { onToggleDictionary(dictionary.path) },
@@ -275,4 +295,5 @@ private fun DictionaryListSection(
                 }
             }
         }
+    }
 }