diff --git a/app/src/main/java/com/example/login_v3/data/local/UserPreferences/UserPreferences_Repository.kt b/app/src/main/java/com/example/login_v3/data/local/UserPreferences/UserPreferences_Repository.kt
index da1e1f1..3507c9a 100644
--- a/app/src/main/java/com/example/login_v3/data/local/UserPreferences/UserPreferences_Repository.kt
+++ b/app/src/main/java/com/example/login_v3/data/local/UserPreferences/UserPreferences_Repository.kt
@@ -1,5 +1,7 @@
 package com.example.login_v3.data.local.UserPreferences
 
+import android.content.Context
+import android.net.Uri
 import androidx.datastore.core.DataStore
 import androidx.datastore.preferences.core.Preferences // 確保是這個 Preferences
 import androidx.datastore.preferences.core.edit
@@ -8,6 +10,8 @@ import androidx.datastore.preferences.core.stringPreferencesKey
 import kotlinx.coroutines.flow.Flow
 import kotlinx.coroutines.flow.catch
 import kotlinx.coroutines.flow.map
+import java.io.File
+import java.io.FileOutputStream
 import java.io.IOException
 
 
@@ -15,6 +19,8 @@ class UserPreferencesRepository(private val dataStore: DataStore<Preferences>) {
 
     private object PreferencesKeys {
         val THEME_MODE = stringPreferencesKey("theme_mode")
+        // 新增：儲存自訂壁紙檔案路徑的 Key
+        val CUSTOM_WALLPAPER_PATH = stringPreferencesKey("custom_wallpaper_path")
     }
 
     // 讀取設定：直接在宣告時賦值，簡潔又安全
@@ -30,9 +36,74 @@ class UserPreferencesRepository(private val dataStore: DataStore<Preferences>) {
             preferences[PreferencesKeys.THEME_MODE] ?: "system"
         }
 
+    // 2. 新增：讀取自訂壁紙路徑（預設為 null，代表使用系統預設背景）
+    val wallpaperPathFlow: Flow<String?> = dataStore.data
+        .catch { exception ->
+            if (exception is IOException) {
+                emit(emptyPreferences())
+            } else {
+                throw exception
+            }
+        }
+        .map { preferences ->
+            preferences[PreferencesKeys.CUSTOM_WALLPAPER_PATH]
+        }
+
     suspend fun saveThemeMode(mode: String) {
         dataStore.edit { preferences ->
             preferences[PreferencesKeys.THEME_MODE] = mode
         }
     }
+
+
+    /**
+     * 4. 新增：將用戶選擇的圖片複製到內部存儲，並將路徑存入 DataStore
+     * @param context 用於獲取 filesDir 與 contentResolver
+     * @param uri 用戶從相簿選擇的圖片 Uri
+     * @return 儲存成功返回 true，失敗返回 false
+     */
+    suspend fun saveWallpaper(context: Context, uri: Uri): Boolean {
+        return try {
+            // 將圖片固定命名為 "custom_wallpaper.jpg"，這樣每次上傳新圖片會自動覆蓋舊圖
+            val fileName = "custom_wallpaper.jpg"
+            val targetFile = File(context.filesDir, fileName)
+
+            // 開啟輸入流並複製到 App 的私有目錄下
+            context.contentResolver.openInputStream(uri)?.use { inputStream ->
+                FileOutputStream(targetFile).use { outputStream ->
+                    inputStream.copyTo(outputStream)
+                }
+            }
+
+            // 將檔案的絕對路徑存入 DataStore 記錄起來
+            dataStore.edit { preferences ->
+                preferences[PreferencesKeys.CUSTOM_WALLPAPER_PATH] = targetFile.absolutePath
+            }
+            true
+        } catch (e: Exception) {
+            e.printStackTrace()
+            false
+        }
+    }
+
+    /**
+     * 5. 新增：清除自訂壁紙設定，並刪除手機內的實體檔案（省空間）
+     */
+    suspend fun clearWallpaper(context: Context) {
+        try {
+            // 1. 刪除實體檔案
+            val fileName = "custom_wallpaper.jpg"
+            val targetFile = File(context.filesDir, fileName)
+            if (targetFile.exists()) {
+                targetFile.delete()
+            }
+        } catch (e: Exception) {
+            e.printStackTrace()
+        } finally {
+            // 2. 無論檔案刪除成功與否，都清除 DataStore 內的紀錄
+            dataStore.edit { preferences ->
+                preferences.remove(PreferencesKeys.CUSTOM_WALLPAPER_PATH)
+            }
+        }
+    }
 }
\ No newline at end of file
diff --git a/app/src/main/java/com/example/login_v3/home/setting/setting_detail_page/detail_UI/setting_Theme_Page.kt b/app/src/main/java/com/example/login_v3/home/setting/setting_detail_page/detail_UI/setting_Theme_Page.kt
index 3bb43d9..fba06b6 100644
--- a/app/src/main/java/com/example/login_v3/home/setting/setting_detail_page/detail_UI/setting_Theme_Page.kt
+++ b/app/src/main/java/com/example/login_v3/home/setting/setting_detail_page/detail_UI/setting_Theme_Page.kt
@@ -1,96 +1,220 @@
 package com.example.login_v3.home.setting.setting_detail_page.detail_UI
 
+import android.net.Uri
+import androidx.activity.compose.rememberLauncherForActivityResult
+import androidx.activity.result.PickVisualMediaRequest
+import androidx.activity.result.contract.ActivityResultContracts
+import androidx.compose.animation.AnimatedVisibility
 import androidx.compose.foundation.background
 import androidx.compose.foundation.border
-import androidx.compose.foundation.layout.Box
-import androidx.compose.foundation.layout.Column
-import androidx.compose.foundation.layout.Row
-import androidx.compose.foundation.layout.Spacer
-import androidx.compose.foundation.layout.fillMaxWidth
-import androidx.compose.foundation.layout.height
-import androidx.compose.foundation.layout.padding
+import androidx.compose.foundation.layout.*
 import androidx.compose.foundation.selection.selectable
 import androidx.compose.foundation.shape.RoundedCornerShape
-import androidx.compose.material3.MaterialTheme
-import androidx.compose.material3.RadioButton
-import androidx.compose.material3.Text
-import androidx.compose.runtime.Composable
-import androidx.compose.runtime.collectAsState
-import androidx.compose.runtime.getValue
+import androidx.compose.material3.*
+import androidx.compose.runtime.*
 import androidx.compose.ui.Alignment
 import androidx.compose.ui.Modifier
 import androidx.compose.ui.draw.blur
+import androidx.compose.ui.draw.clip
 import androidx.compose.ui.graphics.Color
+import androidx.compose.ui.layout.ContentScale
+import androidx.compose.ui.platform.LocalContext
 import androidx.compose.ui.unit.dp
+import coil.compose.AsyncImage
 import com.example.login_v3.home.setting.setting_detail_page.viewmodel.Theme_ViewModel
 import com.example.login_v3.ui.theme.AppTheme
+import java.io.File
 
 @Composable
 fun setting_theme_page(
     viewModel: Theme_ViewModel
 ){
-    // 直接讀取，不需要 .value
+    val context = LocalContext.current
+
+    // 1. 監聽狀態
     val selectedTheme by viewModel.currentTheme.collectAsState()
+    val wallpaperPath by viewModel.customWallpaperPath.collectAsState()
 
-    Box(
-        modifier = Modifier
-            .padding(10.dp)
-    ) {
-        //glass effect
+    // 2. 建立相簿照片選擇器 Launcher
+    val photoPickerLauncher = rememberLauncherForActivityResult(
+        contract = ActivityResultContracts.PickVisualMedia()
+    ) { uri: Uri? ->
+        // 用戶選完照片後，若不為 null 則交給 ViewModel 儲存
+        uri?.let { viewModel.uploadWallpaper(context, it) }
+    }
+
+    Column() {
+
+        // theme mode
         Box(
             modifier = Modifier
-                .matchParentSize()
-                .blur(10.dp)
-        )
-        Box(
-            modifier = Modifier
-                .matchParentSize()
-                .background(
-                    color = MaterialTheme.colorScheme.primary,
-                    RoundedCornerShape(16.dp)
-                )
-                .border(
-                    1.dp,
-                    Color.White.copy(alpha = 0.3f),
-                    RoundedCornerShape(16.dp)
-                )
-        )
-
-
-        //dark light mode
-        Column(modifier = Modifier.padding(16.dp)) {
-            Text(
-                text = "主題設定",
-                style = MaterialTheme.typography.headlineMedium,
-                color = MaterialTheme.colorScheme.onBackground
+                .padding(10.dp)
+        ) {
+            //glass effect
+            Box(
+                modifier = Modifier
+                    .matchParentSize()
+                    .blur(10.dp)
+            )
+            Box(
+                modifier = Modifier
+                    .matchParentSize()
+                    .background(
+                        color = MaterialTheme.colorScheme.primary,
+                        RoundedCornerShape(16.dp)
+                    )
+                    .border(
+                        1.dp,
+                        Color.White.copy(alpha = 0.3f),
+                        RoundedCornerShape(16.dp)
+                    )
             )
 
-            Spacer(modifier = Modifier.height(8.dp))
 
-            // 遍歷所有 Enum 選項
-            AppTheme.entries.forEach { theme ->
-                Row(
-                    verticalAlignment = Alignment.CenterVertically,
-                    modifier = Modifier
-                        .fillMaxWidth()
-                        .selectable(
+            //dark light mode
+            Column(modifier = Modifier.padding(16.dp)) {
+                Text(
+                    text = "主題設定",
+                    style = MaterialTheme.typography.headlineMedium,
+                    color = MaterialTheme.colorScheme.onBackground
+                )
+
+                Spacer(modifier = Modifier.height(8.dp))
+
+                // 遍歷所有 Enum 選項
+                AppTheme.entries.forEach { theme ->
+                    Row(
+                        verticalAlignment = Alignment.CenterVertically,
+                        modifier = Modifier
+                            .fillMaxWidth()
+                            .selectable(
+                                selected = (theme == selectedTheme),
+                                onClick = { viewModel.updateTheme(theme) }
+                            )
+                            .padding(8.dp)
+                    ) {
+                        RadioButton(
                             selected = (theme == selectedTheme),
                             onClick = { viewModel.updateTheme(theme) }
                         )
-                        .padding(8.dp)
+                        Text(
+                            text = when(theme) {
+                                AppTheme.SYSTEM -> "follow"
+                                AppTheme.LIGHT -> "light"
+                                AppTheme.DARK -> "dark"
+                            },
+                            modifier = Modifier.padding(start = 8.dp)
+                        )
+                    }
+                }
+            }
+        }
+
+
+        // 3. 新增：upload wallpaper 區塊
+        Box(
+            modifier = Modifier
+                .padding(10.dp)
+        ) {
+            // glass effect (與上方卡片一致)
+            Box(
+                modifier = Modifier
+                    .matchParentSize()
+                    .blur(10.dp)
+            )
+            Box(
+                modifier = Modifier
+                    .matchParentSize()
+                    .background(
+                        color = MaterialTheme.colorScheme.primary,
+                        RoundedCornerShape(16.dp)
+                    )
+                    .border(
+                        1.dp,
+                        Color.White.copy(alpha = 0.3f),
+                        RoundedCornerShape(16.dp)
+                    )
+            )
+
+            // 卡片內元件
+            Column(modifier = Modifier.padding(16.dp)) {
+                Text(
+                    text = "自訂背景壁紙",
+                    style = MaterialTheme.typography.headlineMedium,
+                    color = MaterialTheme.colorScheme.onBackground
+                )
+
+                Spacer(modifier = Modifier.height(16.dp))
+
+                Row(
+                    modifier = Modifier.fillMaxWidth(),
+                    verticalAlignment = Alignment.CenterVertically,
+                    horizontalArrangement = Arrangement.spacedBy(16.dp)
                 ) {
-                    RadioButton(
-                        selected = (theme == selectedTheme),
-                        onClick = { viewModel.updateTheme(theme) }
-                    )
-                    Text(
-                        text = when(theme) {
-                            AppTheme.SYSTEM -> "follow"
-                            AppTheme.LIGHT -> "light"
-                            AppTheme.DARK -> "dark"
-                        },
-                        modifier = Modifier.padding(start = 8.dp)
-                    )
+                    // 左側：圖片預覽框（手機螢幕比例 9:16 微縮版）
+                    Box(
+                        modifier = Modifier
+                            .size(90.dp, 160.dp)
+                            .clip(RoundedCornerShape(8.dp))
+                            .background(Color.Black.copy(alpha = 0.2f))
+                            .border(1.dp, Color.White.copy(alpha = 0.2f), RoundedCornerShape(8.dp)),
+                        contentAlignment = Alignment.Center
+                    ) {
+                        val file = wallpaperPath?.let { File(it) }
+                        if (file != null && file.exists()) {
+                            // 讀取本地檔案並顯示
+                            AsyncImage(
+                                model = file,
+                                contentDescription = "Wallpaper Preview",
+                                modifier = Modifier.fillMaxSize(),
+                                contentScale = ContentScale.Crop
+                            )
+                        } else {
+                            // 沒上傳過，顯示預設文字
+                            Text(
+                                text = "未設定",
+                                style = MaterialTheme.typography.bodyMedium,
+                                color = MaterialTheme.colorScheme.onPrimary.copy(alpha = 0.6f)
+                            )
+                        }
+                    }
+
+                    // 右側：操作按鈕們
+                    Column(
+                        modifier = Modifier.weight(1f),
+                        verticalArrangement = Arrangement.spacedBy(12.dp)
+                    ) {
+                        // 選擇按鈕
+                        Button(
+                            onClick = {
+                                // 啟動相簿選取器
+                                photoPickerLauncher.launch(
+                                    PickVisualMediaRequest(ActivityResultContracts.PickVisualMedia.ImageOnly)
+                                )
+                            },
+                            modifier = Modifier.fillMaxWidth(),
+                            colors = ButtonDefaults.buttonColors(
+                                containerColor = MaterialTheme.colorScheme.onPrimary,
+                                contentColor = MaterialTheme.colorScheme.primary
+                            )
+                        ) {
+                            Text("選擇圖片")
+                        }
+
+                        // 刪除按鈕：有壁紙時才動畫浮現
+                        AnimatedVisibility(visible = !wallpaperPath.isNullOrEmpty()) {
+                            Button(
+                                onClick = { viewModel.deleteWallpaper(context) },
+                                modifier = Modifier.fillMaxWidth(),
+                                colors = ButtonDefaults.buttonColors(
+                                    containerColor = MaterialTheme.colorScheme.errorContainer,
+                                    contentColor = MaterialTheme.colorScheme.onErrorContainer
+                                )
+                            ) {
+                                Text("清除壁紙")
+                            }
+                        }
+                    }
                 }
             }
         }
diff --git a/app/src/main/java/com/example/login_v3/home/setting/setting_detail_page/viewmodel/Theme_ViewModel.kt b/app/src/main/java/com/example/login_v3/home/setting/setting_detail_page/viewmodel/Theme_ViewModel.kt
index b6b0e41..8e9de69 100644
--- a/app/src/main/java/com/example/login_v3/home/setting/setting_detail_page/viewmodel/Theme_ViewModel.kt
+++ b/app/src/main/java/com/example/login_v3/home/setting/setting_detail_page/viewmodel/Theme_ViewModel.kt
@@ -1,5 +1,7 @@
 package com.example.login_v3.home.setting.setting_detail_page.viewmodel
 
+import android.content.Context
+import android.net.Uri
 import android.util.Log
 import androidx.lifecycle.ViewModel
 import androidx.lifecycle.viewModelScope
@@ -33,6 +35,14 @@ class Theme_ViewModel @Inject constructor(
             initialValue = AppTheme.DARK // 初始值
         )
 
+    // 新增 1：讀取自訂壁紙路徑的 StateFlow
+    val customWallpaperPath: StateFlow<String?> = repository.wallpaperPathFlow
+        .stateIn(
+            scope = viewModelScope,
+            started = SharingStarted.WhileSubscribed(5000),
+            initialValue = null // 初始值為 null，代表還沒有自訂壁紙
+        )
+
     // 4. 更新：除了更新狀態，還要存入 DataStore
     fun updateTheme(newTheme: AppTheme) {
         Log.d("ThemeDebug", "ViewModel 更新主題並儲存至 DataStore: $newTheme")
@@ -40,4 +50,29 @@ class Theme_ViewModel @Inject constructor(
             repository.saveThemeMode(newTheme.name) // 儲存 Enum 的名稱 (例如 "DARK")
         }
     }
+
+    /**
+     * 新增 2：呼叫 Repository 儲存壁紙圖片
+     */
+    fun uploadWallpaper(context: Context, uri: Uri) {
+        Log.d("ThemeDebug", "ViewModel 開始上傳壁紙: $uri")
+        viewModelScope.launch {
+            val success = repository.saveWallpaper(context, uri)
+            if (success) {
+                Log.d("ThemeDebug", "壁紙儲存成功")
+            } else {
+                Log.e("ThemeDebug", "壁紙儲存失敗")
+            }
+        }
+    }
+
+    /**
+     * 新增 3：呼叫 Repository 刪除壁紙圖片並清理 DataStore
+     */
+    fun deleteWallpaper(context: Context) {
+        Log.d("ThemeDebug", "ViewModel 開始刪除壁紙")
+        viewModelScope.launch {
+            repository.clearWallpaper(context)
+        }
+    }
 }
\ No newline at end of file