UI: 增大摇杆尺寸至180dp；视频全屏延展（ZOOM模式）并加入缩放模式设置项

- 左右摇杆 Modifier.size 140dp -> 180dp (MainScreen.kt)
- RtspVideoPlayer 新增 resizeMode: VideoResizeMode 参数，默认 ZOOM
- 新增 VideoResizeMode 枚举 (FIT/ZOOM/FILL) 及 Media3 常量映射
- 设置界面新增"视频缩放模式"下拉选项，持久化到 DataStore
- AGENTS.md 更新已完成项和配置项表格

Generated by Mistral Vibe.
Co-Authored-By: Mistral Vibe <vibe@mistral.ai>

app/src/main/java/com/example/m20_gamepad/data/AppSettings.kt

@@ -2,6 +2,18 @@ package com.example.m20_gamepad.data
 
 import com.example.m20_gamepad.video.VideoCodec
 
+/**
+ * 视频缩放模式。
+ */
+enum class VideoResizeMode {
+    /** 等比缩放，完整显示（留黑边） */
+    FIT,
+    /** 等比缩放，填充全屏（裁切多余部分） */
+    ZOOM,
+    /** 拉伸填满全屏 */
+    FILL
+}
+
 /**
  * 应用配置数据类。
  *
@@ -12,7 +24,8 @@ data class AppSettings(
     val robotHost: String = DEFAULT_ROBOT_HOST,
     val robotPort: Int = DEFAULT_ROBOT_PORT,
     val rtspUrl: String = DEFAULT_RTSP_URL,
-    val videoCodec: VideoCodec = VideoCodec.AUTO
+    val videoCodec: VideoCodec = VideoCodec.AUTO,
+    val videoResizeMode: VideoResizeMode = VideoResizeMode.ZOOM
 ) {
     companion object {
         const val DEFAULT_ROBOT_HOST = "10.21.31.103"

app/src/main/java/com/example/m20_gamepad/data/SettingsRepository.kt

@@ -34,7 +34,8 @@ class SettingsRepository(context: Context) {
             robotHost = prefs[KEY_HOST] ?: AppSettings.DEFAULT_ROBOT_HOST,
             robotPort = prefs[KEY_PORT] ?: AppSettings.DEFAULT_ROBOT_PORT,
             rtspUrl = prefs[KEY_RTSP_URL] ?: AppSettings.DEFAULT_RTSP_URL,
-            videoCodec = VideoCodec.entries.getOrElse(prefs[KEY_CODEC] ?: 0) { VideoCodec.AUTO }
+            videoCodec = VideoCodec.entries.getOrElse(prefs[KEY_CODEC] ?: 0) { VideoCodec.AUTO },
+            videoResizeMode = VideoResizeMode.entries.getOrElse(prefs[KEY_RESIZE_MODE] ?: 1) { VideoResizeMode.ZOOM }
         )
     }
 
@@ -61,6 +62,7 @@ class SettingsRepository(context: Context) {
             prefs[KEY_PORT] = settings.robotPort.coerceIn(1, 65535)
             prefs[KEY_RTSP_URL] = settings.rtspUrl.trim()
             prefs[KEY_CODEC] = settings.videoCodec.ordinal
+            prefs[KEY_RESIZE_MODE] = settings.videoResizeMode.ordinal
         }
     }
 
@@ -69,5 +71,6 @@ class SettingsRepository(context: Context) {
         private val KEY_PORT = intPreferencesKey("robot_port")
         private val KEY_RTSP_URL = stringPreferencesKey("rtsp_url")
         private val KEY_CODEC = intPreferencesKey("video_codec")
+        private val KEY_RESIZE_MODE = intPreferencesKey("video_resize_mode")
     }
 }

app/src/main/java/com/example/m20_gamepad/ui/MainScreen.kt

@@ -103,6 +103,7 @@ fun MainScreen(
         RtspVideoPlayer(
             url = settings.rtspUrl,
             codec = settings.videoCodec,
+            resizeMode = settings.videoResizeMode,
             modifier = Modifier.fillMaxSize()
         )
 
@@ -255,7 +256,7 @@ private fun BottomControls(
     ) {
         // 左摇杆（X/Y 移动）
         Joystick(
-            modifier = Modifier.size(140.dp),
+            modifier = Modifier.size(180.dp),
             type = JoystickType.EIGHT_AXIS,
             padColor = Color(0x55808080),
             buttonColor = Color(0xCCFFFFFF),
@@ -273,7 +274,7 @@ private fun BottomControls(
 
         // 右摇杆（Yaw 旋转）
         Joystick(
-            modifier = Modifier.size(140.dp),
+            modifier = Modifier.size(180.dp),
             type = JoystickType.EIGHT_AXIS,
             padColor = Color(0x55808080),
             buttonColor = Color(0xCCFFFFFF),

app/src/main/java/com/example/m20_gamepad/ui/SettingsScreen.kt

@@ -37,6 +37,7 @@ import androidx.compose.ui.text.input.KeyboardType
 import androidx.compose.ui.unit.dp
 import com.example.m20_gamepad.data.AppSettings
 import com.example.m20_gamepad.data.SettingsRepository
+import com.example.m20_gamepad.data.VideoResizeMode
 import com.example.m20_gamepad.video.VideoCodec
 import kotlinx.coroutines.flow.first
 import kotlinx.coroutines.launch
@@ -65,6 +66,7 @@ fun SettingsScreen(
     var portText by remember { mutableStateOf(AppSettings.DEFAULT_ROBOT_PORT.toString()) }
     var rtspUrl by remember { mutableStateOf(AppSettings.DEFAULT_RTSP_URL) }
     var codec by remember { mutableStateOf(VideoCodec.AUTO) }
+    var resizeMode by remember { mutableStateOf(VideoResizeMode.ZOOM) }
     var hostError by remember { mutableStateOf<String?>(null) }
     var portError by remember { mutableStateOf<String?>(null) }
     var initialized by remember { mutableStateOf(false) }
@@ -76,6 +78,7 @@ fun SettingsScreen(
             portText = s.robotPort.toString()
             rtspUrl = s.rtspUrl
             codec = s.videoCodec
+            resizeMode = s.videoResizeMode
             initialized = true
         }
     }
@@ -161,6 +164,12 @@ fun SettingsScreen(
                 modifier = Modifier.fillMaxWidth()
             )
 
+            ResizeModeDropdown(
+                selected = resizeMode,
+                onSelect = { resizeMode = it },
+                modifier = Modifier.fillMaxWidth()
+            )
+
             Spacer(Modifier.padding(top = 8.dp))
 
             // ---- 操作按钮 ----
@@ -183,7 +192,8 @@ fun SettingsScreen(
                                     robotHost = host,
                                     robotPort = port,
                                     rtspUrl = rtspUrl,
-                                    videoCodec = codec
+                                    videoCodec = codec,
+                                    videoResizeMode = resizeMode
                                 )
                             )
                             onSaved()
@@ -264,3 +274,59 @@ private fun CodecDropdown(
         }
     }
 }
+
+@OptIn(ExperimentalMaterial3Api::class)
+@Composable
+private fun ResizeModeDropdown(
+    selected: VideoResizeMode,
+    onSelect: (VideoResizeMode) -> Unit,
+    modifier: Modifier = Modifier
+) {
+    var expanded by remember { mutableStateOf(false) }
+    val options = VideoResizeMode.entries
+    val labels = mapOf(
+        VideoResizeMode.FIT to "等比缩放（留黑边）",
+        VideoResizeMode.ZOOM to "等比缩放（填充全屏）",
+        VideoResizeMode.FILL to "拉伸填充"
+    )
+
+    Column(modifier = modifier) {
+        Text(
+            text = "视频缩放模式",
+            style = androidx.compose.material3.MaterialTheme.typography.titleSmall,
+            color = androidx.compose.material3.MaterialTheme.colorScheme.primary
+        )
+        Spacer(Modifier.padding(top = 4.dp))
+        ExposedDropdownMenuBox(
+            expanded = expanded,
+            onExpandedChange = { expanded = it }
+        ) {
+            OutlinedTextField(
+                value = labels[selected] ?: selected.name,
+                onValueChange = {},
+                readOnly = true,
+                singleLine = true,
+                trailingIcon = {
+                    ExposedDropdownMenuDefaults.TrailingIcon(expanded)
+                },
+                modifier = Modifier
+                    .fillMaxWidth()
+                    .menuAnchor()
+            )
+            ExposedDropdownMenu(
+                expanded = expanded,
+                onDismissRequest = { expanded = false }
+            ) {
+                options.forEach { m ->
+                    DropdownMenuItem(
+                        text = { Text(labels[m] ?: m.name) },
+                        onClick = {
+                            onSelect(m)
+                            expanded = false
+                        }
+                    )
+                }
+            }
+        }
+    }
+}

app/src/main/java/com/example/m20_gamepad/video/RtspVideoPlayer.kt

@@ -23,7 +23,9 @@ import androidx.media3.exoplayer.DefaultRenderersFactory
 import androidx.media3.exoplayer.ExoPlayer
 import androidx.media3.exoplayer.mediacodec.MediaCodecInfo
 import androidx.media3.exoplayer.mediacodec.MediaCodecSelector
+import androidx.media3.ui.AspectRatioFrameLayout
 import androidx.media3.ui.PlayerView
+import com.example.m20_gamepad.data.VideoResizeMode
 
 /**
  * 视频解码器选择策略。
@@ -58,12 +60,14 @@ sealed class RtspState {
  *
  * @param url RTSP 流地址，如 `rtsp://10.21.31.103:554/stream`
  * @param codec 解码器选择策略
+ * @param resizeMode 视频缩放模式，默认 ZOOM（等比填充全屏）
  * @param modifier 布局修饰符
  */
 @Composable
 fun RtspVideoPlayer(
     url: String,
     codec: VideoCodec = VideoCodec.AUTO,
+    resizeMode: VideoResizeMode = VideoResizeMode.ZOOM,
     modifier: Modifier = Modifier
 ) {
     val context = LocalContext.current
@@ -132,6 +136,7 @@ fun RtspVideoPlayer(
             factory = { ctx ->
                 PlayerView(ctx).apply {
                     useController = false
+                    this.resizeMode = resizeMode.toMedia3ResizeMode()
                     this.player = player
                     setShutterBackgroundColor(android.graphics.Color.BLACK)
                 }
@@ -139,6 +144,7 @@ fun RtspVideoPlayer(
             // player 引用变化时（codec 重建）更新 PlayerView
             update = { view ->
                 view.player = player
+                view.resizeMode = resizeMode.toMedia3ResizeMode()
             }
         )
 
@@ -222,4 +228,13 @@ private fun forceHardware(): MediaCodecSelector = object : MediaCodecSelector {
             mimeType, requiresSecureDecoder, requiresTunnelingDecoder
         ).filter { it.hardwareAccelerated }
     }
+}
+
+// ==================== 缩放模式映射 ====================
+
+/** 将 [VideoResizeMode] 映射为 [AspectRatioFrameLayout] 的 resizeMode 常量。 */
+private fun VideoResizeMode.toMedia3ResizeMode(): Int = when (this) {
+    VideoResizeMode.FIT -> AspectRatioFrameLayout.RESIZE_MODE_FIT
+    VideoResizeMode.ZOOM -> AspectRatioFrameLayout.RESIZE_MODE_ZOOM
+    VideoResizeMode.FILL -> AspectRatioFrameLayout.RESIZE_MODE_FILL
 }