feat(translation): 为翻译模式选择器添加锚点动画效果

修改翻译模式选择器的显示方式，从底部弹窗改为从按钮位置展开的动画效果
计算拖拽按钮位置作为锚点，实现更自然的用户交互体验

lib/modules/translation/views/dialogs/translation_mode_selector.dart

@@ -8,16 +8,57 @@ import '../../controllers/translation_controller.dart';
 /// 翻译模式选择对话框
 class TranslationModeSelector {
   /// 显示翻译模式选择器
-  static void show(bool isDarkMode) {
+  static void show(bool isDarkMode, {Offset? anchor}) {
     final controller = Get.find<TranslationController>();
 
-    Get.bottomSheet(
+    // 计算缩放对齐点（-1..1）。如果未提供 anchor，则从底部中间展开
-      BackdropFilter(
+    Alignment alignment = Alignment.bottomCenter;
-        filter: ImageFilter.blur(sigmaX: 10.0, sigmaY: 10.0),
+    if (anchor != null) {
-        child: _buildTranslationModeSelector(controller),
+      final Size screenSize = MediaQuery.of(Get.context!).size;
-      ),
+      final double ax = (anchor.dx / screenSize.width) * 2 - 1;
-      isScrollControlled: true,
+      final double ay = (anchor.dy / screenSize.height) * 2 - 1;
-      backgroundColor: Colors.transparent,
+      alignment = Alignment(ax, ay);
+    }
+
+    Get.generalDialog(
+      barrierLabel: 'translation_mode_selector',
+      barrierDismissible: true,
+      barrierColor: Colors.black.withOpacity(0.35),
+      transitionDuration: const Duration(milliseconds: 250),
+      pageBuilder: (context, animation, secondaryAnimation) {
+        return const SizedBox.shrink();
+      },
+      transitionBuilder: (context, animation, secondaryAnimation, child) {
+        final curved = CurvedAnimation(
+            parent: animation,
+            curve: Curves.easeOutCubic,
+            reverseCurve: Curves.easeInCubic);
+        return Stack(
+          children: [
+            // 模糊背景
+            Positioned.fill(
+              child: BackdropFilter(
+                filter: ImageFilter.blur(sigmaX: 10.0, sigmaY: 10.0),
+                child: Container(color: Colors.transparent),
+              ),
+            ),
+            // 将缩放应用在一个全屏容器上，以便 alignment 以屏幕为参考
+            ScaleTransition(
+              alignment: alignment,
+              scale: Tween<double>(begin: 0.0, end: 1.0).animate(curved),
+              child: FadeTransition(
+                opacity: curved,
+                child: SizedBox.expand(
+                  child: Align(
+                    alignment: Alignment.bottomCenter,
+                    child: _buildTranslationModeSelector(controller),
+                  ),
+                ),
+              ),
+            ),
+          ],
+        );
+      },
     );
   }
 

lib/modules/translation/views/translation_view.dart

@@ -144,7 +144,16 @@ class TranslationView extends GetView<TranslationController> {
       title: Obx(() => GestureDetector(
             onTap: () {
               // 点击标题时弹出翻译模式选择器
-              TranslationModeSelector.show(isDarkMode);
+              // 从拖拽按钮位置作为锚点打开
+              final pos = controller.floatingButtonPosition.value;
+              final Size screen = MediaQuery.of(Get.context!).size;
+              // 已保存的是距右、下的偏移，需要换算为屏幕坐标中的中心点
+              final double buttonSize = 56.w;
+              final double left = screen.width - pos.dx - buttonSize;
+              final double top = screen.height - pos.dy - buttonSize;
+              final Offset anchor =
+                  Offset(left + buttonSize / 2, top + buttonSize / 2);
+              TranslationModeSelector.show(isDarkMode, anchor: anchor);
             },
             child: Text(
               controller.currentModeTitle.value.tr,

lib/modules/translation/views/widgets/draggable_floating_button.dart

@@ -108,6 +108,13 @@ class DraggableFloatingButton extends StatelessWidget {
 
   /// 显示翻译模式选择器
   void _showTranslationModeSelector(bool isDarkMode) {
-    TranslationModeSelector.show(isDarkMode);
+    // 使用保存的位置换算按钮中心点（与标题点击一致）
+    final pos = controller.floatingButtonPosition.value; // 距右、下的偏移
+    final Size screen = MediaQuery.of(Get.context!).size;
+    final double buttonSize = 56.w;
+    final double left = screen.width - pos.dx - buttonSize;
+    final double top = screen.height - pos.dy - buttonSize;
+    final Offset anchor = Offset(left + buttonSize / 2, top + buttonSize / 2);
+    TranslationModeSelector.show(isDarkMode, anchor: anchor);
   }
 }