feat: 优化年月视图共享元素转场动画

- 月→年切换时自动展开折叠状态
- 将 sharedElement 精确绑定到日历网格区域
- YearGridView 为每个 MiniMonth 添加共享元素转场

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

core/src/main/kotlin/plus/rua/project/CalendarViewModel.kt

@@ -129,7 +129,15 @@ class CalendarViewModel(
                 animJob.join()
                 composeTraceEndSection()
             } else {
-                // 月 → 年：先启动动画（月视图开始缩小），等一帧后翻转 isYearView（年视图开始组合）
+                // 月 → 年：如果折叠，先展开
+                if (isCollapsed) {
+                    _collapseAnimatable.animateTo(
+                        targetValue = 0f,
+                        animationSpec = spring(dampingRatio = 0.8f, stiffness = 400f)
+                    )
+                    isCollapsed = false
+                }
+                // 先启动动画（月视图开始缩小），等一帧后翻转 isYearView（年视图开始组合）
                 composeTraceBeginSection("MonthView→YearView")
                 yearViewYear = selectedDate.year
                 _yearViewAnimatable.snapTo(0f)

core/src/main/kotlin/plus/rua/project/ui/CalendarMonthView.kt

@@ -159,25 +159,16 @@ fun CalendarMonthView(
                 targetState = viewModel.isYearView,
                 label = "month_year_transition",
                 transitionSpec = {
-                    fadeIn(tween(300, easing = FastOutSlowInEasing)) togetherWith
+                    fadeIn(tween(0)) togetherWith fadeOut(tween(0))
-                        fadeOut(tween(300, easing = FastOutSlowInEasing))
                 },
                 modifier = Modifier.fillMaxSize()
             ) { isYearView ->
-                with(sharedScope) {
                 if (!isYearView) {
                     composeTraceBeginSection("MonthView:Compose")
                     val layoutReady = rowHeightPx > 0
                     Box(
                         modifier = Modifier
                             .fillMaxSize()
-                            .sharedBounds(
-                                sharedContentState = rememberSharedContentState(key = "month_content"),
-                                animatedVisibilityScope = this@AnimatedContent,
-                                boundsTransform = { _, _ ->
-                                    tween(400, easing = FastOutSlowInEasing)
-                                }
-                            )
                             .alpha(if (layoutReady) 1f else 0f)
                     ) {
                         Column(
@@ -197,6 +188,7 @@ fun CalendarMonthView(
                             WeekdayHeader(
                                 modifier = Modifier.fillMaxWidth().padding(bottom = ROW_PADDING_DP.dp)
                             )
+                            with(sharedScope) {
                                 CalendarPagerArea(
                                     viewModel = viewModel,
                                     today = today,
@@ -206,8 +198,19 @@ fun CalendarMonthView(
                                         if (h > 0) rowHeightPx = h
                                     },
                                     pagerState = pagerState,
-                                modifier = Modifier.clipToBounds()
+                                    modifier = Modifier
+                                        .sharedElement(
+                                            sharedContentState = rememberSharedContentState(
+                                                key = "month_grid_${currentYear}_${currentMonth}"
+                                            ),
+                                            animatedVisibilityScope = this@AnimatedContent,
+                                            boundsTransform = { _, _ ->
+                                                tween(400, easing = FastOutSlowInEasing)
+                                            }
                                         )
+                                        .clipToBounds()
+                                )
+                            }
                             BottomCardArea(
                                 viewModel = viewModel,
                                 today = today,
@@ -222,13 +225,6 @@ fun CalendarMonthView(
                     Column(
                         modifier = Modifier
                             .fillMaxSize()
-                            .sharedBounds(
-                                sharedContentState = rememberSharedContentState(key = "month_content"),
-                                animatedVisibilityScope = this@AnimatedContent,
-                                boundsTransform = { _, _ ->
-                                    tween(400, easing = FastOutSlowInEasing)
-                                }
-                            )
                             .padding(horizontal = HORIZONTAL_PADDING_DP.dp)
                     ) {
                         YearHeader(
@@ -273,6 +269,8 @@ fun CalendarMonthView(
                                         coroutineScope.launch { pagerState.scrollToPage(targetPage) }
                                     }
                                 },
+                                sharedTransitionScope = sharedScope,
+                                animatedVisibilityScope = this@AnimatedContent,
                                 modifier = Modifier.alpha(crossFadeAlpha)
                             )
                         }
@@ -280,7 +278,6 @@ fun CalendarMonthView(
                     composeTraceEndSection()
                 }
             }
-            }
 
             // FAB 浮动按钮
         FloatingActionButton(

core/src/main/kotlin/plus/rua/project/ui/YearGridView.kt

@@ -1,6 +1,10 @@
 package plus.rua.project.ui
 
 import androidx.compose.animation.AnimatedContent
+import androidx.compose.animation.AnimatedVisibilityScope
+import androidx.compose.animation.ExperimentalSharedTransitionApi
+import androidx.compose.animation.SharedTransitionScope
+import androidx.compose.animation.core.FastOutSlowInEasing
 import androidx.compose.animation.core.animateFloatAsState
 import androidx.compose.animation.core.tween
 import androidx.compose.animation.slideInVertically
@@ -63,14 +67,19 @@ private data class MiniMonthColors(
  * @param selectedMonth 当前选中月份（1-12）
  * @param today 今天的日期
  * @param onMonthClick 月份点击回调
+ * @param sharedTransitionScope 共享元素转场作用域
+ * @param animatedVisibilityScope 动画可见性作用域
  * @param modifier 外部布局修饰符
  */
+@OptIn(ExperimentalSharedTransitionApi::class)
 @Composable
 fun YearGridView(
     year: Int,
     selectedMonth: Int,
     today: LocalDate,
     onMonthClick: (Int) -> Unit,
+    sharedTransitionScope: SharedTransitionScope,
+    animatedVisibilityScope: AnimatedVisibilityScope,
     modifier: Modifier = Modifier
 ) {
     composeTraceBeginSection("YearGridView:$year")
@@ -156,6 +165,7 @@ fun YearGridView(
                 ) {
                     (0 until 3).forEach { col ->
                         val month = row * 3 + col + 1
+                        with(sharedTransitionScope) {
                             MiniMonth(
                                 month = month,
                                 isSelected = month == selectedMonth,
@@ -166,8 +176,19 @@ fun YearGridView(
                                 titleLayouts = titleLayouts,
                                 weekdayLayouts = weekdayLayouts,
                                 onClick = { onMonthClick(month) },
-                            modifier = Modifier.weight(1f)
+                                modifier = Modifier
+                                    .weight(1f)
+                                    .sharedElement(
+                                        sharedContentState = rememberSharedContentState(
+                                            key = "month_grid_${year}_$month"
+                                        ),
+                                        animatedVisibilityScope = animatedVisibilityScope,
+                                        boundsTransform = { _, _ ->
+                                            tween(400, easing = FastOutSlowInEasing)
+                                        }
                                     )
+                            )
+                        }
                     }
                 }
             }