基于坐标系计算

dimensionhub/Views/Index/IndexMainView.swift

@@ -79,13 +79,13 @@ struct IndexMainView: View {
                 LazyVStack(alignment: .center, spacing: 10) {
                     ForEach(Array(indexModel.dramaGroupElements.enumerated()), id: \.offset) { idx, item in
                         switch item {
-                        case .label(let groupId, let groupName):
+                        case .label(let groupId, let groupName, _):
                             DramaGroupLabelView(group_name: groupName) {
                                 selectGroupId = groupId
                                 indexModel.selectedDate = groupId
                                 showDateNavPopover = true
                             }
-                        case .item(let groupId, let item):
+                        case .item(let groupId, let item, _):
                             DramaGroupItemView(groupId: groupId, item: item)
                                 .id(idx)
                         }
@@ -100,6 +100,7 @@ struct IndexMainView: View {
             .scrollPosition(id: $scrollID)
             .onChange(of: scrollOffset) {
                 self.showFloatGroupLabel = scrollOffset < 0
+                indexModel.offsetChanged(offset: scrollOffset)
             }
             .refreshable {
                 guard !self.showDateNavPopover && !self.headerRefreshing else {

dimensionhub/Views/Index/IndexModel.swift

@@ -52,9 +52,9 @@ final class IndexModel {
     
     enum GroupElement {
         // groupId, groupName
-        case label(String, String)
+        case label(String, String, Double)
         // groupId, UpdateDramaGroup.Item
-        case item(String, UpdateDramaGroup.Item)
+        case item(String, UpdateDramaGroup.Item, Double)
     }
     
     var selectedDate: String
@@ -95,6 +95,10 @@ final class IndexModel {
     @ObservationIgnored
     private var cancel: AnyCancellable?
     
+    // 定义几个关键元素的高度
+    @ObservationIgnored
+    private var elementHeight: (Double, Double, Double) = (10, 21.6, 180) // spacing: 10, label height: 21.6, item: 180
+    
     init() {
         self.selectedDate = ""
         
@@ -102,9 +106,9 @@ final class IndexModel {
             .sink { userId, scrollID in
                 // 更新group的label的部分
                 switch self.dramaGroupElements[scrollID] {
-                case .label(_, _):
+                case .label(_, _, _):
                     ()
-                case .item(let groupId, _):
+                case .item(let groupId, _, _):
                     DispatchQueue.main.async {
                         self.setFixedDrameGroup(groupId: groupId)
                     }
@@ -122,6 +126,32 @@ final class IndexModel {
             }
     }
     
+    // 位置变化
+    func offsetChanged(offset: Double) {
+        // 判断当前的offset在那个视图所在的区间
+        var rangeGroupId: String? = nil
+        let (spacing, labelHeight, elementHeight) = self.elementHeight
+        
+        self.dramaGroupElements.forEach { element in
+            switch element {
+            case .label(let groupId, _, let y):
+                if offset + y >= -labelHeight && offset + y <= 0 {
+                    rangeGroupId = groupId
+                }
+            case .item(let groupId, _, let y):
+                if offset + y >= -elementHeight && offset + y <= 0 {
+                    rangeGroupId = groupId
+                }
+            }
+        }
+        
+        if let rangeGroupId {
+            DispatchQueue.main.async {
+                self.setFixedDrameGroup(groupId: rangeGroupId)
+            }
+        }
+    }
+    
     func loadData(userId: String) async {
         guard !isLoaded else {
             return
@@ -219,11 +249,16 @@ final class IndexModel {
     
     // 转换成显示的元素信息
     private func transformUpdateDramaGroups(groups: [UpdateDramaGroup]) -> [GroupElement] {
+        var offset: Double = 0
+        let (spacing, labelHeight, elementHeight) = self.elementHeight
+        
         var groupElements: [GroupElement] = []
         for group in groups {
-            groupElements.append(.label(group.group_id, group.group_name))
+            groupElements.append(.label(group.group_id, group.group_name, offset))
+            offset += labelHeight + spacing
             for item in group.items {
-                groupElements.append(.item(group.group_id, item))
+                groupElements.append(.item(group.group_id, item, offset))
+                offset += elementHeight + spacing
             }
         }