文本消息长按菜单

lib/package/chat_dash/src/widgets/message_row/pop_menu.dart

@@ -115,6 +115,7 @@ class _CustomPopupMenuState extends State<CustomPopupMenu> {
             ),
             child: CustomMultiChildLayout(
               delegate: _MenuLayoutDelegate(
+                itemSize: _childBox?.size ?? Size.zero,
                 tapedPoint: _controller?.localPosition ?? Offset.zero,
                 anchorSize: _childBox!.size,
                 anchorOffset: _childBox!.localToGlobal(
@@ -289,9 +290,14 @@ class _MenuLayoutDelegate extends MultiChildLayoutDelegate {
     required this.anchorOffset,
     required this.verticalMargin,
     required this.tapedPoint,
+    required this.itemSize,
     this.position,
   });
 
+  // 消息列表的的大小
+  final Size itemSize;
+
+  /// 消息列表点击的位置
   final Offset tapedPoint;
   final Size anchorSize;
   final Offset anchorOffset;
@@ -328,7 +334,8 @@ class _MenuLayoutDelegate extends MultiChildLayoutDelegate {
         BoxConstraints.loose(size),
       );
     }
-    print("文本内容大小 $size $contentSize $anchorOffset 点击位置$tapedPoint");
+    print(
+        "文本内容大小 $size $contentSize 子 $itemSize $anchorOffset  点击位置$tapedPoint");
     bool isTop = false;
     if (position == null) {
       // auto calculate position
@@ -336,6 +343,13 @@ class _MenuLayoutDelegate extends MultiChildLayoutDelegate {
     } else {
       isTop = position == PreferredPosition.top;
     }
+
+    // 长消息上滑后底部有充分的空间才可以
+    if (itemSize.height + anchorOffset.dy - size.height <
+            -(contentSize.height * 1.2 + arrowOffset.dy + verticalMargin) &&
+        anchorOffset.dy < 0) {
+      isTop = false;
+    }
     if (anchorCenterX - contentSize.width / 2 < 0) {
       menuPosition = isTop ? _MenuPosition.topLeft : _MenuPosition.bottomLeft;
     } else if (anchorCenterX + contentSize.width / 2 > size.width) {
@@ -373,19 +387,31 @@ class _MenuLayoutDelegate extends MultiChildLayoutDelegate {
         );
         break;
       case _MenuPosition.topCenter:
+        double contentOffsetY = 0.0;
+        double arrowOffsetY = 0.0;
+        if (anchorTopY <= contentSize.height) {
+          // 使用 点击位置
+          contentOffsetY =
+              tapedPoint.dy - contentSize.height + anchorTopY - verticalMargin;
+          arrowOffsetY = tapedPoint.dy + anchorTopY - verticalMargin;
+        } else {
+          arrowOffsetY = math.max(
+              anchorTopY - verticalMargin - arrowSize.height,
+              contentSize.height * 2);
+          contentOffsetY = math.max(
+              anchorTopY -
+                  verticalMargin -
+                  arrowSize.height -
+                  contentSize.height,
+              contentSize.height);
+        }
         arrowOffset = Offset(
           anchorCenterX - arrowSize.width / 2,
-          math.max(anchorTopY - verticalMargin - arrowSize.height,
-              contentSize.height * 2),
+          arrowOffsetY,
         );
         contentOffset = Offset(
           anchorCenterX - contentSize.width / 2,
-          math.max(
-              anchorTopY -
-                  verticalMargin -
-                  arrowSize.height -
-                  contentSize.height,
-              contentSize.height),
+          contentOffsetY,
         );
         break;
       case _MenuPosition.topLeft: