新增一个chat_popup 来显示聊天窗口

lib/widgets/_hole_overlay.dart

@@ -0,0 +1,80 @@
+import 'package:flutter/material.dart';
+import 'package:flutter/gestures.dart';
+
+/// 遮罩层，icon 区域挖洞可交互
+class HoleOverlay extends StatelessWidget {
+  final Offset iconPosition;
+  final double iconSize;
+  final VoidCallback? onTap;
+
+  const HoleOverlay({
+    super.key,
+    required this.iconPosition,
+    required this.iconSize,
+    this.onTap,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    return Listener(
+      behavior: HitTestBehavior.translucent,
+      onPointerDown: (PointerDownEvent event) {
+        final RenderBox box = context.findRenderObject() as RenderBox;
+        final Offset local = box.globalToLocal(event.position);
+        final iconRect = Rect.fromLTWH(
+          iconPosition.dx,
+          iconPosition.dy,
+          iconSize,
+          iconSize,
+        );
+        if (!iconRect.contains(local)) {
+          // 遮罩区域，拦截并关闭弹窗
+          if (onTap != null) {
+            onTap!();
+          }
+        }
+        // 如果点在icon区域，什么都不做，事件会传递到下层
+      },
+      child: CustomPaint(
+        size: Size.infinite,
+        painter: _HolePainter(
+          iconPosition: iconPosition,
+          iconSize: iconSize,
+        ),
+      ),
+    );
+  }
+}
+
+class _HolePainter extends CustomPainter {
+  final Offset iconPosition;
+  final double iconSize;
+
+  _HolePainter({required this.iconPosition, required this.iconSize});
+
+  @override
+  void paint(Canvas canvas, Size size) {
+    final paint = Paint()
+      ..color = Colors.white.withOpacity(0.0)
+      ..blendMode = BlendMode.srcOver;
+
+    // 画全屏遮罩
+    canvas.drawRect(Offset.zero & size, paint);
+
+    // 挖洞
+    final holeRect = Rect.fromLTWH(
+      iconPosition.dx,
+      iconPosition.dy,
+      iconSize,
+      iconSize,
+    );
+    final holePath = Path()..addOval(holeRect);
+    paint.blendMode = BlendMode.clear;
+    canvas.drawPath(holePath, paint);
+  }
+
+  @override
+  bool shouldRepaint(covariant _HolePainter oldDelegate) {
+    return iconPosition != oldDelegate.iconPosition || iconSize != oldDelegate.iconSize;
+  }
+}