重写了节点的view、viewmodel关系，实现了对画布元素的选取功能，重构了底层依赖，添加了对net .Framework4.6.1以上的Framework类库支持

Library.Core/SerinExpression/SerinExpressionEvaluator.cs

@@ -0,0 +1,216 @@
+using System.Data;
+
+namespace Serein.LibraryCore.SerinExpression
+{
+    public class SerinArithmeticExpressionEvaluator
+    {
+        private static readonly DataTable table = new DataTable();
+
+        public static double Evaluate(string expression, double inputValue)
+        {
+            // 替换占位符@为输入值
+            expression = expression.Replace("@", inputValue.ToString());
+            try
+            {
+                // 使用 DataTable.Compute 方法计算表达式
+                var result = table.Compute(expression, string.Empty);
+                return Convert.ToDouble(result);
+            }
+            catch
+            {
+                throw new ArgumentException("Invalid arithmetic expression.");
+            }
+        }
+    }
+
+    public class SerinExpressionEvaluator
+    {
+        /// <summary>
+        /// 
+        /// </summary>
+        /// <param name="expression">表达式</param>
+        /// <param name="targetObJ">操作对象</param>
+        /// <param name="isChange">是否改变了对象（get语法）</param>
+        /// <returns></returns>
+        /// <exception cref="ArgumentException"></exception>
+        /// <exception cref="NotSupportedException"></exception>
+        public static object Evaluate(string expression, object targetObJ, out bool isChange)
+        {
+            var parts = expression.Split([' '], 2);
+            if (parts.Length != 2)
+            {
+                throw new ArgumentException("Invalid expression format.");
+            }
+
+            var operation = parts[0].ToLower();
+            var operand = parts[1][0] == '.' ? parts[1][1..] : parts[1];
+
+            var result = operation switch
+            {
+                "@num" => ComputedNumber(targetObJ, operand),
+                "@call" => InvokeMethod(targetObJ, operand),
+                "@get" => GetMember(targetObJ, operand),
+                "@set" => SetMember(targetObJ, operand),
+                _ => throw new NotSupportedException($"Operation {operation} is not supported.")
+            };
+
+            isChange = operation switch
+            {
+                "@num" => true,
+                "@call" => true,
+                "@get" => true,
+                "@set" => false,
+                _ => throw new NotSupportedException($"Operation {operation} is not supported.")
+            };
+
+            return result;
+        }
+
+
+        private static readonly char[] separator = ['(', ')'];
+        private static readonly char[] separatorArray = [','];
+
+        private static object InvokeMethod(object target, string methodCall)
+        {
+            var methodParts = methodCall.Split(separator, StringSplitOptions.RemoveEmptyEntries);
+            if (methodParts.Length != 2)
+            {
+                throw new ArgumentException("Invalid method call format.");
+            }
+
+            var methodName = methodParts[0];
+            var parameterList = methodParts[1];
+            var parameters = parameterList.Split(separatorArray, StringSplitOptions.RemoveEmptyEntries)
+                                          .Select(p => p.Trim())
+                                          .ToArray();
+
+            var method = target.GetType().GetMethod(methodName);
+            if (method == null)
+            {
+                throw new ArgumentException($"Method {methodName} not found on target.");
+            }
+
+            var parameterValues = method.GetParameters()
+                                        .Select((p, index) => Convert.ChangeType(parameters[index], p.ParameterType))
+                                        .ToArray();
+
+
+            return method.Invoke(target, parameterValues);
+
+        }
+
+        private static object GetMember(object target, string memberPath)
+        {
+            var members = memberPath.Split('.');
+            foreach (var member in members)
+            {
+
+                if (target == null) return null;
+
+
+                var property = target.GetType().GetProperty(member);
+                if (property != null)
+                {
+
+                    target = property.GetValue(target);
+
+                }
+                else
+                {
+                    var field = target.GetType().GetField(member);
+                    if (field != null)
+                    {
+
+                        target = field.GetValue(target);
+
+                    }
+                    else
+                    {
+                        throw new ArgumentException($"Member {member} not found on target.");
+                    }
+                }
+            }
+
+
+            return target;
+
+        }
+
+        private static object SetMember(object target, string assignment)
+        {
+            var parts = assignment.Split(new[] { '=' }, 2);
+            if (parts.Length != 2)
+            {
+                throw new ArgumentException("Invalid assignment format.");
+            }
+
+            var memberPath = parts[0].Trim();
+            var value = parts[1].Trim();
+
+            var members = memberPath.Split('.');
+            for (int i = 0; i < members.Length - 1; i++)
+            {
+                var member = members[i];
+
+                var property = target.GetType().GetProperty(member);
+
+                if (property != null)
+                {
+
+                    target = property.GetValue(target);
+
+                }
+                else
+                {
+                    var field = target.GetType().GetField(member);
+                    if (field != null)
+                    {
+
+                        target = field.GetValue(target);
+
+                    }
+                    else
+                    {
+                        throw new ArgumentException($"Member {member} not found on target.");
+                    }
+                }
+            }
+
+            var lastMember = members.Last();
+
+            var lastProperty = target.GetType().GetProperty(lastMember);
+
+            if (lastProperty != null)
+            {
+                var convertedValue = Convert.ChangeType(value, lastProperty.PropertyType);
+                lastProperty.SetValue(target, convertedValue);
+            }
+            else
+            {
+                var lastField = target.GetType().GetField(lastMember);
+                if (lastField != null)
+                {
+                    var convertedValue = Convert.ChangeType(value, lastField.FieldType);
+                    lastField.SetValue(target, convertedValue);
+                }
+                else
+                {
+                    throw new ArgumentException($"Member {lastMember} not found on target.");
+                }
+            }
+
+            return target;
+        }
+
+        private static double ComputedNumber(object value, string expression)
+        {
+            double numericValue = Convert.ToDouble(value);
+            if (!string.IsNullOrEmpty(expression))
+            {
+                numericValue = SerinArithmeticExpressionEvaluator.Evaluate(expression, numericValue);
+            }
+
+            return numericValue;
+        }
+    }
+}