修改块中属性值，属性文多文本类型。

tbeahgl · 发表于 2018-10-15 12:02:00

C#程序修改块中的属性，当属性是多文本类型是，为何总不成功？
关键代码如下：
string ls = "wewefwe//Pwsefwefw";
AttributeReference ar = (AttributeReference)ta.GetObject(id, OpenMode.ForWrite);
ar.MTextAttribute.Contents = ls;
请问为何原因？

yshf · 发表于 2018-10-18 22:23:00

Attribute prompt from AttributeReference ?
using System;
using System.Collections.Generic;
using Autodesk.AutoCAD.Runtime;
using AcRx = Autodesk.AutoCAD.Runtime;

namespace Autodesk.AutoCAD.DatabaseServices
{
public static class ExtensionMethods
{
      static RXClass attDefClass = RXClass.GetClass(typeof(AttributeDefinition));

      public static void SynchronizeAttributes(this BlockTableRecord target)
      {
         if (target == null)
            throw new ArgumentNullException("target");

         Transaction tr = target.Database.TransactionManager.TopTransaction;
         if (tr == null)
            throw new AcRx.Exception(ErrorStatus.NoActiveTransactions);

         List attDefs = target.GetAttributeDefinitions();
         foreach (ObjectId id in target.GetBlockReferenceIds(true, false))
         {
            BlockReference br = (BlockReference)tr.GetObject(id, OpenMode.ForWrite);
            br.ResetAttributes(attDefs, tr);
         }
         if (target.IsDynamicBlock)
         {
            target.UpdateAnonymousBlocks();
            foreach (ObjectId id in target.GetAnonymousBlockIds())
            {
                  BlockTableRecord btr = (BlockTableRecord)tr.GetObject(id, OpenMode.ForRead);
                  attDefs = btr.GetAttributeDefinitions();
                  foreach (ObjectId brId in btr.GetBlockReferenceIds(true, false))
                  {
                     BlockReference br = (BlockReference)tr.GetObject(brId, OpenMode.ForWrite);
                     br.ResetAttributes(attDefs, tr);
                  }
            }
         }
      }

      public static List GetAttributeDefinitions(this BlockTableRecord target)
      {
         if (target == null)
            throw new ArgumentNullException("target");

         Transaction tr = target.Database.TransactionManager.TopTransaction;
         if (tr == null)
            throw new AcRx.Exception(ErrorStatus.NoActiveTransactions);

         List attDefs = new List();
         foreach (ObjectId id in target)
         {
            if (id.ObjectClass == attDefClass)
            {
                  AttributeDefinition attDef = (AttributeDefinition)tr.GetObject(id, OpenMode.ForRead);
                  attDefs.Add(attDef);
            }
         }
         return attDefs;
      }

      private static void ResetAttributes(this BlockReference br, List attDefs, Transaction tr)
      {
         Dictionary attValues = new Dictionary();
         foreach (ObjectId id in br.AttributeCollection)
         {
            if (!id.IsErased)
            {
                  AttributeReference attRef = (AttributeReference)tr.GetObject(id, OpenMode.ForWrite);
                  if (!attValues.ContainsKey(attRef.Tag))
                  {
                     attValues.Add(attRef.Tag,
                        attRef.IsMTextAttribute ? attRef.MTextAttribute.Contents : attRef.TextString);
                  }
                  attRef.Erase();
            }
         }
         foreach (AttributeDefinition attDef in attDefs)
         {
            AttributeReference attRef = new AttributeReference();
            attRef.SetAttributeFromBlock(attDef, br.BlockTransform);
            if (attDef.Constant)
            {
                  attRef.TextString = attDef.IsMTextAttributeDefinition ?
                     attDef.MTextAttributeDefinition.Contents :
                     attDef.TextString;
            }
            else if (attValues.ContainsKey(attRef.Tag))
            {
                  attRef.TextString = attValues[attRef.Tag];
            }
            br.AttributeCollection.AppendAttribute(attRef);
            tr.AddNewlyCreatedDBObject(attRef, true);
         }
      }
}
}