Tracing a boundary defined by AutoCAD geometry using .NET

csharp

http://through-the-interface.typepad.com/through_the_interface/2010/06/tracing-a-boundary-defined-by-autocad-geometry-using-net.html

Tracing a boundary defined by AutoCAD geometry using .NET



As alluded to in this previous post, today we’re going to see some code that makes use of a very cool new API feature in AutoCAD 2011: the Editor.TraceBoundary() function. This little gem performs something developers have struggled with – and have asked us for – for many years. Previously you had to jump through significant hoops (or should that be loops? <groan>) to get this to work: one common approach would be to drive the BOUNDARY command programmatically and check the results appended to the database. All very messy.

Anyway, we got there eventually. This function takes a “seed” point and returns a collection of newly-created entities that define our boundary. We can then either pump these through the transient graphics sub-system or – and this is the approach we’re going to take – add them to the drawing to make them persistent.

You need to bear in mind that this function ultimately has similar constraints to the BOUNDARY and BHATCH commands: it also works off AutoCAD’s display list and so the user will need to be appropriately ZOOMed into the geometry that is to be used for boundary detection.

Here’s some C# code to create boundaries – with a lineweight applied and of an automatically incremented colour index – for points the user selects:

1. using Autodesk.AutoCAD.ApplicationServices;
   
2. 
   
3. using Autodesk.AutoCAD.EditorInput;
   
4. 
   
5. using Autodesk.AutoCAD.DatabaseServices;
   
6. 
   
7. using Autodesk.AutoCAD.Runtime;
   
8. 
   
9. 
   
10. 
    
11. namespace TraceBoundary
    
12. {
    
13.   public class Commands
    
14.   {
    
15.     static int _index = 1;
    
16.     [CommandMethod("TB")]
    
17.     public void TraceBoundary()
    
18.     {
    
19.       Document doc =  Application.DocumentManager.MdiActiveDocument;
    
20.       Database db = doc.Database;
    
21.       Editor ed = doc.Editor;
    
22. 
    
23.       // Select a seed point for our boundary
    
24. 
    
25.       PromptPointResult ppr =  ed.GetPoint("
    
26. Select internal point: ");
    
27. 
    
28.       if (ppr.Status != PromptStatus.OK)        return;
    
29. 
    
30.       // Get the objects making up our boundary
    
31. 
    
32.       DBObjectCollection objs =  ed.TraceBoundary(ppr.Value, true);
    
33. 
    
34.       if (objs.Count > 0)
    
35.       {
    
36.         Transaction tr =
    
37.           doc.TransactionManager.StartTransaction();
    
38. 
    
39.         using (tr)
    
40.         {
    
41. 
    
42.           // We'll add the objects to the model space
    
43. 
    
44.           BlockTable bt =
    
45.             (BlockTable)tr.GetObject(
    
46.               doc.Database.BlockTableId,
    
47.               OpenMode.ForRead
    
48.             );
    
49. 
    
50.           BlockTableRecord btr =
    
51.             (BlockTableRecord)tr.GetObject(
    
52.               bt[BlockTableRecord.ModelSpace],
    
53.               OpenMode.ForWrite
    
54.             );
    
55. 
    
56.           // Add our boundary objects to the drawing and
    
57.           // collect their ObjectIds for later use
    
58. 
    
59.           ObjectIdCollection ids = new ObjectIdCollection();
    
60.           foreach (DBObject obj in objs)
    
61. 
    
62.           {
    
63. 
    
64.             Entity ent = obj as Entity;
    
65.             if (ent != null)
    
66.             {
    
67. 
    
68.               // Set our boundary objects to be of
    
69.               // our auto-incremented colour index
    
70. 
    
71.               ent.ColorIndex = _index;
    
72. 
    
73.               // Set the lineweight of our object
    
74. 
    
75.               ent.LineWeight = LineWeight.LineWeight050;
    
76. 
    
77.               // Add each boundary object to the modelspace
    
78.               // and add its ID to a collection
    
79. 
    
80.               ids.Add(btr.AppendEntity(ent));
    
81. 
    
82.               tr.AddNewlyCreatedDBObject(ent, true);
    
83. 
    
84.             }
    
85.           }
    
86. 
    
87.           // Increment our colour index
    
88. 
    
89.           _index++;
    
90. 
    
91.           // Commit the transaction
    
92. 
    
93.           tr.Commit();
    
94. 
    
95.         }
    
96.       }
    
97.     }
    
98.   }
    
99. }
    

using Autodesk.AutoCAD.ApplicationServices;<br /> <br /> using Autodesk.AutoCAD.EditorInput;<br /> <br /> using Autodesk.AutoCAD.DatabaseServices;<br /> <br /> using Autodesk.AutoCAD.Runtime;<br /> <br /> <br /> <br /> namespace TraceBoundary<br /> {<br />   public class Commands<br />   {<br />     static int _index = 1;<br />     [CommandMethod("TB")]<br />     public void TraceBoundary()<br />     {<br />       Document doc =  Application.DocumentManager.MdiActiveDocument;<br />       Database db = doc.Database;<br />       Editor ed = doc.Editor; <br /> <br />       // Select a seed point for our boundary<br /> <br />       PromptPointResult ppr =  ed.GetPoint("<br /> Select internal point: "); <br /> <br />       if (ppr.Status != PromptStatus.OK)        return; <br /> <br />       // Get the objects making up our boundary <br /> <br />       DBObjectCollection objs =  ed.TraceBoundary(ppr.Value, true);<br /> <br />       if (objs.Count > 0)<br />       {<br />         Transaction tr =<br />           doc.TransactionManager.StartTransaction();<br /> <br />         using (tr)<br />         {<br /> <br />           // We'll add the objects to the model space <br /> <br />           BlockTable bt =<br />             (BlockTable)tr.GetObject(<br />               doc.Database.BlockTableId,<br />               OpenMode.ForRead<br />             ); <br /> <br />           BlockTableRecord btr =<br />             (BlockTableRecord)tr.GetObject(<br />               bt[BlockTableRecord.ModelSpace],<br />               OpenMode.ForWrite<br />             ); <br /> <br />           // Add our boundary objects to the drawing and<br />           // collect their ObjectIds for later use <br /> <br />           ObjectIdCollection ids = new ObjectIdCollection();<br />           foreach (DBObject obj in objs)<br /> <br />           {<br /> <br />             Entity ent = obj as Entity;<br />             if (ent != null)<br />             {<br /> <br />               // Set our boundary objects to be of<br />               // our auto-incremented colour index <br /> <br />               ent.ColorIndex = _index; <br /> <br />               // Set the lineweight of our object <br /> <br />               ent.LineWeight = LineWeight.LineWeight050; <br /> <br />               // Add each boundary object to the modelspace<br />               // and add its ID to a collection <br /> <br />               ids.Add(btr.AppendEntity(ent));<br /> <br />               tr.AddNewlyCreatedDBObject(ent, true);<br /> <br />             }<br />           } <br /> <br />           // Increment our colour index <br /> <br />           _index++; <br /> <br />           // Commit the transaction <br /> <br />           tr.Commit();<br /> <br />         }<br />       }<br />     }<br />   }<br /> }<br />

Here’s our TB command in action.

Before…

/db_自贡黄明儒_

LZ，没有lisp版的？

csharp

/db_自贡黄明儒_ 发表于 2014-5-9 11:41
LZ，没有lisp版的？

可以写成一个lisp函数，就如xdrxapi
低版本的Net没有这个函数，2011以上

xinxirong

hpgaptol系统变量不能自动找到封闭区域，有办法自定义traceboundary吗？
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szjyf123456

非常感谢楼主，学习一下

史巴燕

感谢楼主分享！学习中！
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史巴燕

感谢楼主分享！学习中！
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brainstorm

图很大的时候 这个会很慢吧
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