用.Net实现AutoCAD实体的多重选择

　　在使用.NET开发AutoCAD时，获取的选择集可以用SelectionFilter对象进行过滤，这样用户就可以只选择对自己操作有用的实体了。关于这个SelectionFilter选择过滤器，偶以前只知道用DxfCode.Start组码来过滤单种类形的实体（如直线、圆、圆弧等）。今天在才鸟兄的指点下，找到了几个多重选择CAD实体的方法，现总结如下：

只过滤直线实体

PromptSelectionOptions CurOption
                  = new PromptSelectionOptions();
CurOption.SingleOnly = false;
CurOption.AllowDuplicates = false;
CurOption.MessageForAdding = "<Ben>请选择曲线:";

TypedValue[] filList = new TypedValue[]{
     new TypedValue((int)DxfCode.Start,"LINE")
     };//只过滤直线

SelectionFilter filter = new SelectionFilter(filList);
PromptSelectionResult ssr
                 = ed.GetSelection(CurOption, filter);

同时过滤直线、圆和圆弧

PromptSelectionOptions CurOption
                 = new PromptSelectionOptions();
CurOption.SingleOnly = false;
CurOption.AllowDuplicates = false;
CurOption.MessageForAdding = "<Ben>请选择曲线:";

TypedValue[] filList = new TypedValue[]{
     new TypedValue((int)DxfCode.Start,"LINE,ARC,CIRCLE")
     };//同时过滤直线、圆和圆弧

SelectionFilter filter = new SelectionFilter(filList);
PromptSelectionResult ssr
               = ed.GetSelection(CurOption, filter);

过滤所有曲线

PromptSelectionOptions CurOption
              = new PromptSelectionOptions();
CurOption.SingleOnly = false;
CurOption.AllowDuplicates = false;
CurOption.MessageForAdding = "<Ben>请选择曲线:";

TypedValue[] filList = new TypedValue[]{
     new TypedValue((int)DxfCode.Subclass,"CURVE")
     };//过滤所有曲线

SelectionFilter filter = new SelectionFilter(filList);
PromptSelectionResult ssr
             = ed.GetSelection(CurOption, filter);

过滤0层上的所有曲线

PromptSelectionOptions CurOption
               = new PromptSelectionOptions();
CurOption.SingleOnly = false;
CurOption.AllowDuplicates = false;
CurOption.MessageForAdding = "<Ben>请选择曲线:";

TypedValue[] filList = new TypedValue[]{
     new TypedValue((int)DxfCode.Subclass,"CURVE"),
     new TypedValue((int)DxfCode.LayerName,"0")
     };//过滤0层上的所有曲线

SelectionFilter filter = new SelectionFilter(filList);
PromptSelectionResult ssr
             = ed.GetSelection(CurOption, filter);

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