1. 点的拾取

有时候我们需要在CAD画布上实时选取起始点和结束点，然后绘制出来一条直线。实现如下：

public void getPoint()
        {
            var doc = Application.DocumentManager.MdiActiveDocument;
            var editor = doc.Editor;
            var docDatabase = doc.Database;
            PromptPointOptions ppo = new PromptPointOptions("拾取线段起点：");
            //获取线段起点的输入
            PromptPointResult pointResult = editor.GetPoint(ppo);
            var start = pointResult.Value;
            
            //基点到光标的虚线标识
            ppo.BasePoint = start;
            ppo.UseBasePoint=true;
            ppo.UseDashedLine=true;
            //如果用户设置了起始节点，再让用户获取结束节点
            if (pointResult.Status == PromptStatus.OK)
            {
                ppo.Message = "拾取线段终点：";
                pointResult = editor.GetPoint(ppo);
                var end = pointResult.Value;
                if (pointResult.Status == PromptStatus.OK)
                {
                    //方式一：绘制临时向量，并不存储到数据库中
                    // editor.DrawVector(start,end,1,false);
                    //方式二：提交到数据库
                    docDatabase.AddEnityToModelSpace(new Line(start, end));
                }
            }
        }

AddEnityToModelSpace方法见我前面文章封装的工具类

效果如下：

2. 角度的拾取

 public void getAngle()
        {
            var editor = Application.DocumentManager.MdiActiveDocument.Editor;
            PromptAngleOptions pao = new PromptAngleOptions("拾取角度：");
            pao.AllowNone = false;
            pao.UseDashedLine = true;
            pao.UseAngleBase=false;
            PromptDoubleResult startAngle = editor.GetAngle(pao);
            if (startAngle.Status == PromptStatus.OK)
            {
                editor.WriteMessage("\n角度：{0}", startAngle.Value);
            }
        }

最终效果：

3. 单个实体对象的拾取

public void getOneEntity()
        {
            var doc = Application.DocumentManager.MdiActiveDocument;
            Editor editor = doc.Editor;
            PromptEntityResult per = editor.GetEntity("\n拾取任意实体：");
            if (per.Status == PromptStatus.OK)
            {
                var perObjectId = per.ObjectId;
                using (Transaction ts = doc.Database.TransactionManager.StartTransaction())
                {
                    var entity = (Entity)ts.GetObject(perObjectId, OpenMode.ForRead,true);
                    editor.WriteMessage("\n拾取实体对象：{0},类型：{1}", entity.ToString(),entity.GetType().FullName);
                    ts.Commit();
                }
            }
        }

4. 特定实体对象的拾取

利用过滤器进行选择。

 public void getSpecificEntity()
        {
            var doc = Application.DocumentManager.MdiActiveDocument;
            Editor editor = doc.Editor;
            PromptEntityOptions peo = new PromptEntityOptions("\n拾取线条：");
            peo.SetRejectMessage("\n 选择的对象类型不是线条，请重新选择！");
            peo.AddAllowedClass(typeof(Line), true);
            PromptEntityResult per = editor.GetEntity(peo);
            if (per.Status == PromptStatus.OK)
            {
                var perObjectId = per.ObjectId;
                using (Transaction ts = doc.Database.TransactionManager.StartTransaction())
                {
                    var entity = (Entity)ts.GetObject(perObjectId, OpenMode.ForRead,true);
                    editor.WriteMessage("\n拾取实体对象：{0},类型：{1}", entity.ToString(),entity.GetType().FullName);
                    ts.Commit();
                }
            }
        }

5. 利用选择集拾取多个实体对象

/// <summary>
        /// 利用选择集选择多个实体对象
        /// </summary>
        [CommandMethod("selectEntities")]
        public void selectEntitiesTest()
        {
            List<Entity> entities = selectEntities();
        }
        
        public List<Entity> selectEntities()
        {
            var doc = Application.DocumentManager.MdiActiveDocument;
            Editor editor = doc.Editor;
            var docDatabase = doc.Database;

            SelectionSet selectionSet;
            //清空选择集
            var objectIds = new ObjectId[0];
            editor.SetImpliedSelection(objectIds);
            //请求从图形区域选择对象
            PromptSelectionResult psr = editor.GetSelection();
            if (psr.Status == PromptStatus.OK)
            {
                selectionSet = psr.Value;
                var objectIdList = selectionSet.GetObjectIds().ToList();
                List<Entity> entities = new List<Entity>();
                using (Transaction tr = docDatabase.TransactionManager.StartTransaction())
                {
                    foreach (var objectId in objectIdList)
                    {
                        var entity = (Entity)objectId.GetObject(OpenMode.ForRead);
                        entities.Add(entity);
                    }
                    tr.Commit();
                    return entities;
                }
            }
            return null;
        }