得到图上所有PL线，然后再PL线打碎，变成直线，和圆弧,得样条线，并离散成点.

• 回答：

         procedure TForm3.Button1Click(Sender: TObject);
          var ss        : IMxDrawSelectionSet;
          filter        : IMxDrawResbuf;
          ii,jj                    : Integer;
          pEnt,pTmp                  : IMxDrawEntity;
          pPolyline             : IMxDrawPolyline;
          param        : IMxDrawResbuf;
          line         : IMxDrawLine;
          pts,pte,minPt,maxPt,pt      : IMxDrawPoint;
          arc          : IMxDrawArc;
          spl          : IMxDrawSpline;
          points       : IMxDrawPoints;
          dApproxEps   : DOUBLE;
          blkRef       : MxDrawBlockReference;
          begin                // 创建一个选择集对象                ss :=  CoMxDrawSelectionSet.Create();                // 创建一个过滤条件对象                filter := CoMxDrawResbuf.Create();                // 选择图上所有实体                ss.AllSelect(filter);                // 遍历构造后的选择集实体，找到边界线。
                  for ii := 0 to ss.Count -1 do
                  begin                        // 遍历所有实体
                      pEnt := ss.Item(ii);                    // 对图块的处理.
                      pEnt.QueryInterface(MxDrawBlockReference, blkRef);                    if blkRef <> nil then
                      begin                    // 是个图块文件.
                          param := blkRef.Explode();                        for jj := 0 to param.Count -1 do
                          begin
                                  pTmp :=  IMxDrawEntity(param.AtObject(jj) );
                                  pTmp.QueryInterface(IMxDrawLine, line);                                if(line <> nil) then
                                  begin                                  // 这是图块内的直线。                                  showmessage('Line');
                                  end;                                // 处理其它实体，图块里面还可能再嵌套图块，这时需要递归处理.
                                  // ...
  
                                  // 删除临时生成的文件.
                                  pTmp.Erase();
                          end;
  
                      end;                    ///
                      pEnt.QueryInterface(IMxDrawSpline, spl);                    if spl <> nil then
                      begin                      // 对象是个样条线。
                        // 得到样条线的外包
                        points := spl.GetBoundingBox2();                      //   dApproxEps样条线的离形精度
                        dApproxEps := 0.01;                      // 根据样条线的大小，动态确定离线精度。
                        if points.Count > 1 then
                        begin                          // 外包的最小点，和最大点
                            minPt := points.Item(0);
                            maxPt := points.Item(1);                          //    dApproxEps取外包最短边长的 1/20
                            if abs(minPt.x - maxPt.x) < abs(minPt.y - maxPt.y)then
                            begin
                              dApproxEps := abs(minPt.x - maxPt.x) / 20;
                            end                          else
                            begin
                              dApproxEps := abs(minPt.y - maxPt.y) / 20;
                            end;                          // 如果为 dApproxEps零，就默认取   0.01
                            if dApproxEps < 0.0000001 then
                                 dApproxEps := 0.01;
  
  
                        end;                     // showmessage(Format('dApproxEps:%g',[dApproxEps]) );
  
                       // 离散样条线.
                        points := spl.GetSamplePoints(dApproxEps);                      // 遍历样条线上的所有点，可以把这些点，做为样条线的拟合点，用来重生样条线。
                         for jj := 1 to points.Count -1 do
                         begin
                               pt :=   points.Item(jj);
                               showmessage(Format('X:%g,Y:%g',[pt.x,pt.y]) );
  
                         end;
  
                      end;
  
                      pEnt.QueryInterface(IMxDrawPolyline, pPolyline);                    if pPolyline <> nil then
                      begin                           // 得到一个PL线对象。
                             // 打碎PL线，把PL线变成直线，和圆弧                           param :=    CoMxDrawResbuf.Create();
                             param.AddObjectId(pEnt.ObjectID);                           // 调用打碎函数，打碎实体.
                             param := MxDrawResbuf(MxDrawX1.CallEx('Mx_Explode', param));                           // 遍历打碎后的实体，得到所有曲线。
                             for jj := 1 to param.Count -1 do
                             begin                                //
                                  pEnt := IMxDrawEntity(param.AtObject(jj));
                                  pEnt.QueryInterface(IMxDrawLine, line);                                if(line <> nil) then
                                  begin                                    // 这是PL线里的直线
                                      // 得到直线的，开始点，和结束点，
                                      pts := line.StartPoint;
                                      pte := line.EndPoint;                                      //showmessage('line');
                                      // 调用Delphi的绘制直线函数，绘直线
                                      // ...
  
                                  end;
  
                                  pEnt.QueryInterface(IMxDrawArc, arc);                                 if(arc <> nil) then
                                   begin                                    // 这是PL线里的圆弧
                                      // 得到圆弧中点，半径，开始角，结束角，
                                      // arc.Center;
                                      // arc.StartAngle;
                                      // arc.EndAngle;
                                      // arc.Radius;
  
                                     //showmessage('arc');
  
                                      // 调用Delphi的绘圆弧函数，绘直线
                                      // ...
  
                                  end;
                                  pEnt.Erase();
  
                             end;
                      end;
                  end;
              end;