AutoCAD .Net 创建直线Line

以下代码展示：
* 创建直线
* 设置图元的图层
* 设置图元的颜色
* 设置图元的线型
* 设置图元的线宽

using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Geometry;
using Autodesk.AutoCAD.EditorInput;
using Autodesk.AutoCAD.Colors;

[CommandMethod("NewLine")]
public static void NewLine()
{
    Document doc = Application.DocumentManager.MdiActiveDocument;
    Database db = doc.Database;

    using (Transaction tr = db.TransactionManager.StartTransaction())
    {
        //-------------------------------
        // 获取模型空间
        //-------------------------------
        BlockTable blockTbl = tr.GetObject(
            db.BlockTableId, OpenMode.ForRead) as BlockTable;
        BlockTableRecord modelSpace = tr.GetObject(
            blockTbl[BlockTableRecord.ModelSpace], OpenMode.ForWrite) as BlockTableRecord;

        //-------------------------------
        // 创建直线
        //-------------------------------
        Line line = new Line();
        line.StartPoint = new Point3d(0, 0, 0);
        line.EndPoint = new Point3d(100, 100, 0);

        //-------------------------------
        // 图层: test_layer
        //-------------------------------
        string layerName = "test_layer";
        LayerTable layerTbl = tr.GetObject(
            db.LayerTableId, OpenMode.ForRead) as LayerTable;
        if (layerTbl.Has(layerName))
        {
            line.Layer = layerName;
        }

        //-------------------------------
        // 颜色
        //-------------------------------
        // 颜色索引
        //line.Color = Color.FromColorIndex(ColorMethod.ByAci, 4);
        // 随块
        //line.Color = Color.FromColorIndex(ColorMethod.ByBlock, 0);
        // 随层
        //line.Color = Color.FromColorIndex(ColorMethod.ByLayer, 256);
        // RGB
        line.Color = Color.FromRgb(255, 0, 0);

        //-------------------------------
        // 线型: Center
        //-------------------------------
        string linetypeName = "Center";
        LinetypeTable linetypeTbl = tr.GetObject(
            db.LinetypeTableId, OpenMode.ForRead) as LinetypeTable;
        if (!linetypeTbl.Has(linetypeName))
        {
            db.LoadLineTypeFile(linetypeName, "acad.lin");
        }
        if (linetypeTbl.Has(linetypeName))
        {
            line.Linetype = linetypeName;
        }

        //-------------------------------
        // 线宽
        //-------------------------------
        //line.LineWeight = LineWeight.ByLayer;
        //line.LineWeight = LineWeight.ByBlock;
        //line.LineWeight = LineWeight.ByLineWeightDefault;
        line.LineWeight = LineWeight.LineWeight106;

        //-------------------------------
        // 添加到模型空间并提交到数据库
        //-------------------------------
        modelSpace.AppendEntity(line);
        tr.AddNewlyCreatedDBObject(line, true);
        tr.Commit();
    }
}