You are always drawing on the active layer. When you make a layer active, you create new objects on that layer. If you make a different layer active, any new objects you create is assigned that new active layer and uses its color and linetype. You cannot make a layer active if it is frozen.
用户总是在活动的图层上绘制图形。图层置为活动时，用户可以在该图层上创建新对象。如果将其他图层置为活动图层，所有新对象都将在新的活动图层上创建并且使用该图层的颜色和线型。如果图层被冻结，则不能将其置为活动。
To make a layer active, use the Clayer property of the Database object or the CLAYER system variable. For example:
若要使一个图层成为活动的，请使用 Database 对象的 Clayer 属性或 CLAYER 系统变量。例如：
This example sets a layer current through the Database object with the Clayer property.
本示例通过 Database 对象的 Clayer 属性将一个图层设置为当前图层。
Imports Autodesk.AutoCAD.Runtime
Imports Autodesk.AutoCAD.ApplicationServices
Imports Autodesk.AutoCAD.DatabaseServices
<CommandMethod("SetLayerCurrent")> _Public Sub SetLayerCurrent()
'' 获得当前文档和数据库 Get the current document and database
Dim acDoc As Document = Application.DocumentManager.MdiActiveDocument
Dim acCurDb As Database = acDoc.Database
''启动一个事务 Start a transaction
Using acTrans As Transaction = acCurDb.TransactionManager.StartTransaction()
'' 以只读方式打开图层表 Open the Layer table for read
Dim acLyrTbl As LayerTable
acLyrTbl = acTrans.GetObject(acCurDb.LayerTableId, _
OpenMode.ForRead)
Dim sLayerName As String = "Center"
If acLyrTbl.Has(sLayerName) = True Then
'' 设置 Center 层为当前图层 Set the layer Center current
acCurDb.Clayer = acLyrTbl(sLayerName)
'' 保存修改 Save the changes
acTrans.Commit()
End If
'' 销毁事务 Dispose of the transaction
End Using
End Sub
using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
[CommandMethod("SetLayerCurrent")]public static void SetLayerCurrent()
{// 获得当前文档和数据库 Get the current document and database
Document acDoc = Application.DocumentManager.MdiActiveDocument;
Database acCurDb = acDoc.Database;
// 启动一个事务 Start a transaction
using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
{// 以只读方式打开图层表 Open the Layer table for read
LayerTable acLyrTbl;
acLyrTbl = acTrans.GetObject(acCurDb.LayerTableId,
OpenMode.ForRead) as LayerTable;
string sLayerName = "Center";
if (acLyrTbl.Has(sLayerName) == true)
{// Set the layer Center current
acCurDb.Clayer = acLyrTbl[sLayerName];
// Save the changes
acTrans.Commit();
}
// Dispose of the transaction
}
}
