创建弧长尺寸 （.NET）

弧长尺寸测量沿圆弧的长度，并使用弧形符号显示尺寸文本，该圆弧符号位于弧上方或继续。当您需要标注弧的实际长度而不仅仅是弧起点和终点之间的距离时，可以使用弧长尺寸。

通过创建对象的实例来创建弧长半径尺寸。创建对象的实例时，它需要一组定义维度的参数。创建新对象时必须提供以下参数：ArcDimensionArcDimensionArcDimension

• 中心点（属性）Center
• 延长线 1 点（属性）XLine1Point
• 延长线2点（属性）XLine2Point
• 弧点（属性）ArcPoint
• 尺寸文本（属性）DimensionText
• 标注样式（或属性）DimensionStyleNameDimensionStyle

创建弧长尺寸

本示例在模型空间中创建弧长尺寸。

Imports Autodesk.AutoCAD.Runtime
Imports Autodesk.AutoCAD.ApplicationServices
Imports Autodesk.AutoCAD.DatabaseServices
Imports Autodesk.AutoCAD.Geometry
 
<CommandMethod("CreateArcLengthDimension")> _
Public Sub CreateArcLengthDimension()
    '' Get the current database
    Dim acDoc As Document = Application.DocumentManager.MdiActiveDocument
    Dim acCurDb As Database = acDoc.Database

    '' Start a transaction
    Using acTrans As Transaction = acCurDb.TransactionManager.StartTransaction()

        '' Open the Block table for read
        Dim acBlkTbl As BlockTable
        acBlkTbl = acTrans.GetObject(acCurDb.BlockTableId, _
                                     OpenMode.ForRead)

        '' Open the Block table record Model space for write
        Dim acBlkTblRec As BlockTableRecord
        acBlkTblRec = acTrans.GetObject(acBlkTbl(BlockTableRecord.ModelSpace), _
                                        OpenMode.ForWrite)

        '' Create an arc length dimension
        Using acArcDim As ArcDimension = New ArcDimension(New Point3d(4.5, 1.5, 0), _
                                                          New Point3d(8, 4.25, 0), _
                                                          New Point3d(0, 2, 0), _
                                                          New Point3d(5, 7, 0), _
                                                          "<>", _
                                                          acCurDb.Dimstyle)

            '' Add the new object to Model space and the transaction
            acBlkTblRec.AppendEntity(acArcDim)
            acTrans.AddNewlyCreatedDBObject(acArcDim, True)
        End Using

        '' Commit the changes and dispose of the transaction
        acTrans.Commit()
    End Using
End Sub

using Autodesk.AutoCAD.Runtime;
using Autodesk.AutoCAD.ApplicationServices;
using Autodesk.AutoCAD.DatabaseServices;
using Autodesk.AutoCAD.Geometry;
 
[CommandMethod("CreateArcLengthDimension")]
public static void CreateArcLengthDimension()
{
    // Get the current database
    Document acDoc = Application.DocumentManager.MdiActiveDocument;
    Database acCurDb = acDoc.Database;

    // Start a transaction
    using (Transaction acTrans = acCurDb.TransactionManager.StartTransaction())
    {
        // Open the Block table for read
        BlockTable acBlkTbl;
        acBlkTbl = acTrans.GetObject(acCurDb.BlockTableId,
                                        OpenMode.ForRead) as BlockTable;

        // Open the Block table record Model space for write
        BlockTableRecord acBlkTblRec;
        acBlkTblRec = acTrans.GetObject(acBlkTbl[BlockTableRecord.ModelSpace],
                                        OpenMode.ForWrite) as BlockTableRecord;

        // Create an arc length dimension
        using (ArcDimension acArcDim = new ArcDimension(new Point3d(4.5, 1.5, 0),
                                                        new Point3d(8, 4.25, 0),
                                                        new Point3d(0, 2, 0),
                                                        new Point3d(5, 7, 0),
                                                        "<>",
                                                        acCurDb.Dimstyle))
        {

            // Add the new object to Model space and the transaction
            acBlkTblRec.AppendEntity(acArcDim);
            acTrans.AddNewlyCreatedDBObject(acArcDim, true);
        }

        // Commit the changes and dispose of the transaction
        acTrans.Commit();
    }
}

Sub CreateArcLengthDimension()
    Dim dimObj As AcadDimArcLength
    Dim arcCenterPoint(0 To 2) As Double
    Dim firstPoint(0 To 2) As Double
    Dim secondPoint(0 To 2) As Double
    Dim arcPoint(0 To 2) As Double
 
    ' Define the dimension
    arcCenterPoint(0) = 4.5: arcCenterPoint(1) = 1.5: arcCenterPoint(2) = 0
    firstPoint(0) = 8: firstPoint(1) = 4.25: firstPoint(2) = 0
    secondPoint(0) = 0: secondPoint(1) = 2: secondPoint(2) = 0
    arcPoint(0) = 5: arcPoint(1) = 7: arcPoint(2) = 0
 
    ' Create the arc length dimension in Model space
    Set dimObj = ThisDrawing.ModelSpace. _
                     AddDimArc(arcCenterPoint, firstPoint, _
                     secondPoint, arcPoint)
 
    ZoomAll
End Sub