[求助] 菜鸟学习VBA二次开发遇到的弱问题……

Option Explicit On. ]1 ~# i; w7 l" l
Imports AutoCAD
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Public Class Form1
' Q/ t6 N+ x. ~8 s7 t( M+ I) _    Sub Ch2_ConnectToAcad()
" C1 K' S* `4 L8 f        Dim acadApp As AcadApplication
, q7 l% P+ K  Y$ x( k) l3 c. r! T! B        On Error Resume Next
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        acadApp = GetObject(, "AutoCAD.Application")
6 o8 x0 T4 q- x' K' z3 d        If Err.Number Then/ l' Q) `5 p9 z+ b3 S% }3 d
            Err.Clear()9 a, s6 x" {/ n0 p7 Q5 i
            acadApp = CreateObject("AutoCAD.Application")+ y  H* H: Q; ^5 a, U9 A9 l* G" ~
            If Err.Number Then, O6 G7 d- ]8 N5 B  S
                MsgBox(Err.Description)8 m+ f9 w" b9 |; o5 f# {$ S7 X- d+ v
                Exit Sub/ A- x/ {# `8 l( i
            End If) n+ i3 @. J) ^9 }- u0 R1 t, R* W
        End If
1 F2 ^' g, n+ R3 P        MsgBox("Now running " + acadApp.Name + _
( s5 P) z; O+ M$ b- V) U; t9 [        " version " + acadApp.Version), f& Y$ R: c$ Z1 u

: s/ P6 @, q- z' [) M    End Sub- g) H  _/ X' F0 v( \

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    Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
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    End Sub- f. ?* Q+ w( M% {

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5 T9 h- N7 X1 ]( i: B0 }    Private Sub Button1_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button1.Click4 c! O7 J! |, E: ^/ y
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        Dim Arc As AutoCAD.AcadArc
5 k& j4 R  g2 y5 S        Dim Pnt As Object- T& _2 N8 Q5 W$ x  Z" F& c
        Err.Clear()! d3 o: C3 m/ i  u
        On Error Resume Next% ]; V1 I) }8 Y3 z' m7 |) H
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        '选择圆弧0 b. M; v2 m$ N
        ThisDrawing.Utility.GetEntity(Arc, Pnt, "请选择圆弧：")
: i+ w* _' F! _1 W8 l. N0 g1 G        If Err.Number <> 13 And Err.Number <> 0 Then Exit Sub
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  P, R8 N5 c; q6 ~$ O  K        Do Until Arc.ObjectName = "AcDbArc"
5 w% J& m- U2 f$ m2 D            Err.Clear()( i: n7 P7 z; V- @& X
            ThisDrawing.Utility.GetEntity(Arc, Pnt, "你所选的不是圆弧，请重新选择圆弧：")# V% f; U9 P% {5 Y$ B9 x
            If Err.Number <> 13 And Err.Number <> 0 Then Exit Sub6 v6 F9 @9 t8 p. A
        Loop( k) ~  v$ z; h" ~7 z3 s
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        '获取圆弧各属性: }4 B" Q& Q+ [  E
        Dim Leng As Double+ F2 {. {- R" x6 E, D+ k
        Dim SPnt As Object
& I* S9 b" p& F, d( v8 j' ^        Dim EPnt As Object; t" o$ k. Q# k+ ^, E6 e) T. z' V1 w. P
        Dim CPnt As Object
2 }: g: Y$ v; M+ p2 G0 d        Leng = Arc.ArcLength: e% q# w6 u3 t$ f# h0 u
        SPnt = Arc.StartPoint
- R* }3 L, P! x        EPnt = Arc.EndPoint
; v8 }' ?8 h1 b- ?        CPnt = Arc.Center5 b1 ?3 S8 E0 X9 S9 x
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        '选择标注点: d, p5 z8 t. m; S5 e
        Dim PntforDim As Object
# G' R6 U: u% h7 w/ I7 a        PntforDim = ThisDrawing.Utility.GetPoint(, "选择标注点位置：")8 A( f! R7 a( ^1 u2 y) \# \4 m. ^
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        '对圆弧进行角度标注
& {' |) l; _% F* P  C9 f( U        Dim DimAng As AutoCAD.AcadDim3PointAngular, h( I( R+ Q5 y& j4 D2 [
        DimAng = ThisDrawing.ModelSpace.AddDim3PointAngular(CPnt, SPnt, EPnt, PntforDim)
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        '获取角度标注的精度控制(小数点位)
' _2 \/ h! |0 L: ^        Dim FormatDot As Integer
/ Z0 y) d2 ~( l        Dim FormatTxt As String
7 x8 b) S% g" m3 c        FormatDot = DimAng.TextPrecision
& |# {0 k) W8 V& l8 I/ m        '转换为精度控制格式. d7 O# U6 e3 {$ {- N! ~1 B; S8 H
        FormatTxt = "0."
* N; G& Q, K5 e0 O) e- s        Dim I As Integer2 n* Q- U* e9 m0 S7 L
        For I = 0 To FormatDot
* ^! U% L6 t9 w3 `            If I > 0 Then
# ^# v5 K7 p# d2 W" g- x                FormatTxt = FormatTxt & "0"4 s, w& T+ A8 ]( p, H
            End If. u# t1 I  h5 ]% }7 S6 ^
        Next
5 q8 S! P) B# H- F8 \        '更改角度标注的文字内容# f# k# e- c: h7 n* [0 h$ X
        DimAng.TextOverride = Format(Leng, FormatTxt)
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    End Sub
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End Class