如何在excel VBA中在窗口边缘绘制半圆

我试图用msoShapeArc和AddShape画一个半圆。半圆需要触到页面的顶部。为此，我将y值设置为-radius。这在C#中可以使用图形，但excel会忽略负坐标，并将形状降为零

    Sub DrawArrowArc(CentX As Single, CentY As Single, radius As Single, Ang1 As Single, Ang2 As Single)
       Dim Arc        As Shape
       'Draw 90-degree arc with radius = Radius and center at (CenterX,CenterY)
       Set Arc = ActiveSheet.Shapes.AddShape(msoShapeArc, CentX, CentY - radius, radius, radius)
       'Add arrowhead on clockwise end
       Arc.Line.EndArrowheadStyle = msoArrowheadNone
       'adjust arrow to start at Ang1 and end at Ang2
       '(measured clockwise positive from vertical)
       Arc.Adjustments.Item(1) = 90 - Ang1
       Arc.Adjustments.Item(2) = 90 - Ang2
    End Sub

DrawArrowArc 0, -100, 100, 90, -90

我对实现这一目标的不同方式持开放态度。圆不需要像形状一样可以选择或编辑，它的图片就可以了

它确实需要动态绘制

它必须是一个完美的半圆。压扁它是不可接受的

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你觉得怎么样？

这在左上角画了一个半圆：

 Call DrawArrowArc(0, -100, 100, -90, 90)

Sub DrawArrowArc(CentX As Single, CentY As Single, radius As Single, Ang1 As 
    Single, Ang2 As Single)
    Dim Arc As Shape    ' 
    'Draw 90-degree arc with radius = Radius and center at (CenterX,CenterY)
    Set Arc = ActiveSheet.Shapes.AddShape(msoShapeArc, CentX, CentY - 
    radius,radius, radius)
    'Add arrowhead on clockwise end
    Arc.Line.EndArrowheadStyle = msoArrowheadNone
    'adjust arrow to start at Ang1 and end at Ang2
    '(measured clockwise positive from vertical)
    Arc.Adjustments.Item(1) = 90 - Ang1
    Arc.Adjustments.Item(2) = 90 - Ang2
    Arc.ThreeD.RotationY = 180

End Sub

Sub CallDrawArrowArc()
    DrawArrowArc 0, -100, 100, -90, 90
End Sub