无法在表格上画线 [英] Can not draw lines on form

问题描述

我有Windows 7(64位)

我有一个名为Form1的表单.

我也有一个名为DrawGid
的过程

I have Windows 7 (64Bit)

I have a form named Form1.

I also have a Procedure called DrawGid

Public Sub DrawGrid()
        Dim g As Graphics = Me.CreateGraphics
        Dim XN, YN As Integer
        Dim midx, midy As Single
        Dim UnitX, UnitY, OffsetX, OffsetY As Single
        Dim P As New Pen(Color.Black, 4)

        XN = 3 : YN = 3
        OffsetX = 30 : OffsetY = 30
        XN = 3 : YN = 3

        With Me
            midx = (.Width / 2)
            midy = (.Height / 2)
            UnitX = (.Width - OffsetX) / (2 * XN)
            UnitY = (.Height - OffsetY) / (2 * YN)
        End With

        'Draw Horizondal Lines of the grid
        '---------------------------------
        g.DrawLine(Pens.Orchid, 0, midy, Me.Width, midy)
        For i = 1 To YN
            g.DrawLine(Pens.Black, 0, midy + UnitY * i, Me.Width, midy + UnitY * i)
            g.DrawLine(Pens.Black, 0, midy - UnitY * i, Me.Width, midy - UnitY * i)
        Next
        'Draw Vertical Lines of the grid
        '---------------------------------
        g.DrawLine(Pens.Orchid, midx, 0, midx, Me.Height)
        For i = 1 To XN
            g.DrawLine(Pens.PaleGoldenrod, midx + UnitX * i, 0, midx + UnitX * i, Me.Height)
            g.DrawLine(Pens.PaleGoldenrod, midx - UnitX * i, 0, midx - UnitX * i, Me.Height)
        Next
    End Sub
End Class

加载Form1时，我编写以下代码:

When I load Form1 I write the following code:

Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load
      DrawGrid()
  End Sub

当我运行程序时，没有画线.任何人都可以

When I run the programe no lines are drawn. Could anybody please
help me?

推荐答案

为此，您将不得不覆盖"OnPaint"方法形式，并在其中添加绘图代码，如下所示:

For this you''ll have to override the forms ''OnPaint'' method and add the drawing code there, like so:

Protected Overrides Sub OnPaint(ByVal e As System.Windows.Forms.PaintEventArgs)

        Dim xn, yn, i As Integer
        Dim midx, midy As Single
        Dim Unitx, UnitY, OffsetX, OffsetY As Single
        Dim p As New Pen(Color.Black, 4)
        xn = 3
        yn = 3
        OffsetX = 30
        OffsetY = 30
        With Me
            midx = (.Width / 2)
            midy = (.Height / 2)
            Unitx = (.Width - OffsetX) / (2 * xn)
            UnitY = (.Height - OffsetY) / (2 * yn)
        End With

        e.Graphics.DrawLine(Pens.Orchid, 0, midy, Me.Width, midy)
        For i = 1 To yn
            e.Graphics.DrawLine(Pens.Black, 0, midy + UnitY * i, Me.Width, midy + UnitY * i)
            e.Graphics.DrawLine(Pens.Black, 0, midy - UnitY * i, Me.Width, midy - UnitY * i)
        Next i
        e.Graphics.DrawLine(Pens.Orchid, midx, 0, midx, Me.Height)
        For i = 1 To xn
            e.Graphics.DrawLine(Pens.PaleGoldenrod, midx + Unitx * i, 0, midx + Unitx * i, Me.Height)
            e.Graphics.DrawLine(Pens.PaleGoldenrod, midx - Unitx * i, 0, midx - Unitx * i, Me.Height)
        Next i

    End Sub

尝试使用图片框.

请参阅:使用VB在WinForms中绘制图形 [

Try using a picture box.

See: Drawing with Graphics in WinForms using VB[^]

Hope it helps.

Ahmed Djobby

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