CODEWITHSUNDEEP
vb.netgdi+metafile
meduzaHUN
meduzaHUN

Reputation: 3

VB.Net Metafile generates error ("A generic error occurred in GDI+")

I would like get a little help from you. I am working on a diagram creator which can be called more than once. The diagram every time is different than the earlier version but I would like to use the same filename. The problem is that when I click on the button the program is showing the diagram form with the diagram in the picturebox but if the form is closed and I am clicking on the button again I have an error ("A generic error occurred in GDI+"). I think the mf.dispose() does not close the file and it opened. What do you think what is the problem, how can I solve it?

Main Form:

Imports System.Runtime.InteropServices
Imports System.Drawing.Imaging

Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
        Diagram.create_diagram()
        Diagram_FORM.PictureBox1.Image = New Metafile("c:\temp\test.wmf")
        Diagram_FORM.Show()
    End Sub

Diagram Class:


Imports System.Runtime.InteropServices
Imports System.Drawing.Imaging

Class Diagram

Public Sub create_diagram()
        Dim diagram_width As Integer = 600
        Dim diagram_Height As Integer = 600
        Dim filename As String = "c:\temp\test.wmf"
        
        Dim gr As Graphics
        gr = Graphics.FromImage(New Bitmap(diagram_width, diagram_Height))

        ' Make a Graphics object so we can use its hDC as a reference.
        Dim hdc As IntPtr = gr.GetHdc


        ' Make the Metafile, using the reference hDC.
        Dim bounds As New RectangleF(0, 0, Diagram_WidthSize, Diagram_HeightSize)
        Dim mf As New Metafile(filename, hdc, bounds, MetafileFrameUnit.Pixel)

        gr.ReleaseHdc(hdc)

        ' Make a Graphics object and draw.
        gr = Graphics.FromImage(mf)
        gr.PageUnit = GraphicsUnit.Pixel
        gr.Clear(Color.White)

        draw_diagram_background(gr)
        draw_diagram_curve(gr)

        gr.Dispose()
        mf.Dispose()

    End Sub

Private Sub draw_diagram_background(Byval gr as Graphics)

     'some code

End Sub

Private Sub draw_diagram_curve(Byval gr as Graphics)

    'some code

End Sub

End Class

Upvotes: 0

Views: 190

Answers (1)

Dallon Xu
Dallon Xu

Reputation: 80

You need to dispose Diagram_FORM.PictureBox1.Image when you close Form Diagram_FORM, otherwise exception will occur when you init Metafile with same filename c:\temp\test.wmf next time in method create_diagram() of class Diagram:

Dim mf As New Metafile(filename, hdc, bounds, MetafileFrameUnit.Pixel)

You can add the following code in your Diagram_FORM Form to dispose it's PictureBox1.Image when you close it.

Protected Overrides Sub OnFormClosed(e As FormClosedEventArgs)
    If PictureBox1.Image IsNot Nothing Then
        PictureBox1.Image.Dispose()
    End If
    MyBase.OnFormClosed(e)
End Sub

Upvotes: 1

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