VB.Net 图元文件生成错误 ("A generic error occurred in GDI+")

Question

我想得到你的一点帮助。我正在研究可以多次调用的图表创建器。图表每次都与早期版本不同，但我想使用相同的文件名。问题是，当我单击按钮时，程序显示的是带有图片框中图表的图表表单，但是如果表单已关闭并且我再次单击该按钮，则会出现错误（“GDI+ 中发生一般错误” ).我认为 mf.dispose() 不会关闭文件并打开它。你觉得是什么问题，我该如何解决？

主要形式：

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

图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

Answer 1

关闭表单Diagram_FORM时需要处理Diagram_FORM.PictureBox1.Image，否则下次在方法[=]中初始化Metafile相同文件名c:\temp\test.wmf时会出现异常16=] 共 class Diagram:

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

您可以在您的 Diagram_FORM 表单中添加以下代码，以便在您关闭它时处理它 PictureBox1.Image。

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

VB.Net 图元文件生成错误 ("A generic error occurred in GDI+")

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

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gdi+

metafile