vb.net - 在 VB.NET 中将 JPEG 转换为 PNG（保存的输出没有扩展名）

Question

这是我转换图像的代码

Public Sub ConvertImage(ByVal Filename As String, _
      ByVal DesiredFormat As System.Drawing.Imaging.ImageFormat, _
      ByVal NewFilename As String)
        NewFilename = "ConvertedToPNG-" + NewFilename + "-" + Format(Date.Now, "MMMMddyyyyhhmmtt")
        Try
            Dim imgFile As System.Drawing.Image = _
              System.Drawing.Image.FromFile(Filename)
            imgFile.Save(txtPNGFileDestination.Text & "\" & NewFilename, DesiredFormat)
        Catch ex As Exception
            Throw ex
        End Try
    End Sub

它运行正常，但保存的图像没有 PNG 文件扩展名，因此它只是一个文件。我做错什么了吗？

谢谢你的帮助

Answer 1

只需将扩展名添加到 NewFileName。您还需要声明 NewFileName "ByRef"：

Public Sub ConvertImage(ByVal Filename As String, ByVal DesiredFormat As System.Drawing.Imaging.ImageFormat, ByRef NewFilename As String)
  NewFilename = "ConvertedToPNG-" + NewFilename + "-" + Format(Date.Now, "MMMMddyyyyhhmmtt") & "." & DesiredFormat.ToString