以编程方式在 vb.net 中插入分页符

Question

所以我试图在直接从我的 VB.NET 程序打印时强制分页。我基本上是使用 MSDN 中的这段代码来打印我的文档：

Private Sub printDocument1_PrintPage(ByVal sender As Object, _
    ByVal e As PrintPageEventArgs)

    Dim charactersOnPage As Integer = 0
    Dim linesPerPage As Integer = 0

    ' Sets the value of charactersOnPage to the number of characters 
    ' of stringToPrint that will fit within the bounds of the page.
    e.Graphics.MeasureString(stringToPrint, Me.Font, e.MarginBounds.Size, _
        StringFormat.GenericTypographic, charactersOnPage, linesPerPage)

    ' Draws the string within the bounds of the page
    e.Graphics.DrawString(stringToPrint, Me.Font, Brushes.Black, _
    e.MarginBounds, StringFormat.GenericTypographic)

   ' Remove the portion of the string that has been printed.
    stringToPrint = stringToPrint.Substring(charactersOnPage)

    ' Check to see if more pages are to be printed.
    e.HasMorePages = stringToPrint.Length > 0

End Sub

这使它可以很好地打印，但我想在特定位置放置分页符。我试过 e.HasMorePages = true，但我不明白这如何让我在特定位置中断。假设我的 stringToPrint 长度为 5000 个字符，我想在 1000 个字符后开始新页面，然后在接下来的 2500 个字符后重新开始。我该怎么做？

此外，将 linesOnPage 和 charactersOnPage 更改为其他值似乎根本没有任何改变。

编辑：我想有关我的程序所做的更多信息会有所帮助。基本上它所做的是程序将创建大约 4 页完整的数据，并将其打印到 .txt 文件中。现在，我想打印整个 .txt 文件。我知道如何做到这一点的唯一方法是打印一个字符串，所以我让它逐行读取整个 .txt 文件并将其全部存储为一个字符串（即 stringToPrint）。现在，使用上面的代码，我打印 stringToPrint。

Answer 1

您当前的代码基于打印到矩形：e.MarginBounds

为了测试，我使用了这段代码：

Private pageNum As Integer

Private Sub Button1_Click(ByVal sender As Object, ByVal e As EventArgs) _
                          Handles Button1.Click
  Dim sb As New StringBuilder
  For i As Integer = 1 To 100
    sb.AppendLine(i.ToString & ") This is a line.")
  Next
  stringToPrint = sb.ToString

  pageNum = 0
  Using pvw As New PrintPreviewDialog()
    pvw.Document = printDocument1
    pvw.ShowDialog()
  End Using
End Sub

然后我将您的例程更改为在第一页上使用较小的矩形：

Private Sub printDocument1_PrintPage(ByVal sender As Object, _
                                     ByVal e As PrintPageEventArgs) _
                                     Handles printDocument1.PrintPage
  Dim charactersOnPage As Integer = 0
  Dim linesPerPage As Integer = 0

  pageNum += 1

  Dim printSize As Size = e.MarginBounds.Size
  If pageNum = 1 Then
    printSize = New Size(printSize.Width, printSize.Height / 2)
  End If
  e.Graphics.MeasureString(stringToPrint, Me.Font, printSize, _
      StringFormat.GenericTypographic, charactersOnPage, linesPerPage)

  ' Draws the string within the bounds of the page
  e.Graphics.DrawString(stringToPrint, Me.Font, Brushes.Black, _
    New Rectangle(e.MarginBounds.Location, printSize), _
    StringFormat.GenericTypographic)

  ' Remove the portion of the string that has been printed.
  stringToPrint = stringToPrint.Substring(charactersOnPage)

  ' Check to see if more pages are to be printed.
  e.HasMorePages = stringToPrint.Length > 0
End Sub

如果您需要根据字符控制打印，则必须放弃打印文本块的代码并逐行打印所有内容。