我已经为此苦苦挣扎了一段时间，所以我想我会将这个发布给任何能够找到解决方案的大师。
我有一个要复制的 PDF 文档，当我复制它时，我想将页面大小调整为自定义大小。例如，原始文档的页面大小为 8 1/2 x 16。新文档需要为 8 1/2 x 22。新文档中的 8 1/2 来自原文档的宽度；22 是固定的（常数）。使问题复杂化的是新文档需要将旧文档内容放在页面中心。因此，在新文档中，它需要具有顶部 3 英寸、底部 3 英寸的边距，以便原始的 16 英寸居中。宽度无关紧要，只是高度需要居中。
寻找 iTextSharp 的代码片段。
创建了以下有效的解决方案。发回社区，希望它可以帮助某人。解决方案在 VB.NET 中。
使用带有 2 个布尔值的调用 resizeAndRotateDocument。“旋转” - 将每一页旋转 90 度 - 真，假。和“调整大小” - 将页面大小调整为 22 英寸高度，并将页边距添加到顶部/底部到中心页面 - 真/假。还有 2 个字符串：要处理的输入 pdf 文件的名称和要创建的输出 pdf 文件的名称。
Private Sub AdjustMediaBoxSize(ByRef mediaBoxSize As PdfArray, ByVal rotationIsPresent As Boolean)
Const Fixed_22_Inch_Page As Integer = 22 * 72
Dim ll_x, ll_y, ur_x, ur_y As Integer
Dim heightDiff, heightAdjustment As Integer
Dim new_ll_x, new_ll_y, new_ur_x, new_ur_y As Integer
' Read current coordinates of the Mediabox
ll_x = mediaBoxSize(0).ToString
ll_y = mediaBoxSize(1).ToString
ur_x = mediaBoxSize(2).ToString
ur_y = mediaBoxSize(3).ToString
' Figure out the height difference and the adjustment factor.
If rotationIsPresent = True Then
heightDiff = Fixed_22_Inch_Page - ur_x
Else
heightDiff = Fixed_22_Inch_Page - ur_y
End If
' adjustment needed to top and to bottom
heightAdjustment = heightDiff / 2
' Apply the adjustments; only use the ones we need.
new_ll_x = ll_x - heightAdjustment
new_ur_x = ur_x + heightAdjustment
new_ll_y = ll_y - heightAdjustment
new_ur_y = ur_y + heightAdjustment
If rotationIsPresent = True Then
mediaBoxSize(0) = New iTextSharp.text.pdf.PdfNumber(new_ll_x)
mediaBoxSize(2) = New iTextSharp.text.pdf.PdfNumber(new_ur_x)
Else
' Make the adjustment. Value is passed back by reference.
mediaBoxSize(1) = New iTextSharp.text.pdf.PdfNumber(new_ll_y)
mediaBoxSize(3) = New iTextSharp.text.pdf.PdfNumber(new_ur_y)
End If
End Sub
Private Sub resizeAndRotateDocument(ByVal rotate As Boolean, ByVal resize As Boolean, ByVal inPDF As String, ByVal outPDF As String)
Const desiredRot As Integer = 90
Dim reader As New PdfReader(inPDF)
Dim pageCount As Integer = reader.NumberOfPages
Dim pageDict As PdfDictionary
Dim mediabox As New PdfArray
Dim cropbox As New PdfArray
For i As Integer = 1 To pageCount
pageDict = reader.GetPageN(i)
' Rotation is hard coded to 90 degrees.
If rotate = True Then
pageDict.Put(PdfName.ROTATE, New PdfNumber(desiredRot))
End If
If resize = True Then
' Read the current mediabox dimensions.
' Then adjust the size to scale up to 22 inches adjusting for rotation if necessary.
' Finally, write the updated mediabox back to the dictionary -> to the reader.
mediabox = pageDict.GetAsArray(PdfName.MEDIABOX)
AdjustMediaBoxSize(mediabox, rotate)
pageDict.Put(PdfName.MEDIABOX, mediabox)
End If
' Since the PDFs are created in-house, they should NEVER contain a cropbox.
cropbox = pageDict.GetAsArray(PdfName.CROPBOX)
If cropbox IsNot Nothing Then
MsgBox("Error ... found a valid cropbox !!!")
End If
Next
' Use the stamper to create and write the pdf output file.
Dim pdfStamper As New PdfStamper(reader, New FileStream(outPDF, FileMode.Create))
pdfStamper.Close()
End Sub
再次感谢布鲁诺！