我正在使用ITextSharp将HTML文档转换为PDF。我使用HTMLWorker.ParseToList并依次循环遍历每个项目。这很好，但是第一页要求后续页面具有不同的边距大小。我可以通过调用MyDocument.NewPage（）并调用MyDocument.SetMargins（）来完成此任务。
尝试检测页面转换时出现问题。
我可以使用循环来跟踪页面转换，然后调用NewPage（）并重置边距，但是，只有在我实际添加了一个包装到新页面的段落时才会发生这种情况，只留下一个几乎是白色的整个页面-space。
如果我添加某个Paragraph对象，我需要一种预先检测页面是否会改变的方法。
我已经尝试使用ColumnText.Go（true）来模拟它（如果结果是ColumnText.NO_MORE_COLUMN，那么让它成为一个分页符），不幸的是，这似乎是最好的，并且倾向于检测分页符完全错误的地方。
这是我目前的代码：
ColumnText simulation = new ColumnText(Writer.DirectContent);
simulation.SetSimpleColumn(Writer.PageSize);
bool FirstPage = true;
foreach (var item in ItemList)
{
var para = new Paragraph("", Normal);
para.AddAll(item.Chunks);
para.SpacingAfter = 10;
foreach (Chunk c in item.Chunks)
{
simulation.AddText(c);
}
if(FirstPage) {
int simresult = simulation.Go(true);
if(simresult == (int)ColumnText.NO_MORE_COLUMN)
{
textDocument.SetMargins(100,100,100,100);
textDocument.NewPage();
FirstPage = false;
}
}
textDocument.Add(para);
}
这导致它在第2页结束之前没有检测到分页符。这是不好的。
我发现让它工作的唯一方法是HALF进入simulation.SetSimpleColumn的高度。
它有效，但我不知道为什么，老实说，这不好。如果有人能给我任何有用的见解。
internal class MainTextEventsHandler : PdfPageEventHelper
{
public override void OnStartPage(PdfWriter writer, Document document)
{
document.SetMargins(document.LeftMargin, document.LeftMargin, document.TopMargin, document.BottomMargin); //Mirror the horizontal margins
document.NewPage(); //do this otherwise the margins won't take
}
}
接下来，我设置了Writer对象的PageEvent属性，并修改了我的循环以删除模拟。
Writer.PageEvent = new MainTextEventsHandler();
foreach (var item in ItemList)
{
var para = new Paragraph("", Normal);
para.AddAll(item.Chunks);
/* per-paragraph stuff here */
para.SpacingAfter = 10;
textDocument.Add(para);
}
答案 0 :(得分：2)
请查看Page Events，特别是onStartPage和/或onEndPage，以确定是否必须更改文档的边距。
请注意，这些示例适用于Java版本，但转换为iTextSharp应该很简单。
答案 1 :(得分：2)
试试这段代码：
public const string pageBreakHtmlMarker = "<!-- pageBreak -->";
public MemoryStream htmlToPdf(string html)
{
MemoryStream msOutput = new MemoryStream();
string[] sep = new string[] { pageBreakHtmlMarker };
string[] arrHtml = html.Split(sep, 9999, StringSplitOptions.RemoveEmptyEntries);
htmlToPdf(arrHtml, ref msOutput);
return msOutput;
}
private void htmlToPdf(string[] arrHtmlPages, ref MemoryStream msOutput)
{
using (Document document = new Document(PageSize.A4, 30, 30, 30, 30))
{
using (HTMLWorker worker = new HTMLWorker(document))
{
PdfWriter writer = PdfWriter.GetInstance(document, msOutput); // writer to listen doc ad direct a XML-stream to a file
document.Open();
worker.StartDocument();
foreach (string html in arrHtmlPages)
{
TextReader reader = new StringReader(html); // parse the html into the document
worker.Parse(reader);
document.Add(Chunk.NEXTPAGE);
}
worker.EndDocument();
}
}
}
答案 2 :(得分：0)
Visual Basic中的示例代码段
在LoadPage中使用：
Dim pdfPageEvents As pdfPageEvents = New pdfPageEvents
writer = PdfWriter.GetInstance(doc, memMemoryStream)
writer.CloseStream = False
writer.PageEvent = pdfPageEvents
doc.Open()
将此类放在相同的文件或命名空间
Public Class pdfPageEvents
Inherits iTextSharp.text.pdf.PdfPageEventHelper
Private _strTitle As String, _strPrintFeatures As String
Public Sub New(ByVal Title As String, ByVal PrintFeatures As String)
_strTitle = Title
_strPrintFeatures = PrintFeatures
End Sub
Public Overrides Sub OnStartPage(ByVal writer As PdfWriter, ByVal doc As Document)
If InStr(_strPrintFeatures, "header") > 0 Then
Dim fntFont As Font = FontFactory.GetFont("Tahoma", BaseFont.CP1250, True, 10, Font.NORMAL, New BaseColor(128, 128, 128))
Dim imgImage As iTextSharp.text.Image = iTextSharp.text.Image.GetInstance(HttpContext.Current.Server.MapPath("../LocalResources/Images/print_company_logo_medium.png"))
Dim tblTable As New PdfPTable(2)
Dim celRightCell As PdfPCell
tblTable.WidthPercentage = 100
tblTable.HorizontalAlignment = Element.ALIGN_CENTER
imgImage.ScalePercent(70)
Dim celLeftCell As New PdfPCell(New Phrase(_strTitle, fntFont))
celLeftCell.HorizontalAlignment = Element.ALIGN_LEFT
celLeftCell.Border = 0
celLeftCell.BorderWidthBottom = 0.5
celLeftCell.BorderColorBottom = New BaseColor(128, 128, 128)
celLeftCell.VerticalAlignment = Element.ALIGN_BOTTOM
celLeftCell.PaddingBottom = 3
tblTable.AddCell(celLeftCell)
If InStr(_strPrintFeatures, "logo") > 0 Then
celRightCell = New PdfPCell(imgImage)
Else
celRightCell = New PdfPCell(New Paragraph(""))
End If
celRightCell.HorizontalAlignment = Element.ALIGN_RIGHT
celRightCell.Border = 0
celRightCell.BorderWidthBottom = 0.5
celRightCell.BorderColorBottom = New BaseColor(128, 128, 128)
celRightCell.VerticalAlignment = Element.ALIGN_BOTTOM
celRightCell.PaddingBottom = 3
tblTable.AddCell(celRightCell)
doc.Add(tblTable)
doc.Add(New Paragraph(vbNewLine))
End If
End Sub
Public Overrides Sub OnEndPage(ByVal writer As PdfWriter, ByVal doc As Document)
If InStr(_strPrintFeatures, "footer") > 0 Then
Dim fntFont As Font = FontFactory.GetFont("Tahoma", BaseFont.CP1250, True, 10, Font.NORMAL, New BaseColor(128, 128, 128))
Dim tblTable As New PdfPTable(2)
Dim strDate As String = IIf(InStr(_strPrintFeatures, "date") > 0, FormatDateTime(Date.Today, DateFormat.GeneralDate), "")
tblTable.TotalWidth = doc.PageSize.Width - doc.LeftMargin - doc.RightMargin
tblTable.HorizontalAlignment = Element.ALIGN_CENTER
Dim celLeftCell As New PdfPCell(New Phrase(strDate, fntFont))
celLeftCell.HorizontalAlignment = Element.ALIGN_LEFT
celLeftCell.Border = 0
celLeftCell.BorderWidthTop = 0.5
celLeftCell.BorderColorTop = New BaseColor(128, 128, 128)
celLeftCell.VerticalAlignment = Element.ALIGN_BOTTOM
tblTable.AddCell(celLeftCell)
Dim celRightCell As New PdfPCell(New Phrase(CStr(doc.PageNumber), fntFont))
celRightCell.HorizontalAlignment = Element.ALIGN_RIGHT
celRightCell.Border = 0
celRightCell.BorderWidthTop = 0.5
celRightCell.BorderColorTop = New BaseColor(128, 128, 128)
celRightCell.VerticalAlignment = Element.ALIGN_BOTTOM
tblTable.AddCell(celRightCell)
tblTable.WriteSelectedRows(0, -1, doc.LeftMargin, (doc.BottomMargin), writer.DirectContent)
End If
End Sub
End Class