为什么我不能将包含 PdfFormField 的 PdfPTable 写入现有PDF？ iTextSharp告诉我

在此上下文中不受支持 . 使用PdfStamper.addAnnotation（） .

Private Sub RR(PdfFileName As String)
    Dim reader As New PdfReader(PdfFileName)
    Dim RandomFileName As String = System.IO.Path.GetRandomFileName
    Dim OutputPdf As String = System.IO.Path.GetDirectoryName(PdfFileName) & "\" & System.IO.Path.GetFileNameWithoutExtension(RandomFileName) & ".pdf"

    Dim stamper As New PdfStamper(reader, New FileStream(OutputPdf, FileMode.Create))
    Dim table As New PdfPTable(1)
    Dim PageMargin As Single = 20
    Dim tbCell As New PdfPCell()

    table.TotalWidth = (reader.GetPageSize(1).Right - reader.GetPageSize(1).Left) - 20
    Dim PDfFormField As PdfFormField = CreateTextField(stamper.Writer, "TestField", 0, 0)
    tbCell = New PdfPCell With {.CellEvent = New iTextSharp.text.pdf.events.FieldPositioningEvents(stamper.Writer, PDfFormField), .MinimumHeight = 10, .BorderWidth = 0.1}

    With table
        .AddCell(tbCell)
    End With

    table.WriteSelectedRows(0, -1, PageMargin, Bottom + table.TotalHeight + PageMargin, stamper.GetOverContent(1))

    stamper.Close()
    reader.Close()

End Sub

1 回答

问题

iTextSharp类 FieldPositioningEvents 只能在将 PdfWriter 与 PdfDocument 实例结合使用时从头开始创建新PDF，因为它使用了冲压上下文中不支持的 writer.addAnnotation(field) / fieldWriter.addAnnotation(cellField) 调用 .

解决方案

要解决此限制，只需创建自己的单元格事件侦听器，该侦听器使用 addAnnotation 重载，并在 PdfStamper 中显示页码 .

（遗憾的是，我在本世纪尚未完成任何VB编码;但我希望，C＃中的示例也可以提供帮助 . ）

例如 . 以下是从原始 FieldPositioningEvents 代码派生的事件监听器，但仅限于单元格事件并适用于 PdfStamper ：

public class StampingFieldPositioningEvents : IPdfPCellEvent
{
    /** Keeps the form field that is to be positioned in a cellLayout event. */
    protected PdfFormField cellField = null;

    /** The PdfStamper to use when a field has to added in a cell event. */
    protected PdfStamper fieldStamper = null;

    /** Some extra padding that will be taken into account when defining the widget. */
    public float padding;

    /** The page on which the field is added */
    int fieldPage = 0;

    /** Creates a new event. This constructor will be used if you need to position fields with a Cell Event. */
    public StampingFieldPositioningEvents(PdfStamper stamper, PdfFormField field, int page)
    {
        this.cellField = field;
        this.fieldStamper = stamper;
        this.fieldPage = page;
    }

    /** Creates a new event. This constructor will be used if you need to position fields with a Cell Event. */
    public StampingFieldPositioningEvents(PdfStamper stamper, String text, int page)
    {
        this.fieldStamper = stamper;
        TextField tf = new TextField(stamper.Writer, new Rectangle(0, 0), text);
        tf.FontSize = 14;
        cellField = tf.GetTextField();
        this.fieldPage = page;
    }

    /** The padding to set. */
    virtual public float Padding
    {
        set
        {
            padding = value;
        }
        get
        {
            return padding;
        }
    }

    /** IPdfPCellEvent implementation */
    virtual public void CellLayout(PdfPCell cell, Rectangle rect, PdfContentByte[] canvases)
    {
        cellField.Put(PdfName.RECT, new PdfRectangle(rect.GetLeft(padding), rect.GetBottom(padding), rect.GetRight(padding), rect.GetTop(padding)));
        fieldStamper.AddAnnotation(cellField, fieldPage);
    }
}

它的使用方式类似于OP的原始代码：

PdfReader reader = new PdfReader(SOURCE);
PdfStamper stamper = new PdfStamper(reader, new FileStream(DESTINATION, FileMode.Create));

int pageMargin = 20;
PdfPTable table = new PdfPTable(1);
table.TotalWidth = reader.GetPageSize(1).Width - 40;

PdfFormField formField = PdfFormField.CreateTextField(stamper.Writer, false, false, 50);
formField.SetWidget(new Rectangle(0, 0), null);
formField.FieldName = "TestField";
PdfPCell tbCell = new PdfPCell
{
    CellEvent = new StampingFieldPositioningEvents(stamper, formField, 1),
    MinimumHeight = 10,
    BorderWidth = 0.1f
};

table.AddCell(tbCell);

table.WriteSelectedRows(0, -1, reader.GetPageSize(1).Left + pageMargin, reader.GetPageSize(1).Bottom + table.TotalHeight + pageMargin, stamper.GetOverContent(1));

stamper.Close();
reader.Close();

回复于 2024-06-02T15:24:16+08:00

iTextsharp PdfPTable writeselectedrows

1 回答

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