1

是否有一些建议来构建带有段落的单元格的表格，以避免在将某些单元格添加到表格或将表格添加到文档时出现异常？我明白了，但我不知道会发生什么：

[NullReferenceException: Object reference not set to an instance of an object.]
   iText.Layout.Renderer.TableRenderer.DrawBorders(DrawContext drawContext) +2493
   iText.Layout.Renderer.TableRenderer.DrawChildren(DrawContext drawContext) +1497
   iText.Layout.Renderer.AbstractRenderer.Draw(DrawContext drawContext) +153
   iText.Layout.Renderer.TableRenderer.Draw(DrawContext drawContext) +637
   iText.Layout.Renderer.AbstractRenderer.DrawChildren(DrawContext drawContext) +104
   iText.Layout.Renderer.BlockRenderer.Draw(DrawContext drawContext) +525
   iText.Layout.Renderer.TableRenderer.DrawChildren(DrawContext drawContext) +1382
   iText.Layout.Renderer.AbstractRenderer.Draw(DrawContext drawContext) +153
   iText.Layout.Renderer.TableRenderer.Draw(DrawContext drawContext) +637
   iText.Layout.Renderer.DocumentRenderer.FlushSingleRenderer(IRenderer resultRenderer) +473
   iText.Layout.Renderer.RootRenderer.AddChild(IRenderer renderer) +1999
   iText.Layout.RootElement`1.Add(BlockElement`1 element) +92
   iText.Layout.Document.Add(BlockElement`1 element) +81

这是一个使用 Windows 控制台项目的简单快照（与真实项目相比）：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using iText.Layout;
using iText.Layout.Borders;
using iText.Layout.Element;

namespace iTextTest
{
    public static class iTextSharpHelper
    {
        public static T SetBorderEx<T>(this ElementPropertyContainer<T> element, Border border)
           where T : ElementPropertyContainer<T>
        {
            element.SetBorder(border);

            return (T)element;
        }

        public static Paragraph Style(this BlockElement<Paragraph> element)
        {
            element
                .SetBorderEx(iText.Layout.Borders.Border.NO_BORDER)
                .SetFont(iText.Kernel.Font.PdfFontFactory.CreateFont(iText.IO.Font.FontConstants.HELVETICA))
                .SetFontSize(10.0f)
                .SetFixedLeading(12.0f)
                .SetVerticalAlignment(iText.Layout.Properties.VerticalAlignment.BOTTOM)
                .SetMargin(0f);

            return (Paragraph)element;
        }
    }

    class Program
    {
        private static float[] tableColumns = { 0.35f, 0.25f, 0.15f, 0.25f };

        static void Main(string[] args)
        {
            iText.Kernel.Pdf.PdfDocument pdf = new iText.Kernel.Pdf.PdfDocument(new iText.Kernel.Pdf.PdfWriter("test.pdf"));

            iText.Layout.Document document = new iText.Layout.Document(pdf, iText.Kernel.Geom.PageSize.A4);

            document.SetMargins(50f, 50f, 25f, 50f);

            iText.Layout.Element.Table mainTable = new iText.Layout.Element.Table(tableColumns)
                .SetBorderEx(iText.Layout.Borders.Border.NO_BORDER)
                .SetWidthPercent(100)
                .SetHorizontalAlignment(iText.Layout.Properties.HorizontalAlignment.LEFT)
                .SetPadding(0f);

            for (int i = 0; i < 10; i++)
            {
                AddRow(mainTable, "ABCDEFGHIJ", "ABCDEFGHIJ", "ABCDEFGHIJ");
            }

            document.Add(mainTable);

            document.Close();
        }

        private static void AddRow(iText.Layout.Element.Table table, string col1, string col2, string col3)
        {
            // Label
            AddCell(table, col1, true)
                .SetBorderTop(new iText.Layout.Borders.SolidBorder(iText.Kernel.Colors.Color.BLACK, 0.5f));

            // Product - Voucher and price/pcs        
            AddCell(table, col2, true)
                .SetBorderTop(new iText.Layout.Borders.SolidBorder(iText.Kernel.Colors.Color.BLACK, 0.5f));

            // Message
            AddCell(table, col3, true, 2)
                .SetBorderTop(new iText.Layout.Borders.SolidBorder(iText.Kernel.Colors.Color.BLACK, 0.5f))
                //.SetBorderRight(new iText.Layout.Borders.SolidBorder(iText.Kernel.Colors.Color.BLACK, 0.5f))
                .SetHorizontalAlignment(iText.Layout.Properties.HorizontalAlignment.RIGHT)
                .SetTextAlignment(iText.Layout.Properties.TextAlignment.RIGHT);
        }

        private static iText.Layout.Element.Cell AddCell(iText.Layout.Element.Table table, string text, bool setBold = false, int colSpan = 1)
        {
            iText.Layout.Element.Cell cell = new iText.Layout.Element.Cell(1, colSpan)
                .SetBorderEx(iText.Layout.Borders.Border.NO_BORDER)
                .SetVerticalAlignment(iText.Layout.Properties.VerticalAlignment.BOTTOM);

            if (!string.IsNullOrEmpty(text))
            {
            iText.Layout.Element.Paragraph paragraph = new iText.Layout.Element.Paragraph(text)
               .Style();

            if (setBold)
                paragraph.SetBold();

            cell.Add(paragraph);
            }

            table.AddCell(cell);

            return cell;
        }
    }
}

注意，注释掉的代码行：

//.SetBorderRight(new iText.Layout.Borders.SolidBorder(iText.Kernel.Colors.Color.BLACK, 0.5f))

添加它作为一种解决方法，使文档无异常呈现。

4

1 回答 1

3

鉴于 OP 添加的示例代码，可以轻松重现该问题。

此外，在将代码移植到 iText/Java 之后，问题也可以在那里重现，参见。MikesTableIssue.java测试方法testMikesCode。因此，从 Java（原始 iText 代码）到 C# 没有移植错误。

该示例甚至可以大大简化并仍然重现该问题：

try (   FileOutputStream target = new FileOutputStream("mikesTableIssueSimple.pdf");
        PdfWriter pdfWriter = new PdfWriter(target);
        PdfDocument pdfDocument = new PdfDocument(pdfWriter)    )
{
    Document document = new Document(pdfDocument);
    Table mainTable = new Table(1);
    Cell cell = new Cell()
            .setBorder(Border.NO_BORDER)
            //.setBorderRight(new SolidBorder(Color.BLACK, 0.5f))
            .setBorderTop(new SolidBorder(Color.BLACK, 0.5f));
    cell.add("TESCHTINK");
    mainTable.addCell(cell);
    document.add(mainTable);
}

( MikesTableIssue.java 测试方法testSimplified)

如果一个问题不会发生

  • 删除setBorder(Border.NO_BORDER)或
  • 删除setBorderTop(new SolidBorder(Color.BLACK, 0.5f))或
  • 补充道setBorderRight(new SolidBorder(Color.BLACK, 0.5f))。

在这种情况下com.itextpdf.layout.renderer.TableRenderer.drawBorders(DrawContext)执行以下代码：

if (lastBorder != null) {
    if (verticalBorders.get(j).size() > 0) {
        if (i == 0) {
            x2 += verticalBorders.get(j).get(i).getWidth() / 2;
        } else if(i == horizontalBorders.size() - 1 && verticalBorders.get(j).size() >= i - 1 && verticalBorders.get(j).get(i - 1) != null) {
            x2 += verticalBorders.get(j).get(i - 1).getWidth() / 2;
        }
    }

    lastBorder.drawCellBorder(drawContext.getCanvas(), x1, y1, x2, y1);
}

whilelastBorder是SolidBorder实例，verticalBorders是和。[[null], [null]]j == 1i == 0

因此，null这里应该引入一些额外的检查。

于 2016-08-01T16:27:50.590 回答