Question

如何使用iTextSharp获取每页写入PdfPTable的总行数？

我想把我的所有代码onStartPage

public class MyPdfPageEventHelpPageNo : iTextSharp.text.pdf.PdfPageEventHelper
{
    public override void OnStartPage(PdfWriter writer, Document document)
    {
        /// my code
    }
}

Answer 1

正如布鲁诺所说，你想要调查IPdfPTableEvent。该特定界面的缺点是它在每个页面上都被调用，只有一个表格的副本被打印到该特定页面。因此，如果您有一个200行表，在第一页上，您可能只会看到一个包含50行的表，而您永远不会知道总行数。然而，有一个更有趣的界面，它来自于它IPdfPTableEventSplit，它接收原始表的副本，这也是你正在寻找的。

以下是该界面的基本实现。您可能需要应用一些额外的逻辑来考虑标题，但它应该相对容易。我也写在页面底部，但你可能想要调整它。

一个非常重要的注意事项是，如果表格没有拆分，则永远不会调用SplitTable。我通过检查TableLayout的默认行数是否已更改为其他内容，在-1方法中对此进行了说明。

public class TableRowCounter : IPdfPTableEventSplit {
    /// <summary>
    /// Will hold the total number of rows in the table if a split occurs,
    /// or negative one if no split happened.
    /// </summary>
    private int totalRowCount = -1;

    /// <summary>
    /// Holds the number of rows previously processed
    /// </summary>
    private int currentRowIndex = 0;

    /// <summary>
    /// Called if/when a table split happens
    /// </summary>
    /// <param name="table"></param>
    public void SplitTable(PdfPTable table) {
        this.totalRowCount = table.Rows.Count;
    }

    public void TableLayout(PdfPTable table, float[][] widths, float[] heights, int headerRows, int rowStart, PdfContentByte[] canvases) {
        //Count the number of rows processed in this iteration
        var thisRowCount = table.Rows.Count;

        //Get one of the canvases to draw on. You could also use one of these
        //PdfPTable.BACKGROUNDCANVAS or PdfPTable.LINECANVAS or PdfPTable.TEXTCANVAS 
        var writer = canvases[PdfPTable.BASECANVAS].PdfWriter;

        //Create our text
        var txt = String.Format(
            "Showing rows {0} through {1} of {2} total rows",
            (currentRowIndex + 1),                                  //Zero-based index convert to one-based
            (currentRowIndex + thisRowCount),   
            ( -1 == totalRowCount ? thisRowCount : totalRowCount)   //If a table split doesn't occur then our class variable won't be reset, just use the local count
            );

        //Draw our text
        ColumnText.ShowTextAligned(writer.DirectContent, Element.ALIGN_LEFT, new Phrase(txt), 10, 10, 0);

        //Increment our total row count
        currentRowIndex += table.Rows.Count;
    }
}

此代码的一个非常简单的实现是：

var testFile = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.Desktop), "test.pdf");

using (var fs = new FileStream(testFile, FileMode.Create, FileAccess.Write, FileShare.None)) {
    using (var doc = new Document()) {
        using (var writer = PdfWriter.GetInstance(doc, fs)) {
            doc.Open();

            var t = new PdfPTable(1);

            //Bind an instance of our table counter to the table event
            t.TableEvent = new TableRowCounter();
            for (var i = 1; i < 500; i++) {
                t.AddCell(i.ToString());
            }

            doc.Add(t);

            doc.Close();
        }
    }
}

将表行计数添加到每个页面

1 个答案: