c# - Itextsharp PDFPTable 如何在整个表格周围制作边框

Question

我正在使用 PDFPTable 通过 Itextsharp 中的数据库构建表格，要求表格中的行/单元格没有顶部或底部底部边框，但每个单元格的左侧和右侧都有黑色边框(换句话说，每列都有一个左右边框)，表格的底部也需要用黑色边框关闭，这就是我的问题所在。

我正在做的是将边框设置为 0，然后手动分配边框，这样我就只能在每个单元格上获得左右边框，如下所示，这是生成“数量”列的示例:

    cell = new PdfPCell(new Phrase(Qty.value, subheaderFont));
    cell.HorizontalAlignment = Element.ALIGN_CENTER;
    cell.VerticalAlignment = Element.ALIGN_MIDDLE; 
    cell.BackgroundColor = new iTextSharp.text.BaseColor(220, 220, 220);
    cell.Border = 0;
    cell.BorderColorLeft = BaseColor.BLACK;
    cell.BorderWidthLeft = .5f;
    cell.BorderColorRight = BaseColor.BLACK;
    cell.BorderWidthRight = .5f;
    table.AddCell(cell); 

问题显然是我无法检测最后一行以添加边框底部，但我想必须有一种方法来控制“表格”本身的边框，或者我采取了错误的方法到这个？

Answer 1

如您所见，PdfPTable没有边框，可能是因为 PDF 一开始就没有表格。将边框放在 PdfPCell 上可能更有意义直接(即使 PDF 也不支持这些)。无论如何，表格只是单元格的集合，所以让他们处理它。

无论如何，解决方案是在 PdfPTable 类的实例上设置 TableEvent。为此，您需要自定义实现 IPdfPTableEvent界面。下面的代码通常应该为您执行此操作(请参阅底部的“一般”注释)

class TopBottomTableBorderMaker : IPdfPTableEvent {
    private BaseColor _borderColor;
    private float _borderWidth;

    /// <summary>
    /// Add a top and bottom border to the table.
    /// </summary>
    /// <param name="borderColor">The color of the border.</param>
    /// <param name="borderWidth">The width of the border</param>
    public TopBottomTableBorderMaker(BaseColor borderColor, float borderWidth ) {
        this._borderColor = borderColor;
        this._borderWidth = borderWidth;
    }
    public void TableLayout(PdfPTable table, float[][] widths, float[] heights, int headerRows, int rowStart, PdfContentByte[] canvases) {
        //widths (should be thought of as x's) is an array of arrays, first index is for each row, second index is for each column
        //The below uses first and last to calculate where each X should start and end
        var firstRowWidths = widths[0];
        var lastRowWidths = widths[widths.Length - 1];

        var firstRowXStart = firstRowWidths[0];
        var firstRowXEnd = firstRowWidths[firstRowWidths.Length - 1] - firstRowXStart;

        var lastRowXStart = lastRowWidths[0];
        var lastRowXEnd = lastRowWidths[lastRowWidths.Length - 1] - lastRowXStart;

        //heights (should be thought of as y's) is the y for each row's top plus one extra for the last row's bottom
        //The below uses first and last to calculate where each Y should start and end
        var firstRowYStart = heights[0];
        var firstRowYEnd = heights[1] - firstRowYStart;

        var lastRowYStart = heights[heights.Length - 1];
        var lastRowYEnd = heights[heights.Length - 2] - lastRowYStart;

        //Where we're going to draw our lines
        PdfContentByte canvas = canvases[PdfPTable.LINECANVAS];

        //I always try to save the previous state before changinge anything
        canvas.SaveState();

        //Set our line properties
        canvas.SetLineWidth(this._borderWidth);
        canvas.SetColorStroke(this._borderColor);

        //Draw some rectangles
        canvas.Rectangle(
                        firstRowXStart,
                        firstRowYStart,
                        firstRowXEnd,
                        firstRowYEnd
                        );
        //They aren't actually drawn until you stroke them!
        canvas.Stroke();

        canvas.Rectangle(
                        lastRowXStart,
                        lastRowYStart,
                        lastRowXEnd,
                        lastRowYEnd
                        );
        canvas.Stroke();

        //Restore any previous settings
        canvas.RestoreState();

    }
}

使用起来非常简单，只需将一个实例绑定(bind)到属性上即可:

//Create your name as you normally do
var table = new PdfPTable(3);

//Bind and instance with properties set
table.TableEvent = new TopBottomTableBorderMaker(BaseColor.BLACK, 0.5f);

//The rest is the same
for (var i = 0; i < 6; i++) {
    var cell = new PdfPCell(new Phrase(i.ToString()));
    cell.HorizontalAlignment = Element.ALIGN_CENTER;
    cell.VerticalAlignment = Element.ALIGN_MIDDLE;
    cell.BackgroundColor = new iTextSharp.text.BaseColor(220, 220, 220);
    cell.Border = 0;
    cell.BorderColorLeft = BaseColor.BLACK;
    cell.BorderWidthLeft = .5f;
    cell.BorderColorRight = BaseColor.BLACK;
    cell.BorderWidthRight = .5f;
    table.AddCell(cell);
}

上面我说“一般”它应该有效。但是，如果您有表格页眉和/或页脚，您也需要将它们考虑在内。这应该不会太难，但您需要调整 y 值以考虑 table.HeaderRows 和 table.FooterRows。