iText - 避免最后一行不将页面拆分到下一页 [英] iText - avoid last row not to cut tables on page split to next page

问题描述

我正在使用java在itext 5上工作。我的页面包含多个动态行表。在某些情况下，表格的最后一行将被拆分为下一页，其中包含以下标题。我正在使用 setHeaderRows（）和 setSkipFirstHeader（）来管理下一页的继续。最后一行有足够的空间放在前面的页面上。我想将最后一行放在同一页面而不是下一页。

I am working on itext 5 using java. I have pages with mutiple tables with dynamic rows. In some instances, the table last row is splitted into next page with the folowing header. I am using setHeaderRows() and setSkipFirstHeader() to manage continuation of next page. The last row has enough space to fit on earlier page. I would like to fit that last row in same page instead of next page.

例如，在第1页，最后一行被拆分为下一页的第一行。相反，我想在第1页中安装该行，因此请保留一个包含所有空格的额外页面。

For example, on page 1, the last row is splitted into first row of next page. Instead I would like to fit that row in page 1 so save one extra page with all blanks.

我尝试使用 setExtendLastRow（），但它不起作用。有谁知道如何解决这个问题。我附加了一个工作示例代码。

I tried using setExtendLastRow(), but its not working. Does anyone know how to fix this problem. I am attaching a working sample code.

public class ProposalItextSplitLastRow {
 public static void main(String[] args) {
    try {
        Document document = new Document();
        document.setPageSize(PageSize.LETTER);
        document.setMargins(16, 14, 14, 14);
        PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream("C:/SplitLastRow.pdf"));
        document.open();
        document.setPageSize(PageSize.LETTER);
        document.setMargins(16, 14, 42, 38);

        for (int m = 1; m < 20; m++) {

            int row = 0;
            PdfPTable table = new PdfPTable(1);
            table.setSpacingAfter(0);
            table.setSpacingBefore(0);
            table.setWidthPercentage(100);

            table.setHeaderRows(1);
            table.setSkipFirstHeader(true);
            add(table, "Header Row continued " + m, BaseColor.LIGHT_GRAY, row++);
            add(table, "Header Row normal " + m, BaseColor.LIGHT_GRAY, row++);

            add(table, "Text Row 1 ", BaseColor.WHITE, row++);
            add(table, "Text Row 2 ", BaseColor.WHITE, row++);
            add(table, "Text Row 3 ", BaseColor.WHITE, row++);

            addPadding(table);

            document.add(table);
        }

        document.close();
    } catch (Exception de) {
        de.printStackTrace();
    }
}

private static void add(PdfPTable table, String text, BaseColor color, int row) {
    PdfPCell pdfCellHeader = new PdfPCell();
    pdfCellHeader.setBackgroundColor(color);
    pdfCellHeader.addElement(new Paragraph(new Phrase(text)));
    table.addCell(pdfCellHeader);
}

private static void addPadding(PdfPTable table) {
    PdfPCell cell = new PdfPCell();
    cell.setFixedHeight(2f);
    cell.setBorder(Rectangle.NO_BORDER);
    cell.setColspan(table.getNumberOfColumns());
    table.addCell(cell);
}
}

推荐答案

我必须执行示例才能理解您的问题。你通过谈论一个不是标题的标题（标题行正常的行不是标题行！）和你对 setExtendLastRow（）的引用让我感到困惑。也没有帮助（提到这种方法对我来说没有意义;这非常令人困惑）。

I had to execute the example to understand your question. You confused me by talking about a header that isn't a header (the rows with "Header Row normal" aren't header rows!) and your reference to setExtendLastRow() didn't help either (mentioning that method doesn't make sense to me; it's very confusing).

这就是说，问题的解决方案是 - 闻风而动。我重写了主要类：

This being said, the solution to your problem is a no-brainer. I've rewritten the main class:

public static void main(String[] args) {
    try {
        Document document = new Document();
        document.setPageSize(PageSize.LETTER);
        document.setMargins(16, 14, 14, 14);
        PdfWriter writer = PdfWriter.getInstance(document,
                new FileOutputStream("SplitLastRow.pdf"));
        document.open();
        document.setPageSize(PageSize.LETTER);
        document.setMargins(16, 14, 42, 38);

        for (int m = 1; m < 20; m++) {

            int row = 0;
            PdfPTable table = new PdfPTable(1);
            table.setSpacingAfter(0);
            table.setSpacingBefore(0);
            table.setTotalWidth(document.right() - document.left());
            table.setLockedWidth(true);

            table.setHeaderRows(1);
            table.setSkipFirstHeader(true);
            add(table, "Header Row continued " + m, BaseColor.LIGHT_GRAY, row++);
            add(table, "Header Row normal " + m, BaseColor.LIGHT_GRAY, row++);

            add(table, "Text Row 1 ", BaseColor.WHITE, row++);
            add(table, "Text Row 2 ", BaseColor.WHITE, row++);
            add(table, "Text Row 3 ", BaseColor.WHITE, row++);

            addPadding(table);
            if (writer.getVerticalPosition(true) - table.getRowHeight(0) - table.getRowHeight(1) < document.bottom()) {
                document.newPage();
            }
            document.add(table);
        }

        document.close();
    } catch (Exception de) {
        de.printStackTrace();
    }
}

确保定义总宽度而不是宽度百分比，而锁定宽度。如文档所述（以及常识告诉您），如果您定义宽度百分比， PdfPTable 对象不知道其实际宽度。不言而喻，你无法计算不知道它的实际宽度的表的高度。

Make sure you define a total width instead of a width percentage, and lock the width. As documented (and as common sense tells you), a PdfPTable object doesn't know its actual width if you define a width percentage. It goes without saying that you can't calculate the height of a table that doesn't know it's actual width.

然后使用 getVerticalPosition（） 获取光标当前位置的方法，并检查前两行是否适合页面。如果他们在添加表之前没有转到新页面。如果要检查整个表是否适合，请使用 getTotalHeight（）方法而不是 getRowHeight（）方法。

Then use getVerticalPosition() method to get the current position of the cursor, and check if the first two rows fit on the page. If they don't go to a new page before adding the table. If you want to check if the complete table fits, use the getTotalHeight() method instead of the getRowHeight() method.

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