iText pdf表格画斜线

在使用iText输出pdf表格文件时，有时存在较复杂的报表样式，需要支持在表格中画斜线，支持斜线表头，
iText在单元格中画斜线采用PdfContentByte的lineTo方法，斜线的坐标位置是采用相对于Document的绝对位置，
并不是相对于单元格的相对位置.



单元格画斜线
1. 创建一个iText Document 对象，pdf文档大小设置为A4，通过PdfWriter对象获取PdfContentByte 对象为 canvas，
下面是通过canvas去画图形

Document document = new Document();
PdfWriter writer = PdfWriter.getInstance(document, fos);
writer.setViewerPreferences(PdfWriter.PageModeUseThumbs);
document.setPageSize(PageSize.A4);
document.open();
PdfContentByte canvas = writer.getDirectContent();

2. 创建一个PdfPTable 对象，Pdf Table需要指定每列的宽度，pdf的宽度=像素宽*0.75, 指定Table的总宽度，总宽度是每列宽度之和，
设置Table相对于Document居左对齐。

PdfPTable table = new PdfPTable(widths);
table.setLockedWidth(true);
table.setTotalWidth(458 * PDF_PERCENT);
table.setHorizontalAlignment(Element.ALIGN_LEFT);

3. 画第一个单元格3个斜线，x1,y1,x2,y2,x3,y3为线的坐标终止位置，开始坐标为单元格开始位置，
LEFT=36，TOP=36，是PdfTable距离文档的左边距和上边距，而Pdf的y坐标位置是从底部开始计算的，所以第一个单元格的坐标位置是
document.getPageSize().getHeight() - TOP 与 LEFT, canvas.moveTo()单元格坐标位置，3条线分别lineTo()每个条线的终止坐标。

int x1 = 61, y1 = 77;
int x2 = 132, y2 = 76;
int x3 = 144, y3 = 31;
float top = document.getPageSize().getHeight() - TOP;
drawLine(canvas, LEFT, top, x1, y1);
drawLine(canvas, LEFT, top, x2, y2);
drawLine(canvas, LEFT, top, x3, y3);
 
canvas.saveState();
canvas.moveTo(left, top);
canvas.lineTo(left + x * PDF_PERCENT, top - y * PDF_PERCENT);
canvas.stroke();
canvas.restoreState();

4. 画表头斜线坐标比较容易确定，如果画表格中间单元格的斜线需要计算单元格的坐标位置，如下cellX=第一列宽 + 第二列宽，
cellY = 第一行高 * PDF_PERCENT

int cellX = (int) (widths[0] + widths[1]);
int cellY = (int) (77 * PDF_PERCENT);
int x = 201, y = 84;
drawLine(canvas, LEFT + cellX, top - cellY, x, y);

完整示例
下面是输出pdf斜线完整的示例代码，使用的iText类库为：itextpdf-5.5.1.jar

import java.awt.Color;
import java.io.FileOutputStream;
 
import com.itextpdf.text.BaseColor;
import com.itextpdf.text.Document;
import com.itextpdf.text.Element;
import com.itextpdf.text.Font;
import com.itextpdf.text.PageSize;
import com.itextpdf.text.Paragraph;
import com.itextpdf.text.pdf.BaseFont;
import com.itextpdf.text.pdf.PdfContentByte;
import com.itextpdf.text.pdf.PdfPCell;
import com.itextpdf.text.pdf.PdfPTable;
import com.itextpdf.text.pdf.PdfWriter;
 
public class TestPdf {
 
    private static final float PDF_PERCENT = 0.75f;
 
    public static void main(String[] args) throws Exception {
        float[] widths = { 144 * PDF_PERCENT, 113 * PDF_PERCENT, 91 * PDF_PERCENT,
                110 * PDF_PERCENT };
        int TOP = 36, LEFT = 36;
 
        FileOutputStream fos = new FileOutputStream("D:/line.pdf");
 
        Document document = new Document();
        PdfWriter writer = PdfWriter.getInstance(document, fos);
        writer.setViewerPreferences(PdfWriter.PageModeUseThumbs);
        document.setPageSize(PageSize.A4);
        document.open();
 
        PdfContentByte canvas = writer.getDirectContent();
        float top = document.getPageSize().getHeight() - TOP;
 
        PdfPTable table = new PdfPTable(widths);
        table.setLockedWidth(true);
        table.setTotalWidth(458 * PDF_PERCENT);
        table.setHorizontalAlignment(Element.ALIGN_LEFT);
 
        PdfPCell pdfCell = new PdfPCell();
        final String text = "                              AB\n\n\n CD";
        setBorderColor(pdfCell);
        pdfCell.setMinimumHeight(77 * PDF_PERCENT);
        pdfCell.setPhrase(new Paragraph(text, getPdfChineseFont()));
        table.addCell(pdfCell);
 
        // draw cell line
        int x1 = 61, y1 = 77;
        int x2 = 132, y2 = 76;
        int x3 = 144, y3 = 31;
        drawLine(canvas, LEFT, top, x1, y1);
        drawLine(canvas, LEFT, top, x2, y2);
        drawLine(canvas, LEFT, top, x3, y3);
 
        pdfCell = new PdfPCell();
        setBorderColor(pdfCell);
        pdfCell.setMinimumHeight(77 * PDF_PERCENT);
        table.addCell(pdfCell);
 
        pdfCell = new PdfPCell();
        setBorderColor(pdfCell);
        pdfCell.setMinimumHeight(77 * PDF_PERCENT);
        table.addCell(pdfCell);
 
        pdfCell = new PdfPCell();
        setBorderColor(pdfCell);
        pdfCell.setMinimumHeight(77 * PDF_PERCENT);
        table.addCell(pdfCell);
 
        pdfCell = new PdfPCell();
        setBorderColor(pdfCell);
        pdfCell.setMinimumHeight(83 * PDF_PERCENT);
        table.addCell(pdfCell);
 
        pdfCell = new PdfPCell();
        setBorderColor(pdfCell);
        pdfCell.setMinimumHeight(83 * PDF_PERCENT);
        table.addCell(pdfCell);
 
        pdfCell = new PdfPCell();
        setBorderColor(pdfCell);
        pdfCell.setColspan(2);
        pdfCell.setMinimumHeight(83 * PDF_PERCENT);
        table.addCell(pdfCell);
        setBorderColor(pdfCell);
 
        int cellX = (int) (widths[0] + widths[1]);
        int cellY = (int) (77 * PDF_PERCENT);
        int x = 201, y = 84;
        drawLine(canvas, LEFT + cellX, top - cellY, x, y);
 
        document.add(table);
        document.close();
    }
 
    // draw cell line
    private static void drawLine(PdfContentByte canvas, float left, float top, int x, int y) {
        canvas.saveState();
        canvas.moveTo(left, top);
        canvas.lineTo(left + x * PDF_PERCENT, top - y * PDF_PERCENT);
        canvas.stroke();
        canvas.restoreState();
    }
 
    // 设置边框样式
    public static void setBorderColor(PdfPCell pdfCell) {
        Color rgbColor = Color.BLACK;
        BaseColor baseColor = new BaseColor(rgbColor.getRed(), rgbColor.getGreen(), rgbColor
                .getBlue());
 
        pdfCell.setBorderWidthTop(0.1f);
        pdfCell.setBorderWidthBottom(0.1f);
        pdfCell.setBorderWidthLeft(0.1f);
        pdfCell.setBorderWidthRight(0.1f);
        pdfCell.setBorderColorBottom(baseColor);
        pdfCell.setBorderColorLeft(baseColor);
        pdfCell.setBorderColorRight(baseColor);
        pdfCell.setBorderColorTop(baseColor);
    }
 
    public static Font getPdfChineseFont() throws Exception {
        BaseFont bfChinese = BaseFont.createFont("STSongStd-Light", "UniGB-UCS2-H",
                BaseFont.NOT_EMBEDDED);
        Font fontChinese = new Font(bfChinese, 12, Font.NORMAL);
        return fontChinese;
    }
}