Pdfbox2(1) - 坐标判断和文本换行

目录

坐标概念

如何换行

坐标概念

想要做好文本样式，首先需要理解Pdfbox的坐标概念。

可以看到默认的（0，0）是页面的左下角，如果要计算页面开始布局的坐标，就需要左上角的位置。

这个时候还需要理解一个概念--box。Pdfbox默认做了多种盒子的布局，目前我们只需要理解

MediaBox就行，简单理解就是纸张尺寸。
 

try (PDDocument pdDocument = new PDDocument()) {        
    PDPage pdPage = new PDPage();
    pdDocument.addPage(pdPage);
    PDRectangle mediaBox = pdPage.getMediaBox();
    // 页边距
    float marginY = 88;
    // 真实宽度
    float width = mediaBox.getWidth() - 2 * marginX;
    // 开始x坐标
    float startX = mediaBox.getLowerLeftX() + marginX;
    // 开始y坐标
    float startY = mediaBox.getUpperRightY() - marginY;
} catch (IOException e) {
    log.error("", e);
}

可以看到通过MediaBox，可以初步定为到页面长和宽，以及开始坐标。

如何换行

PDDocument doc = null;
try
{
    doc = new PDDocument();
    PDPage page = new PDPage();
    doc.addPage(page);
    PDPageContentStream contentStream = new PDPageContentStream(doc, page);

    PDFont pdfFont = PDType1Font.HELVETICA;
    float fontSize = 25;
    float leading = 1.5f * fontSize;

    PDRectangle mediabox = page.getMediaBox();
    float margin = 72;
    float width = mediabox.getWidth() - 2*margin;
    float startX = mediabox.getLowerLeftX() + margin;
    float startY = mediabox.getUpperRightY() - margin;

    String text = "I am trying to create a PDF file with a lot of text contents in the document. I am using PDFBox"; 
    List<String> lines = new ArrayList<String>();
    int lastSpace = -1;
    while (text.length() > 0)
    {
        int spaceIndex = text.indexOf(' ', lastSpace + 1);
        if (spaceIndex < 0)
            spaceIndex = text.length();
        String subString = text.substring(0, spaceIndex);
        float size = fontSize * pdfFont.getStringWidth(subString) / 1000;
        System.out.printf("'%s' - %f of %f\n", subString, size, width);
        if (size > width)
        {
            if (lastSpace < 0)
                lastSpace = spaceIndex;
            subString = text.substring(0, lastSpace);
            lines.add(subString);
            text = text.substring(lastSpace).trim();
            System.out.printf("'%s' is line\n", subString);
            lastSpace = -1;
        }
        else if (spaceIndex == text.length())
        {
            lines.add(text);
            System.out.printf("'%s' is line\n", text);
            text = "";
        }
        else
        {
            lastSpace = spaceIndex;
        }
    }

    contentStream.beginText();
    contentStream.setFont(pdfFont, fontSize);
    contentStream.newLineAtOffset(startX, startY);
    for (String line: lines)
    {
        contentStream.showText(line);
        contentStream.newLineAtOffset(0, -leading);
    }
    contentStream.endText(); 
    contentStream.close();

    doc.save(new File(RESULT_FOLDER, "break-long-string.pdf"));
}
finally
{
    if (doc != null)
    {
        doc.close();
    }
}