Creating paginated table with PDFBox

I've recently needed to modify a file generation that was offered in CSV files to PDF format. I'll enumerate some of challenges on doing that:

Finding the right API to do the heavy work
PDF is a complex format created to display documents. It supports texts, graphics and a whole set of features, and has an 747 pages specification that can be bought here: ISO 32000-1 specification. One does not simply start writing to a PDF file, as unlike a text file, they usually contain non-ASCII binary characters and should always be considered as binary files.

Using an off the shelf API can greatly reduce the burden of trying to do that kind of file creation or modification manually. After some quick research I've realized that most o the available libs on the web were paid. The most used standard is iText, which needs a commercial license if being used for commercial purposes (http://itextpdf.com/salesfaq) The best free solution I found was PDFBox, which immediately drew my attention for being an Apache project. It is currently on the 1.8.4 release, is stable and has a fairly extensive amount of documentation on it's website and forums.

Now the thing is, I went through mailing lists and documentation and it doesn't come with any ready-made feature for tables generation. That requires for the developer to handle the drawing of the table's columns and rows. The following code performs that task and also handles paginating the table to multiple pages in case it doesn't fit.

Output sample:

I've meant to do just an essay here, so there are many optimizations to be done, but you can get some ideas from it to adapt to your needs. (full working code: https://github.com/eduardohl/Paginated-PDFBox-Table-Sample)

	package littleproject;
	import java.io.IOException;
	import java.util.Arrays;
	import org.apache.pdfbox.exceptions.COSVisitorException;
	import org.apache.pdfbox.pdmodel.PDDocument;
	import org.apache.pdfbox.pdmodel.PDPage;
	import org.apache.pdfbox.pdmodel.edit.PDPageContentStream;
	public class PDFTableGenerator {
	// Generates document from Table object
	public void generatePDF(Table table) throws IOException, COSVisitorException {
	PDDocument doc = null;
	try {
	doc = new PDDocument();
	drawTable(doc, table);
	doc.save("sample.pdf");
	} finally {
	if (doc != null) {
	doc.close();
	}
	}
	}
	// Configures basic setup for the table and draws it page by page
	public void drawTable(PDDocument doc, Table table) throws IOException {
	// Calculate pagination
	Integer rowsPerPage = new Double(Math.floor(table.getHeight() / table.getRowHeight())).intValue() - 1; // subtract
	Integer numberOfPages = new Double(Math.ceil(table.getNumberOfRows().floatValue() / rowsPerPage)).intValue();
	// Generate each page, get the content and draw it
	for (int pageCount = 0; pageCount < numberOfPages; pageCount++) {
	PDPage page = generatePage(doc, table);
	PDPageContentStream contentStream = generateContentStream(doc, page, table);
	String[][] currentPageContent = getContentForCurrentPage(table, rowsPerPage, pageCount);
	drawCurrentPage(table, currentPageContent, contentStream);
	}
	}
	// Draws current page table grid and border lines and content
	private void drawCurrentPage(Table table, String[][] currentPageContent, PDPageContentStream contentStream)
	throws IOException {
	float tableTopY = table.isLandscape() ? table.getPageSize().getWidth() - table.getMargin() : table.getPageSize().getHeight() - table.getMargin();
	// Draws grid and borders
	drawTableGrid(table, currentPageContent, contentStream, tableTopY);
	// Position cursor to start drawing content
	float nextTextX = table.getMargin() + table.getCellMargin();
	// Calculate center alignment for text in cell considering font height
	float nextTextY = tableTopY - (table.getRowHeight() / 2)
	- ((table.getTextFont().getFontDescriptor().getFontBoundingBox().getHeight() / 1000 * table.getFontSize()) / 4);
	// Write column headers
	writeContentLine(table.getColumnsNamesAsArray(), contentStream, nextTextX, nextTextY, table);
	nextTextY -= table.getRowHeight();
	nextTextX = table.getMargin() + table.getCellMargin();
	// Write content
	for (int i = 0; i < currentPageContent.length; i++) {
	writeContentLine(currentPageContent[i], contentStream, nextTextX, nextTextY, table);
	nextTextY -= table.getRowHeight();
	nextTextX = table.getMargin() + table.getCellMargin();
	}
	contentStream.close();
	}
	// Writes the content for one line
	private void writeContentLine(String[] lineContent, PDPageContentStream contentStream, float nextTextX, float nextTextY,
	Table table) throws IOException {
	for (int i = 0; i < table.getNumberOfColumns(); i++) {
	String text = lineContent[i];
	contentStream.beginText();
	contentStream.moveTextPositionByAmount(nextTextX, nextTextY);
	contentStream.drawString(text != null ? text : "");
	contentStream.endText();
	nextTextX += table.getColumns().get(i).getWidth();
	}
	}
	private void drawTableGrid(Table table, String[][] currentPageContent, PDPageContentStream contentStream, float tableTopY)
	throws IOException {
	// Draw row lines
	float nextY = tableTopY;
	for (int i = 0; i <= currentPageContent.length + 1; i++) {
	contentStream.drawLine(table.getMargin(), nextY, table.getMargin() + table.getWidth(), nextY);
	nextY -= table.getRowHeight();
	}
	// Draw column lines
	final float tableYLength = table.getRowHeight() + (table.getRowHeight() * currentPageContent.length);
	final float tableBottomY = tableTopY - tableYLength;
	float nextX = table.getMargin();
	for (int i = 0; i < table.getNumberOfColumns(); i++) {
	contentStream.drawLine(nextX, tableTopY, nextX, tableBottomY);
	nextX += table.getColumns().get(i).getWidth();
	}
	contentStream.drawLine(nextX, tableTopY, nextX, tableBottomY);
	}
	private String[][] getContentForCurrentPage(Table table, Integer rowsPerPage, int pageCount) {
	int startRange = pageCount * rowsPerPage;
	int endRange = (pageCount * rowsPerPage) + rowsPerPage;
	if (endRange > table.getNumberOfRows()) {
	endRange = table.getNumberOfRows();
	}
	return Arrays.copyOfRange(table.getContent(), startRange, endRange);
	}
	private PDPage generatePage(PDDocument doc, Table table) {
	PDPage page = new PDPage();
	page.setMediaBox(table.getPageSize());
	page.setRotation(table.isLandscape() ? 90 : 0);
	doc.addPage(page);
	return page;
	}
	private PDPageContentStream generateContentStream(PDDocument doc, PDPage page, Table table) throws IOException {
	PDPageContentStream contentStream = new PDPageContentStream(doc, page, false, false);
	// User transformation matrix to change the reference when drawing.
	// This is necessary for the landscape position to draw correctly
	if (table.isLandscape()) {
	contentStream.concatenate2CTM(0, 1, -1, 0, table.getPageSize().getWidth(), 0);
	}
	contentStream.setFont(table.getTextFont(), table.getFontSize());
	return contentStream;
	}
	}

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