iText 7 pdhHtml keep table rows together - itext7

Question

I am new in iText 7, i am developing a spa project (asp.net, c#, and angularjs), where i need to implement a report for existing html page.I found iText 7 (.Net) has a easy way to implement it. Using below code of line, that's return me a byte array and i can easily show in browser as pdf also can download.
var memStream = new MemoryStream();
ConverterProperties converterProperties = new ConverterProperties();
converterProperties.SetFontProvider(fontProvider); converterProperties.SetBaseUri(System.AppDomain.CurrentDomain.BaseDirectory);
HtmlConverter.ConvertToPdf(htmlText, memStream, converterProperties);
In my raw html there has some html tables (every table has some particular rows) and i want to keep them in a page (i mean if table rows not fit in a single page then start from next page). I got a solution like below
Paragraph p = new Paragraph("Test");
PdfPTable table = new PdfPTable(2);
for (int i = 1; i < 6; i++) {
table.addCell("key " + i);
table.addCell("value " + i);
}
for (int i = 0; i < 40; i++) {
document.add(p);
}
// Try to keep the table on 1 page
table.setKeepTogether(true);
document.add(table);
But in my case i cannot implement like that way because content already exist in html tables (in my existing html page).
Advance thanks, if anyone can help me.

Answer 1

This can easily be done using a custom TagWorkerFactory and TableTagWorker class.
Take a look at the code samples below.
The first thing we should do is create a custom TableTagWorker that tells iText to keep the table together. We do this using the code you've mentioned: table.setKeepTogether(true).
class CustomTableTagWorker extends TableTagWorker{
public CustomTableTagWorker(IElementNode element, ProcessorContext context) {
super(element, context);
}
#Override
public void processEnd(IElementNode element, ProcessorContext context) {
super.processEnd(element, context);
((com.itextpdf.layout.element.Table) getElementResult()).setKeepTogether(true);
}
}
As you can see the only thing we changed on our custom TableTagWorker is the fact that it has to keep the table together.
The next step would be to create a custom TagWorkerFactory that maps our CustomTableTagWorker to the table tag in HTML. We do this like so:
class CustomTagWorkerFactory extends DefaultTagWorkerFactory{
#Override
public ITagWorker getCustomTagWorker(IElementNode tag, ProcessorContext context) {
if (tag.name().equalsIgnoreCase("table")) {
return new CustomTableTagWorker(tag, context); // implements ITagWorker
}
return super.getCustomTagWorker(tag, context);
}
}
All we do here is tell iText that if it finds a table tag it should pass the element to the CustomTableTagWorker, in order to be converted to a PDF object (where setKeepTogether == true).
The last step is registering this CustomTagWorkerFactory on our ConverterProperties.
ConverterProperties converterProperties = new ConverterProperties();
converterProperties.setTagWorkerFactory(new CustomTagWorkerFactory());
HtmlConverter.convertToPdf(HTML, new FileOutputStream(DEST), converterProperties);
Using these code samples I was able to generate an output PDF where tables, if small enough to render on an entire page, will never be split across multiple pages.

Answer 2

I had a similar issue of trying to keep together content within a div. I applied the following css property and this kept everything together. This worked with itext7 pdfhtml.
page-break-inside: avoid;