C＃MVC使用NReco.PdfGenerator从View生成PDF

Question

I'm currently working on a project where I need to create a "dashboard" which can be exported as pdf. I wanted to use Rotativa but as our application uses .NET framework 4.0 it's not possible. So I found the NReco PdfGenerator.

Now that's the code how I create the PDF result:

var ViewAsString = RenderViewAsString("~/Views/QMetrics/StandardDashboard.cshtml", viewModel);
var htmlToPdf = new NReco.PdfGenerator.HtmlToPdfConverter();
htmlToPdf.PageWidth = 1600;
htmlToPdf.PageHeight = 900;
var pdfBytes = htmlToPdf.GeneratePdf(ViewAsString);
FileResult FileResult = new FileContentResult(pdfBytes, "application/pdf");
FileResult.FileDownloadName = "Dashboard-" + viewModel.ProjectName + "-" + 
DateTime.Now.ToString() + "-.pdf";
return FileResult;

It successfully creates the PDF page with all the content that comes from the backend (Project information, and so on) but the page looks very ugly. On the original page I have 2 columns and on the PDF page it puts everything in one column. I tried a few different page sizes and I also changed the layout to be non-responsive but nothing has changed.

My first suggesstion was that the referenced CSS and JS files are not included when the PDF get's created, so I copied all the stuff that comes from external files (bootstrap, Chart.js) and pasted it directly in the .cshtml file. But nothing changed at all. My Chart is not rendering/loading and the missing CSS stuff is still not there.

On the NReco PDFGenerator website they say that it supports complex CSS code and also javascript code so I don't really understand why this is not working.

Has anyone here experiences with NReco or can someone recommend something else that works for .NET 4.0?

Answer 1

NReco PdfGenerator internally uses wkhtmltopdf tool, so you can check it and its options.

Regarding 2 columns: if you don't use flex/grid layout everything should work fine. Possibly you need to disable wkhtmltopdf smart shrinking logic (enabled by default) and define web page 'window' size explicitely (with "--viewport-size 1600" option).

Regarding CSS and charts: you need to check that CSS files could be accessed by wkhtmltopdf, simplest way to do that is running wkhtmltopdf.exe from the command line and check console log output (or, handle PdfGenerator's "LogReceived" event in C#). For Chart.js ensure that chart container div has explicit width (not in %), and that there are no js errors (you can get them in console by specifying "--debug-javascript" option). If your js code uses 'bind' method you have to include polyfill as WebKit engine version used in wkhtmltopdf doesn't support 'bind'.