How to retrieve(!) HTML from BrowserFrame

Hi,
using JMix 1.5 and a BrowserFrame,

we set some HTML/CSS/JS to browserFrame.setSrcdoc(). Works nicely.

But as the JS part does nice rearrangements, how can I get the content of the browserFrame back?
There’s no getter like .getCurrentSource(), isn’t it?

Br
HP

To add some more about the workflow here:

We have some nice report in HTML, displayed in browserFrame.
Then iText should do the conversion to PDF.
Because we embedded several ECharts, we need an evaluation of JavaScript, to get real images from the Canvas parts.
But as those images are rendered in the browserFrame, using the HTML engine from it, we have to retrieve that HTML source again, with all the now fixed rendered images.
Now, iText can build the PDF.