Log stops updating beyond 2 Mbyte size

[Tom Goddard]

The Log panel and file history html panels stop updating or display nothing if an attempt is made to show more than 2 Mbytes of html content. It is easy to exceed this limit if images are included since they are inlined in the html (using <img src="data:image/png;base64,[data]">).

This is a bug in Qt 5.6.0 WebEngineView setContent() and setHtml() methods that can only handle 2 Mbytes of content. This comes from the Chromium backend used by Qt 5.6 which limits URL size to 2 Mbytes. Qt converts the html content to a url (like "data:text/html,...") for passing to the rendering process.

This is Qt bug 53414

​https://bugreports.qt.io/browse/QTBUG-53414

The owner of that bug will look at using shared memory to pass html content instead of a URL.

[Tom Goddard]

Conrad put in code to work around this that saves the log to a temporary file once the html is larger than 1 Mbyte.