HTMLViewer - long time to get TitleChanged event

  1. 2 months ago

    Tim S

    Oct 11 Canterbury, UK

    I've been doing some timings of how long it takes between issuing:

    myHTMLViewer.ExecuteJavaScript ("getTitle();")

    and getting the subsequent TitleChanged event. The javascript function getTitle() is very short:

    function  gettitle ()
         document.title = "myEventMarker:GetTitle:" + titleCount + ":" + titlestuff;

    where titlestuff is a 100 byte string (the prefixed stuff is to distinguish between wanted/unwanted events and the various wanted ones).

    Now, under macOS, the time in question is a couple of milliseconds at worst. However, under Win7 in a virtual machine (VirtualBox under macOS), using the IE11 renderer, this time consistently shoots up to 110 msec, there or thereabouts. Similar code has been tried by someone with a real Win10 machine, he reports similar timings.

    I'm now working on porting an app to Windows. Historically I've used the StatusChanged event to pass data from an HTMLViewer back to Xojo, but this may cease working at any time. The problem with using the TitleChanged event is the data length limitation of some 200 bytes (under the IE11 renderer). If I have a few k of text to recover from the HTMLViewer, that could take some seconds which will not work well with the rest of the app.

    Is there a reason for this long lag with the HTMLViewer/TitleChanged under Windows? Any way I can mitigate it or use an alternative strategy?

  2. 8 weeks ago

    Tim S

    Oct 19 Canterbury, UK

    Just submitted Feedback Case #53769 about this.

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