[webkit-help] WebKit Plugin Printing Issues -- Request for Help Understanding Rendering Logic

[Brent Fulgham]

I've been attempting to use a third party control in a new
WebKit-based UI to maintain backwards compatibility with an existing
product.  So far, everything works great on screen.  However, when I
attempt to print a page containing the widget, the areas of the page
where the widget are supposed to live appear as blank space.

I've filed a bug (https://bugs.webkit.org/show_bug.cgi?id=33022) to
document the issue and my attempts to understand and work around the
cause.

I've created a very simple win32 plugin that draws a simple blue box
inside the bounds of the <embed> tag region, and have verified that I
do enter this code during drawing and printing.  (Project is attached
to the issue).  I've also included screenshots of the on-screen and
printed output.

I have found that if I create an artificial header/footer region, but
do not draw to this region, the portions of my blue box that fit into
the area of the header will be printed.  This seems to be caused by
the printing logic ignoring header (and footer) bounds when laying out
the page (filed as https://bugs.webkit.org/show_bug.cgi?id=32909).

I was hoping to find someone who could help me understand the
rendering pass, and whether there might be some logic drawing a blank
region as a plugin placeholder that is over-writing the regions my
plugin is drawing.  Is there perhaps some kind of Z-ordering issue I
need to work around?

Thanks,

-Brent