Qt SVG renderer

Matthew Woehlke mw_triad at users.sourceforge.net
Tue Jul 29 20:42:42 BST 2008

Thiago Macieira wrote:
> On Tuesday 29 July 2008 18:20:01 Matthew Woehlke wrote:
>> Rafael Fern�ndez L�pez wrote:
>>> http://media.ereslibre.es/2008/07/icons/
>>> Here you can find a full list of icons that are misdrawn, and how
>>> inkscape draws it.
>> What's with all the icons that have "junk" behind them? Is that extra
>> stuff in the svg (that could, and probably should, be deleted), or how
>> is Qt managing to munge those?
> That's what I'm most alarmed about. How did that junk appear?
> Are those things in the SVG files? If they are, it's like Microsoft Word 
> keeping old revisions when you publish a .doc.

I suspect they're really there, but I was/am (ahem) hoping that one of 
the artists that's familiar with the icons will comment. Otherwise I 
will probably try to dig out one of the offending files and take a look.

I remember old versions of the Oxygen cursors had ~6 draft versions in 
the svg as well as the one that was meant to actually be rendered, which 
is why I say I wouldn't be surprised if cruft had been left in the 
svg's. Probably off to one side or on hidden layers. In fact, since IIRC 
layers are an inkscape extension, I'd bet on that being the culprit.

In fact, if the problem is hidden layers, then IMO Qt doesn't need to 
fix that; the SVG's need to be fixed (preferably to have the junk 
deleted, which will make them smaller also, but at least moved to where 
it won't render).

It would be REALLY helpful if you could somehow provide the 
mis-rendering svg's as well (link to websvn is probably ok); I'm sure 
this would be a tremendous help to the Qt folk.

>> @TT (ah, "Qt Group"? What is it these days? ;-) ):
> Qt Software dept., part of the Devices Organisation (for short, "D-Qt"). At 
> least until the next corporate reorganisation. TT/N is also valid, a short for 
> "Trolltech, a Nokia Company".

Guess I can still think of you as "TT" then (and we can still call you 
"Trolls") ;-).

>> I'm sure it's been said many times, but the biggest hole in Qt's SVG
>> support (in my opinion, but I've seen it shared by others as well) is
>> the lack of support for masks and blur. Mask can be overcome somewhat by
>> CSG operations in inkscape, but this is destructive to the SVG. To be
>> honest, I'd almost say that blur is most needed. Even /just/ blur but
>> not other filters would I think be a serious improvement... the thing
>> is, it's by far the best/easiest way to do shadows or soft shading, both
>> of which are ubiquitous.
>> Note: I don't do icons. I *have* done (and am currently doing) some game
>> graphics, and those two are noticeably limiting of my artistic expression.
> I have found someone in the office who seemed interested in fixing issues. He 
> has, however, no more clue than I do about the filters and blurs. So we cannot 
> promise anything for the time being, other than fixing the blatant problems.

Thanks for the info. I don't know the specs very well, but I think as a 
stop-gap, even a crude approximation of blur (i.e. just recognize blur 
and make the right stuff fuzzy) would be a significant improvement.

I'm not sure about masking, again I don't know the SVG syntax, but as 
for the drawing side, I'd think with the P-D drawing modes that would be 
relatively easy?

IOW, from my perspective the priorities are:
- fix any egregious issues* (high)
- *some* form of working blur (high)
- clipping/masking (med-high)
- fix any significant issues* (medium)
- "correct" blur (med-low)
- support common filters (low)

(* where "issue" is defined as doing something wrongly, as opposed to a 
missing feature)

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