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From Simon Pepping <spepp...@leverkruid.eu>
Subject Re: Intermediate Format Performance: Necessary changes to IFPainter interface
Date Tue, 03 Feb 2009 19:51:31 GMT
Sounds impressive.

On Tue, Feb 03, 2009 at 07:35:03AM -0800, The Web Maestro wrote:
> Sounds exciting! Cool!
> 
> On Tue, Feb 3, 2009 at 2:31 AM, Jeremias Maerki <dev@jeremias-maerki.ch> wrote:
> > Oh, yes, I almost forgot: I'm removing the "dy" parameter for now since
> > it's not supported anyway until we support different writing-modes.
> > Doesn't make sense to keep that around until then.
> >
> > On 03.02.2009 11:10:03 Jeremias Maerki wrote:
> >> I'm getting near to finishing my work on the new intermediate format.
> >> Logically, performance tests have to show whether the goals have been
> >> achieved. Generally, they have:
> >> - Rendering directly from the new intermediate is a lot faster than from
> >> the old area tree XML format.
> >> - The new intermediate files are also a lot smaller.
> >> - New output formats are much easier to implement than the old Renderers.
> >>
> >> However, the performance tests showed that the improvement for the
> >> PostScript output was rather small (and that's one of the most important
> >> formats in that context). The cause was my simplistic approach to glyph
> >> positioning (using the xshow operator). It causes at least one
> >> DecimalFormat.format() call per glyph even if the text has no kerning,
> >> letter/wordspacing or justification. So I had to revise my decision to
> >> simply carry a "dx" (from SVG) property with glyph offsets. Adding SVG's
> >> letter-spacing and word-spacing attributes made it possible to keep dx
> >> to null in many cases. Furthermore, a custom text painting operator in
> >> PostScript (similar to PDF's TJ) allowed much more compact PostScript
> >> code and brought the performance back in the region of PDF and AFP.
> >>
> >> So, IFPainter.drawText will get two new parameters letterSpacing and
> >> wordSpacing. I'm currently updating the rest of the output formats in a
> >> similar way (for example, PDF gets to use the Tc operator for
> >> letter-spacing). AFP will also profit from that. I'll commit when
> >> everything's working again.
> >>
> >> I'll also publish performance figures when this is done.

Simon

-- 
Simon Pepping
home page: http://www.leverkruid.eu

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