On Thu, Feb 7, 2013 at 1:44 PM, Rik Cabanier <cabanier@adobe.com> wrote: > Robert O'Callahan wrote: > > I don't think so. AFAIK glyph bounding-boxes, unlike other text metrics, > don't affect shaping. (I hope > > we're talking about the same thing here: by bounding-box I mean a > rectangle that encloses everything > > drawn for a glyph.) In Gecko we only use them to optimize painting by > ignoring text that doesn't intersect > > the area to be painted. (Except for a very special case involving MathML > layout that is not relevant here.) > > There is no particular reason why glyph bounding-boxes need to be > constant over time; bounding boxes for > > other kinds of content are not constant over time. > > In PDF, the width of the bounding box influences where the next glyph will > start. > That seems odd. I would have expected it to rely on advance widths. > So, if you have different sized glyphs between the OpenType and SVG > representations, text will come out misaligned. > Text layout should depend only on existing OpenType tables, so a PDF viewer that wants to support SVG glyphs should use the OpenType bounding boxes for text layout. Since PDFs usually aren't dynamic, the true ink bounding box probably isn't even relevant to a PDF viewer. Rob -- Wrfhf pnyyrq gurz gbtrgure naq fnvq, “Lbh xabj gung gur ehyref bs gur Tragvyrf ybeq vg bire gurz, naq gurve uvtu bssvpvnyf rkrepvfr nhgubevgl bire gurz. Abg fb jvgu lbh. Vafgrnq, jubrire jnagf gb orpbzr terng nzbat lbh zhfg or lbhe freinag, naq jubrire jnagf gb or svefg zhfg or lbhe fynir — whfg nf gur Fba bs Zna qvq abg pbzr gb or freirq, ohg gb freir, naq gb tvir uvf yvsr nf n enafbz sbe znal.” [Znggurj 20:25-28]
Received on Thursday, 7 February 2013 01:02:05 UTC