Re: Glyphs in vertical text are drawn on top of each other

[Behdad Esfahbod <behdad behdad org>]

ogg k ogg k googlemail com wrote:
> Hi,
> 
> [ this list was described as 'help using pango' despite its name]
> 
> I'm trying to display text using Pango and Cairo. It all works fine using
> horizontal text (r2l and l2r). When I try vertical text, however, Katakana
> glyphs become superimposed with each other. A run of Latin characters
> in the same string are properly spaced.

Hi,

I have seen some reports about such problems, with glyphs partially
overlapping, not completely superimposed.  Is that what you are seeing?  A
screenshot helps.  In the past, it always looked like a font problem and
people reported that switching to another CJK font fixed it.  I have heard
this issue reported in conjunction with one of default Vista fonts even.  I
never could reproduce it myself though.  I suspect a bug in FreeType's
vertical metrics parsing code.

Hope that helps,

behdad


> What I do to use vertical text rather than horizontal text is:
> 
> + Set base gravity on the Pango context to auto.
> + cairo_rotate the cairo_t to M_PI/2
> 
> I've tried various other combinations, calling various update routines
> from pangocairo, etc, and I can get vertical text with Katakana not
> rotated, in which case they are properly spaced (eg, they're 'horizontal'
> but rotated by the Cairo CTM).
> 
> I've tried both showing the layout directly, or line by line. Both cases
> exhibit the same behavior. I've also tried using the Pango matrix rather
> than the Cairo matrix (but it's not very nice as I use Cairo to offset/scale
> text, so that becomes lost in the process).
> 
> Is this a known problem with a known solution ? Is there a known gotcha,
> maybe some setup call people often forget ?
> 
> Thank you.
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