[Libreoffice-bugs] [Bug 48965] FORMATTING: Incorrect alignment of characters from Catalog

[bugzilla-daemon at bugs.documentfoundation.org]

https://bugs.documentfoundation.org/show_bug.cgi?id=48965

V Stuart Foote <vstuart.foote at utsa.edu> changed:

           What    |Removed                     |Added
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                 CC|                            |mikekaganski at hotmail.com

--- Comment #11 from V Stuart Foote <vstuart.foote at utsa.edu> ---
(In reply to john from comment #9)
> I don't understand why others are concluding here that the problem is with
> the rendering engine... as my earlier-attached example image ('rendering
> with OpenSymbol and Liberation Sans') shows, everything works fine if the
> OpenSymbol font is replaced with Liberation Sans in the Symbol Catalog (this
> must be done manually, one symbol at a time, using the GUI).
> 
> If that is not a problem with the OpenSymbol font itself, then where else
> could the problem be?

Well you are sort of right. Adjusting OpenSymbol typo/hhea metrics may be
needed.

Issue here is the way the fonts are sized/scaled for the SmBinVerNode [1][2],
as the nodes are being calculated, and when the OpenSymbol glyphs are _mixed_
with Liberation Serif in a subnode the Denominator spacing (nDenomDist) picks
up the spacing for Liberation Serif--the OpenSymbol only subnode gets a
different spacing.

That OpenSymbol only nodes are assigned an unhelpful Height metric can be
demonstrated by modifying the Format -> Fonts: Numbers font to use the
OpenSymbol glyphs. 

The "1 over %alpha + 1 over {%alpha + 1}" sample formula will then be
calculated with OpenSymbol only Numerator spacing (nNumDist) and Denomenator
spacing (nDenomDist) and collapses the spacing to the over bar.

Alternatively, modify the iGreek %ialpha "α" and assign it Liberation Serif (so
to match default Numbers format) and the formula gets matching spacing for all
the nodes.

@Takeshi, Khaled, Mike -- is the answer to chase the font metrics for errant
fonts (notably OpenSymbol that we control, but others like Asana and STIX get
assigned ugly spacing) or can we improve the logic for the node spacing to set
minimum distances and handle mixed font composition of a node?

=-ref-=

[1] http://opengrok.libreoffice.org/xref/core/starmath/inc/node.hxx?#739
[2] http://opengrok.libreoffice.org/xref/core/starmath/source/node.cxx?#818

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