[Libreoffice-bugs] [Bug 118165] Adding a new paragraph to a text block is rather CPU hogging

[bugzilla-daemon at bugs.documentfoundation.org]

https://bugs.documentfoundation.org/show_bug.cgi?id=118165

Telesto <telesto at surfxs.nl> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|bibisectRequest             |
             Status|NEW                         |RESOLVED
         Resolution|---                         |DUPLICATE

--- Comment #20 from Telesto <telesto at surfxs.nl> ---
This one is a dupe of, or interconnected with bug 112989. It also happens in
LibO5.3 with Harfbuzz enabled. It's OK without it. 

Still no clue why this is working in 5.4 until commit
559bb1420cd7fe699e139e20ea3b4205b9e6937d. 

This should be looked after a fix is published for bug 112989.

I would definitely vote for "Text layout performance" as Tender budget 2018.
Spell-check & Text shaping isn't a great combo at this point.

---
Text layout performance

CostEstimate: 6 weeks Contact: Khaled

Our text layout performance is abysmal, all over the code base it is assumed
that shaping text is cheap and we can do it over and over again. Want to
measure the text? Shape it and discard the output afterwards. Want to measure
part of the same text? Shape again. Want to find line breaks? Shape again. Want
to finally draw it? Shape again. This might have been cheap for Latin script in
the olden days when all we did is query font cmap table and put glyphs next to
each other, which is not the case anymore and never been the case for more
involved scripts. We need to work on this, and there are many possibilities;
retaining shaping results much longer, improving the wasteful OutputDevice API,
caching etc.

*** This bug has been marked as a duplicate of bug 112989 ***

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