[HarfBuzz] Using Harfbuzz & ICU & Glyphy in OpenES2 Engine
vincent.isambart at gmail.com
Tue Feb 11 13:00:06 CET 2014
Out of curiosity, I think you’re already using ICU, so why would you use libunibreak and not ICU’s line break iterator?
On Sunday, February 9, 2014 at 18:01, Ariel Malka wrote:
> Hi Jeremy,
> I have developed a solution based on Harfbuzz and ICU for rendering Unicode text with C++ and OpenGL from the ground-up:
> The topic of line-breaking is also on my agenda (more on the long term, nothing urgent...)
> One of the directions I'm planning to check in the future: https://github.com/adah1972/libunibreak
> I wonder how do you handle topics like font-fallback, script-itemization and BIDI, prior to shaping and line-breaking?
> Regarding one of your questions, it's easy to pass to Harfbuzz some text previously processed with ICU, as demonstrated here:
> On Sat, Feb 8, 2014 at 12:01 AM, Jeremy Moles <cubicool at gmail.com (mailto:cubicool at gmail.com)> wrote:
> > Hey guys! I'm working on a Python3-based OpenGL library and I want to use the union of Harfbuzz and libicu to do some (a small subset) of what Pango currently does. I cannot, unfortunately, simply use Pango, as its dependency chain will likely stop my clients' interest dead in its tracks. Further, there are some issues when customizing Pango's rendering model (and I'm not speaking without experience here, I've done it when I wrote osgPango) that aren't ideal to work with.
> > So, I would like to use hb and icu to accomplish some very basic layout in my OpenGL scenes (note: I will also be using Glyphy instead of my own rasterized SDF font textures too). I will need basic left|right|center alignment (potentitally justify, but it isn't a request yet), some basic markup support, etc.
> > I nearly have everything working locally, but the one area I'm having a lot of trouble with is knowing how--and in fact, WHOSE responsibility it is--to determine how to break large lines of text given my sizing constraints. This doesn't appear to be something harfbuzz attempts to do, but it may have helper functions nonetheless.
> > What I'm looking for are a few hints on how people (Behdad?) might tackle this problem. ALL text in this library gets converted in whitespace-normalized UTF8 using libicu and line breaks can only be FORCED by using <p/> or <br/> markup. Otherwise, all breaks should behave similarly to how they do in HTML.
> > If I feed my force-delimited lines of text (that is, break my input feed up by <br>/<p>) one huge chunk at a time to harfbuzz, I can get the extents for each glyph as if I had unlimited X coordinate space. I can use these extents to position as required by the calling function, but again, I'm having trouble determining where it is safe to break.
> > Is this something libicu can handle? Can harfbuzz make it easier?
> > NOTE: When I "whitespace normalize" my string before ever passing it harfbuzz, I use the UBRK API of libicu. There are also functions like:
> > u_isspace()
> > ...which look promising, but it expects a UChar32, which I do not know how to easily fetch while using harfbuzz's UTF8 functions, who operate on potential multibyte chars.
> > Thanks in advance!
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