Add fribidi_reorder_runs()

[anood]

This function reorders all runs from logical to final visual order, similar to
fribidi_reorder_line() but without reordring the text inside the runs, so that
it can be used e.g. with HarfBuzz.

[behdad]

Thanks. One problem I have with this patch is that it exposes FriBidiRun publicly. But I think if we are ever going to change that, we call it a new library anyway. I'm merging this.

Also, check out this algorithm that should be faster, but I never got to integrate in any codebase:
https://github.com/behdad/linear-reorder

[khaledhosny]

I’m not sure I get the library naming comment since this is now merged, are we changing the library name, bumping the soname version or what?

[behdad]

I’m not sure I get the library naming comment since this is now merged, are we changing the library name, bumping the soname version or what?

No. I meant, if we ever want to change the structure of FriBidiRun, we can make that a different library or a soname bump.

[khaledhosny]

I see, good then. I misread the original comment somehow.

[khaledhosny]

Hmm, the unicode63 branch adds a new member to FriBidiRun, which breaks rebasing it on top of master. Also I don’t like that we don’t initialize all members of the returned structs in this function as they are unused here. I think it is better to have a different public struct for this function, and leave FriBidiRun alone? WDYT?

[behdad]

I was actually thinking about this very same thing yesterday. Let me think about it.

[khaledhosny]

Any updates?

[behdad]

Hey. Sorry, busy with travel and working with the Hague people. So, I probably want to revert this, and do it in a slightly different way that doesn't expose the entire FriBidiRun, just the header. Will try to get it done by next week so we can move on with other changes.