Fix very long fragmentParts not wrapping in chat render

[ScrubN]

Fixes #421
Fixed a few memory leaks - i.e. after rendering about ~800 RTL messages, 3GB of memory had leaked
Fixes #229 - fixed most RTL outlines¹

Footnotes

1. RTL scripts with adapting characters (like Arabic) do not render outlines properly. This is an issue with SkiaSharp, not us. See code comment for more details ↩

[ScrubN]

I've sorted out all the issues and edge cases I can think of with LTR characters.

@HellbringerOnline also requested that I add wrapping on the last ? in a render line to aid in URL readability, like how Twitch wraps URLs. Though in 0.01% scenarios it's not completely faithful to Twitch.

[ScrubN]

I wonder how I should go about adding RTL support. I believe in arabic script the shape of a character changes depending on what comes after it, meaning word wrap could alter the readability right?

[mohad12211]

I hope that I can help with RTL (Arabic speaker)
yes that's right, it changes depending on the letter before it and after it.
twitch adds a Arabic Tatweel ـ character at the end of the breaking at the top line, and the beginning at the bottom line.
like this:

I'm not sure if that what you mean by word wrapping.
of course twitch will try to split words to their own lines before trying to split the word letters.
it's very rare tho and I wouldn't really focus on it that much.

[HellbringerOnline]

I've sorted out all the issues and edge cases I can think of with LTR characters.

@HellbringerOnline also requested that I add wrapping on the last ? in a render line to aid in URL readability, like how Twitch wraps URLs. Though in 0.01% scenarios it's not completely faithful to Twitch.

Also I see that links also break after the sign -

[ScrubN]

of course twitch will try to split words to their own lines before trying to split the words themselves.

Yes it will stay that way, but in the case that a word needs to be split to multiple lines due to length it can be pretty complicated in select languages. I'm trying to work on those select languages, which are primarily RTL.

Thanks for the help with arabic

[ScrubN]

I was able to confirm the RTL is wrapped correctly

[ScrubN]

I was able to partially fix RTL outlines. For example Hebrew looks perfect, but Arabic's outlines are quite significantly wider than the drawn text. I tried scaling the outlines to the text width but the issue is the character kerning/fontface

[ScrubN]

I've realized what the issue is now, and it's an issue with SkiaSharp.

SKPaint.GetTextPath() prints RTL strings in reverse order, so the easy solution was to just reverse the character order before calling it, but in the case of Arabic that changes how certain characters look, resulting in the wider outlines.

[mohad12211]

I compiled your branch and tested a chat render.
you are right, skiasharp is not aware that the text is RTL for some reason, so you you first had to reverse the letters, but that's not enough, each letter has a different shape depending on its position in a word. skia is also not aware of that and its just displaying letters with the wrong shape.