Basic new line support for left to right scripts

[hmaarrfk]

So my team seemed to need to use newline to set text.

I gave it a go since it seemed easier than to try to always just guess the height of lines.

• Add relevant tests that test the positions:
  • Tokenizing
  • Geometry alignment
  • Text with leading and lagging new line
  • Text with whitespace before the words
  • Text alignment with spaces before and after
• Text alignment anchor center looks weird with the ability to have multiple lines. I would somewhat like to get the alignment correctly since I feel like it can be tricky for multi line cases.
  • Left
  • Center
  • Right
• Text justificaiton text_justify as a new parameter. Options:
  • False
  • True
  • True but not the last line. <-- is this useful? maybe it should be "true but not the last line of my paragraph".
• Test for different alignments of text when space is surrounding a new line
  • "hello \nworld" vs "hello\n world" vs "hello \nworld"
  • Should the above be different? Maybe in the regular font rendering, but maybe not for markdown rendering.
  • Yes they should be different.
• Decide on how to handle
  • \r, (as before, mostly ignored)
  • \f, (who uses this for real?)
  • \t (just ignore)

outdated comment

I'm not too proud of this, but it does most of the things we need.

I'm struggling to choose the best path for the implementation. I'm still trying to understand what things mean:

1. "\n\n" means new paragraph.
2. is "\n" a forced new line? So if text wraps.

I might have to put this on pause while we internally pursue a different approach, but leaving it here for a bit while I give it more thought. It was interesting to learn about fonts by reading your discussion.

xref: #391
Touches on the points:

• Line breaking.

Performance stats:

• Main: generate_glyph: 18.1 ms total 1.81 us per glyph
• This branch: generate_glyph: 27.8 ms total 2.78 us per glyph

For future work:

• Newline in markdown support
• Top to bottom and bottom to top
  • https://developer.mozilla.org/en-US/docs/Web/CSS/writing-mode
  • https://developer.mozilla.org/en-US/docs/Web/CSS/text-orientation

[hmaarrfk]

text_justify = False

text_justify = True

[hmaarrfk]

i made the example more interactive. Its pretty fun now. and added a few justification options that we can toggle or remove code for.

Screencast.from.2024-04-07.21-18-42.webm

[Korijn]

I think it is worthwhile to add a validation example (screenshot test) to cover the different cases you have supported.

Very cool and super useful! Awesome work.

[almarklein]

Really nice work! Exciting to see the text rendering improving on this front 🚀

[hmaarrfk]

I'm not sure how far I want to push this concept.

Text shaping is "hard" the concept of a new line in latin languages (left to right, top to bottom) is something I understand.

I cannot say that I really understand right to left languages, nor that I would be able to give meaningful inputs on top to bottom languages.

I'm also concerned about just the viability of me writing this for the first time as I am definitely not an expert in this.

To be clear, I think that a "new line" is really useful, but I just don't know if I can meaningfully setup good test case even for myself for other writing orientations.

[Korijn]

We can cut off the scope at this point and save the rest for the future. Let's wrap it up nicely and address any remaining code review comments.

[hmaarrfk]

I added:

• tests for the use cases I considered
• Test cases for questions raised during the review
• A note about only supporting left to right text.
• A note about performance in the top comment. On my machine 1.8us / glyph -> 2.7us / glyph on the existing benchmark

I noticed that you don't seem to care too much about the git history within the pull request.
I won't rebase my commits the next time.

[Korijn]

@almarklein can you review this once more in its final state? (I don't know enough about the text rendering subsystems to judge)

[almarklein]

Really nice work. Great to see a validation example and unit tests!

[almarklein]

🚀

[hmaarrfk]

Thank for you working on the scope and merging this!

We are super excited to try this out along in production to help our many aspects of our communication to end users!

[hmaarrfk]

But most of all, thank you for helping teach me all about different aspects of text rendering!