Text rendering hates you (2019)
faultlore.com
faultlore.com
The style change mid ligature has a related problem. While it might be reasonable not to support style change in the middle of ligature, you still want to select individual letters within ligatures like "ff", "ffi" and "fl". The problem just like with color change is that neither the text shaper nor program rendering text knows where each individual letter within ligature glyph is positioned. Font simply lacks this information.
From what I have seen most programs which support it use similar approximation as what Firefox uses for coloring - split the ligature into equal parts. Works good enough for something like "fi", "fl" not so much for some of ligatures within programming fonts that combine >= into ≥.
There are even worse edge cases in scripts for other languages. There are ligatures which look roughly like the 2 characters which formed it side by side but in reverse order. There are also some ligatures in CJK fonts which combine 4 characters in a square.
Backspace erases characters at finer granularity than it's possible to select them.
With regards to LTR/RTL selection weirdness I recently discovered that some editors display small flag on the cursor displaying current position direction when it's in mixed direction text.
I was amazed to see IDEA/RustRover doing exactly this [1] when I added BIDI texts to my code to test things out.
[1] https://i.imgur.com/Qqlyqpc.png (image taken from IDEA issue tracker)
[1]: https://learn.microsoft.com/en-us/typography/opentype/spec/g...
Right after TFA was published, someone put together the text editing version: Text editing hates you too: https://lord.io/text-editing-hates-you-too/
Another aspect of mid ligature color changes is that if you allow color you probably allow any other style change including font size or the font itself, which in turn can have completely different size and shaped glyph for the corresponding ligature and even different set of ligatures. Thus making drawing of corresponding characters as single ligature impossible.
One of the most warranted and also one of the trickiest cases for wanting mid ligature style change is language education materials. You might want to highlight individual subcomponents of complex character combinations to explain rules behind them. For these cases the firefox splitting hack is not good enough. Although it seems like in current version of Firefox on Linux न्हृे is handling much better than in 2019 screenshot. This might be as much as improvement in Firefox and underlying libraries as it was in font. At the end of day if font draws a complex character combination as single shape there is nothing font rendering software can do to correctly split into logical components. Instead of ligatures you can draw such characters as multiple overlapping and appropriately placed glyphs (possibly in combination with context aware substitutions). Kind of like zalgo text, no font has separate glyphs for each letter with every combination of 20 stacked diacritic marks. That way the information about components isn't lost making it technically possible to correctly style each of them, but it's still not easy.
Nitpicking, but if you're writing about text rendering you should know:
Yes, ligatures are really about presentation and not semantics. For example fi (U+FB01) means the same thing as fi; it just looks neater in some situations.
æ (U+00E6) is not a ligature; it's a mostly obsolete character, with different semantics (or phonetics) than ae.
For example, for purely typsetting beauty, your word processor might substitute the ligature fi for the two letters fi (which can f* search, and I resent both the ligature and lazy search function developers). It would never substitute æ for ae; that would misspell the word as much as substituting an o.
Reading that a letter in my alphabet is mostly obsolete feels really weird. No rebuttal, just a comment.
> It would never substitute æ for ae; that would misspell the word as much as substituting an o.
While that is correct, a lot of other systems actually do this exact substition. If your name contains æ it will be substituted with ae in passports, plane tickets and random other systems throughout your life.
My own username on this website is an example of a similar substition. The oe should be read as the single character ø.
Sorry, I should have specified 'in English'.
> a lot of other systems actually do this exact substition. If your name contains æ it will be substituted with ae
I agree and to clarify, I meant that the reverse substitution doesn't happen.
Re-reading your comment, yeah its obvious that that was what you meant. My apologies, that’s on me.
Using handwriting, additional characters are simple and in fact Medieval European scribes used many abbreviations, etc. When you need to set type on a printing press, or even input a character not already on your computer keyboard, the barrier is higher.
doing non-ascii first needs awareness and then quickly becomes tricky (encodings yay).
getting combining characters and/or homoglyphs right is hard.
and if you're still bored out: have fun with Unicode confusables.txt ...
with this in mind I dare to give them lazy bums the honor of the doubt and rather call them something between naïve and scared.
Isn't there a library out there for this common set of problems? I know Unicode provides normalization tables, though I don't know how good they are and I don't know if Unicode also provides a library.
The "ae" example was used as an introductory example for us English readers. Unlike the Arabic examples where ligatures are mandatory and supported by most Arabic fonts, not many English fonts have an "ae" ligature these days. Not to mention this is a web page and a user can freely apply their !important font styles.
Using æ to mean "treat it as an 'ae' rendered by ligature which is visually indistinguishable" does not mean the author knows nothing about this (although the wording can use some improvement to reduce the ambiguity).
Also, most fonts have many characters beyond ASCII, including æ. If your font lacked it then you would see an empty box, not the two letters ae. Applying a font style would not change the rendering of æ into ASCII letters; I don't think it changes the rendering of English ligatures, which are separate code points in Unicode.
The Nordic languages beg to differ!
Edit: Checked out your profile, correcting myself: "you silly north-Danes!"
2023 (290 points, 119 comments) https://news.ycombinator.com/item?id=36478892
2022 (399 points, 154 comments) https://news.ycombinator.com/item?id=30330144
2019 (542 points, 170 comments) https://news.ycombinator.com/item?id=21105625
I like the way that the CJK fonts render without anti-aliasing on windows. I want to know why and how to cause windows to render a non-cjk font of my choosing in this aliased style. I am not opposed to hex-editing or otherwise modifying the font if that's necessary. I've never been able to find information bout the mechanism or how it's triggered.
So true!
> and english is bad at expressing these nuances.
I think English is a terrible shitpile of grammar and syntax. I'm very impressed that anyone who speaks another language natively can get good at it.
But I'm interested in the notion that it lacks nuance to describe the intricacies of text rendering. Can someone tell me where that would apply?
From my completely anecdotal observations, native speakers are the worst at English. They struggle with homophones, prepositions, tenses, confuse meanings of words, apostrophes and I could go on and on.
English grammar is easier to learn by reading and writing than speaking, what most native speakers do.
Its/it's, they/their/they're, who's/whose, prepositions like a lot, a while and confused words like definitely and defiantly are the first that come to mind. See if you are better than a foreigner.
You don't say "You give I the apple.", but "You give me the apple." (similar for he, she, we, they), i.e. the pronoun is inflected depending on whether it is subject or object, so English speakers are perfectly aware on the difference between subject and object.
When you refer to the subject, you use "who" and when you refer to the object, you use "whom".
Spoken languages are like programming languages, there are the ones people complain about and the ones nobody uses.
For example, goose/geese is the result of the plural form and singular form undergoing different paths in the Great Vowel Shift resulting in the different vowels in the modern form.
There's also evidence that Proto-Indo-European had laryngeal consonants that have disappeared in all modern languages derived from it [1], but have left their mark on the descendant languages.
Eg. receipt, which has the p only in Latin, but had long lost it by the time Old French brought it to Britain.
English will always have my respect for being open/inclusive and adaptive.
Interesting fact: If you are looking for a spoken language with the cleanest/composable grammar - it's Sanskrit. The panini grammar is actually like a programming language where sentences are just compositions of lower level similar units.
But like I said it's practically dead (not used as a spoken language). But interestingly used as a proxy language for translation and other nlp tasks due to it's clean grammar :)
I took this to mean that any non-domain-specific language may be bad at describing that domain, e.g. why physicists, mathematicians, chemists, etc. have a common symbology for the discipline, or why programming languages exist. i.e., not so much that English is uniquely bad among written human language for conveying these topics, but just that any non-specialized language may be.
Though, I think the author did a fair job, but I lack the domain experience to guess at where the misconceptions might lie.
Bantu languages, which cover much of subsaharan Africa, have many noun classes ("genders")—sometimes as many as 20. You have to learn all sorts of prefixes for each noun class depending on their grammatical role in tying to the noun.
However, it's really not so bad. Once you get the hang of the noun classes, it actually makes picking up the ear for it faster. Of course this is more true the more consistent the language in applying its internal rules.
Especially when you have a monitor with unusual subpixel layout, which is very common for OLEDs that don't have any standard for it. In practice, developers of common font libraries like FreeType simply didn't bother with trying to support all that. And that trickles down to toolkits like Qt. Surprising the article doesn't mention this major problem with modern displays.
> Retina displays really don’t need it
Assuming this means high resolution displays - unfortunately that's not always what you end up using. So subpixel antialiasing can still be useful, if it can work. But as above, it's often just broken on OLEDs.
Exceptions can apply if the consumers of the screen can't resolve details finer than "emulated sRGB pixels" anyways.
I once resolved that by keeping a vertically shrunken but really wide glyph around in a cache. Just resample it for a different horizontal offset.
Also, I had (though never tested) the impression that in the Windows world ClearType uses 3x the horizontal resolution internally (I vaguely remember that being mentioned in the horror novel^W^W Raster Tragedy[2] somewhere?..). Given many font designers’ testing process for their hinting bytecode seems to be to run it through ClearType and check if it looks OK (not unlike firmware programmers...), we all, including Microsoft, are essentially stuck with that choice forever (or at least until people with painfully low-res displays become rare enough that the complaining about blurry text can be disregarded). So I’d expect 1/3 of a pixel to be the natural resolution for a glyph cache, not 1/4? Or have things changed in the transition from GDI to GDI+ to DirectWrite?
[1] https://agg.sourceforge.net/antigrain.com/research/font_rast...
I wish they provided an example video of this since I can't visualize it. My natural thinking is subpixel antialiasing should look fine.
>the characters will jiggle as each glyph bounces around between different subpixel snappings and hints on each frame.
This shouldn't be a big issue unless your animation is slow and your subpixels are big.
The article is talking about "rerasterize the glyphs in their new location", which means it's rasterizing post animation. I think he's implying that there is something unstable with his each pixel is treated that breaks the illusion.
On Windows it may or may not be using DirectWrite for text rasterization as a general thing, and in some cases text might be rasterized using a different fallback path if DirectWrite can't handle the font, I think.
IIRC this was/is true for Chrome as well, where in some cases it software rasterizes text using Skia instead of calling through to the OS's font implementation.
I believe Firefox leans on the system raserizers a little more heavily (using them for everything they support), and also still uses FreeType on Linux.
Wondered about this. All the circular dependencies sound like you could feasibly get some style/layout combinations that lead to self-contradictory situations.
E.g. consider a ligature that's wider than the characters' individual glyphs. If the ligature is at the end of the box, it could trigger a line break. But that line break would also break up the ligature and cause the characters to be rendered as individual glyphs, reducing their width - which would undo the line break. But without the line break, the ligature would reconnect, increase the width and restore the line break, etc etc...
1. Layout the entire paragraph of text as a single line.
2. If this doesn't fit into the available width, bisect to the nearest line-break opportunity which might fit.
3. Reshape the text up until this line-break opportunity.
4. If it fits great! If not goto 2.
This converges as it always steps backwards, and avoids the contradictory situations.
Harfbuzz also provides points along the section of text which is safe to reuse, so reshaping typically involes only a small portion of text at the end of the line, if any. https://github.com/harfbuzz/harfbuzz/issues/224
This approach is different to how many text layout engines approach this problem e.g. by adding "one word at a time" to the line, and checking at each stage if it fits.
Do you know why Chrome does it this way?
For the word-by-word approach to be performant you need a cache for each word you encounter. The shape-by-paragraph approach we found was faster for cold-start (e.g. the first time you visit a webpage). But this is also more difficult to show in standard benchmarks as benchmarks typically reuse the same renderer process.
(posted in other other threads too)
1. Styling (parse markup, query system for fonts)
2. Layout (break text into lines)
3. Shaping (compute the glyphs in a line and their positions)
4. Rasterization (rasterize needed glyphs into an atlas/cache)
5. Composition (copy glyphs from the atlas to their desired positions)
Why is layout done so early? It seems to me that that would be later in the process.
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Yes. Let's be thankful that isn't the case for browsers and major GUI toolkits though.