5 ms·

Modern Text Rendering with Linux

111 points by daww 7y ago

robin_reala 7y ago
Do projects like Pathfinder fit into this stack anywhere? At a guess you could replace Freetype with it, but I guess it does more?
- Jasper_ 7y ago
  Pathfinder replaces FreeType. It doesn't do more, and shouldn't: it's focused on glyph (and image) rendering.
- daww 7y ago
  Interesting question, from my understanding Pathfinder is only concerned with rendering so it doesn't completely replace FreeType: you still need some software to extract the curves path data from the font file. This can be done in rust with skribo and font-kit You can check out this issue for more info: https://github.com/servo/pathfinder/issues/143 https://github.com/servo/pathfinder/issues/143
Jasper_ 7y ago
This is missing a text layout engine: separating a string of texts into multiple blocks with word wrap. This is handled in GTK+ through Pango and in Qt with an internal algorithm. I don't believe FreeBiDi/ICU is used in either.
- microcolonel 7y ago
  HarfBuzz for shaping, too.
sayusyz 7y ago
Great detailed pictures. I'm curious where general hinting belongs.
- Jasper_ 7y ago
  "Hinting" is a combination of techniques. Subpixel placement hinting is done by the shaper, which would be HarfBuzz in this case. Metrics hinting (adjusting the glyph width) is done by a combination of the shaper and the renderer, which would be HarfBuzz and FreeType. Outline hinting (fitting outline to the grid by distoring shapes without) is done by FreeType. Behdad Esfahboh, the author of HarfBuzz, has a great paper on the different choices and tradeoffs here: https://docs.google.com/document/d/1wpzgGMqXgit6FBVaO76epnnFC_rQPdVKswrDQWyqO1M/edit https://docs.google.com/document/d/1wpzgGMqXgit6FBVaO76epnnF...
  - criddell 7y ago
    Now that very high dpi screens are so popular and inexpensive, is subpixel rendering worth doing anymore?
    - raphlinus 7y ago
      It's important to make the distinction between subpixel positioning and subpixel (RGB) rendering. I'd personally say yes to the former, even at high dpi, and no to the latter if you're on a mobile device. The kerning errors you get from quantizing the position of glyphs to integer pixels are, to my eyes, a noticeable degradation of quality.
      - criddell 7y ago
        Do you know if the layout engines for laser printers do subpixel stuff?
        microcolonel 7y ago
        Most laser printers tend to use PostScript (a Turing complete language), which does not know about displays hardly at all. It does arbitrary positioning.
        7y ago
amelius 7y ago
To make it more modern, hopefully they will replace the XML by JSON at some point.
- Mister_Snuggles 7y ago
  How does replacing XML with JSON make it more modern?
  - rurban 7y ago
    smaller, more readable, faster, safer.
dang 7y ago
Two weeks ago: https://news.ycombinator.com/item?id=20491203 https://news.ycombinator.com/item?id=20491203

111 points by daww 7y ago

Do projects like Pathfinder fit into this stack anywhere? At a guess you could replace Freetype with it, but I guess it does more?

Jasper_ 7y ago
Pathfinder replaces FreeType. It doesn't do more, and shouldn't: it's focused on glyph (and image) rendering.
daww 7y ago
Interesting question, from my understanding Pathfinder is only concerned with rendering so it doesn't completely replace FreeType: you still need some software to extract the curves path data from the font file. This can be done in rust with skribo and font-kit You can check out this issue for more info: https://github.com/servo/pathfinder/issues/143 https://github.com/servo/pathfinder/issues/143

Jasper_ 7y ago

This is missing a text layout engine: separating a string of texts into multiple blocks with word wrap. This is handled in GTK+ through Pango and in Qt with an internal algorithm. I don't believe FreeBiDi/ICU is used in either.

microcolonel 7y ago
HarfBuzz for shaping, too.

sayusyz 7y ago

Great detailed pictures. I'm curious where general hinting belongs.

Jasper_ 7y ago
"Hinting" is a combination of techniques. Subpixel placement hinting is done by the shaper, which would be HarfBuzz in this case. Metrics hinting (adjusting the glyph width) is done by a combination of the shaper and the renderer, which would be HarfBuzz and FreeType. Outline hinting (fitting outline to the grid by distoring shapes without) is done by FreeType. Behdad Esfahboh, the author of HarfBuzz, has a great paper on the different choices and tradeoffs here: https://docs.google.com/document/d/1wpzgGMqXgit6FBVaO76epnnFC_rQPdVKswrDQWyqO1M/edit https://docs.google.com/document/d/1wpzgGMqXgit6FBVaO76epnnF...
- criddell 7y ago
  Now that very high dpi screens are so popular and inexpensive, is subpixel rendering worth doing anymore?
  - raphlinus 7y ago
    It's important to make the distinction between subpixel positioning and subpixel (RGB) rendering. I'd personally say yes to the former, even at high dpi, and no to the latter if you're on a mobile device. The kerning errors you get from quantizing the position of glyphs to integer pixels are, to my eyes, a noticeable degradation of quality.
    - criddell 7y ago
      Do you know if the layout engines for laser printers do subpixel stuff?
      - microcolonel 7y ago
        Most laser printers tend to use PostScript (a Turing complete language), which does not know about displays hardly at all. It does arbitrary positioning.
        7y ago

amelius 7y ago

To make it more modern, hopefully they will replace the XML by JSON at some point.

Mister_Snuggles 7y ago
How does replacing XML with JSON make it more modern?
- rurban 7y ago
  smaller, more readable, faster, safer.

dang 7y ago

Two weeks ago: https://news.ycombinator.com/item?id=20491203 https://news.ycombinator.com/item?id=20491203