State of Text Rendering (on Linux) | Hacker News Reader

State of Text Rendering (on Linux)

behdad.org

53 pointsnaner8 comments

This article begs for a link to the old rasterization experiment (http://antigrain.com/research/font_rasterization/index.html) that was and is very promising but isn't apparently widely adopted anywhere yet.

One very minor mention of subpixel rendering, no mentions of antialiasing, no mentions of hinting. This piece focuses almost entirely on structural and library issues rather than the actual rendering of text (which is still subpar on Linux compared to OS X, though somewhat better than Windows).

Behdad is a core developer of both Pango and Cairo, along with being the #1 guy on all things Linux i18n, specially BiDi hacking. I don't think the article was meant to be technical and indepth, rather, imo, it aimed for breadth to help someone get started quickly.

"Since 2008 the author has been working on rewriting the layout engine to be more robust and use mmap()ed fonts efficiently..."

That's not technical?

From my experience, this seems to be mostly an issue of configuration, which is impossible to get right, because it's incredibly painful and hostile. He mentions this issue. (Of course, most likely, there are issues with the actual rendering too.)

> One very minor mention of subpixel rendering, no mentions of antialiasing, no mentions of hinting.

This isn't a technical limitation, but a legal one. The functionality already exists[1]:

> Most other systems use the FreeType library, which falls somewhere between Microsoft's [optimized for on-screen clarity] and Apple's [optimized to closely match print] implementations; it supports hinting and anti-aliasing, and optionally performs subpixel rendering. Due to problems with patent licensing, many binary distributions of it do not support hinting non-Free fonts with the same quality as the Windows and OS X rasterizers, although the functionality is present and easily enabled. The Free fonts included with most Linux distributions look better with FreeType's "auto-hinting" mode, which is high-quality and not encumbered by patents.

1: http://en.wikipedia.org/wiki/Font_rasterization

FreeType offers more rasterization tweaking than you could ask for. And it appears some major distributions (I've seen it in Ubuntu) just ignore the patent issues and enable the probably-patented rendering techniques.

It surprises me that anyone could say Windows' third-world font rendering is "optimized for on-screen clarity." Even the current Ubuntu level of font rendering looks streets ahead of ClearType.

Harfbuzz really sucks at asian fonts because of compound alphabets (http://scripts.sil.org/cms/scripts/page.php?site_id=nrsi&...)

SIL Graphite smartfont technology is probably better suited for this - but I dont think that anyone considers that important enough.. even though there are all indications that Asia might be the biggest market for Linux.

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