[Fontconfig] Changing to hintslight globally by default + hintfull for otfs

[Jerry Casiano]

Hello,

Scrapping properties seems like a bad idea.

Re-defining what existing properties actually do in regards to
rendering seems like the way to go. Do anything possible via default
configuration and use the current hintstyles to do what's desired.

Also, rendering is subjective.



On Thu, 2015-10-08 at 10:39 +0200, Nikolaus Waxweiler wrote:
> (reposting because I wasn't subscribed to the list)
> 
> Hello fontconfig people,
> I'm currently trying to save the world, ehm, bring more order into
> the
> font rendering world.
> 
> The first problem is, I personally don't like hintslight/medium/full
> because they are coarse descriptions that mean different things to
> different font formats:
> 
> 1. OpenType/CFF (.otf) fonts: medium == full == snapping glyphs to
> the
> y-axis only. By design, this tries to preserve outline fidelity.
> 2. TrueType (.ttf) fonts: Full currently (FreeType 2.6.1) snaps to
> x-and-y-axis and FT doesn't fully handle ClearType yet (so no
> y-only-snapping like on Windows). Medium is similar to full, but
> seems
> to be less aggressive on the x-axis. Both sacrifice outline fidelity
> and
> "harmoniousness" for absolute sharpness with varying success. Even
> when
> ClearType is fully handled, it depends on the bytecode in the font if
> you get y-only or x-and-y snapping.
> 3. Postscript fonts: not sure, but the native hinter produces
> sub-optimal results anyway.
> 4. Slight invokes the autohinter regardless of font format. Like for
> .otfs, it snaps to the y-axis only.
> 
> The problem is nicely visible when you go medium or full and mix font
> formats. A default installation of Fedora will have Cantarell in
> OpenType/CFF format in the UI and DejaVu (.ttf) on the console.
> Cantarell is y-snapped (and slightly emboldened), DejaVu
> x-and-y-snapped. The difference is jarring.
> 
> The second problem is that FreeType currently doesn't fully handle
> ClearType. TrueType fonts developed with ClearType in mind will look
> sub-optimal by default. The OpenType/CFF hint support is top notch in
> contrast, thanks to Adobe's contributed CFF engine. The autohinter
> has
> been doing a mighty fine job across the board and for different
> languages for a while.
> 
> 
> I propose that fontconfig defaults to the autohinter == hintslight
> globally and sets hintfull only for OpenType/CFF fonts. That way, the
> default for all fonts is to snap them to the y-axis, leading to a
> much
> more coherent and harmonious look out of the box. Ubuntu has been
> doing
> global hintslight for years and I personally found rendering to be
> mostly fine there.
> 
> Ideally, fontconfig exposes something like "hintnative", "hintauto",
> "hintnone" and the modifiers "y-only", "x-and-y-if-supported", and
> scraps "hintslight/medium/full" and the "hinting" and "autohint"
> attributes.
> 
> Thoughts?
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