[Fontconfig] Marking glyphs as deliberately blank, per font

[Behdad Esfahbod]

On 11/25/2009 07:01 AM, Paul Flo Williams wrote:
> I have been attempting to create some fonts that reproduce the look of old
> text terminals. One of the features of terminals like the VT100 was
> double-height, double-width mode on certain lines. In order to do this, I
> have created two fonts, one for the upper half of characters, and one for
> the bottom half. However, for characters where all the marks would appear
> in just one half of the glyph, say quote marks or the underscore, I am
> left with blank glyphs in places where fontconfig doesn't expect them, and
> those glyphs are marked as broken by fontconfig, and substituted.
>
>> From my reading of the fonts.conf page, I think that the<blank>  element
> is a global configuration, and I don't believe I can say for a given font,
> "these glyphs are intentionally blank", which leaves me with these two
> questions:
>
> 1. Is my understanding correct, that I can't override<blank>  per font?

I believe so.

> 2. The fonts.conf page says that 'fonts often include "broken" glyphs which
>     appear in the encoding but are drawn as blanks on the screen.' A trawl of
>     the mailing list suggests that this configuration option is ancient -- at
>     least I can't find any discussion of its introduction -- so is this form
>     of breakage common in fonts we use today?

Donno.

behdad


> I am aware that I'm attempting to do something rather odd here, so I think
> I'll have to do my own substituting with spaces when producing "screen
> shots" of these old terminal displays, but I wanted to check my
> understanding of fontconfig's blank mechanism.