RE: Revised proposal for "Missing character" glyph

From: Carl W. Brown (cbrown@xnetinc.com)
Date: Thu Aug 22 2002 - 19:01:40 EDT


David,

> -----Original Message-----
> From: unicode-bounce@unicode.org [mailto:unicode-bounce@unicode.org]On
> Behalf Of David Hopwood
> Sent: Monday, August 19, 2002 6:57 PM
> To: unicode@unicode.org
> Subject: Re: Revised proposal for "Missing character" glyph
>
>
> -----BEGIN PGP SIGNED MESSAGE-----
>
> "Carl W. Brown" wrote:
> > Proposed unknown and missing character representation. This would be an
> > alternate to method currently described in 5.3.
> >
> > The missing or unknown character would be represented as a series of
> > vertical hex digit pairs for each byte of the character.
>
> Why vertical? Hexadecimal is almost invariably written left-to-right,
> top-to-bottom, and that's the order I would expect.

It was pointed out that if you have 6 hex digits that an upper row of three digits and a lower row of three digits will render better at a small point size that three rows of two digits.

             xx
  xxx vs xx
  xxx xx

By using vertical hex you have two additional advantages:

1) You can render BMP as xx rather than 0xx
                         xx 0xx

This means that text is less likely to overflow a text box or line area.

2) It allows you to implement it with engines that do not support glyph positioning with a special font that has 257 glyphs as long as it supports proportional spacing which most systems do.

Very few users will be able to decode the hex anyway. They will be able to print the screen or web page and send it to an expert. That person should be able to read vertical hex almost as easily. It will be easier to adjust the vertical hex rather that try to decode very small hex digits. Doing plane 1-16 as vertical and BMP as horizontal will be too confusing.

>
> > Garbage data with non-zero bits 24-31 may require 8 digits or 4 pairs of
> > digits.
>
> I thought this proposal was intended for characters that cannot be
> rendered by a font, not ill-formed encodings?

Why not use it for both?

Carl



This archive was generated by hypermail 2.1.2 : Thu Aug 22 2002 - 17:06:30 EDT