Martin J. Dürst wrote:
So rich text technology is already way ahead when it comes to styled
text. Do we want to encode background-color variant selectors in
Unicode? If yes, how many?
Yes.
You would only need one.
Background colour was a feature of teletext in the United Kingdom from
1976. It was very effective in its application.
In teletext, there were seven choices of foreground colour (red, green,
yellow, blue, magenta, cyan, white), the default background was black.
The New Background control character caused the background colour to
become the same as the current foreground colour in which text was being
displayed. One could then change the foreground colour.
There was also a Black Background control code. This was necessary
because neither text nor graphics could be black in teletext.
In teletext those control codes were stateful and applied until a change
or to the end of the line of text, whichever came first.
So, given that Unicode is starting to encode colour choices for emoji
and black is in the set of colours - and that might possibly extend to
choosing colour for text - if Unicode were to encode CHANGE BACKGROUND
COLOUR then the background colour could become the current foreground
colour, even if that chosen foreground colour had just been selected and
not actually used to colour text.
The implementation in Unicode need not be stateful.
[Hint: The last two questions are rhetorical.]
Maybe that was the intention, but the questions were asked and the
concept is an interesting possibility for implementation.
William Overington
Tuesday 15 January 2019
