Teletext separated mosaic graphics

[Asmus Freytag (c)]

On 10/13/2020 10:00 AM, Kent Karlsson wrote:
>
> Well, the short answer is of course: HTML. Details may vary.

Right, it's those details,

A./

>
> /Kent K
>
>
>> 13 okt. 2020 kl. 18:45 skrev Asmus Freytag <asmusf at ix.netcom.com 
>> <mailto:asmusf at ix.netcom.com>>:
>>
>> How do existing websites represent teletext?
>> A./
>>
>>
>> On 10/13/2020 9:34 AM, Kent Karlsson via Unicode wrote:
>>>> 13 okt. 2020 kl. 16:30 skrev William_J_G Overington via Unicode<unicode at unicode.org>:
>>>>
>>>> I am now thinking that the best solution for encoding the teletext control characters using just already existing Unicode characters is to use the Escape format listed in the PDF document linked from the post by Harriet Riddle.
>>> That is out of the question for several reasons.
>>>
>>> 1) ECMA-48 specifies such escape sequences as aliases (formally for 7-bit encodings, but in practice not limited that way) for the ECMA-48 C1 control codes. This suggestion is thus incompatible with ECMA-48. (And promoting anything else is a bad idea, even though compatibility with ECMA-48 is not required by Unicode/10646.)
>>>
>>> 2) That ”solution” does not in any way remove the gross ill-designedness of the Teletext ”control” codes (most of them do three things in one go: colour change, code page change, display as SPACE or as ”kept” ”mosaic” character).
>>>
>>> 3) That ”solution” still cannot handle the ”object” format overrides (more colors, bold, Italics, underline, proportional font [and G3 character substitutions, but that falls under encoding conversion, not under styling]) in Teletext (a horrendous idea, the only excuse for which is compatibility with the original Teletext ”controls” which are left untouched in ”advanced” Teletext). The ”object” overrides are in a control section of the Teletext protocol.
>>>
>>> /Kent Karlsson
>>>
>>>
>>>> https://www.itscj.ipsj.or.jp/iso-ir/056.pdf
>>>>
>>>> https://corp.unicode.org/pipermail/unicode/2020-October/009048.html
>>>>
>>>> This appears to be what is used in the export format named viewdata from the editor that Kent Karlsson mentioned.
>>>>
>>>> https://zxnet.co.uk/teletext/editor
>>>>
>>>> https://corp.unicode.org/pipermail/unicode/2020-October/009071.html
>>>>
>>>> If one then uses a specially made OpenType font, one can arrange for each such two character escape sequence to be displayed as one of the glyph designs that I mentioned in the following post, by using the OpenType liga facility..
>>>>
>>>> https://corp.unicode.org/pipermail/unicode/2020-October/009047.html
>>>>
>>>>> For example, Alphanumerics Green would have a visible glyph of an A above a G on a pale.
>>>> This morning I tried making a test font with a visible glyph for the Escape character and a liga glyph substitution for Escape followed by capital A.
>>>>
>>>> I made the font using the High-Logic FontCreator program and tested it in the Serif Affinity Publisher program, producing a PDF document.
>>>>
>>>> I was hoping to be able to paste a copy of the substituted glyph copied from the PDF to WordPad and recover the underlying two character sequence. However I could only seem to get the capital A back. Maybe I did not get the technique quite right and so it might perhaps be possible to get the underlying sequence back from a PDF, but that requires further investigation.
>>>>
>>>> William Overington
>>>>
>>>> Tuesday 13 October 2020
>>>>
>>>>
>>>>
>>>>
>>>>
>>>>
>>
>

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