Sunday, February 19, 2017

Re: Help with print encoding

On 19/02/2017 10:11, Mike Williams wrote:
> On 14/02/2017 20:32, Lifepillar wrote:
>> On 14/02/2017 16:43, Mike Williams wrote:
>>> On 14/02/2017 07:25, Lifepillar wrote:
>>>> On 13/02/2017 18:08, Mike Williams wrote:
>>>>> The reason you see the upside-down question marks is because VIM
>>>>> converts the buffer content from utf-8 to latin1, but the latin1
>>>>> character set does not include the left and right single quotes and
>>>>> VIM
>>>>> will change them to upside-down quotes so they stand out. On Macs
>>>>> there
>>>>> is special code to convert utf-8 to Mac encoding where the left and
>>>>> right quotes exist, so that should work for you. Unfortunately I
>>>>> don't
>>>>> have access to a Mac to confirm this.
>>>>
>>>> I do not know much about print encondings, but... wouldn't it be
>>>> possible to define new print encodings, namely a UTF-8 print encoding?
>>>
>>> That would make life easier, but history is against you I'm afraid.
>>
>> Would you care to elaborate? Is PostScript the problem? If so, can Vim
>> bypass generating a PostScript file?
>
> Almost all printing technology pre-dates Unicode and earlier unified
> character set technology. Early products would be sales region specific
> - for example Western printers would not print East Asian text and vice
> versa (OK they did ASCII but not the wider European character set, but I
> digress).
>
> The early printers were very limited in processing power and available
> memory. The original methods of font definition and use were organised
> around minimising font sizes and a lot of the print file text encoding
> methods were designed to support this. They provide some internal fonts
> but because of font licensing and hardware constraints there were only a
> few fonts covering the basic design styles - fixed width, serif,
> sans-serif, and symbols.
>
> This means if you wanted to use any other fonts on the printer they have
> to be downloaded to the printer. These fonts could be large, and if you
> use multiple fonts your print file size balloons, and then your printer
> runs out of memory and fails to print. Techniques developed to reduce
> the final file size to help printing these complex files, but they were
> not trivial.
>
> VIM printing support was added in the late 90s. It uses four fonts
> (each of the Courier normal, bold, italic and bold-italic variations are
> distinct fonts) which are all provided by default in PostScript printing
> systems. Importantly this also means that everything is known about the
> fonts (glyph sizes, complement, etc.).
>
> Most printing technology in use today (PS, PDF, XPS) supports fonts with
> a large number of glyphs, and multi-byte character encodings (including
> various Unicode encodings) for the text to be printed. It would be
> possible to add support to VIM given time - it would need to include a
> font reader, font rewriter (to avoid including a few megabytes of font
> data not needed), four fonts to be used for the four styles (although it
> could implement a poor man's version for bold and italic versions) which
> are suitably licensed for inclusion with VIM. Adding support for
> arbitrary fonts provided by the user raises the bar further due to the
> various font formats available and varying glyph complements. And you
> still have the issue of what to do if a font does not contain the glyph
> for the character you want printed.
>
> At the end of the day VIM is a text editor. It supports basic printing
> with limited styling - it is not a full Unicode scripting engine with
> printing. Generally text files are written in a single well defined
> script, or character set, which can normally be handled by an 8-bit
> encoding (there is support for CJK MBCS printing as well). The
> immediate problem is handling the transcoding of Unicode to a suitable
> single byte character set. There are two possible solutions, selection
> of single byte character set based on glyphs to be printed, or use
> Unicode character alternates when transcoding to a character set. For
> example converting your left and right quotes to apostrophes. I will be
> suggesting the latter one to start with to the dev team.
>
> Basically yes it could be done, but the amount of work and additions to
> VIM seems out of proportion to the benefit gained. Some may say they
> would love a full Unicode print support, possibly even with proportional
> fonts but they their will be issues with composing characters and
> possibly a layout-engine. These are far from trivial to implement and
> most VIM users would have other priorities.
>
> I hope that helps understand some of the issues to do with printing
> these days.

Thanks for the thorough explanation!
Life.

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