Re: "Final" version of tty child frames

[Gerd Möllmann]

Gerd Möllmann <gerd.moellmann@gmail.com> writes:

> Feng Shu <tumashu@163.com> writes:
>
>> Gerd Möllmann <gerd.moellmann@gmail.com> writes:
>>
>>> Feng Shu <tumashu@163.com> writes:
>>>
>>>> border do not work well when current buffer is CJK, maybe because CJK
>>>> Char width is not 1
>>>
>>> Could you please send me a bit of CJK text so that I have something I
>>> can test this with?
>
> Thanks!

Hm, okay, but not sure how to fix that.

The problem comes indeed from the root frame displaying characters that
are more then 1 column wide, say N. When we output such a character to
the terminal, the cursor moves by N columns. Emacs represents that in
the glyph matrix by producing N glyphs for the character, all bu tthe
first have a padding flag set. So we have

  ... (C, 0) (C, 1) ...

in the glpyh matrix, where C is the character, and the number is the
padding flag.

Now assume, for example, that the child frame is posititoned so that its
left border where we want to display a '|' is in the column for the (C,
1).

That can't work, because writing C to the terminal moves 2 columns and 
will skip over the column where we want the '|' to appear.

I think the same should happen, in principle, without borders. Haven't
checked that though. Maybe we have to "clear the field" to the left and
right of child frames in the root frame matrix so that wide characters
don't interfere.