Re: Unfortunate pixel width of one TAB

[Markus Gritsch]

Kenichi Handa wrote:
> I don't think that solves the problem.  See this example
> lines (the first line has three spaces after "wwwww", and
> the next line has one TAB after "wwwww", the last line is
> just TAB and "a"):
> wwwww   a
> wwwww   a
>         a
>
> Provided that space width is 5 pixels and "w" width is 10
> pixels, the "a" of the first line is at 65 pixels from the
> left, but the "a" of the second line is at 80 pixels from
> the left, and the "a" of third lines is at 40 pixels from
> the left.

I agree, that there is no canonical solution to the problem which 
behaves for all users like they expect.  However using the space pixel 
width to calculate the tab pixel width at least solves the problem of 
indentation in source code where only tabs and spaces (but no other 
glyphs) are used for indentation at the beginning of the line.

> When we change FONT_WIDTH to return the width of space
> glyph, the current tab width problem will be solved.  But,
> as FRAME_COLUMN_WIDTH is also a base of calculating the
> frame width, such a change leads to too narrow frame width.

That's exactly what I have to fight with when lying to Emacs in the font 
definition string.  Decoupling FONT_WIDTH and FONT_SPACE_WIDTH as 
suggested by you will probably solve the problem.

King regards,
Markus