Re: Bidi reordering engine upgraded

[Eli Zaretskii]

> From: Thien-Thi Nguyen <address@hidden>
> Date: Fri, 17 Oct 2014 09:50:30 +0200
> 
> 
> [1:text/plain Hide]
> 
> () Eli Zaretskii <address@hidden>
> () Fri, 17 Oct 2014 09:16:05 +0300
> 
>    > Left-most pixel is numbered 0, and "at 0"
>    > refers to that pixel.
> 
>    But with that model, a 1-pixel line "at 0"
>    does NOT "invade" on pixel 1.
> 
> Granted (if i take "1-pixel" to mean the length of
> the line, and not its "line width" (a measure
> orthogonal to the line's orientation), which is
> what i normally understand "1-pixel line" to mean),
> but a foo-pixel line "from X to X+W"[0] renders X,
> X+1, X+2 ... X+W, for a total count of W+1 pixels.
> OBOE!  The invading pixel is not X+1, but X+W.

But there are W+1 pixels in a line that starts at X and ends at X+W.
W+1, not W.

> 
>  | 1         2         3
>  | 012345678901234567890123456789
>  |           ***********
>  |                     ^ out out damned dot!

Count the stars, and you will see there are 11 of them, not 10.  Where
did the 11th one come from, when we requested a width of 10?

>    decide first what we would like to see as the
>    hollow cursor for a glyph that is 1-pixel wide.
> 
> Perhaps "hollow" in the vertical sense only could be
> expressed as two pixels, one at top, one at bottom.
> That's almost invisible, though; maybe two or three
> at top and two at bottom is better.

Why not just a single-pixel vertical line instead?