Re: Pixel-based display functions

[Eli Zaretskii]

> Date: Sat, 07 Feb 2015 14:51:10 +0100
> From: martin rudalics <address@hidden>
> CC: address@hidden, address@hidden
> 
>  >> The latter calls `vertical-motion' so this should work indeed.  But does
>  >> `vertical-motion' have to go back to the beginning of a logical line
>  >> when it's broken into several visual lines?
>  >
>  > Yes, it does.  There's no other place where the display engine can
>  > _know_ that the X coordinate is zero.
>  >
>  >> This would mean that we'd always have to rescan from the beginning
>  >> of the logical line for each visual line break
>  >
>  > Yes.
> 
> This would get us quadratic time.  We should stay linear.

The only way to stay linear is to display the entire physical line in
one go.