Re: Redisplay problems?

[Eli Zaretskii]

> From: Stefan Monnier <address@hidden>
> Cc: address@hidden, address@hidden, address@hidden, address@hidden,
>         address@hidden
> Date: Thu, 27 Mar 2014 09:55:40 -0400
> 
> >> Do we use things like "block move"?
> > Not sure what you mean by "block move".
> 
> Moving a block of pixels.

Got that part, thanks.

> My concern is whether the redraw may decide to use some other part of
> the display to draw a particular region (typically for scrolling).
> If we do, then it's important to make sure that part is in-sync with the
> current matrices, but if we don't then we don't need to worry about the
> display being out-of-sync with the current matrices.

Here you lost me.  Are we still talking about redrawing a frame as
response to expose event that exposes the entire frame?  If so,
expose_frame doesn't bother to check whether the current matrix is up
to date, it blindly uses all of it to redraw every screen line of the
frame.

In case of text lines, this redraws each screen line by calling the
'draw' method of the font driver, passing it a "glyph string"
structure, which describes a sequence of characters that come from the
same face (font. colors, etc.).

How does all this relate to moving blocks of pixels?