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Re: Can we make set_point_both less expensive?


From: martin rudalics
Subject: Re: Can we make set_point_both less expensive?
Date: Fri, 20 Mar 2015 20:53:53 +0100

>> Strictly spoken I see no reason why the display engine should not handle
>> that property by itself.
>
> Redisplay never moves point, except when it was forced to keep a
> specific window-start position.  In all other cases, it scrolls the
> display, but leave point intact.

But when redisplay moves point (usually after scrolling the window) it
could check whether it would end up in an intangible region and adjust
point accordingly.  Why would this be such a big deal?

> And cursor is always set where point is, we have no other strategy for
> positioning the cursor.

After `scroll-left'?

> So I don't see how handling intangible could
> be the job of redisplay, without significant changes.

Isn't adjust_point_for_property some sort of redisplay revisited?

>> Someone would have to handle the scroll margins too when determining
>> on which side of the area to move point.
>
> Scroll margins don't cause point movement; they cause movement of text
> wrt the window.

They would determine the position of the cursor when an intangible area
starts or ends within them.

martin



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