GNU bug report logs - #11484
23.4; Scrolling leaves traces of old text behind

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From: Jan Djärv <jan.h.d <at> swipnet.se>
To: Eli Zaretskii <eliz <at> gnu.org>
Cc: 11484 <at> debbugs.gnu.org
Subject: bug#11484: 23.4; Scrolling leaves traces of old text behind
Date: Mon, 22 Oct 2012 07:07:33 +0200

Hello.

21 okt 2012 kl. 21:56 skrev Eli Zaretskii <eliz <at> gnu.org>:

>> From: Jan Djärv <jan.h.d <at> swipnet.se>
>> Date: Sun, 21 Oct 2012 21:07:11 +0200
>> Cc: 11484-done <at> debbugs.gnu.org
>> 
>> The current solution is to turn off LCD-smoothing.  A better
>> solution would be to draw the whole line every time.
> 
> What do you mean by "redrawing the whole line", and how would that be
> different from what was redrawn in the recipe for this bug?

In the file helix.pqr, there are columns of A:s followed by space.  When scrolling fast (or sometimes just going to the end of the buffer), the A:s are replaced with Y:s.  But the spacees following the A:s are not redrawn.  I assume the display engine correctly assumes that from a character view they have not changed and need not be redrawn.  But that extra pixel in A:s lower right corner is in the box for the space.  Redrawing the whole line in this case would also redraw the space.

That isn't a very good solution now that I think about it, as it would require a redraw of the whole line just to draw the cursor.  A more efficient way would be to include the previous unchanged character and the following unchanged character when redrawing a block of changed characters.

So redrawing the cursor for example would involve redrawing three characters.

	Jan D.

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