[ scummvm-Patches-643464 ] MI1VGA: Possible scroll arrow fix

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Patches item #643464, was opened at 2002-11-25 12:10
You can respond by visiting: 
https://sourceforge.net/tracker/?func=detail&atid=418822&aid=643464&group_id=37116

Category: None
Group: None
Status: Open
Resolution: None
Priority: 5
Submitted By: Torbjörn Andersson (eriktorbjorn)
Assigned to: Nobody/Anonymous (nobody)
Summary: MI1VGA: Possible scroll arrow fix

Initial Comment:
I've taken a closer look at the second issue of bug
#599442 ("MI1VGA: the last few glitches") -- the one
with scroll arrows covering part of the text.

I've compared ScummVM to the original (that is, if you
consider DOSBox to be a faithful rendition of the
original), and the arrows are positioned correctly. The
problem is that restoreVerbBG() thinks the arrows are
wider than they really are, so it erases too much.

What this patch does is to make the charset renderer
keep track of how wide the text it draws is (the arrows
are being drawn as verb text, apparently) if you only
consider the pixels that are actually painted. I
originally intended to do the same for the text height
but a) I couldn't get it to work properly for some
reason, and b) it wasn't needed.

One possible reason I couldn't get it to work is that
restoreBG() seems a bit dodgy. It has the lines

height = bottom - top;
width = right - left;

which I take to mean that both height and width will be
one too small. Well, width won't be since we already
increase 'right' by one (with a FIXME comment), but
what about height? On the other hand, even when
"fixing" this I couldn't get it to work, so maybe I'm
just mistaken.

My main concern about this patch is that it adds to a
part of the code that already looks dangerously
overloaded with strange variables. Maybe a cleaner
solution would be to make restoreVerbBG() more clever,
e.g. by drawing the verb string again, with the verb's
background colour. But I couldn't see any easy way of
doing that.


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