[Qt-interest] Drawing rectangles with non-full opacity.

[Bram Schoenmakers]

Hello,

I have a problem with giving a QPixmap a soft border in Qt 4.4.x. The original 
pixmap does not have an alpha channel, but I use the trick described at [1]. 
This involves creating a new pixmap of the same size and draw the original 
pixmap on it.
Then, I draw a rectangle around the border, adjust the rectangle, decrease 
opacity and draw a new rectangle. The latter happens with composition mode 
DestinationIn.

This is causing problems. QPainter::drawRect() , but as soon as I draw 
rectangles with a pen with non-full opacity I don't see the rectangle on 
screen. What is going on and how should I fix this?

[1] 
http://techbase.kde.org/Development/Tutorials/Graphics/Performance#The_right_way_to_do_it

Thanks in advance,

-- 
Bram Schoenmakers

What is mind? No matter. What is matter? Never mind.
(Punch, 1855)