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List:       kde-devel
Subject:    Re: [PATCH] Transparency support and bugfixes
From:       Jo Dillon <emily () thelonious ! new ! ox ! ac ! uk>
Date:       1999-02-22 18:22:32
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Roberto Alsina (ralsina@unl.edu.ar) spake thusly:
> Qt 1.42:
> 
> void QWidget::setMask ( QBitmap bitmap )
> 
> 
> Causes only the pixels of the widget for which bitmap has a corresponding 
> 1 bit to be visible. If the region includes pixels outside the rect() of 
> the widget, window system controls in that area may or may not be 
> visible, depending on the platform. 
> 
> 
> Note that this effect can be slow if the region is particularly complex. 

 The trouble here is that anything drawn onto the widget is clipped,
so having a transparent window with text on would involve resetting the
mask using the text. The real killer, though, is that any vaguely complicated
mask (let alone lines of text!) will be /very slow/ because of the calculations
involved. It's not really usable for any more complicated mask shape than
that used by, say, xeyes. Oh, and you still don't get /proper/ transparency
- bits are either on or off, you don't get nice alpha-blended 50% transparent
windows. /That/ would be best done with an X extension ;)

-- 
	Jo

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