[Qt-interest] Adding arbitrary depth to Graphics Scene & Friends

[Jason H]

Yes, you are missing something. None of the GV operations change underlying 
data. They only transform the view of it. The Item is the data. The Scene is the 
object hierarchy. The View is the scene objects with transforms applied.

If you are trying to use GV to modify your item data, you are going up the wrong 
tree. Only a QPainter will do that. 


You might be able to Subclass QGraphicsView and use your derived high BPP 
painter. Also, you'd need a QGraphicsItem that would paint() in high BPP. But 
how would you do that with standard ARGB items?...






________________________________
From: Javier Urien <javierurien at gmail.com>
To: Jason H <scorp1us at yahoo.com>
Cc: qt-interest at trolltech.com
Sent: Tue, April 26, 2011 10:36:17 AM
Subject: Re: [Qt-interest] Adding arbitrary depth to Graphics Scene & Friends




On Tue, Apr 26, 2011 at 11:28, Jason H <scorp1us at yahoo.com> wrote:

That is all fine and well.
>
>Your data will always be in your maximum bit depth. Your operations (graphics or 
>I/O) would write in your bit depth.
>You'd probably want something like:
>QByteArray highBPPData;
>QPixmap displayData;
>
>Do your operations on highBPPData, and when you modify it, either copy/convert 
>the effected region of highBPPData (raster op) and splice it into displayData, 
>or call the same function on the displayData (like for drawLine() (vector ops)). 
>And just use paint(...)to paint the displayData.
>

But what of the operations that the framework provides? For example, if the 
framework operates a QGraphicsTransform, it would be on displayData, and if 
highBPPData is of different data type I would not be able to map it back. Or 
perhaps I am missing something.

Regards.
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