[Qt-interest] QGraphicsPixmapItem setPixmap() problem

[hakiim the dream]

Hi all,
I have been implementing a Pencil Tool (image editing tool) which uses layers. Therefore, I have used QGraphicsView and QGraphicsPixmapItem for layers. 
The problem is that, when drawing on high resolution images, rendering is very slow.  I have been using QGraphicsPixmapItem::setPixmap() method for pencil , and it tries to draw all the 
image again and again for every pencil move. I think it is the main reason. Is there any solution to render a smaller portion of  a QGraphisPixmapItem::pixmap() instead of updating all the pixmap?
Any idea is welcome. 		 	   		  
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