[PyQt] Simple Draw/Erase on image

Aaron Digulla digulla at hepe.com
Wed Apr 30 21:44:46 BST 2008

Jake Richards schrieb:
> Hello:
>   I am looking to write just a simple drawing program that would load an
> image, and then allow me to draw and erase on top of it.  I looked at the
> scribble example and it has basically everything I need except the ability
> to erase any marks I've made over the source image.  What would be the best
> way to erase any drawn lines I've created over the image?  I tried setting
> the image to ARGB and then switching the pen to (0,0,0,0) but that draws
> nothing (I was hoping it would draw 0,0,0,0 instead of adding color*alpha).
> Is there a way to use the source image as my pen color (basically painting
> with a texture)?  Thanks for any help!

Two solutions:

1. Draw the line again with the background color (for example,
white+full opaque: 255,255,255,255)

2. Use a QGraphiceView and delete the line object from the scene when
you click on it with the "delete tool" (see


Aaron "Optimizer" Digulla a.k.a. Philmann Dark
"It's not the universe that's limited, it's our imagination.
Follow me and I'll show you something beyond the limits."
http://darkviews.blogspot.com/          http://www.pdark.de/

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