You probably want to scale the image, not the pixmap item.
You are currently scaling the by 0.1 in both dimensions, reducing the visible image to a hundreth of its orginal size. But you still keep the image in its full size.
If you scale the image and then create the pixmap item, each item will only have the thumbnail image to hold.
Something you could try additionally is to use a QListView in icon view mode and write a simple list model that returns thumbnail images as Qt:ecorationRole value.
That way the list view can decide which images it needs to fill its area and you only need to load and scale those.
Cheers,
_
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