QGraphicsItem leaves junk on screen

[durbrak]

Hey,
I was wondering regarding your attached screenshot - what's that at the left side of your application where it says vertically "Components"? Is this some kind of Sidebar or something? Did you do it on your own or does Qt has something like that? Or do you even have it from somewhere else?
Just curious

[Gopala Krishna]

Hey,
I was wondering regarding your attached screenshot - what's that at the left side of your application where it says vertically "Components"? Is this some kind of Sidebar or something? Did you do it on your own or does Qt has something like that? Or do you even have it from somewhere else?
Just curious

Yes, it is a sidebar(more appropriately toolview). I am using krawek's ideality library - an external library which really makes it easy to use.

[Gopala Krishna]

Hi guys,
Though the wires in my app were moving appropriately the performance was bit low when I tried on my old low end comp. The problem was , one of the lines in wire wasn't being drawn at all when the wires geometry changes rapidly espescially, when lines of wire were perpendicular and lengthy as shown below , where "dash-line" represents undrawn line.

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The reason I guess is overhead in scene's index management system caused due to repeated "prepareGeometryChange()" calls and also to the fact that the boundingRect coveres unwanted areas resulting in more updates.

So, I came up with an ugly/good hack by replacing wires with "QRubberBand" of unit width (to represent line) while changing geometry and "QGraphicsLineItem" while static. I hide the QGraphicsLineItem when wire's geometry starts changing and show QRubberBand and vice-versa otherwise . This is working as I expected - fast and clean.
(I've attached screenshot with QRubberBand "proxying" lines.)

Do you think this hack is a better alternative or Is there any better way ? Is there any potential problem ?

[wysota]

Maybe you should turn off BSP indexing while moving objects around? Or if you have composite lines, make them separate objects, so that their bounding rect is much smaller.