Important: Please read the Qt Code of Conduct -

Precision problem with QGraphicsScene using NoCache on items

  • Hi,

    I have a precision problem with QGraphicsScene/View.

    The problem was not discovered before as all items were cached with DeviceCoordinateCache. But this mode makes the application really slow as I have a very large scale in my scene (zoom can go from 10e7 to 10e-5) and the pixmap cache were enormous. Many items must be redrawn each frame too as they kind of animate. So DeviceCoordinateCache is really not a thing to do IMHO.

    So I changed to NoCache and now I have precision problems. When I zoom in, paths starts to flicker, the width of the line flickers to and also totally disappears. The problem was not appearing at all when using DeviceCoordinateCache, all paths were drawn perfectly.

    So my question is:

    Is there a way to have the same drawing behavior as DeviceCoordinateCache (i.e perfect drawing) in NoCache Mode?

Log in to reply