hi koen, > I think you will also need to use composition, since WCartesianChart > is a WPaintedWidget. > And specialize WCartesianChart to customize its rendering.
so you think the WVirtualCartesianChart (if the name is appropriate) should inherit from WCartesianChart and use some WPaintedWidget's for painting the rendered data and use the functionality from WVirtualImage for scrolling. sounds tricky, but possible. > (Not by coincidence coming to Fosdem ?) oh. i think that's to far from here (austria) but would be nice and interesting. > Well, WAbstractItemModel does not really hold any data, it's just an > interface. I would rather then suggest that you have a custom > implementation of the model that does not need everything in memory ? > > We just need to make sure that the chart only attempts to fetch > relevant data from the model. This is only doable if there is a way to > calculate X range -> relevant row indexes. I haven't thought about > this yet, but we could add virtual methods so that a user can specify > this (in any case it is an optimisation to render less?). The default > implementation would just return the range (0, model->rowCount()). my problem is, that i fetch the data form a database (mysql) which holds up to 500.000 entries and more. i don't think a model can handle this. or can DBO help here? thanx, johannes ------------------------------------------------------------------------------ The Planet: dedicated and managed hosting, cloud storage, colocation Stay online with enterprise data centers and the best network in the business Choose flexible plans and management services without long-term contracts Personal 24x7 support from experience hosting pros just a phone call away. http://p.sf.net/sfu/theplanet-com _______________________________________________ witty-interest mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/witty-interest
