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NOTICE: This version of the NSF Unidata web site (archive.unidata.ucar.edu) is no longer being updated.
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>From: "Mattheus, Henner" <Henner.Mattheus@xxxxxxxxxxxxxxxxx> >Organization: >Keywords: 200008141307.e7ED7VN20893 henner- >i want to add and remove dataReferences to/from a displayImpl. they all have >the same domain (time) but eventually different ranges (several currencies). >i wonder if there isn't an easier way to achieve this goal, than allways > >a) remove all ScalarMaps and dataReferences >b) add all the previously used Maps >c) add eventually newly needed maps >d) add all the previously used dataReferences >e) add the new dataReferences. > >it would be great if somebody could show me an easier way, I don't think there is an easier way except to create your own framework that does all this for you. Unidata has been prototyping a concept that does some of what you want. We have created a DisplayMaster/Displayable framework where the DisplayMaster is basically the controller for a VisAD display to which Displayables are added/removed, etc. The Displayables each have the set of ScalarMaps that they need as well as the DataReferences and ConstantMaps and basically controls how data will be displayed. An example is an abstract class called ContourLines which has setable properties like Color, LineWidth, ContourLevels and the RealType that is mapped to Display.IsoContour. The ContourLines Displayable is added to a DisplayMaster. When new Data is set in the ContourLines displayable, the RealType is checked to see if it is different than the previous. The Displayable maintains a list of ScalarMaps that it uses in a TreeMap. If a new ScalarMap is needed (because the RealType has changed), then the TreeMap is updated and a PropertyChangeEvent is fired. The DisplayMaster listens for the changes and rebuilds the display (steps a-e in your example). There are some things you can change without rebuilding the display. In ContourLines, you can set the Color which is done through ConstantMaps. In that case, you can change the color and all that happens is that the DataReference is removed and readded with the new set of ConstantMaps. This whole framework is not without problems though. One of them is that a ScalarMap may have a Control associated with it. When you change the ScalarMap, you get a new Control and you have to account for that. The current framework does not account for RemoteDisplays either. We are currently reassessing the best way to deal with Controls and may have to rethink the whole design. However, the basic idea that the Displayable knows how to keep track of it's DataReference is very powerful. Don ************************************************************* Don Murray UCAR Unidata Program dmurray@xxxxxxxxxxxxxxxx P.O. Box 3000 (303) 497-8628 Boulder, CO 80307 ************************************************************* Unidata WWW Server http://www.unidata.ucar.edu/ McIDAS Demonstration Machine http://mcdemo.unidata.ucar.edu/ *************************************************************
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