Path: utzoo!attcan!uunet!mcsun!hp4nl!esatst!neil From: neil@yc.estec.nl (Neil Dixon) Newsgroups: comp.sys.hp Subject: Picking from Device Independent Starbase Display List Keywords: Starbase, SBDL, X Message-ID: <1059@esatst.yc.estec.nl> Date: 12 Feb 90 12:55:44 GMT Reply-To: neil@esatst.UUCP (Neil Dixon) Organization: ESTEC/YCV, Noordwijk, The Netherlands Lines: 34 Some months ago I inquired about the correct method of picking from a device independent display list in SBDL, in this newsgroup. Since there is no equivalent of `pick_from_segment' for device independent display lists in SBDL, the answer appears to be that the programmer must perform his/her own traversal of the display list, looking for a hit after each `display_element' call. If somebody already has the code to do this sort of thing, could they send it to me, before I go ahead and implent it myself. At first glance it looks like a very messy thing to have to do. I also see no reason why HP have not implemented this type of thing in SBDL (other than for PHIGS compatibility?), since I've discovered at least one situation in which it's virtually vital for this functionality to exist; namely when running an SBDL application in an X window. When running an application under X, it's necessary to be able to handle resizeing of the window containing the graphics. In this case you normally need to redraw whatever graphics are displayed in the new sized window. The only way Starbase can see this change in size is for the user to reopen the graphics window with a call to `gopen'. However, if you are using a device dependent display list, the display list is destroyed by the gopen call (or is this a bug?) and this then has to be regenerated, which may well be a non-trivial task. The most efficient solution is to use a device independent display list, but if the application is required to perform picking on the resulting graphics output, then the above described functionality is required. Is there anybody at HP prepared to comment on my suggestions; refute my arguments; give me a better solution; etc... -- Neil Dixon UUCP:...!mcvax!esatst!neil, BITNET: NDIXON@ESTEC Thermal Control & Life Support Division (YC) European Space Research and Technology Centre (ESTEC), Noordwijk, The Netherlands.