tomt@maui.coral.COM (Tom Tulinsky) (08/18/90)
A while back I asked several times, in various ways, how to manually reposition the WorkArea of an AUTOMATIC XmScrolledWindow. I finally received a response which showed me how to do it from Peter Hennige at Cadlab in Germany. Following is my question and his response. In article <9006202040.AA05018@maui.coral.com> I wrote: >I am using a Motif ScrolledWindow widget with ScrollingPolicy=AUTOMATIC. >Usually I want to let Motif move my work area window automatically >in response to the user moving the scroll bar. Sometimes however I >want to position the scroll bar, and the work area, under program control. >When I try XmScrollBarSetValues, the scroll bar moves but the work area >(the window I'm looking at thru the scrolled window) does not. I have set >the Notify parameter of XmScrollBarSetValues to True. Is this supposed >to work? If not, I think it ought to be added to Motif. Peter's Answer: > The reason for this behaviour is that the ScrolledWindow widget > doesn't add any ValueChangedCallbacks to the ScrollBar widgets. You > have to supply these callbacks by yourself, for example in the > following way: > > > void > value_changed_cb (widget, client_data, call_data) > Widget widget; > caddr_t client_data; > XmScrollBarCallbackStruct *call_data; > { > XtCallCallbacks (widget, XmNincrementCallback, call_data); > /* Ugly, but it works. */ > } > > . > . > . > > > XtAddCallback (vertical_scrollbar_widget, XmNvalueChangedCallback, > value_changed_cb, NULL); > XtAddCallback (horizontal_scrollbar_widget, XmNvalueChangedCallback, > value_changed_cb, NULL); > > > With this callbacks added the work area is repositioned (as everyone > would expect it) after each call to XmScrollBarSetValues, which > changes the ScrollBar values. > > > Peter Hennige > Cadlab > Bahnhofstrasse 32 > 4790 Paderborn > FRG > > Email: pit@tunix.cadlab.de Coral * ** Tom Tulinsky 508 460-6010 * ** Coral Network Corporation fax 508 481-6258 * ** 734 Forest St net: tomt@coral.com *** Marlboro, MA 01752 ** U S A ********* NETWORKS