Athena Widget Set - C Language Interface - X Consortium ... - X.Org

Simple Widgetsvoid JumpProc( scrollbar, client_data, percent_ptr);scrollbarclient_dataSpecifies the ID of the scroll bar widget.Specifies the client data.percent_ptr Specifies the floating point position of the thumb (0.0\- 1.0).The jumpProc callback is used to implement smooth scrolling and is called by theNotifyThumb action. Percent_ptr must be cast to a pointer to float before use; i.e.float percent = *(float*)percent_ptr;With the default button bindings, button 2 moves the thumb interactively, and thejumpProc is called on each new position of the pointer, while the pointer buttonremains down. The value specified by percent_ptr is the current location of thethumb (from the top or left of the Scrollbar) expressed as a percentage of the lengthof the Scrollbar.Convenience RoutinesTo set the position and length of a Scrollbar thumb, usevoid XawScrollbarSetThumb( w, top, shown);wtopshownSpecifies the Scrollbar widget.Specifies the position of the top of the thumb as a fraction ofthe length of the Scrollbar.Specifies the length of the thumb as a fraction of the totallength of the Scrollbar.XawScrollbarThumb moves the visible thumb to a new position (0.0 \- 1.0) and length(0.0 \- 1.0). Either the top or shown arguments can be specified as \-1.0, in whichcase the current value is left unchanged. Values greater than 1.0 are truncated to1.0.If called from jumpProc, XawScrollbarSetThumb has no effect.Setting Float ResourcesThe shown and topOfThumb resources are of type float. These resources can be difficultto get into an argument list. The reason is that C performs an automatic castof the float value to an integer value, usually truncating the important information.The following code fragment is one portable method of getting a float into an argumentlist.top = 0.5;if (sizeof(float) > sizeof(XtArgVal)) {/*\ * If a float is larger than an XtArgVal then pass this47