1.141.3 Send methods

scroll_bar ->length: int

Total length of object.

scroll_bar ->start: int

Start of visible part.

scroll_bar ->view: int

Length of visible part.

scroll_bar ->bubble: length=int, start=int, view=int

The three parameters scroll_bar<-length, scroll_bar<-start and scroll_bar<-view tell the scrollbar which part of the object scrolled is currently in the window:

scroll_bar->length	Total size of the object
scroll_bar->start	Start of the visible part
scroll_bar->view	Size of the visible part

The method scroll_bar->bubble allows the user to change all three parameters with one message. See also scroll_bar->compute.

See also

class scroll_bar

scroll_bar ->compute:

If graphical<-request_compute is not @nil, this method will:

1. test if the scroll_bar<-object has the send method scroll_bar->bubble_scroll_bar. If this is the case, this method is called with this scrollbar as argument. The receiving object is supposed to activate scroll_bar->bubble, passing the current viewport settings to the scrollbar.
2. If the scroll_bar<-object has all the methods scroll_bar<-start, scroll_bar<-view and scroll_bar<-length, the scrollbar will invoke them and update the viewport using the result. Backward compatibility only.

   If the scrolled object or the viewport is modified, the window or scroll_bar<-object should invoke graphical->request_compute on the scroll_bar to activate this mechanism.

scroll_bar ->event: event

Operate the scrollbar The exact definition depends on scroll_bar<-look. After user-interaction that should affect the scrolled scroll_bar<-object, the scroll_bar object determines -direction, -unit and -amount. Next:

• Invoke scroll_bar->scroll_vertical: -direction, -unit, -amount on the associated scroll_bar<-object if scroll_bar<-orientation is vertical and scroll_bar->scroll_horizontal otherwise. If this method is understood and succeeds the event is considered handled. See, for example, window->scroll_vertical
• Else, forward using the associated scroll_bar<-message.

scroll_bar ->initialise: object=object, orientation={horizontal,vertical}, message=[code]*

Create a scroll_bar to scroll object either horizontally or vertically. See also scroll_bar->message.

scroll_bar ->place: [graphical]

Position scrollbar relative to the given object. If no object is given, scroll_bar<-object is used. Exploits the variables

scroll_bar<-placement	to place left/right, top/bottom.
scroll_bar<-distance	to determine the distance to the object.

The scrollbar is displayed on the same graphical<-device as the given graphical.