Re: Not a regression, but shuld go into emacs-24

[Jan Djärv]

Hello.

2 jun 2014 kl. 20:02 skrev martin rudalics <address@hidden>:

> > Only for a jump scroll.  When dragging or scrolling by page, PORTION
> > passed to x_send_scroll_bar_event is zero, as is WHOLE.
> 
> IIUC in XmCR_DRAG we set PORTION to 'cs->value',

XmCR_DRAG is jump in Motif speak.

> in xg_scroll_callback
> we set PORTION to 'position'

No we don't, please look at the current code.  portion and whole are 
initialized to 0 and
only set for JUMP.

> and in xaw_scroll_callback we explicitly
> pass 'position' as PORTION argument.

Because that callback does not distinguish between the different scroll modes.


>  So in all three cases we pass a
> position.  And IIUC we pass zero for PORTION and WHOLE iff when we end
> scrolling (when the user releases the slider).

Iff is clearly wrong.  Look  at xg_scroll_callback and do tell me how portion 
and whole gets a value other than zero when scroll is not GTK_SCROLL_JUMP.
Ditto for xm_scroll_callback when cs->reason is not XmCR_DRAG.

> 
> > For jump scroll, PORTION is the position of the scroll bar thumb that we 
> > jump to.
> 
> I didn't look into jump scroll so far.  But what you say here indicates
> that jump scroll also passes a position via the PORTION argument.
> 
> > The values of PORTION in x_send_scroll_bar_event and
> > x_set_toolkit_scroll_bar_thumb are different.  The first has values as
> > defined by the scroll bar.  For Gtk+, Motif and Xaw this is a value
> > between 0 or 1 and 10000000.
> 
> Yes (in my experience Gtk+ can handle WHOLE directly as is).

This looks ugly when WHOLE changes.  The Gtk+ scroll bar does not redraw nicely.

        Jan D.

> 
> > The values to x_set_toolkit_scroll_bar_thumb are in characters,
> > i.e. show PORTION characters for the buffer, starting at character
> > POSITION.  The buffer has a total of WHOLE characters.
> 
> But the values passed to x_send_scroll_bar_event are in characters too
> (and the value of WHOLE is supposed to be the same as when setting the
> thumb).  Or am I missing something?
> 
> martin