[xmonad] darcs patch: Decoration: fix mouse dragging jump ...

[Andrea Rossato]

On Fri, Feb 08, 2008 at 09:47:02PM +0100, Andrea Rossato wrote:
> Fri Feb  8 21:41:20 CET 2008  Andrea Rossato <andrea.rossato at unibz.it>
>   * Decoration: fix mouse dragging jump ...

please forget this one. see below.

> +    decoEventHook _ (DS dwrs@(((_,r),(dw, Just dr)):_) _) ButtonEvent { ev_window     = ew
> +                                                                      , ev_event_type = ty
> +                                                                      , ev_x          = ex }
> +        | ty == buttonPress
> +        , dw == ew = mouseDrag (\x y -> do
> +                                  let rect = Rectangle (x - fi ex) (y - rect_y dr + rect_y r)
> +                                             (rect_width r) (rect_height r)
> +                                  sendMessage (SetGeometry rect)) (return ())

can you please check if the reasoning is fine?

1. I have 1 point (pointer even: px,py) relative to the (absolute)
   decoration window's origin (dx,dy)

2. the absolute coordinates of the pointer events are:
   (dx + px), (dy + py)

3. the distance of the pointer event from the decorated window's
   origin (wx,wy) is: 
   (dx + px) - wx, (dy + py) -wy

4. when I start grabbing I get the absolute position of the pointer
   (ex,ey), and so I need to subtract the above distance to set the
   new decorated window's origin like this:
   ex - (dx + px - wx), ey - (dy + py - wy)

This seems to be working fine (I'm going to push within a couple of
hours, but if you find a mistake please drop me a line - here or on
IRC).

Sorry for this noise but I find this a quite subtle issue if you are
not that used to this kind of stuff... high school memories here...
;)

Andrea

ps: I'm going to write a small DecorationMadness module for storing,
well... you'll see!