[cells-devel] Cello: 'find-view-under: Semantics ?

[Frank Goenninger]

Hi again -

thanks again for the fast response on my last request - hoping for  
another fast one here ;-)

So, Cello (the original one) has this function:

(defun find-ix-under (self os-pos &key (test #'true))
   (when (and (not (typep self 'tool-tip)) ;; <g>
           (visible self)
           (not (collapsed self)))
     (trc nil "find-ix-under" self os-pos (screen-box self))
     (let ((inself (point-in-box os-pos (screen-box self))))
       (or (when (or inself (not (clipped self)))
             (trc nil "inside self sbox" self os-pos (screen-box self))
             (dolistreversed (k (or (render-order self)(kids  
self))) ;; overlap goes to last kid displayed
               (unless (typep k 'window)
                 (trc nil "fixunder kid!!!!!!!!" k)
                 (bwhen (ix (find-ix-under k os-pos :test test))
                   (return-from find-ix-under ix)))))

           (when (and inself
                      (funcall test self)
                      (not (ix-click-transparent self)))
             (trc nil self os-pos (screen-box self))
             self)))))

which is used as follows:

(defmd mouse-view-tracker ()
   (mouse-view :initarg :mouse-view :accessor mouse-view
     :initform (c? (let ((pos (mouse-pos .og.)))
                     (trc nil "mouseview sees pos" .w. pos)
                     (when pos
                       (eko (nil "ix-togl mouseview >" self)
                         (without-c-dependency
                             (find-ix-under self pos)))))))
   (:documentation "Mixin to have mouse view tracked in a subtree of  
the window, mostly so other GUI layout can depend on
the sub-tree layout without creating a cyclic dependency, as would  
happen iof the whole window were watched."))

(defmd ix-togl (mouse-view-tracker #+not focuser ogl-lit-scene control  
ogl-shared-resource-tender togl ix-view)
...

So, the togl widget is a sub-class of mouse-view-tracker. I understand  
this as "show me the control that is currently being pointed at by the  
mouse".

Only thing is: When looking at the code for 'find-ix-under I can't see  
how this could possibly work? May I ask for a walk-through of find-ix- 
under ? Thanks!!!

Cheers
    Frank


--
   Frank Goenninger

   Cell: 	+49 175 4321058
   E-Mail: 	frgo at me.com