Re: [cgmo-webcgm] ISSUE: should no-target-object block event dispatch?

[Benoit Bezaire <benoit@itedo.com>]

Hi Lofton,

That seems to be a copy/paste error. The text should be bullet 1, 4
and 5:

* If there are no graphics objects whose interactive region is under
the mouse (i.e., there is no target object), the event is not dispatched.
* Otherwise, the Picture is checked to see if it has an appropriate
event handler. The event is dispatched to the Picture if one is found.
* Otherwise, the event is discarded.

But now replace Picture with Metafile (since we did the change of
moving addEventListner to the Metafile interface).

-- 
 Benoit   mailto:benoit@itedo.com

 
Tuesday, August 23, 2005, 6:51:26 PM, Lofton wrote:


LH> 5.7.10
LH> ----------
LH> There are some things in the 2nd bullet list that I don't understand:

>>* If there are no graphics objects whose interactive region is under the
>>mouse (i.e., there is no target object), the event is not dispatched.
>>* Otherwise, there is a target object. If there is an event handler at the
>>Picture level with event capturing for the given event, then the event is
>>dispatched to the Picture.
>>* Otherwise, if the target object has an appropriate event handler for the
>>given event, the event is dispatched to the target object.
>>* Otherwise, the Picture is checked to see if it has an appropriate event
>>handler. The event is dispatched to the Picture if one is found.
>>* Otherwise, the event is discarded.

LH> (Long story short ... draw a flowchart of the above, with four Y/N decision
LH> branches ... something is wrong.  In words, the long story is...)

LH> I don't understand how the 2nd sentence of 2nd bullet relates to the 4th
LH> bullet.  If there is an appropriate event handler at the Picture level, how
LH> would the event-dispatch algorithm ever get past the 2nd bullet?  2nd
LH> bullet says that eligible Picture gets the event before eligible target
LH> object (eligible = has handler), while 4th says eligible picture gets it
LH> *after* eligible target object.  I would think that we mean the 4th,
LH> right?  I.e., most specific wins?  I.e., closest to leaf wins?

LH> I'm unclear why the dispatch-to-Picture (if eligible) of the 2nd bullet
LH> should be contingent upon there being a target object.  It basically
LH> says:  if you click on a blank area of the picture, the event is not
LH> dispatched (so Picture could not receive the event).  Is that what we
LH> intended?

LH> (Btw, the first bullet is effectively the same as SVG1.1.  SVG is now
LH> debating whether to change it, even at the expense of being non-backward
LH> compatible[!], so that the containing SVG element [i.e., our "Picture"]
LH> gets a chance at the event if there is no target object.)

LH> Thoughts?

LH> Regards,
LH> -Lofton.