Dear Joshua Gargus

Hi. I have been trying to learn squeak. Recently I
have been reading the code in MouseClickState event
handling. The original version of this has your
initials on it and was written/added in Sept 2001. 
The routine that calls it for action is
HandMorph>>handleEvent; and that was written six
months earlier.

MouseClickState>>handleEvent:from:  is nonrecursive
except at one point where it is processing the first
mouseup. There it calls handleEvent: with a copy of
the mouseup event after firing the click selector.

I've check with a diagnostic and this is definitely a
recursive call. The same mouseup comes thru a second
time (the click state has changed. And the recursive
event glides thru without causing anymore changes.)
The recursive call releases it back to handleEvent
with the true flag. It is processed to completion. 

When handleEvent exits the remaining unrecursed event
is released back to handleEvent with the original
false flag. Furthur processing is not done and
handleEvent releases back to its original caller.

I do not believe this is what was actually intended.
But I do not understand what the actual intention was
either.

Changing the code so that instead of

self click.
aHand handleEvent: copiedEvt .
^false

we have just:

self click.
^true

would seem to do the trick as far as the post
processing results are concerned.

So if there is a difference then it would have to be
in what happens before clickstate is checked a second
time. 



>From the rest of the method, it would be the most
logical way to have coded it.  So obvious that the
fact that it was not is curious.

Was there something click was supposed to change such
as mouse focus that would make the recurssion useful?

If click does not change mouse focus then you have the
same old listeners to mouse up being fired twice.
Which would explain a few things.

So I am trying to track down the history and the
folklore on ClickState to see what I'm missing.

Any help would be appreciated.

Here is the diagnostics in text:


'From Squeak3.8alpha of ''17 July 2004'' [latest
update: #5976] on 1 August 2004 at 12:18:18 pm'!
"Change Set:		ClickStateDiagnostics-wiz
Date:			1 August 2004
Author:			Jerome Peace (wiz)
			
wiz 8/1/2004 12:17

ClickStateDiagnostic tools to explore what Clickstate
is doing. This changeset limits itself to the looking
routines.

I've set up a subclass of MouseClickState to and a
history iVar and a PastHistory cVar. The former stores
all the events ClickState is called with; the latter
the past ClickStates instances.
MouseClickState did not have to be patched.
HandMorph is patched to attach the hooks.
Also HandMorph class now has accessors to EventStats.

This is very useful for seeing just what actually
passed thru clickstate. It does not show the actions
of clickstate though they can mostly be arrived at by
inference.

I use the method name #preserve to have an instance
save itself in its Past History.
The method has been added to Object as a nop to avoid
objections from nil and other non approriate classes.

The subclass and preserve technique is a pattern that
could be used to observe other instances.




Third attempt. wiz 7/29/2004 10:29
Added a size limit to PastHistory. No sense causing
out of space crashes.

Second attempt at ClickTestTools. 

This is a first pass at tools to examine in
MouseClickState.

I made a nosy subclass of MouseClickState which copys
the events as they are sent to a history collection.

The states objects themselves are preserved in a
classVar ordered collection with the idea of them
being explored and reset e.g. 
(WizClickStage resetPastHistory explore) .

HandMorph class was modified to give access to the
eventStats that handleEvent stores.
(HandMorph eventStatsReset explore).

HandMorph was modified to use and preserve my
clickstate subclass.
 "!

MouseClickState subclass: #WizClickState
	instanceVariableNames: 'history'
	classVariableNames: 'PastHistory'
	poolDictionaries: ''
	category: 'Morphic-Kernel'!

!WizClickState commentStamp: '<historical>' prior: 0!
I am a nosy click state subclass. I collect a history
of events passed to my super.

"WizClickState resetPastHistory explore."


Structure:
 history		OrderedCollection or nil -- collects event
sent to clickstate
 PastHistory	OrderedCollection or nil -- collects
clickstates as they are reset.

Use me as a microscope to check what MouseClickState
will do.!


!Object methodsFor: '*ClickTest' stamp: 'wiz 7/29/2004
02:22'!
preserve
	"Subclass WizClickState redifines. Just ignore here."
	^ self! !


!HandMorph methodsFor: 'double click support' stamp:
'wiz 7/29/2004 01:15'!
resetClickState
	"Reset the double-click detection state to normal
(i.e., not waiting for a 
	double-click). "
	mouseClickState preserve. 
	mouseClickState := nil! !

!HandMorph methodsFor: 'double click support' stamp:
'wiz 7/29/2004 00:58'!
waitForClicksOrDrag: aMorph event: evt selectors:
clickAndDragSelectors threshold: threshold 
	"Wait for mouse button and movement events, informing
aMorph about 
	events interesting to it via callbacks. 
	This message is typically sent to the Hand by aMorph
when it first 
	receives a mouse-down event. 
	The callback methods, named in clickAndDragSelectors
and passed a 
	copy of evt, are: 
	1 (click) sent when the mouse button goes up within
doubleClickTime. 
	2	(doubleClick) sent when the mouse goes up, down,
and up again all 
	within DoubleClickTime. 
	3	(doubleClickTimeout) sent when the mouse does not
have a doubleClick 
	within DoubleClickTime. 
	4	(startDrag) sent when the mouse moves more than
threshold pixels 
	from evt's position within DoubleClickTime. 
	Note that mouseMove: and mouseUp: events are not sent
to aMorph until 
	it becomes the mouse focus, 
	which is typically done by aMorph in its click:,
doubleClick:, or drag: 
	methods. "
	mouseClickState := WizClickState new
				client: aMorph
				click: clickAndDragSelectors first
				dblClick: clickAndDragSelectors second
				dblClickTime: DoubleClickTime
				dblClickTimeout: clickAndDragSelectors third
				drag: clickAndDragSelectors fourth
				threshold: threshold
				event: evt! !


!HandMorph class methodsFor: 'accessing' stamp: 'wiz
7/28/2004 00:08'!
eventStats
^ EventStats! !

!HandMorph class methodsFor: 'accessing' stamp: 'wiz
8/1/2004 11:54'!
eventStatsReset
| oldStats |
"HandMorph eventStatsReset explore"
	oldStats _ EventStats.
	EventStats _ nil .
	^oldStats! !


!WizClickState methodsFor: 'access' stamp: 'wiz
7/29/2004 00:43'!
history
^ history
! !

!WizClickState methodsFor: 'access' stamp: 'wiz
7/29/2004 01:09'!
pastHistory
^ PastHistory! !

!WizClickState methodsFor: 'access' stamp: 'wiz
7/29/2004 10:05'!
preserve
(PastHistory
		ifNil: [PastHistory := OrderedCollection new]) size
< 100 ifTrue:
		[PastHistory add: self] .! !

!WizClickState methodsFor: 'access' stamp: 'wiz
7/29/2004 02:41'!
resetPastHistory
self class resetPastHistory! !

!WizClickState methodsFor: 'event handling' stamp:
'wiz 7/29/2004 00:46'!
handleEvent: evt from: aHand 
	(history
		ifNil: [history := OrderedCollection new])
		add: evt.
	^ super handleEvent: evt from: aHand ! !


!WizClickState class methodsFor: 'accessing' stamp:
'wiz 7/29/2004 02:39'!
pastHistory
	^ PastHistory! !

!WizClickState class methodsFor: 'accessing' stamp:
'wiz 7/29/2004 02:44'!
resetPastHistory
"WizClickState resetPastHistory explore."
	| oldPastHistory |
	oldPastHistory := PastHistory.
	PastHistory := nil.
	^ oldPastHistory! !



Attached is the changeset with the diagnostic routines
for examining ClickStates and the events that flow
thru them.

Yours in service,  --Jerome Peace



		
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