Distinguishing simple and double clicks

[Eric Chatonet]

Bonsoir Richard,

Le 23 sept. 08 à 17:48, Richard Gaskin a écrit :

> Eric Chatonet wrote:
>> I just want to make something that was easy with HC: e.g. allow the
>> user to use simple and double clicks on the same button but with
>> different actions.
>> MouseUp is always sent by the engine first then mouseDoubleUp is sent
>> if appropriate.
>
> Is that not how HyperCard works?

Yes for sure but as mouseDoubleUp did not exist, it was making things  
finally simpler ;-)

> If HC sends only one message or the other, then it must be adding a
> delay to the mouseUp before firing its mouseUp message in order to  
> be able to distinguish it from mouseDoubleUp.  :\

Sure but I wonder: in many apps when does exist this ability, it does  
not seem there is an extra delay: how is this possible?
Actually, I don't think it's possible without extra delay...

> As for the task itself, your handlers look good for what you want  
> to do so I'd go with those, but the question has me curious:  What  
> is it you're working on?

I have web pages filmstrips and a simple click opens a viewer related  
to a database while a double click goes to the 'real' page in your  
current browser.
Of course I could replace the double click with a shift click but,  
from an ergonomic point of view, it's not satisfying: two hands  
instead of one...
All that knowing that hovering a thumb is enough to select it.

> I ask because when I read David Bovill's comment that this is a  
> common task, at first glance I thought so too but after thinking  
> about it some more I wonder if there's a subtle distinction at play  
> here between common and less common use of those two messages in a  
> single control.
>
> --
> A little background for those who may not have considered the  
> abstraction of the "noun-verb" interaction model:
>
> Most modern GUIs employ a noun-verb model, in which a noun object  
> is selected and then a verb object is selected which operates on  
> that noun.
>
> For example, when you select text you're specifying the "noun", and  
> then choosing "Bold" from the Style menu selects a "verb" (command)  
> to operate on that noun.
>
> The double-click gesture is commonly used as a shortcut to  
> selecting a verb, and is generally handled in a noun object  (see  
> <http://developer.apple.com/documentation/UserExperience/Conceptual/ 
> AppleHIGuidelines/XHIGUserInput/chapter_12_section_2.html#// 
> apple_ref/doc/uid/TP30000361-TPXREF8>).
>
> For example, in the Mac's Finder or Windows' Explorer, you can  
> select an icon (the noun) and then select File->Open (the verb), or  
> as a shortcut you can double-click the noun object to trigger that  
> most common verb.
>
> We also see this in list controls, where I tend to use  
> mouseDoubleUp most frequently, to trigger a default button.
>
> For example, suppose you have a list picker dialog with three  
> controls:  list field, "OK" button (default) and "Cancel" button.    
> The explicit way of working with the dialog is to select the item  
> in the list (the noun) then click "OK" (the verb), but it's common  
> in many dialogs which have a default button to trigger that default  
> button when the user double-clicks in the list as a shortcut.
>
> In such selector controls I often have a mouseUp handler, but since  
> it's in a noun object it usually just updates the current view to  
> reflect the selection, rather than perform an action.
>
> So while I can think of many examples of noun objects that use  
> double clicks as a short cut for selecting a verb object, offhand I  
> can't think of an example where a verb object handles double-clicks.
> --
>
> From your description it almost sounds like the control in question is
> a verb object such as a command button, rather than a noun object  
> such as an icon or list item.   Do I understand that correctly?

Not exactly: as you have understood it, it's not a button but an  
image in a sophisticated custom control.

> If so, what is it about the interaction that requires that?
>
> Or to word it in a more solutions-oriented way, might a change to  
> the UI  make for an interaction model which maintains the  
> traditional noun-verb expectation?

In a certain sense, yes ;-)
As you, I have deeply studied all guidelines (especially Apple ones  
that always have been better thought :-) but times have changed:
Look at iTunes or iPhoto, and other software that even don't use any  
menu (except contextual ones).
People needed a strong 'layout syntax' ten or twenty years ago: now,  
it's a bit different: intuitive understanding, simplicity, several  
levels to make an app limpid for beginners but able to provide  
sophisticated features to advanced users without overloading its  
interface is the new canon :-)

> While not every difference between HC and Rev favors Rev, this is  
> one where perhaps Dr. Raney's doctorate in cognitive psychology may  
> have shown itself well:  while HyperCard eats clicks on double- 
> click (and presumably introduces a delay to make that possible),  
> Rev gives the developer the freedom to handle them both, confident  
> that in most cases it'll be fine since it conforms to the most  
> common interaction model.

The problem is that a simple click is not another thing than the  
first click of a double click ;-)

> Am I wearing rose-colored glasses on this?  Are there common  
> examples of verb objects handling double-clicks that I've  
> overlooked?  (Sometimes good coffee breeds unwarranted optimism <g>.)

Actually, I agree with you. More: models built twenty years ago have  
to be known precisely in order to be overtaken :-)

Best regards from Paris,
Eric Chatonet.
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