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Re: [pointerevents] Value of button attribute for pointermove event

From: Rick Byers via GitHub <sysbot+gh@w3.org>
Date: Mon, 01 Feb 2016 23:56:41 +0000
To: public-pointer-events@w3.org
Message-ID: <issue_comment.created-178264888-1454370998-sysbot+gh@w3.org>
Ah, that makes sense @bethge / @teddink, thanks.

> But if button is -1, you need to track the actual button state 
somewhere.

Why?  Isn't that what `buttons` is for?  It makes sense to me that 
`button` describes state transitions, and `buttons` describes the 
current state.  The combination of the two (with button=-1 for EVERY 
pointermove where there is no button state change) let you fully 
understand the current state and any state transitions without 
tracking any additional state yourself.

If we agree that this makes sense, I think we definitely need to 
change the spec to describe it - it's definitely not clear.  This text
 is wrong / misleading:
 > the button property takes on a new value when no mouse buttons are 
depressed:
Instead it should say something like "the button property has the 
value -1 when the button state has not changed from the previous 
pointermove event".  Maybe also add the clarifying text "This way 
`button` indicates which button has been pressed or released, while 
`buttons` represents the state of all buttons after any such 
transition".  We also need a test for this.

/cc @mustaqahmed, IIRC we'll need to make changes in blink for this 
too.

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Received on Monday, 1 February 2016 23:56:44 UTC

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