Re: Movinf the mouse pointer

On Mon, 13 Jun 2005 14:38:27 +0200, Luca Cappa said:

> My problem is that I would like to reset the mouse pointer position 
> after each delta movement has been detected: in this
> way the mouse pointer is always placed in the original position it was 
> when the mouse button was pressed.

Please note that most UI design guides rate "warping the mouse pointer" as a
fairly anti-social thing to do, because it confuses users who expect the mouse
pointer to be where they left it.  If their next action is taken thinking that
the mouse pointer is *here*, when it's actually jsut been moved back 150 pixels
to where it *was*, Very Strange Things can happen (for instance, the *next*
drag-n-(drop,select,zoom,ec) isn't what the user intended, and so on).

Even most "rotate the view" applications leave the mouse where it at the
end of the rotate - otherwise Odd Things can happen.  Consider:

1) User starts at 1,0,0 (out on the X axis).
2) User rotates the model 90 degrees with a drag to 0,1,0 (out the Y axis)

3a) Mouse left where it was: User rotates the model with an "up" to 0,1,1 - this causes a rotate around X.

3b) Mouse warped back to 1,0,0 and user doesn't notice, does the *same* "up",
and now the model rotates around the Y axis instead of X.

It violates the "principle of least surprise" that if they had done one continuous
drag from (1) to (2) to (3), it rotates one way, but if they break it into two
pieces it does a different rotate....

Just something to think about as you design....

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