Re: pan, rotation, move and zoom request events

On Mar 12, 2013, at 6:34 AM, Richard Schwerdtfeger <schwer@us.ibm.com> wrote:

> Hi Jason,
> 
> Zoom should first be driven by hit testing in the browser. If you have a point within an object the zoom event should be generated at the object hit and then the object should manage the zoom from that point. The application needs to make the decision how it zooms once the event is received. This will be particularly important, for example, if you have something like a flow chart and your browser deems the hit to be within a line. The application may find the point toward the end of the line and want to zoom around that point. We will need these concepts when we apply zooming to SVG and HTML5 Canvas.
> 
> So, the x,y coordinates are essential. There may be some instances, such as text, or UI controls the app. may wish to zoom off center of the x,y coordinate.

x/y coordinates are useful, but are not required or essential to this event. Many desktop zoom interfaces allow keyboard combinations meaning "zoom centered and then move", or "move centerpoint and then zoom", which achieve more or less that same effect as a mouse-centered zoom, except with with two operations. I see no reason not to support this.


> Rich
> 
> 
> From:	Jason White <jason@jasonjgw.net>
> 
>> James Craig <jcraig@apple.com> wrote:
>> 
>>> I think that depends on the application. In most cases, I would expect the
>>> zoom event to be centered on the x/y coordinates if they were provided. If
>>> origin coordinates are not provided, zoom would probably be centered in the
>>> middle of the current view.
>> 
>> That's reasonable. Could you perhaps clarify it in the text without
>> unduly limiting what applications do?
>> 
>> 
> 

Received on Tuesday, 12 March 2013 18:14:19 UTC