More scrolling queries

[Graham Samuel]

Thanks for the reply. I thought that the object was really moving: to me, the 'frame' was the rect of the visible graphic (actually a group, tho I have no idea why) through which I see my object, but the object (the thing with the contentRect) itself was really moving under the frame. I suppose the problem was that my mental model of what is going on was wrong: I imagined the object full size, sliding under the frame, which is like a hole in a bit of card. What you're saying is that it's the contents of the object which is doing the sliding, not the object itself, and there are kind of two holes, the one which defines the rect and an invisible one coincident with it but underneath it, defining the size of the scrolling object. In the case of a desktop scroll, the 'top' rect wouldn't be needed, but it is needed for iOS.

Of course you are right, but it's quite an elusive concept - that's why I wrote my mail about hScroll and vScroll.

Anyway I shall readjust the mental wiring and try again.

Graham

On 8 Dec 2012, at 21:25, J. Landman Gay wrote:

> On 12/8/12 8:39 AM, Graham Samuel wrote:
> 
>> This message arrives in the Console window as normal, with x changing
>> values as expected, and the loc of the group always the same.
>> 
>> Why is this so, and what am I seeing move if it's not my group?
> 
> I think you've already figured this out, but just in case, the position of an object and its scroll are different things. Position is the place on the card where the object is located. The scroll of an object is the offset of its contents inside the object's rectangle (which acts like a frame.)
> 
> -- 
> Jacqueline Landman Gay         |     jacque at hyperactivesw.com
> HyperActive Software           |     http://www.hyperactivesw.com