Re: clipping and scrolling
Re: clipping and scrolling
- Subject: Re: clipping and scrolling
- From: Torsten Curdt <email@hidden>
- Date: Wed, 17 Aug 2011 01:44:18 +0200
>> 1) I could just create an UIImageView and just move the origin into the negative. The clipping happens naturally through the parent view.
>
> This is basically re-inventing the wheel, except that users won't fully understand what your re-invention has to offer.
I would not go so far to call this an "invention" so it cannot really
be a re-invention ;)
Just trying to understand the details here.
So if one does not care about zooming and all other things
UIScrollView helps with... this is not a terribly wrong thing to do?
It's just that there is something in UIKit that does this, too? After
all -in a very simple setup, think user interaction disabled- changing
the frame of a subview vs changing the content offset of UIScrollView
is not that much different. I am just wondering what's going on "under
the hood" and if the UIScrollView has just some more tricks why it
should be use instead.
>> 2) I could use a UIScrollView and add the large UIImageView to it and move the content offset
>
> Least code, works as users expect, almost certainly the best solution :).
It is implemented like that - but I still want to know :)
>> 3) I could have a custom view that basically just draws a portion of the image. Something along the lines of
>
> This is SLOW. UIKit uses Core Animation to back its views, and Core Animation caches content for speedy redraw in hardware. By re-drawing your image you are defeating all of these optimizations. Even if you have really large content, it would be better to use multiple image views rather than drawing the subsection you need manually.
Ah. Interesting. Didn't think of it like that.
Thanks!
--
Torsten
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