Re: Reordering CALayer sublayers without raping my performance?
Re: Reordering CALayer sublayers without raping my performance?
- Subject: Re: Reordering CALayer sublayers without raping my performance?
- From: Chris Ryland <email@hidden>
- Date: Mon, 19 Nov 2007 13:56:42 -0500
So, just to clarify for posterity, if you had turned off animation by
using a transaction, it would have mostly or completely removed your
slowdown?
On Nov 19, 2007, at 5:02 AM, Jonathan del Strother wrote:
On 19 Nov 2007, at 09:49, David Duncan wrote:
On Nov 19, 2007, at 1:09 AM, Jonathan del Strother wrote:
Would you run that past me again? Changing the zPosition re-sorts
the sibling layers? In which case, is there any point in re-
sorting the child array to specify render order?
Whenever the zPosition of a layer changes, you have to sort the
layers (internally) for presentation, otherwise you wouldn't get
the correct visual effect. It doesn't sort the sublayers array,
just the visual order that the layers are rendered in (which if all
layers have the same zPosition is just the order in the sublayers
array).
I'll test it out later, but I assume that CA is using a depth
buffer to make sure that higher zPositioned objects appear in
front of others, in which case the only time you need to worry
about the order of the child array ought to be if you're dealing
with transparent elements.
CA has no guarantees of having or not having transparent content.
In fact, the most common use for it (Appkit's layer based views)
involves considerable amounts of transparency (mostly for
antialiasing, but since the entire drawing model is supported
arbitrary transparency has to be supported as well).
Is there any way of re-sorting the child element array that
doesn't incur a huge performance & memory hit?
The alternative is what I said last time, to use the current
transaction to disable creating implicit animations.
Oooh, it's finally clicked that re-sorting the sublayers is an
animated process. That would explain the memory usage pattern I was
seeing, since I would have been created a lot of overlapping
animations...
Thanks for clarifying that
Jon
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Cheers!
--Chris Ryland / Em Software, Inc. / www.emsoftware.com
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