THAT is a nice explanation Scott. That particular separation between
layer compositing attributes and the actual 'contents' itself wasn't
something that was really at the forefront of my thought there...
thanks for that.
Now it makes more sense... the delegates are *only* used when getting
the contents property - and thats it. Specifically, they are not
called when any animation properties are being interpolated or
compositing is being performed.
Enlightenment... the 'bing' feeling... aaaahhhhhhhhh euphoria. Ta
--
john
On 28/11/2007, at 7:43 PM, Scott Anguish wrote:
Well, it isn't quite the same.. not drawing, but compositing.
The border is a style attribute (and is an animatable property).
All animatable properties are applied by the render-tree when the
layer is displayed in the UI. So they get composited when you
change the values via the implied animation (unless of course that
has been disabled for the transaction in which case they still will
update and draw, but without interpolating the values from the
current value to the new value).
You can imagine that if the content was redrawn (by the delegate)
every time a value changed and animated (so potentially hundreds of
times for a single animation) that you'd lose most of the advantages
of Core Animation.
Regardless, animatable properties are not aren't cached and are
separate from the content caching process.
You don't have to, and should not, call setNeedsDisplay for any
layers that do not have a delegate that provides the content. This
will create a content cache and cause more memory to be used for the
cached content. For larger empty layers that are used only to
contain other layers it is unnecessary.
I'll spend some time clarifying this in the Core Animation
Programming Guide in both the Providing Layer Content and Layer
Style Properties chapters.
On Nov 28, 2007, at 5:21 AM, John Clayton wrote:
Hi Scott,
But Neil is saying that the border of the layer is visible, thus
the layer must be drawing itself at some point already, right?
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