Re: Sage advice (NSView vs. CALayer)
Re: Sage advice (NSView vs. CALayer)
- Subject: Re: Sage advice (NSView vs. CALayer)
- From: John Pannell <email@hidden>
- Date: Tue, 28 Oct 2008 17:46:24 -0600
Hi Alex-
One difference comes to mind, and is of substance for app design:
- NSView is a subclass of NSResponder, CALayer is not.
So views are happy to field click and keyboard events for you,
participate in the responder chain, handle mouse drag/enter/exit,
etc. I believe a common design is to have the NSView be layer-backed
and "host" your layer tree. The layers are so fantastically
lightweight they can do amazing drawing and animation, but part of the
weight they lost was the ability to field events. Use the host view
to do this, then pass the location of the event to the root CALayer's
hitTest: method to determine what was clicked on.
I'm sure there are many other differences that could be highlighted,
but that one stands out for me!
John
Positive Spin Media
http://www.positivespinmedia.com
On Oct 28, 2008, at 3:43 PM, Alex Kac wrote:
One question I have that maybe this list can help me understand. If
you have views that are layer backed - why would one use any of the
view methods instead of the layer methods? I have to admit in some
ways I am somewhat perplexed why a CALayer doesn't replace the view
itself completely. This is an area I have not yet had to delve into
in the docs too much there, but what I have read it doesn't really
explain much about the perceived dichotomy.
I would love an eye-opener description here :) And for me its a
Leopard/iPhone only world if that makes a difference.
On Oct 28, 2008, at 4:35 PM, DKJ wrote:
When I was but a newbie,
I heard a wise man say,
"When using CALayers,
Put NSViews away."
Yet I set a CALayer,
Then added NSView;
Now many hours later,
I wail, "T'is true, t'is true!"
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