Re: [Semi-OT] Gestures in Cocoa AU Views
Re: [Semi-OT] Gestures in Cocoa AU Views
- Subject: Re: [Semi-OT] Gestures in Cocoa AU Views
- From: Pavol Markovic <email@hidden>
- Date: Tue, 11 Oct 2005 00:27:44 +0200
Sorry, I should have been more exact and I should have tried the Filter
demo before asking (to excuse my mistake I was running 10.3.x at the
time of typing the message). The problem I've had was purely related to
NSNotifications and their observers (not AUEvent listeners). Because I
wanted to have controls-view relations as loosy as possible (creating
reusable framework was my goal) I used [[NSNotificationCenter
defaultCenter] addObserver:selector:name:object: with nil object]. And
that was the problem, because all independent views' notification
observers were receiving the same notification (posted from one of
multiple active views) and thus creating multiple AUEvents (though only
one was valid).
Now I see my concept needs adding observer instance variable (and
connecting it in IB) for each control object embedded into AU view or
one of it's subviews and use it as an object parameter in
postNotificationName:object: method to prevent spreading notifications
across all registered observers. But maybe using control's own delegate
methods would be more readable if control's delegate is not needed for
doing other job.
Again sorry for wasting time and space, but maybe someone will find
this useful :)
PM
On Oct 10, 2005, at 9:39 PM, William Stewart wrote:
The Filter demo uses the AUEvent Listener as the basic API for dealing
with this - if you run this say in AU Lab with the Generic view open
as well, you'll see the appropriate highlighting occurring between the
views as you click on sliders, etc.
There's also a tech note on Apple's developer web site that provides
an overview of this architecture.
Bill
On 10/10/2005, at 2:02 AM, Pavol Markovic wrote:
Sorry for being OT, this is probably more Cocoa question.
I once played with Cocoa AU views and one thing that I've seen as
problem was posting control/parameter's begin and end gestures. I
remember in older CoreAudio SDK there was proposal for getting
parameter ID according to mouse coordinates but it was pulled off
later.
Then I thought about using NSNotifications and converting them into
Carbon AUEvents. But I run into problem when two and more AUs have
opened the view at the same time. Then there were multiple
notification listeners and they responded simultaneously to mouse
events. What was even worse, two different AUs using same code base
might respond.
Because it was only research project I've frozen it, but today I've
looked into latest SDK examples (Filter) and I found out that the
same concept (NSNotification with default notification center) is
used here. I haven't tried it yet, but I guess it suffers from the
same problem. Is there any other way to do this - for example
creating private notification center?
Thanks for suggestions,
Pavol Markovic
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