Re: QTMovieLayer and renderInContext:

FROM : Scott Anguish
DATE : Thu Nov 22 11:36:42 2007

On Nov 22, 2007, at 4:07 AM, John Clayton wrote:

> :-)
>
> Scott, I guess you *may* have seen my DTS support request for 
> CARenderer then? (I think it *is* very convoluted code [that I 
> have], I cant get the thing to go, its all new to me - but I'm 
> willing to learn).


Nope, I'm not in DTS and we don't have access to the support requests.

I've been asking around for a CARenderer example because my current 
method of making the movies for the documentation is not precise 
enough when it comes to start/stop times and timeline, etc. The one 
example I managed to get is really complicated, and I'm not sure what 
it's doing. This is always the problem with just grabbing someone 
else's test app, who knows what the => button does. :-)

once I understand CARenderer I want to add an article to the CA 
Cookbook that describes what needs to be done.

> I will file a bug report for this then, I have a spike/test solution 
> that demonstrates clearly that the rendering fails for a 
> QTMovieLayer that is calling renderInContext:
>
> I guess I can fire you the question thats been hanging around in my 
> head since day 1 then (about 8 months ago actually).  Q is this: 
> how would I use core-anim to render any CALayer tree onto a view, 
> but only at a particular time (i.e. 2.6 seconds) and also make use 
> of all the transitions and animations and so on [that core anim is 
> good at doing]?  E.g. I have a complex CALayer and one of the 
> contained layers has an animation at 2 seconds for a duration of 5 
> seconds that fades that layer out. (think: layers as movie timelines 
> and using a slider to scrub back and forth in time).\


I wish I knew.  The one bit I've seen let's you pause an in progress 
animation and it'll do something when you push a button, but I have no 
idea exactly what the result is I'm getting in the example.  And I've 
not had time to figure it out from the code. (and the guy I got it 
from is out this week, so I can't ask him.  it's driving me crazy).

>
>
> I've tried *a lot* of ways, and the basic problem appears to be 
> telling layers that they should indeed render for time 't', 
> regardless of what the CACurrentMediaTime() and underlying core-anim 
> time-line is.
>


I assume you've tried beginFrameAtTime:timeStamp:?

the one bit I've got seems to

   [renderer beginFrameAtTime:timeInterval timeStamp:NULL];
   [renderer addUpdateRect:CGRectMake(0.0, 0.0, w, h)];
   [renderer render];

in the -(void)drawInCGLContext:(CGLContextObj)glContext pixelFormat:
(CGLPixelFormatObj)pixelFormat forLayerTime:
(CFTimeInterval)timeInterval displayTime:(const CVTimeStamp *)timeStamp


implementation of an opengl layer. the open gl layer has the layers to 
render as it's sublayers.


> Anyways, I'll file a bug report along with my spike solution and let 
> you know its ID.
>


Yes please!

> --
> John Clayton
>
> On Nov 22, 2007, at 9:48 AM, Scott Anguish wrote:
>

>>
>> On Nov 22, 2007, at 3:22 AM, John Clayton wrote:
>>

>>> I'm not, that renderInContext: is a call on CALayer, allowing one 
>>> to place the content of a layer into a CGContextRef
>>>

>>
>> Gah, sorry.  I miss read the original email. I should have 
>> recognized the method, I wrote the reference doc for it.
>>
>>

>>> The CovertFlow example uses this technique to take content into a 
>>> bitmap based context.

>>
>> Wow, it does.  but I wonder why.  It's just creating a bitmap with 
>> a string in it.
>>
>> I'm not sure whose example that is, but I've asked engineering.
>>
>> If you determine that QTMovieLayer isn't rendering using that 
>> method, please file a bug and let me know.
>>
>>

>>> I've got requirements to basically render arbitrarily complex 
>>> CALayer hierarchies onto a view, but I want to render them for a 
>>> particular time.
>>>
>>> What is CARenderer intended for then?  (I've used CARenderer in 
>>> another different spike/test solution so have experience with it).
>>>

>>
>> Yes, that would be a CARenderer situation. I've only seen one 
>> example of it in use and it was, shall we say, convoluted.
>>

>>> Thanks.
>>>
>>> --
>>> John Clayton
>>> http://www.coderage-software.com/
>>>
>>>
>>>
>>> On Nov 22, 2007, at 9:11 AM, Scott Anguish wrote:
>>>

>>>> I'm not sure of the answer..
>>>>
>>>> but why are you using CARenderer to put movie content into a view?
>>>>
>>>> it shouldn't be used for display purposes.
>>>>
>>>>
>>>> On Nov 22, 2007, at 1:47 AM, John Clayton wrote:
>>>>

>>>>> Hi All,
>>>>>
>>>>> I am trying to use the CALayer renderInContext: call to put the 
>>>>> contents of a QTMovieLayer instance onto a view, but I get a 
>>>>> blank view - nothing renders.
>>>>>
>>>>> Is this call supposed to work for a QTMovieLayer?  I suppose the 
>>>>> question could be expanded to: is the renderInContext: method 
>>>>> supposed to work for any type of open-gl based layer class?
>>>>>
>>>>> Thanks,
>>>>> --
>>>>> John Clayton
>>>>> http://www.coderage-software.com/
>>>>>
>>>>>
>>>>> _______________________________________________
>>>>>
>>>>> Cocoa-dev mailing list (<email_removed>)
>>>>>
>>>>> Please do not post admin requests or moderator comments to the 
>>>>> list.
>>>>> Contact the moderators at cocoa-dev-admins(at)lists.apple.com
>>>>>
>>>>> Help/Unsubscribe/Update your Subscription:
>>>>> http://lists.apple.com/mailman/options/cocoa-dev/<email_removed>
>>>>>
>>>>> This email sent to <email_removed>

>>>>

>>>

>>

>