Re: EXC_BAD_ACCESS when calling CGContextDrawLayerInRect

FROM : Carter R. Harrison
DATE : Mon Apr 14 21:46:44 2008

Hi David,

I'm getting the reference to the context by using:

CGContextRef context = [[NSGraphicsContext currentContext] 
graphicsPort];

in my view's initWithFrame: method.  Based upon what you said, how 
would you recommend I draw to a CGLayer prior to the first invocation 
of drawRect: (at which point I could initialize a CGContextRef 
instance variable)?

Thanks for your help!

Regards,
Carter

On Apr 14, 2008, at 3:30 PM, David Duncan wrote:

> On Apr 14, 2008, at 11:56 AM, Carter R. Harrison wrote:
>

>> cgback is a CGLayerRef instance variable that I setup when the view 
>> is inited.  I use the following line:
>>
>> cgback = CGLayerCreateWithContext(context, CGSizeMake([self 
>> bounds].size.width, [self bounds].size.height), NULL);
>>
>> It's my understanding that I do not need to retain cgback with 
>> CFRetain(), but I do need to release cgback in my dealloc() method 
>> - which I'm doing.

>
>
> Where is "context" coming from? CGLayers are made relative to an 
> example context that they optimize themselves for, but at -init your 
> view hasn't been drawn yet, so there is no context. I suspect that 
> your getting something you very much do not expect.
>
> In general if you want to use layers with views, you should create 
> the layer on the first -drawRect: call rather than trying to have 
> them around from -init forward.
> --
> David Duncan
> Apple DTS Animation and Printing
> david.<email_removed>
>
>
>