xmlvm-users

[xmlvm-users] Releasing of CGBitmapContextRef / CGImageRef

[JR S. <sc...@we...>]

I am curious how CGBitmapContextRefs generated by 
CGBitmapContext.create() are handled, if at all.  A similar issue arises 
with CGImageRef created.

I looked at the C implementation, and from my high-level understanding 
of the code it doesn't appear that there are any finalizers to take care 
of this.  (The DELETE method is empty). Adding to my concern is that the 
objc impemtetion does contain a "release" method that properly calls 
CGContextRelease.

So I am wondering:
1)  Is "CG" resource management being done in the c implementation? If 
so, how?
2)  If no resource management is being done, is there a way to release 
them manually?  I fear that this will require modifying the c 
implementation, which looks extremely difficult.
3)  Alternatively, is it possible to mix-and-match the objective c and c 
implementations of the XMLVM classes?  Writing the objective c 
implementations looks far more straightforward, but I still the c back 
end for full java classlib compatibility.

Thanks in advance for any advice!

JR Schmidt

-- 
J.R. Schmidt
WebMO, LLC

Re: [xmlvm-users] Releasing of CGBitmapContextRef / CGImageRef

[Arno P. <ar...@pu...>]

On 7/16/12 7:53 PM, JR Schmidt wrote:
> I am curious how CGBitmapContextRefs generated by
> CGBitmapContext.create() are handled, if at all.  A similar issue arises
> with CGImageRef created.

CGBitmapContext is derived from CFType. The latter overrides finalize(). 
The somewhat funny thing is that the code in 
org_xmlvm_iphone_CFType_finalize_org_xmlvm_iphone_CFType__() is 
commented out. Not sure how that happened.  :)

> So I am wondering:
> 1)  Is "CG" resource management being done in the c implementation? If
> so, how?

Yes, via CFType.finalize(), except that the CFRelease() is commented out 
in the C backend (I have no idea why).

> 2)  If no resource management is being done, is there a way to release
> them manually?  I fear that this will require modifying the c
> implementation, which looks extremely difficult.

It should be handled via the finalizer (in the C backend).

> 3)  Alternatively, is it possible to mix-and-match the objective c and c
> implementations of the XMLVM classes?  Writing the objective c
> implementations looks far more straightforward, but I still the c back
> end for full java classlib compatibility.

No. The ObjC backend relies on reference counting whereas the C backend 
comes with a proper GC. The two backends can't be mixed.

Arno

Re: [xmlvm-users] Releasing of CGBitmapContextRef / CGImageRef

[Kensuke M. <mat...@ki...>]

Hi,

I had similar problem on CGContext, so I'm using '--xmlvm-new-ios-api' now.
Rev 2118 commit comment says "Fixed UIGraphics.popContext() & removed the CFRelease in CFType's finalize".

>> I am curious how CGBitmapContextRefs generated by
>> CGBitmapContext.create() are handled, if at all.  A similar issue arises
>> with CGImageRef created.
>
> CGBitmapContext is derived from CFType. The latter overrides finalize().
> The somewhat funny thing is that the code in
> org_xmlvm_iphone_CFType_finalize_org_xmlvm_iphone_CFType__() is
> commented out. Not sure how that happened.  :)
>
>> So I am wondering:
>> 1)  Is "CG" resource management being done in the c implementation? If
>> so, how?
>
> Yes, via CFType.finalize(), except that the CFRelease() is commented out
> in the C backend (I have no idea why).
>

-- 
松崎 憲介 (MATSUZAKI Kensuke)

Re: [xmlvm-users] Releasing of CGBitmapContextRef / CGImageRef

[Paul P. <bay...@gm...>]

I believe the reason I commented out the "CFRelease" in CFType.finalize()
is that it was only there in the first place because of a bug in
UIGraphics.  Namely, popContext() was popping the context & then releasing
the current context, which is wrong & a different context altogether.  It
should've been releasing the context that was popped, so I fixed that.

Then, the bug in CFType.finalize() which called CFRelease could be fixed.
I.e. if it was left in there, it'd be incorrectly released twice.  Note
that CGContextRelease is equivalent to CFRelease.

Thanks,
Paul


On Tue, Jul 17, 2012 at 1:19 AM, Kensuke Matsuzaki <mat...@ki...>wrote:

> Hi,
>
> I had similar problem on CGContext, so I'm using '--xmlvm-new-ios-api' now.
> Rev 2118 commit comment says "Fixed UIGraphics.popContext() & removed the
> CFRelease in CFType's finalize".
>