[vtkusers] vtkCocoaRenderWindow bug?

[Sean McBride]

On 4/5/08 7:32 AM, Antoine Rosset said:

>Ok, thanks. You are right.
>
>Yes, I'm having problems with this cocoamanager variable and memory  
>management:

Hi Antoine,

Sorry for my delayed reply....

>To create your own NSWindow, you create a subclass of vtkCocoaGLView  
>and you initialize it with:

NSWindow? You mean NSView, right?

>-(id)initWithFrame:(NSRect)frame {
>
>     if ( self = [super initWithFrame:frame])
>	{
>         	_renderer = vtkRenderer::New();
>		_cocoaRenderWindow = vtkCocoaRenderWindow::New();
>		_cocoaRenderWindow->SetWindowId( [self window]);
>		_cocoaRenderWindow->SetDisplayId( self);
>		
>		_cocoaRenderWindow->AddRenderer(_renderer);
>        		 _interactor = vtkCocoaRenderWindowInteractor::New();
>		_interactor->SetRenderWindow(_cocoaRenderWindow);
>
>and a destructor
>
>-(void)dealloc
>{
>     	_renderer->Delete();
>	_cocoaRenderWindow->Delete();
>	_interactor->Delete();
>	[super dealloc];
>}
>
>By calling _cocoaRenderWindow->SetDisplayId( self);, you increase the  
>retain count of the NSView, because you add it to the cocoamanager  
>NSDictionary
>
>Hence, the NSView will not be released automatically, because you will  
>remove this NSView from the cocoamanager in the destructor of  
>vtkCocoaRenderWindow AND the destructor of vtkCocoaRenderWindow will  
>be called from the dealloc of the NSView, that cannot be called  
>because the cocoamanager retains the NSView. (I hope it's not too  
>confuse... :-))
>
>To avoid this memory leak, I had to create a 'prepareForRelease'  
>function, that I call from my NSWindowController dealloc : [myVTKView  
>prepareForRelease]
>
>- (void) prepareForRelease
>{
>	_cocoaRenderWindow->SetWindowId( 0L);
>	_cocoaRenderWindow->SetDisplayId( 0L);
>}
>
>Then, the NSView will be released.
>
>To identify the problem, put an NSLog in your dealloc of your VTKView  
>subclass, to see if it is called.
>
>The solution would be to put the 'displayId' in a variable, instead of  
>adding it to the NSDictionary.

It used to be a variable but we moved it into a dictionary to facilitate
supporting Garbage Collection.  With Obj-C++ GC support is a bit
trickier, as the collector does not scan malloc'ed/new'ed memory.

>What do you think? Is there another way of subclassing the VTKView ?

I think I'll review the changes we made... there may be a nicer way of
doing all this... Could you help me test changes?

Thanks,

-- 
____________________________________________________________
Sean McBride, B. Eng                 sean at rogue-research.com
Rogue Research                        www.rogue-research.com 
Mac Software Developer              Montréal, Québec, Canada