[OpenJDK 2D-Dev] One or many GraphicsConfiguration(s) per toplevel?

Dmitri Trembovetski Dmitri.Trembovetski at Sun.COM
Wed Jan 21 18:16:06 UTC 2009

   Hi Anthony,

Anthony Petrov wrote:
> Hi Dmitri,
> On 1/21/2009 8:43 PM Dmitri Trembovetski wrote:
>>> implementation of this method in the Container class that recursively 
>>> calls this method for every child of the container.
>>> The question is: is it really possible for one toplevel to contain 
>>> components having different GraphicsDevice's (and/or different 
>>> GraphicsConfiguration's)? Or may I assume that all and every 
>>> descendant components of a toplevel window use the same GC that the 
>>> window uses (and therefore the Container.checkGD() may safely be 
>>> removed)?
>>   We should enforce that all components within a toplevel have the
>>   same GC. If checkGD does that I wouldn't remove it.
> "Asserts" are fine as long as they are simple and fast. But if we're 
> sure we don't have several GC/GDs per toplevel window, then I don't see 
> much reason to waste time recursively traversing the whole hierarchy of 
> components of a container when it gets added to another container.
> Perhaps it would make sense to move the graphicsConfig member to
> the Window class and use its value for
> Component.getGraphicsConfiguration()? A component not currently
> contained in a toplevel window obviously should have a null GC.  Thoughts?

   May not be a bad idea. The less copies of GC we have laying around
   the smaller chance it is that someone would use a stale version.

   The only consideration is that getting a GC is a very common operation,
   and traveling the hierarchy every time to retrieve it could
   result in performance degradation (wouldn't you need to grab the tree
   lock for that too?).


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