Make fewer copies when using GrDrawTarget::AutoStateRestore

[bsalomon, 2012-03-27 17:58:03]

GrDrawTarget::AutoStateRestore currently saves a copy of the GrDrawState in its
cons or set and then copies the GrDrawState back in the destructor. Moreover,
often the caller wants a completely reset GrDrawState after the save.

With this change the old GrDrawState is saved by a ptr copy / ref() call and
similar for restore. This always saves a GrDrawState copy on the restore. The
caller communicates to AutoStateRestore whether they want to start from a copy
of the current state or a reset state. If the caller says reset then no
GrDrawState copies are ever made.

[bsalomon, 2012-03-27 17:59:07]

This is the last piece of the GrDrawState changes I've been spinning out from
the large change at http://codereview.appspot.com/5864043/

[TomH, 2012-03-28 01:43:25]

LGTM modulo nits.

http://codereview.appspot.com/5938043/diff/5001/src/gpu/GrDrawTarget.h
File src/gpu/GrDrawTarget.h (right):

http://codereview.appspot.com/5938043/diff/5001/src/gpu/GrDrawTarget.h#newcod...
src/gpu/GrDrawTarget.h:563: *                             // call to to
drawState below asr's cons.
I don't understand the point of the BUG comment-within-a-comment, or really what
this example code is for.

http://codereview.appspot.com/5938043/diff/5001/src/gpu/GrDrawTarget.h#newcod...
src/gpu/GrDrawTarget.h:574: * is destroyed. If this cons is used do not call
set().
Could we spell out constructor here & below? Abbreviation in the internal
comments in other files isn't so bad...

http://codereview.appspot.com/5938043/diff/5001/src/gpu/GrDrawTarget.h#newcod...
src/gpu/GrDrawTarget.h:577: *              previous state or a
default-initialized GrDrawState.
I'm not sure Preserve|Reset conveys this well / this describes those well.

[bsalomon, 2012-03-30 15:56:48]

Closed with r3557

http://codereview.appspot.com/5938043/diff/5001/src/gpu/GrDrawTarget.h
File src/gpu/GrDrawTarget.h (right):

http://codereview.appspot.com/5938043/diff/5001/src/gpu/GrDrawTarget.h#newcod...
src/gpu/GrDrawTarget.h:563: *                             // call to to
drawState below asr's cons.
On 2012/03/28 01:43:26, TomH wrote:
> I don't understand the point of the BUG comment-within-a-comment, or really
what
> this example code is for.

clarified in checked in version

http://codereview.appspot.com/5938043/diff/5001/src/gpu/GrDrawTarget.h#newcod...
src/gpu/GrDrawTarget.h:574: * is destroyed. If this cons is used do not call
set().
On 2012/03/28 01:43:26, TomH wrote:
> Could we spell out constructor here & below? Abbreviation in the internal
> comments in other files isn't so bad...

Done.

http://codereview.appspot.com/5938043/diff/5001/src/gpu/GrDrawTarget.h#newcod...
src/gpu/GrDrawTarget.h:577: *              previous state or a
default-initialized GrDrawState.
On 2012/03/28 01:43:26, TomH wrote:
> I'm not sure Preserve|Reset conveys this well / this describes those well.

Ignored this for now due to lack of better ideas :)