Add SkMatrix::cheapEqualTo, use in Gr code

[bsalomon, 2012-03-21 20:35:40]

This one is for the children.

[reed1, 2012-03-21 20:41:49]

the persnickity in me would like to see this as two CLs:

1. SkMatrix.h + unittest
2. The Gr changes

but not a huge deal

[TomH, 2012-03-21 20:47:16]

http://codereview.appspot.com/5865057/diff/4001/include/core/SkMatrix.h
File include/core/SkMatrix.h (right):

http://codereview.appspot.com/5865057/diff/4001/include/core/SkMatrix.h#newco...
include/core/SkMatrix.h:486: /** Effecient comparison of two matrices. It
distinguishes between zero and
nit: spelling

http://codereview.appspot.com/5865057/diff/4001/include/core/SkMatrix.h#newco...
include/core/SkMatrix.h:487: *  negative zero. It will return false when a zero
sign is the only
zero sign? not clear - do you mean that the matrix type flags aren't up to date
on one of them?

http://codereview.appspot.com/5865057/diff/4001/src/gpu/GrDrawState.h
File src/gpu/GrDrawState.h (right):

http://codereview.appspot.com/5865057/diff/4001/src/gpu/GrDrawState.h#newcode812
src/gpu/GrDrawState.h:812: GrMatrix            fViewMatrix;
Do we need to add initialization code for this? Or, no, I guess the default
constructor will do fine?

[bsalomon, 2012-03-22 21:21:02]

now with unit test.

http://codereview.appspot.com/5865057/diff/4001/include/core/SkMatrix.h
File include/core/SkMatrix.h (right):

http://codereview.appspot.com/5865057/diff/4001/include/core/SkMatrix.h#newco...
include/core/SkMatrix.h:486: /** Effecient comparison of two matrices. It
distinguishes between zero and
On 2012/03/21 20:47:16, TomH wrote:
> nit: spelling

Done.

http://codereview.appspot.com/5865057/diff/4001/include/core/SkMatrix.h#newco...
include/core/SkMatrix.h:487: *  negative zero. It will return false when a zero
sign is the only
On 2012/03/21 20:47:16, TomH wrote:
> zero sign? not clear - do you mean that the matrix type flags aren't up to
date
> on one of them?

I mean +0.0 vs -0.0.

http://codereview.appspot.com/5865057/diff/4001/src/gpu/GrDrawState.h
File src/gpu/GrDrawState.h (right):

http://codereview.appspot.com/5865057/diff/4001/src/gpu/GrDrawState.h#newcode812
src/gpu/GrDrawState.h:812: GrMatrix            fViewMatrix;
On 2012/03/21 20:47:16, TomH wrote:
> Do we need to add initialization code for this? Or, no, I guess the default
> constructor will do fine?

It's already initialized at line 82.

[TomH, 2012-03-22 21:23:53]

LGTM

[bsalomon, 2012-03-26 15:24:43]

Closed witt r3488