add SkMatrix::decomposeScale

add SkMatrix::decomposeScale

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/adf9990cb56ca389f37f02ac637496083b3c3cfc

[reed1, 2015-03-19 18:05:30]

reed@google.com changed reviewers:
+ jvanverth@google.com, robertphillips@google.com, senorblanco@google.com

[reed1, 2015-03-19 18:05:31]

will add tests (and replace existing callers) before trying to land

[robertphillips, 2015-03-19 18:10:35]

API looks good to me

https://codereview.chromium.org/1006173005/diff/1/src/core/SkMatrix.cpp
File src/core/SkMatrix.cpp (right):

https://codereview.chromium.org/1006173005/diff/1/src/core/SkMatrix.cpp#newco...
src/core/SkMatrix.cpp:1612: const SkScalar sy =
SkVector::Length(this->getSkewX(), this->getScaleY());
Should this check be a little fuzzy? We are going to invert these guys.

[Stephen White, 2015-03-19 18:27:49]

senorblanco@chromium.org changed reviewers:
+ senorblanco@chromium.org

[Stephen White, 2015-03-19 18:27:50]

https://codereview.chromium.org/1006173005/diff/20001/src/core/SkMatrix.cpp
File src/core/SkMatrix.cpp (right):

https://codereview.chromium.org/1006173005/diff/20001/src/core/SkMatrix.cpp#n...
src/core/SkMatrix.cpp:1622: remaining->postScale(SkScalarInvert(sx),
SkScalarInvert(sy));
Hmm.. for my uses, I was also extracting the translate component from the
remainder matrix, so that the CTM looks at least positionally similar to what it
was before. Now the translation will be applied by the SkMatrixImageFilter, and
the CTM will always have 0, 0 translation. I guess that's ok, it'll just look a
little weird during debugging.

[reed1, 2015-03-19 20:13:39]

Yea, having started working on the old call-sites, so far no one has wanted the
"generic" remainder matrix :) So I may just remove that parameter option.

https://codereview.chromium.org/1006173005/diff/1/src/core/SkMatrix.cpp
File src/core/SkMatrix.cpp (right):

https://codereview.chromium.org/1006173005/diff/1/src/core/SkMatrix.cpp#newco...
src/core/SkMatrix.cpp:1612: const SkScalar sy =
SkVector::Length(this->getSkewX(), this->getScaleY());
On 2015/03/19 18:10:34, robertphillips wrote:
> Should this check be a little fuzzy? We are going to invert these guys.

Done.

[reed1, 2015-03-19 20:42:42]

ptal

[reed1, 2015-03-19 20:42:46]

The CQ bit was checked by reed@google.com

[commit-bot: I haz the power, 2015-03-19 20:42:52]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1006173005/60001

[commit-bot: I haz the power, 2015-03-19 20:42:53]

Note for Reviewers:
The CQ is waiting for an approval.
If you believe that the CL is not ready yet, or if you would like to L-G-T-M
with comments then please uncheck the CQ checkbox.

Waiting for LGTM from valid reviewer(s) till 2015-03-20 02:42 UTC

[Stephen White, 2015-03-19 20:44:40]

On 2015/03/19 20:42:53, I haz the power (commit-bot) wrote:
> Note for Reviewers:
> The CQ is waiting for an approval.
> If you believe that the CL is not ready yet, or if you would like to L-G-T-M
> with comments then please uncheck the CQ checkbox.
> 
> Waiting for LGTM from valid reviewer(s) till 2015-03-20 02:42 UTC

Looks good, but will leave for Robert.

[Stephen White, 2015-03-19 23:08:49]

On 2015/03/19 20:44:40, Stephen White wrote:
> On 2015/03/19 20:42:53, I haz the power (commit-bot) wrote:
> > Note for Reviewers:
> > The CQ is waiting for an approval.
> > If you believe that the CL is not ready yet, or if you would like to L-G-T-M
> > with comments then please uncheck the CQ checkbox.
> > 
> > Waiting for LGTM from valid reviewer(s) till 2015-03-20 02:42 UTC
> 
> Looks good, but will leave for Robert.

LGTM

[commit-bot: I haz the power, 2015-03-19 23:11:00]

Committed patchset #4 (id:60001) as
https://skia.googlesource.com/skia/+/adf9990cb56ca389f37f02ac637496083b3c3cfc

[robertphillips, 2015-03-20 13:02:53]

lgtm

[Corentin Wallez, 2015-03-20 15:08:27]

A revert of this CL (patchset #4 id:60001) has been created in
https://codereview.chromium.org/1022003003/ by cwallez@chromium.org.

The reason for reverting is: Suspected to break GPU bots for test
WebglConformance.conformance_canvas_drawingbuffer_static_canvas_test as it is
the only relevant commit of the regression range
http://build.chromium.org/p/chromium.webkit/builders/GPU%20Mac%2010.9%20%28In....