Add isScale2d() helper function to SkMatrix44.

Add isScale() helper function to SkMatrix44.

This will be used later in Chromium to cleanup gfx::Transform::IsScale2d().

BUG=408710, skia:997
TEST=None
R=bsalomon@google.com,danakj@chromium.org

Committed: https://skia.googlesource.com/skia/+/20b7960798320e6804ffee78fd92e6c001eba30b

[tomhudson, 2014-10-23 12:28:53]

tomhudson@google.com changed reviewers:
+ tomhudson@google.com

[tomhudson, 2014-10-23 12:28:53]

The CQ bit was checked by tomhudson@google.com

[tomhudson, 2014-10-23 12:28:53]

lgtm

[commit-bot: I haz the power, 2014-10-23 12:29:41]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/676583002/1

[commit-bot: I haz the power, 2014-10-23 12:29:50]

The CQ bit was unchecked by commit-bot@chromium.org

[commit-bot: I haz the power, 2014-10-23 12:29:51]

Presubmit check for 676583002-1 failed and returned exit status 1.

Running presubmit commit checks ...

** Presubmit ERRORS **
Since the CL is editing public API, you must have an LGTM from one of:
('reed@chromium.org', 'reed@google.com', 'bsalomon@chromium.org',
'bsalomon@google.com', 'djsollen@chromium.org', 'djsollen@google.com')

[tomhudson, 2014-10-23 13:27:06]

tomhudson@google.com changed reviewers:
+ reed@google.com
- bsalomon@google.com, tomhudson@google.com

[tomhudson, 2014-10-23 13:27:06]

Ah, public API - technically I think Brian handles the Ganesh API, but anything
in the core Skia API goes through Mike?

[bsalomon, 2014-10-23 13:39:41]

bsalomon@google.com changed reviewers:
+ bsalomon@google.com

[bsalomon, 2014-10-23 13:39:42]

lgtm, but wondering whether we really need this if there are no callers.

[reed1, 2014-10-23 14:30:33]

not lgtm for the moment.

In general, there are a semi-unbounded number of possible helper methods that
could be added here. At some point I suggest callers create their own helper
functions for things like this.

e.g. 

inline bool isScale(const SkMatrix44& mat) {
    return !(mat.getType() & ~SkMatrix44::kScale_Mask);
}

That said, we can add this, but I find the name a little confusing. Why 2D in
the name. Why not isScale?

[tfarina, 2014-10-23 18:21:32]

On 2014/10/23 14:30:33, reed1 wrote:
> not lgtm for the moment.
> 
> In general, there are a semi-unbounded number of possible helper methods that
> could be added here. At some point I suggest callers create their own helper
> functions for things like this.
> 
> e.g. 
> 
> inline bool isScale(const SkMatrix44& mat) {
>     return !(mat.getType() & ~SkMatrix44::kScale_Mask);
> }
> 
> That said, we can add this, but I find the name a little confusing. Why 2D in
> the name. Why not isScale?

Mike, which changes do I need to do, to get this accepted by you? Do I have to
move isScale2d() from SkMatrix44 to a helper file? If yes, which one (where)? Do
I need to rename it isScale or is it fine to keep it as isScale2d() (from your
question, I guess it is not and it should be renamed). Please, let me know your
preference for one or another.

Regards,

[reed1, 2014-10-23 18:58:37]

On 2014/10/23 18:21:32, tfarina wrote:
> On 2014/10/23 14:30:33, reed1 wrote:
> > not lgtm for the moment.
> > 
> > In general, there are a semi-unbounded number of possible helper methods
that
> > could be added here. At some point I suggest callers create their own helper
> > functions for things like this.
> > 
> > e.g. 
> > 
> > inline bool isScale(const SkMatrix44& mat) {
> >     return !(mat.getType() & ~SkMatrix44::kScale_Mask);
> > }
> > 
> > That said, we can add this, but I find the name a little confusing. Why 2D
in
> > the name. Why not isScale?
> 
> Mike, which changes do I need to do, to get this accepted by you? Do I have to
> move isScale2d() from SkMatrix44 to a helper file? If yes, which one (where)?
Do
> I need to rename it isScale or is it fine to keep it as isScale2d() (from your
> question, I guess it is not and it should be renamed). Please, let me know
your
> preference for one or another.
> 
> Regards,

Just renaming to isScale() would be sufficient for me.

[tfarina, 2014-10-24 00:04:45]

On 2014/10/23 18:58:37, reed1 wrote:
> Just renaming to isScale() would be sufficient for me.

Renamed. PTAL!

[reed1, 2014-10-24 14:07:50]

lgtm -- please add a unittest for this either now, or in a subsequent CL.
Doesn't need to be too tricky, but something to help nail down the boundary of
this predicate.

[tfarina, 2014-10-24 14:48:54]

The CQ bit was checked by tfarina@chromium.org

[commit-bot: I haz the power, 2014-10-24 14:49:30]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/676583002/20001

[commit-bot: I haz the power, 2014-10-24 15:07:11]

Committed patchset #2 (id:20001) as 20b7960798320e6804ffee78fd92e6c001eba30b