Add quad to cubic bezier conversion utility to SkPath.

Add quad to cubic bezier conversion utility to SkPath.

This CL exposes SkConvertQuadToCubic in SkGeometry.h as ConvertQuadToCubic in SkPath.h.

BUG=chromium:543671
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1639143002

[karandeepb, 2016-01-27 04:16:59]

Description was changed from

==========
Added convenience function convertQuadToCubic to skpath

BUG=skia:
==========

to

==========
Added convenience function convertQuadToCubic to skpath

BUG=skia:
GOLD_TRYBOT_URL=
https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&is...
==========

[karandeepb, 2016-01-27 04:25:08]

Description was changed from

==========
Added convenience function convertQuadToCubic to skpath

BUG=skia:
GOLD_TRYBOT_URL=
https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&is...
==========

to

==========
Add quad to cubic bezier conversion utility to SkPath.

This CL exposes SkConvertQuadToCubic in SkGeometry.h as ConvertQuadToCubic in
SkPath.h.

BUG=chromium:543671
GOLD_TRYBOT_URL=
https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&is...
==========

[karandeepb, 2016-02-05 03:15:30]

karandeepb@chromium.org changed reviewers:
+ reed@google.com

[karandeepb, 2016-02-05 03:15:31]

reed@ PTAL. Thanks.

[karandeepb, 2016-02-05 03:41:33]

On 2016/02/05 03:15:31, karandeepb wrote:
> reed@ PTAL. Thanks.

This is needed since we need to convert an SkPath to an NSBezierPath (a path
class in Cocoa). Since an NSBezierPath does not support quadratic bezier curves,
we need to convert them to a cubic bezier first. Refer path_mac.mm in
https://codereview.chromium.org/1633403002/.

[reed1, 2016-02-05 14:32:13]

reed@google.com changed reviewers:
+ caryclark@google.com

[reed1, 2016-02-05 14:32:13]

seems like a trivial piece of functionality to add to our public API, but it is
also very well-defined, so I'm on the fence. Adding cary...

[caryclark, 2016-02-05 16:11:17]

What is the motivation for this?

[karandeepb, 2016-02-05 16:12:55]

On 2016/02/05 16:11:17, caryclark wrote:
> What is the motivation for this?

I have described this in comment 5 -
https://codereview.chromium.org/1639143002/#msg5.

[karandeepb, 2016-02-09 07:18:36]

On 2016/02/05 16:12:55, karandeepb wrote:
> On 2016/02/05 16:11:17, caryclark wrote:
> > What is the motivation for this?
> 
> I have described this in comment 5 -
> https://codereview.chromium.org/1639143002/#msg5.

ping @caryclark. Also, let me know if you have any input regarding the
SkPath->NSBezierPath conversion in https://codereview.chromium.org/1633403002/
(file path_mac.mm).

[caryclark, 2016-02-09 12:30:55]

Rather than promote this to a public interface, I recommend copying the
implementation to your own repository.

In general, Skia would like to encourage using native types and not rely on
down-converting, since it is imprecise, creates a lot of data, and
time-consuming. It's implementation may change in the future as the calling
needs change (for instance, it could be removed altogether) as rendering evolves
to use native types directly.