Factor code to rotate a canvas about a point.

Factor code to rotate a canvas about a point.

SkMatrix::scale and ::rotate take a point around which to scale or rotate.
Canvas lacks these helpers, so the code to rotate a canvas around a
point has been duplicated many times. Factor all of these
implementations into SkCanvas::rotate.

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2142033002

Committed: https://skia.googlesource.com/skia/+/7438bfc0804d021aa92cdd5ea644994a4248f3db

[bungeman-skia, 2016-07-12 15:13:45]

Description was changed from

==========
Factor code to rotate a canvas about a point.

SkMatrix scale and rotate take a point around which to scale or rotate.
Canvas lacks these helpers, so the code to rotate a canvas around a
point has been duplicated many times. Factor all of these
implementations into sk_tool_utils::rotate_about.
==========

to

==========
Factor code to rotate a canvas about a point.

SkMatrix scale and rotate take a point around which to scale or rotate.
Canvas lacks these helpers, so the code to rotate a canvas around a
point has been duplicated many times. Factor all of these
implementations into sk_tool_utils::rotate_about.
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2142033002
==========

[bungeman-skia, 2016-07-12 15:14:07]

Description was changed from

==========
Factor code to rotate a canvas about a point.

SkMatrix scale and rotate take a point around which to scale or rotate.
Canvas lacks these helpers, so the code to rotate a canvas around a
point has been duplicated many times. Factor all of these
implementations into sk_tool_utils::rotate_about.
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2142033002
==========

to

==========
Factor code to rotate a canvas about a point.

SkMatrix scale and rotate take a point around which to scale or rotate.
Canvas lacks these helpers, so the code to rotate a canvas around a
point has been duplicated many times. Factor all of these
implementations into sk_tool_utils::rotate_about.

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2142033002
==========

[bungeman-skia, 2016-07-12 15:14:16]

The CQ bit was checked by bungeman@google.com to run a CQ dry run

[commit-bot: I haz the power, 2016-07-12 15:14:22]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-07-12 15:26:39]

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

[commit-bot: I haz the power, 2016-07-12 15:26:40]

Dry run: This issue passed the CQ dry run.

[bungeman-skia, 2016-07-12 15:47:10]

bungeman@google.com changed reviewers:
+ mtklein@google.com, reed@google.com

[bungeman-skia, 2016-07-12 15:47:11]

Maybe SkCanvas::rotate(degrees, px, py) would be of interest?

https://codereview.chromium.org/2142033002/diff/1/gm/strokes.cpp
File gm/strokes.cpp (left):

https://codereview.chromium.org/2142033002/diff/1/gm/strokes.cpp#oldcode296
gm/strokes.cpp:296: canvas->concat(matrix);
With floats the order of operations matters. This code will produce slightly
different numbers from the new code.

[reed1, 2016-07-12 15:52:31]

Happy if we want to add this to canvas (as non-virtual)

[bungeman-skia, 2016-07-12 16:23:12]

The CQ bit was checked by bungeman@google.com to run a CQ dry run

[commit-bot: I haz the power, 2016-07-12 16:23:20]

Dry run: CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[bungeman-skia, 2016-07-12 16:23:36]

Now on canvas.

[commit-bot: I haz the power, 2016-07-12 16:45:43]

The CQ bit was unchecked by commit-bot@chromium.org to run a CQ dry run

[commit-bot: I haz the power, 2016-07-12 16:45:44]

Dry run: This issue passed the CQ dry run.

[bungeman-skia, 2016-07-12 17:00:50]

Description was changed from

==========
Factor code to rotate a canvas about a point.

SkMatrix scale and rotate take a point around which to scale or rotate.
Canvas lacks these helpers, so the code to rotate a canvas around a
point has been duplicated many times. Factor all of these
implementations into sk_tool_utils::rotate_about.

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2142033002
==========

to

==========
Factor code to rotate a canvas about a point.

SkMatrix::scale and ::rotate take a point around which to scale or rotate.
Canvas lacks these helpers, so the code to rotate a canvas around a
point has been duplicated many times. Factor all of these
implementations into sk_tool_utils::rotate_about.

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2142033002
==========

[bungeman-skia, 2016-07-12 17:01:25]

Description was changed from

==========
Factor code to rotate a canvas about a point.

SkMatrix::scale and ::rotate take a point around which to scale or rotate.
Canvas lacks these helpers, so the code to rotate a canvas around a
point has been duplicated many times. Factor all of these
implementations into sk_tool_utils::rotate_about.

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2142033002
==========

to

==========
Factor code to rotate a canvas about a point.

SkMatrix::scale and ::rotate take a point around which to scale or rotate.
Canvas lacks these helpers, so the code to rotate a canvas around a
point has been duplicated many times. Factor all of these
implementations into SkCanvas::rotate.

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2142033002
==========

[reed1, 2016-07-12 17:28:59]

api lgtm

At some point it'd be nice if we supported (clearly, with good names) radians as
well as degrees

https://codereview.chromium.org/2142033002/diff/20001/src/core/SkCanvas.cpp
File src/core/SkCanvas.cpp (right):

https://codereview.chromium.org/2142033002/diff/20001/src/core/SkCanvas.cpp#n...
src/core/SkCanvas.cpp:1501: void SkCanvas::rotate(SkScalar degrees, SkScalar px,
SkScalar py) {
possibly check for 0 == degrees to skip the rest. Just a thought.

[bungeman-skia, 2016-07-12 17:37:42]

https://codereview.chromium.org/2142033002/diff/20001/src/core/SkCanvas.cpp
File src/core/SkCanvas.cpp (right):

https://codereview.chromium.org/2142033002/diff/20001/src/core/SkCanvas.cpp#n...
src/core/SkCanvas.cpp:1501: void SkCanvas::rotate(SkScalar degrees, SkScalar px,
SkScalar py) {
On 2016/07/12 17:28:59, reed1 wrote:
> possibly check for 0 == degrees to skip the rest. Just a thought.

If so, I think it would need to be done above as well. If you think it would be
common enough to be interesting, we can put together a CL to do that.

It turns out that this is already better than the translate-rotate-translate
calls from Patch Set 1, since the matrix is being produced more efficiently and
there is only one concat (as opposed to three concats).

[bungeman-skia, 2016-07-12 17:39:46]

The CQ bit was checked by bungeman@google.com

[commit-bot: I haz the power, 2016-07-12 17:39:52]

CQ is trying da patch. Follow status at
 
https://chromium-cq-status.appspot.com/v2/patch-status/codereview.chromium.or...

[commit-bot: I haz the power, 2016-07-12 22:01:23]

Description was changed from

==========
Factor code to rotate a canvas about a point.

SkMatrix::scale and ::rotate take a point around which to scale or rotate.
Canvas lacks these helpers, so the code to rotate a canvas around a
point has been duplicated many times. Factor all of these
implementations into SkCanvas::rotate.

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2142033002
==========

to

==========
Factor code to rotate a canvas about a point.

SkMatrix::scale and ::rotate take a point around which to scale or rotate.
Canvas lacks these helpers, so the code to rotate a canvas around a
point has been duplicated many times. Factor all of these
implementations into SkCanvas::rotate.

GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2142033002

Committed:
https://skia.googlesource.com/skia/+/7438bfc0804d021aa92cdd5ea644994a4248f3db
==========

[commit-bot: I haz the power, 2016-07-12 22:01:24]

Committed patchset #2 (id:20001) as
https://skia.googlesource.com/skia/+/7438bfc0804d021aa92cdd5ea644994a4248f3db

[commit-bot: I haz the power, 2016-07-12 22:01:31]

CQ bit was unchecked.