Optimize color xforms when src and dst are matching

Optimize color xforms when src and dst are matching

Useful when:
(1) Client does not realize src and dst match (calls color
    xform anyway).
(2) Client wants half floats, src and dst have matching
    gamuts
(3) Client wants premul (done correctly in linear space),
    src and dst have matching gamuts.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2206403003

Committed: https://skia.googlesource.com/skia/+/200877eecaba782e56a1dd9e13a92f36d7b1ba12

[msarett, 2016-08-03 21:15:00]

Description was changed from

==========
Experimental: Optimize color xforms when src and dst are matching

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

to

==========
Experimental: Optimize color xforms when src and dst are matching

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2206403003
==========

[msarett, 2016-08-03 21:22:48]

Patchset #2 (id:20001) has been deleted

[msarett, 2016-08-15 12:59:30]

Description was changed from

==========
Experimental: Optimize color xforms when src and dst are matching

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2206403003
==========

to

==========
Optimize color xforms when src and dst are matching

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2206403003
==========

[msarett, 2016-08-15 13:01:57]

Description was changed from

==========
Optimize color xforms when src and dst are matching

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2206403003
==========

to

==========
Optimize color xforms when src and dst are matching

Useful when:
(1) Client does not realize src and dst match (calls color
    xform anyway).
(2) Client wants half floats, src and dst have matching
    gamuts
(3) Client wants premul (done correctly in linear space),
    src and dst have matching gamuts.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2206403003
==========

[msarett, 2016-08-15 13:02:10]

msarett@google.com changed reviewers:
+ mtklein@google.com

[mtklein_C, 2016-08-15 14:00:01]

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

[mtklein_C, 2016-08-15 14:00:02]

https://codereview.chromium.org/2206403003/diff/40001/src/core/SkColorSpaceXf...
File src/core/SkColorSpaceXform.cpp (right):

https://codereview.chromium.org/2206403003/diff/40001/src/core/SkColorSpaceXf...
src/core/SkColorSpaceXform.cpp:12: #include "SkColorSpaceXformOpts.h"
Probably time to fold SkColorSpaceXformOpts.h into this file.  It's only
included here.

https://codereview.chromium.org/2206403003/diff/40001/src/core/SkColorSpaceXf...
src/core/SkColorSpaceXform.cpp:461:
color_space_almost_equal(srcToDst.getFloat(0, 1), 1.0f) &&
How's this identity?  Isn't this

| 1 1 1 1 |
| 0 1 0 0 |
| 0 0 1 0 |
| 0 0 0 1 |

?

Maybe

for (int i = 0; i < 4; i++)
for (int j = 0; j < 4; j++) {
   float expected = (i == j) ? 1.0f : 0.0f;
   if (!color_space_almost_equal(srcToDst.getFloat(i,j), expected)) {
       return false;
   }
}
return true;

[msarett, 2016-08-15 14:35:19]

Patchset #4 (id:80001) has been deleted

[msarett, 2016-08-15 14:37:17]

https://codereview.chromium.org/2206403003/diff/40001/src/core/SkColorSpaceXf...
File src/core/SkColorSpaceXform.cpp (right):

https://codereview.chromium.org/2206403003/diff/40001/src/core/SkColorSpaceXf...
src/core/SkColorSpaceXform.cpp:12: #include "SkColorSpaceXformOpts.h"
On 2016/08/15 14:00:01, mtklein_C wrote:
> Probably time to fold SkColorSpaceXformOpts.h into this file.  It's only
> included here.

SGTM

https://codereview.chromium.org/2206403003/diff/40001/src/core/SkColorSpaceXf...
src/core/SkColorSpaceXform.cpp:461:
color_space_almost_equal(srcToDst.getFloat(0, 1), 1.0f) &&
On 2016/08/15 14:00:01, mtklein_C wrote:
> How's this identity?  Isn't this
> 
> | 1 1 1 1 |
> | 0 1 0 0 |
> | 0 0 1 0 |
> | 0 0 0 1 |
> 
> ?
> 
> Maybe
> 
> for (int i = 0; i < 4; i++)
> for (int j = 0; j < 4; j++) {
>    float expected = (i == j) ? 1.0f : 0.0f;
>    if (!color_space_almost_equal(srcToDst.getFloat(i,j), expected)) {
>        return false;
>    }
> }
> return true;

Oops, yeah.  Let's use the loops.

[msarett, 2016-08-15 14:37:22]

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

[commit-bot: I haz the power, 2016-08-15 14:37:32]

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, 2016-08-15 14:53:42]

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

[commit-bot: I haz the power, 2016-08-15 14:53:43]

Dry run: This issue passed the CQ dry run.

[mtklein_C, 2016-08-15 15:06:28]

lgtm

[msarett, 2016-08-15 15:07:02]

The CQ bit was checked by msarett@google.com

[commit-bot: I haz the power, 2016-08-15 15:07:04]

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, 2016-08-15 15:10:46]

Description was changed from

==========
Optimize color xforms when src and dst are matching

Useful when:
(1) Client does not realize src and dst match (calls color
    xform anyway).
(2) Client wants half floats, src and dst have matching
    gamuts
(3) Client wants premul (done correctly in linear space),
    src and dst have matching gamuts.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2206403003
==========

to

==========
Optimize color xforms when src and dst are matching

Useful when:
(1) Client does not realize src and dst match (calls color
    xform anyway).
(2) Client wants half floats, src and dst have matching
    gamuts
(3) Client wants premul (done correctly in linear space),
    src and dst have matching gamuts.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2206403003

Committed:
https://skia.googlesource.com/skia/+/200877eecaba782e56a1dd9e13a92f36d7b1ba12
==========

[commit-bot: I haz the power, 2016-08-15 15:10:47]

Committed patchset #4 (id:100001) as
https://skia.googlesource.com/skia/+/200877eecaba782e56a1dd9e13a92f36d7b1ba12