Tweak distance field path renderer behavior in gamma-correct mode

Tweak distance field path renderer behavior in gamma-correct mode to match
recent changes to text rendering.

Uses linear coverage falloff. Produces results that are perceptually more
similar to L32 (raster and gpu). Smoothstep + sRGB was too soft.

Plumb the gamma-correctness via DrawPathArgs, which also paves the way for
other path rendering implementations to easily make decisions about rendering
technique based on that flag.

Fix a few typos and formatting issues from my most recent change.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1889453002

Committed: https://skia.googlesource.com/skia/+/0e3c55431b463b5575983c0c875909e08a3562bf

[Brian Osman, 2016-04-13 13:39:56]

Description was changed from

==========
Tweak distance field path renderer behavior in sRGB (to match recent
text fixes).

Uses linear coverage falloff. Produces results that are perceptually more
similar to L32 (raster and gpu). Smoothstep + sRGB was too soft.

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

to

==========
Tweak distance field path renderer behavior in sRGB (to match recent
text fixes).

Uses linear coverage falloff. Produces results that are perceptually more
similar to L32 (raster and gpu). Smoothstep + sRGB was too soft.

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

[Brian Osman, 2016-04-13 13:41:28]

brianosman@google.com changed reviewers:
+ bsalomon@google.com, jvanverth@google.com

[Brian Osman, 2016-04-13 13:41:37]

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

[commit-bot: I haz the power, 2016-04-13 13:41:44]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1889453002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1889453002/1

[jvanverth1, 2016-04-13 13:45:39]

https://codereview.chromium.org/1889453002/diff/1/src/gpu/GrDrawTarget.h
File src/gpu/GrDrawTarget.h (right):

https://codereview.chromium.org/1889453002/diff/1/src/gpu/GrDrawTarget.h#newc...
src/gpu/GrDrawTarget.h:177: friend class GrAADistanceFieldPathRenderer; // for
fRenderTarget (to query sRGB)
This seems a little squirrely to me. Does it make sense to add an accessor
function that returns fRenderTarget->config() instead?

[Brian Osman, 2016-04-13 13:48:44]

https://codereview.chromium.org/1889453002/diff/1/src/gpu/GrDrawTarget.h
File src/gpu/GrDrawTarget.h (right):

https://codereview.chromium.org/1889453002/diff/1/src/gpu/GrDrawTarget.h#newc...
src/gpu/GrDrawTarget.h:177: friend class GrAADistanceFieldPathRenderer; // for
fRenderTarget (to query sRGB)
On 2016/04/13 13:45:39, jvanverth1 wrote:
> This seems a little squirrely to me. Does it make sense to add an accessor
> function that returns fRenderTarget->config() instead?

Yes - I nearly added a comment before sending this out, because I didn't really
like this.

[commit-bot: I haz the power, 2016-04-13 13:51:19]

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

[commit-bot: I haz the power, 2016-04-13 13:51:19]

Dry run: This issue passed the CQ dry run.

[Brian Osman, 2016-04-13 13:52:49]

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

[commit-bot: I haz the power, 2016-04-13 13:52:54]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1889453002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1889453002/20001

[Brian Osman, 2016-04-13 13:55:18]

https://codereview.chromium.org/1889453002/diff/20001/src/gpu/effects/GrDista...
File src/gpu/effects/GrDistanceFieldGeoProc.cpp (right):

https://codereview.chromium.org/1889453002/diff/20001/src/gpu/effects/GrDista...
src/gpu/effects/GrDistanceFieldGeoProc.cpp:406: // doing gamma-correct rendering
(to an sRGB or F16 buffer), then we actually want distance
This comment is actually incorrect at the moment - F16 is still using
smoothstep. There are various issues with F16 right now (some inconsistent logic
like this, and the fact that it's not fully hooked up end-to-end in SampleApp).
Not sure how much of a priority that is, vs. other aspects right now.

[commit-bot: I haz the power, 2016-04-13 14:01:55]

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

[commit-bot: I haz the power, 2016-04-13 14:01:56]

Dry run: This issue passed the CQ dry run.

[bsalomon, 2016-04-13 14:36:22]

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

[bsalomon, 2016-04-13 14:36:23]

https://codereview.chromium.org/1889453002/diff/20001/src/gpu/GrDrawTarget.h
File src/gpu/GrDrawTarget.h (right):

https://codereview.chromium.org/1889453002/diff/20001/src/gpu/GrDrawTarget.h#...
src/gpu/GrDrawTarget.h:111: GrPixelConfig config() const { return
fRenderTarget->config(); }
+Rob

[robertphillips, 2016-04-13 15:28:45]

https://codereview.chromium.org/1889453002/diff/20001/src/gpu/GrDrawTarget.h
File src/gpu/GrDrawTarget.h (right):

https://codereview.chromium.org/1889453002/diff/20001/src/gpu/GrDrawTarget.h#...
src/gpu/GrDrawTarget.h:111: GrPixelConfig config() const { return
fRenderTarget->config(); }
On 2016/04/13 14:36:23, bsalomon wrote:
> +Rob

Commented in person but, can we make the getter more precise?

[Brian Osman, 2016-04-13 20:41:50]

Description was changed from

==========
Tweak distance field path renderer behavior in sRGB (to match recent
text fixes).

Uses linear coverage falloff. Produces results that are perceptually more
similar to L32 (raster and gpu). Smoothstep + sRGB was too soft.

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

to

==========
Tweak distance field path renderer behavior in gamma-correct mode to match
recent changes to text rendering.

Uses linear coverage falloff. Produces results that are perceptually more
similar to L32 (raster and gpu). Smoothstep + sRGB was too soft.

Plumb the gamma-correctness via DrawPathArgs, which also paves the way for
other path rendering implementations to easily make decisions about rendering
technique based on that flag.

Fix a few typos and formatting issues from my most recent change.

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

[Brian Osman, 2016-04-13 20:43:07]

Rebased after renaming everything to "gamma-correct", and plumbed flag down from
the draw context (via DrawPathArgs). Much cleaner.

[Brian Osman, 2016-04-13 20:43:13]

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

[commit-bot: I haz the power, 2016-04-13 20:43:17]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1889453002/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1889453002/40001

[bsalomon, 2016-04-13 20:47:18]

Agreed, this is much nicer. lgtm.

[Brian Osman, 2016-04-13 20:52:42]

The CQ bit was unchecked by brianosman@google.com

[Brian Osman, 2016-04-13 20:52:48]

The CQ bit was checked by brianosman@google.com

[commit-bot: I haz the power, 2016-04-13 20:52:56]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1889453002/40001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1889453002/40001

[commit-bot: I haz the power, 2016-04-13 20:56:24]

Description was changed from

==========
Tweak distance field path renderer behavior in gamma-correct mode to match
recent changes to text rendering.

Uses linear coverage falloff. Produces results that are perceptually more
similar to L32 (raster and gpu). Smoothstep + sRGB was too soft.

Plumb the gamma-correctness via DrawPathArgs, which also paves the way for
other path rendering implementations to easily make decisions about rendering
technique based on that flag.

Fix a few typos and formatting issues from my most recent change.

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

to

==========
Tweak distance field path renderer behavior in gamma-correct mode to match
recent changes to text rendering.

Uses linear coverage falloff. Produces results that are perceptually more
similar to L32 (raster and gpu). Smoothstep + sRGB was too soft.

Plumb the gamma-correctness via DrawPathArgs, which also paves the way for
other path rendering implementations to easily make decisions about rendering
technique based on that flag.

Fix a few typos and formatting issues from my most recent change.

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

Committed:
https://skia.googlesource.com/skia/+/0e3c55431b463b5575983c0c875909e08a3562bf
==========

[commit-bot: I haz the power, 2016-04-13 20:56:25]

Committed patchset #3 (id:40001) as
https://skia.googlesource.com/skia/+/0e3c55431b463b5575983c0c875909e08a3562bf