Add color emoji fallback for nvpr text

Add color emoji fallback for nvpr text

BUG=skia:

Committed: https://skia.googlesource.com/skia/+/20b373cf3116905fc5ca1928c9b504851335ca43

[Chris Dalton, 2014-11-25 23:13:54]

cdalton@nvidia.com changed reviewers:
+ bsalomon@google.com, jvanverth@google.com

[Chris Dalton, 2014-11-25 23:13:55]

https://codereview.chromium.org/759613005/diff/1/src/gpu/GrStencilAndCoverTex...
File src/gpu/GrStencilAndCoverTextContext.cpp (right):

https://codereview.chromium.org/759613005/diff/1/src/gpu/GrStencilAndCoverTex...
src/gpu/GrStencilAndCoverTextContext.cpp:384: // Stick the glyphs we can't draw
at the end of the buffer, growing backwards.
Looking for feedback here.

Growing backwards will cause the emojis to be drawn in reverse order. If we are
given overlapping positions, this may draw differently than expected. Is this a
scenario we need to worry about? (There is already no correctness guarantee for
path based glyphs when we are given overlapping positions.)

There are several alternatives, if this is important, but I'm not terribly fond
any:

* Make a separate static array for fallbacks
* Flip the fallback array before drawing
* Path-based glyphs grow backwards instead of the fallbacks
* ...

[jvanverth1, 2014-11-26 19:41:00]

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

[jvanverth1, 2014-11-26 19:41:35]

https://codereview.chromium.org/759613005/diff/1/src/gpu/GrStencilAndCoverTex...
File src/gpu/GrStencilAndCoverTextContext.cpp (right):

https://codereview.chromium.org/759613005/diff/1/src/gpu/GrStencilAndCoverTex...
src/gpu/GrStencilAndCoverTextContext.cpp:384: // Stick the glyphs we can't draw
at the end of the buffer, growing backwards.
On 2014/11/25 23:13:54, Chris Dalton wrote:
> Looking for feedback here.
> 
> Growing backwards will cause the emojis to be drawn in reverse order. If we
are
> given overlapping positions, this may draw differently than expected. Is this
a
> scenario we need to worry about? (There is already no correctness guarantee
for
> path based glyphs when we are given overlapping positions.)
> 
> There are several alternatives, if this is important, but I'm not terribly
fond
> any:
> 
> * Make a separate static array for fallbacks
> * Flip the fallback array before drawing
> * Path-based glyphs grow backwards instead of the fallbacks
> * ...

On one hand, drawing them in reverse order doesn't seem quite right if there is
overlap. On the other, we'll almost never see overlap, so I suspect it doesn't
matter. Adding reed@ to get his opinion.

[bsalomon, 2014-11-26 19:57:23]

On 2014/11/26 19:41:35, jvanverth1 wrote:
>
https://codereview.chromium.org/759613005/diff/1/src/gpu/GrStencilAndCoverTex...
> File src/gpu/GrStencilAndCoverTextContext.cpp (right):
> 
>
https://codereview.chromium.org/759613005/diff/1/src/gpu/GrStencilAndCoverTex...
> src/gpu/GrStencilAndCoverTextContext.cpp:384: // Stick the glyphs we can't
draw
> at the end of the buffer, growing backwards.
> On 2014/11/25 23:13:54, Chris Dalton wrote:
> > Looking for feedback here.
> > 
> > Growing backwards will cause the emojis to be drawn in reverse order. If we
> are
> > given overlapping positions, this may draw differently than expected. Is
this
> a
> > scenario we need to worry about? (There is already no correctness guarantee
> for
> > path based glyphs when we are given overlapping positions.)
> > 
> > There are several alternatives, if this is important, but I'm not terribly
> fond
> > any:
> > 
> > * Make a separate static array for fallbacks
> > * Flip the fallback array before drawing
> > * Path-based glyphs grow backwards instead of the fallbacks
> > * ...
> 
> On one hand, drawing them in reverse order doesn't seem quite right if there
is
> overlap. On the other, we'll almost never see overlap, so I suspect it doesn't
> matter. Adding reed@ to get his opinion.

I had a conversation with reed@ about this. We agreed that it is ok to paint the
glyphs in arbitrary order. Also for pixels (partially) inside two glyphs its
undefined whether the pixel is double hit or not.

[Chris Dalton, 2014-11-26 20:31:58]

On 2014/11/26 19:57:23, bsalomon wrote:
> I had a conversation with reed@ about this. We agreed that it is ok to paint
the
> glyphs in arbitrary order. Also for pixels (partially) inside two glyphs its
> undefined whether the pixel is double hit or not.

Great! Thanks for the quick response. With that resolved, this patch is good to
go on my end.

[bsalomon, 2014-12-01 14:45:21]

Jim, if this lgty it 1gtm.

[jvanverth1, 2014-12-01 15:26:11]

lgtm

[Chris Dalton, 2014-12-01 16:19:30]

The CQ bit was checked by cdalton@nvidia.com

[commit-bot: I haz the power, 2014-12-01 16:20:20]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/759613005/1

[commit-bot: I haz the power, 2014-12-01 16:20:24]

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

[commit-bot: I haz the power, 2014-12-01 16:20:25]

Presubmit check for 759613005-1 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')

Presubmit checks took 1.6s to calculate.

[bsalomon, 2014-12-01 16:29:05]

On 2014/12/01 16:20:25, I haz the power (commit-bot) wrote:
> Presubmit check for 759613005-1 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:
> (mailto:, mailto:, mailto:,
> mailto:, mailto:, mailto:)
> 
> Presubmit checks took 1.6s to calculate.

lgtm

[bsalomon, 2014-12-01 16:29:08]

The CQ bit was checked by bsalomon@google.com

[commit-bot: I haz the power, 2014-12-01 16:29:30]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/759613005/1

[commit-bot: I haz the power, 2014-12-01 16:38:59]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/20b373cf3116905fc5ca1928c9b504851335ca43