SkPictureImageFilter - clear local canvas before use

SkPictureImageFilter - clear local canvas before use

In SkPictureImageFilter::onFilterImage, we may create two new surfaces,
one for our final output, and one for a local resolution intermediate.

We clear the final output surface before use, removing any previous
content, however we do not do the same for the local surface. This can
lead to content being incorrectly layered on top of previous content
when we go down this path.

This change adds logic to clear the local surface as well.

BUG=610667
GOLD_TRYBOT_URL= https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&issue=1969193002

Committed: https://skia.googlesource.com/skia/+/a31312cddd51c896b34c5c3382bcf6c50632d70b

[ericrk, 2016-05-11 22:22:10]

Description was changed from

==========
SkPictureImageFilter - clear local canvas before use

In SkPictureImageFilter::onFilterImage, we may create two new surfaces,
one for our final output, and one for a local resolution intermediate.

We clear the final output surface before use, removing any previous
content, however we do not do the same for the local surface. This can
lead to content being incorrectly layered on top of previous content
when we go down this path.

This change adds logic to clear the local surface as well.

BUG=610667
==========

to

==========
SkPictureImageFilter - clear local canvas before use

In SkPictureImageFilter::onFilterImage, we may create two new surfaces,
one for our final output, and one for a local resolution intermediate.

We clear the final output surface before use, removing any previous
content, however we do not do the same for the local surface. This can
lead to content being incorrectly layered on top of previous content
when we go down this path.

This change adds logic to clear the local surface as well.

BUG=610667
GOLD_TRYBOT_URL=
https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&is...
==========

[ericrk, 2016-05-11 22:22:43]

ericrk@chromium.org changed reviewers:
+ bsalomon@google.com, senorblanco@google.com

[reed1, 2016-05-11 23:01:30]

reed@google.com changed reviewers:
+ reed@google.com, robertphillips@google.com

[reed1, 2016-05-11 23:01:31]

Interesting. I thought all of our surface factories were already defined to
return zero'd buffers. Is that not the case? If not, we should either change it
or fix/clarify our documentation.

[robertphillips, 2016-05-12 12:05:08]

On 2016/05/11 23:01:31, reed1 wrote:
> Interesting. I thought all of our surface factories were already defined to
> return zero'd buffers. Is that not the case? If not, we should either change
it
> or fix/clarify our documentation.

Can you add a case to the pictureimagefilter GM that would show the problem?

Mike - the SkSpecialSurface does not clear the canvas. There are some instances
where the initial clear isn't required.

[robertphillips, 2016-05-12 15:24:24]

lgtm.

In https://codereview.chromium.org/1972213002/ (Fix bug & add code to catch
ImageFilter clearing bugs) I've updated the pictureimagefilter GM so it would've
revealed this bug.

[robertphillips, 2016-05-12 15:24:45]

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

[commit-bot: I haz the power, 2016-05-12 15:24:53]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1969193002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1969193002/1

[Stephen White, 2016-05-12 15:25:35]

Good catch! LGTM

[commit-bot: I haz the power, 2016-05-12 15:43:21]

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

[commit-bot: I haz the power, 2016-05-12 15:43:22]

Dry run: This issue passed the CQ dry run.

[robertphillips, 2016-05-12 16:05:47]

The CQ bit was checked by robertphillips@google.com

[commit-bot: I haz the power, 2016-05-12 16:05:50]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1969193002/1
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1969193002/1

[commit-bot: I haz the power, 2016-05-12 16:06:46]

Description was changed from

==========
SkPictureImageFilter - clear local canvas before use

In SkPictureImageFilter::onFilterImage, we may create two new surfaces,
one for our final output, and one for a local resolution intermediate.

We clear the final output surface before use, removing any previous
content, however we do not do the same for the local surface. This can
lead to content being incorrectly layered on top of previous content
when we go down this path.

This change adds logic to clear the local surface as well.

BUG=610667
GOLD_TRYBOT_URL=
https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&is...
==========

to

==========
SkPictureImageFilter - clear local canvas before use

In SkPictureImageFilter::onFilterImage, we may create two new surfaces,
one for our final output, and one for a local resolution intermediate.

We clear the final output surface before use, removing any previous
content, however we do not do the same for the local surface. This can
lead to content being incorrectly layered on top of previous content
when we go down this path.

This change adds logic to clear the local surface as well.

BUG=610667
GOLD_TRYBOT_URL=
https://gold.skia.org/search2?unt=true&query=source_type%3Dgm&master=false&is...

Committed:
https://skia.googlesource.com/skia/+/a31312cddd51c896b34c5c3382bcf6c50632d70b
==========

[commit-bot: I haz the power, 2016-05-12 16:06:47]

Committed patchset #1 (id:1) as
https://skia.googlesource.com/skia/+/a31312cddd51c896b34c5c3382bcf6c50632d70b