Remove full-size bitmap copy on SkImage::scalePixels->IFG::decodeAndScale

Remove full-size bitmap copy on SkImage::scalePixels->IFG::decodeAndScale

This and related skia patch [1] move pixmap scaling from SkImage::scalePixels
to ImageFrameGenerator (IFG) decodeAndScale. In following cases this removes a
full size decoded pixels copy:
1. GIF/WebP animation frames are owned by decoder
2. partially received and decoded images (single and multiple frames) as they
   also cannot be decoded to externally provided pixels.

[1] dependent skia patch
https://skia-review.googlesource.com/c/5960/

BUG=100170, 438323, 472630, 671821

[aleksandar.stojiljkovic, 2016-12-15 00:17:35]

aleksandar.stojiljkovic@intel.com changed reviewers:
+ fmalita@chromium.org

[aleksandar.stojiljkovic, 2016-12-15 00:17:36]

fmalita@, PTAL.
Thanks.

[f(malita), 2016-12-15 20:53:38]

fmalita@chromium.org changed reviewers:
+ scroggo@chromium.org

[f(malita), 2016-12-15 20:53:38]

+scroggo

[f(malita), 2016-12-15 20:56:22]

Description was changed from

==========
Remove full-size bitmap copy on SkImage::scalePixels->IFG::decodeAndScale

This and related skia patch [1] move pixmap scaling from SkImage::scalePixels
to ImageFrameGenerator (IFG) decodeAndScale. In following cases this removes a
full size decoded pixels copy:
1. GIF/WebP animation frames are owned by decoder
2. partially received and decoded images (single and multiple frames) as they
   also cannot be decoded to externally provided pixels.

[1] dependent skia patch
https://skia-review.googlesource.com/c/5960/

BUG=100170, 438323, 472630, 671821
==========

to

==========
Remove full-size bitmap copy on SkImage::scalePixels->IFG::decodeAndScale

This and related skia patch [1] move pixmap scaling from SkImage::scalePixels
to ImageFrameGenerator (IFG) decodeAndScale. In following cases this removes a
full size decoded pixels copy:
1. GIF/WebP animation frames are owned by decoder
2. partially received and decoded images (single and multiple frames) as they
   also cannot be decoded to externally provided pixels.

[1] dependent skia patch
https://skia-review.googlesource.com/c/5960/

BUG=100170, 438323, 472630, 671821
==========

[aleksandar.stojiljkovic, 2017-01-09 21:06:08]

On 2016/12/15 20:53:38, f(malita) wrote:
> +scroggo

scroggo@, since you are the reviewer in skia patch too, PTAL at both:
- https://skia-review.googlesource.com/c/5960/
- this one here.
It is basically moving part of the code from skia to blink and in some cases
this saves a full size allocation and copy.
Thanks.

[scroggo_chromium, 2017-01-12 14:57:44]

scroggo@chromium.org changed reviewers:
+ reed@google.com

[scroggo_chromium, 2017-01-12 15:01:28]

On 2017/01/09 21:06:08, aleksandar.stojiljkovic wrote:
> On 2016/12/15 20:53:38, f(malita) wrote:
> > +scroggo
> 
> scroggo@, since you are the reviewer in skia patch too, PTAL at both:
> - https://skia-review.googlesource.com/c/5960/
> - this one here.
> It is basically moving part of the code from skia to blink and in some cases
> this saves a full size allocation and copy.
> Thanks.

I understand the motivation, but reed@ still needs to sign off on the API change
in Skia. Last I discussed with him, we had not figured out an API that provides
this feature that we are happy with.

[reed1, 2017-01-12 15:15:53]

generate-scaled-pixels is problematic (at least in my mind), so I'd prefer we
have a chat about it before landing code that relies on it.

Is everyone available today for a vc?

[scroggo_chromium, 2017-01-12 15:34:11]

On 2017/01/12 15:15:53, reed1 wrote:
> generate-scaled-pixels is problematic (at least in my mind), so I'd prefer we
> have a chat about it before landing code that relies on it.
> 
> Is everyone available today for a vc?

I am available today. (My calendar shows when I am unavailable.)

[aleksandar.stojiljkovic, 2017-01-12 16:45:53]

On 2017/01/12 15:34:11, scroggo_chromium wrote:
> On 2017/01/12 15:15:53, reed1 wrote:
> > generate-scaled-pixels is problematic (at least in my mind), so I'd prefer
we
> > have a chat about it before landing code that relies on it.
> > 
> > Is everyone available today for a vc?
> 
> I am available today. (My calendar shows when I am unavailable.)

Some input for your discussion around Skia design here [1]
Now 1) getPixels (when info.getBounds() != getInfo().getBounds()) and 2)
generateScaledPixels are covering the same functionality so we could try using
getPixels and remove generateScaledPixels and computeScaled...

Subset decoding might be needed for
https://bugs.chromium.org/p/chromium/issues/detail?id=671821#c2 (Decode
sub-rects for images embedded in SkImageShader) but we could analyze that
separatelly.
 
[1]
https://skia-review.googlesource.com/c/6278/#message-b7e325cc1718fc3cb9c80117...