optimize the disable-caching case for SkImage::readPixels

optimize the disable-caching case for SkImage::readPixels

If the client wants no caching, and we haven't already cached it, pass the
caller's dst-buffer directly down to the generator, avoiding the (previous)
extra memcpy.

BUG=skia:4594
Committed: https://skia.googlesource.com/skia/+/6868c3fccf65d297a64919a7cb74f09780c845c3

[reed1, 2015-11-24 19:21:19]

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

[commit-bot: I haz the power, 2015-11-24 19:21:24]

Dry run: CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1473373002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1473373002/20001

[reed1, 2015-11-24 19:21:31]

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

[commit-bot: I haz the power, 2015-11-24 19:33:55]

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

[commit-bot: I haz the power, 2015-11-24 19:33:55]

Dry run: This issue passed the CQ dry run.

[f(malita), 2015-11-24 19:36:08]

lgtm

https://codereview.chromium.org/1473373002/diff/20001/src/core/SkImageCachera...
File src/core/SkImageCacherator.h (right):

https://codereview.chromium.org/1473373002/diff/20001/src/core/SkImageCachera...
src/core/SkImageCacherator.h:63: bool directGeneratePixels(const SkImageInfo&
dstInfo, void* dstPixels, size_t dstRB,
I guess this matches existing internal APIs, but would it make sense to switch
to SkPixmap at some point?

[reed1, 2015-11-24 19:43:49]

https://codereview.chromium.org/1473373002/diff/20001/src/core/SkImageCachera...
File src/core/SkImageCacherator.h (right):

https://codereview.chromium.org/1473373002/diff/20001/src/core/SkImageCachera...
src/core/SkImageCacherator.h:63: bool directGeneratePixels(const SkImageInfo&
dstInfo, void* dstPixels, size_t dstRB,
On 2015/11/24 19:36:07, f(malita) wrote:
> I guess this matches existing internal APIs, but would it make sense to switch
> to SkPixmap at some point?

Yep. Would probably start with SkImageGenerator, and move our way up. I propose
we tackle that separately (thank goodness this header is private).

[reed1, 2015-11-24 19:44:00]

The CQ bit was checked by reed@google.com

[commit-bot: I haz the power, 2015-11-24 19:44:08]

CQ is trying da patch. Follow status at
 https://chromium-cq-status.appspot.com/patch-status/1473373002/20001
View timeline at
 https://chromium-cq-status.appspot.com/patch-timeline/1473373002/20001

[commit-bot: I haz the power, 2015-11-24 19:44:50]

Committed patchset #2 (id:20001) as
https://skia.googlesource.com/skia/+/6868c3fccf65d297a64919a7cb74f09780c845c3