Null canvas

Null canvas

[bsalomon, 2012-04-24 21:31:56]

We'll have to add the new cpp file to chrome's skia.gyp. Then we should be able
to use SkCreateNullCanvas in chrome to create a do-nothing canvas.

[reed1, 2012-04-26 01:00:11]

http://codereview.appspot.com/6117051/diff/6007/include/utils/SkNullCanvas.h
File include/utils/SkNullCanvas.h (right):

http://codereview.appspot.com/6117051/diff/6007/include/utils/SkNullCanvas.h#...
include/utils/SkNullCanvas.h:17: */
Do we need/want anything other than just width/height for a null-canvas?

[bsalomon, 2012-04-27 15:29:53]

On 2012/04/26 01:00:11, reed1 wrote:
> http://codereview.appspot.com/6117051/diff/6007/include/utils/SkNullCanvas.h
> File include/utils/SkNullCanvas.h (right):
> 
>
http://codereview.appspot.com/6117051/diff/6007/include/utils/SkNullCanvas.h#...
> include/utils/SkNullCanvas.h:17: */
> Do we need/want anything other than just width/height for a null-canvas?

The latest patch is much simpler: it uses SkNWayCanvas. It doesn't take any
params.

[bsalomon, 2012-06-11 12:21:36]

Hey Mike can you take a look at the latest patch. I had forgotten about it but
it turns out that people are actually applying it to their Chrome trees for
testing purposes.

[reed1, 2012-06-11 14:28:14]

Seems fine in general.

1. We might go through the formal exercise of documenting exactly how the APIs
on canvas will behave in this instance.

- drawFoo is easy, it returns void and does nothing, does not invoke Bounder or
DrawLooper

Do these return something meaningful?
- clipFoo
- getTotalClip
- getTotalMatrix

What does getDevice and createCompatibleDevice return?

What does setDevice do?
What does replayClips do?

Having said that, I'm fine to check this in now, so folks can use it, but we
should still document it at some point. LGTM