LayerImpl::tryScroll must convert its content-space point to layer space before comparing to the no…

LayerImpl::tryScroll must convert its content-space point to layer space before comparing to the nonFastScrollableRegion.

The hit test resulting point that the tryScroll() method gets is in content
space, since it is the result of mapping via the inverse screenSpaceTransform.
However, the nonFastScrollableRegion is in layer space, so it should not compare
the point against the region directly. We add a conversion from content to layer
space before doing the test.

This is now covered by the following tests. Because the layer is given a
contentsScale, the tests fail without the above change made to tryScroll.

Tests:
cc_unittests:LayerTreeHostImplTest.nonFastScrollableRegionBasic
cc_unittests:LayerTreeHostImplTest.nonFastScrollableRegionWithOffset

R=enne
BUG=159676
Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=166353

[enne (OOO), 2012-11-06 23:18:58]

https://codereview.chromium.org/11377006/diff/1/cc/layer_impl.cc
File cc/layer_impl.cc (right):

https://codereview.chromium.org/11377006/diff/1/cc/layer_impl.cc#newcode220
cc/layer_impl.cc:220: if (!clipped &&
nonFastScrollableRegion().Contains(gfx::ToFlooredPoint(hitTestPointInLayerSpace)))
{
Can you convince me about the use of ToFlooredPoint here?

What if the contents scale of a layer is < 1, do we need to do
Contains(gfx::Rect)?

[danakj, 2012-11-06 23:21:57]

https://codereview.chromium.org/11377006/diff/1/cc/layer_impl.cc
File cc/layer_impl.cc (right):

https://codereview.chromium.org/11377006/diff/1/cc/layer_impl.cc#newcode220
cc/layer_impl.cc:220: if (!clipped &&
nonFastScrollableRegion().Contains(gfx::ToFlooredPoint(hitTestPointInLayerSpace)))
{
On 2012/11/06 23:18:58, enne wrote:
> Can you convince me about the use of ToFlooredPoint here?

I think I did ToFloored because I wanted no behaviour changes in the gfx::
conversion.

I believe ToRoundedPoint would be better, we want to be as close to their
pointer/finger as possible.

> What if the contents scale of a layer is < 1, do we need to do
> Contains(gfx::Rect)?

I don't think so. We want to know if it contains the center of the rect, still,
I believe. Just cuz the scale is < 1, doesn't mean we want to make the
pointer/touch point larger.

[danakj, 2012-11-06 23:22:27]

https://codereview.chromium.org/11377006/diff/1/cc/layer_impl.cc
File cc/layer_impl.cc (right):

https://codereview.chromium.org/11377006/diff/1/cc/layer_impl.cc#newcode220
cc/layer_impl.cc:220: if (!clipped &&
nonFastScrollableRegion().Contains(gfx::ToFlooredPoint(hitTestPointInLayerSpace)))
{
On 2012/11/06 23:21:57, danakj wrote:
> On 2012/11/06 23:18:58, enne wrote:
> > Can you convince me about the use of ToFlooredPoint here?
> 
> I think I did ToFloored because I wanted no behaviour changes in the gfx::
> conversion.
> 
> I believe ToRoundedPoint would be better, we want to be as close to their
> pointer/finger as possible.
> 
> > What if the contents scale of a layer is < 1, do we need to do
> > Contains(gfx::Rect)?
> 
> I don't think so. We want to know if it contains the center of the rect,
still,
> I believe. Just cuz the scale is < 1, doesn't mean we want to make the
> pointer/touch point larger.

Done.

[enne (OOO), 2012-11-06 23:24:52]

lgtm

[commit-bot: I haz the power, 2012-11-07 01:02:06]

CQ is trying da patch. Follow status at
https://chromium-status.appspot.com/cq/danakj@chromium.org/11377006/7001

[commit-bot: I haz the power, 2012-11-07 04:48:26]

Change committed as 166353