Reduce more matrix math in calculateDrawProperties

Reduce more matrix math in calculateDrawProperties

This patch avoids even more math.  cc_perftests on linux desktop improved by about 3-4%.

(0) Skip applying the layer's anchorPoint + transform + inverseAnchorPoint if the layer's transform was identity.

(1) The surface clipRect, projected from ancestor space to current surface
space, is now cached in calcDrawTransforms so it only needs to be computed
once, instead of onces for every layer that contributes to the surface.

(2) The layer's bounds, transformed into target surface space, are passed into
calculateVisibleContentRect, so that this function does not need to redo the
mapClippedRect computation unnecessarily.

(3) The early exit logic was made more aggressive, to early-out as soon as we
realize that none of the layer's drawProperties need to be computed.

BUG=163769
Committed: https://src.chromium.org/viewvc/chrome?view=rev&revision=172475

[shawnsingh, 2012-12-11 10:54:13]

PTAL, thanks!  I still want to test it a bit more but so far it seems to work
fine manually and on cc_unittests

[jamesr, 2012-12-11 19:13:21]

https://codereview.chromium.org/11534006/diff/3001/cc/layer_tree_host_common.cc
File cc/layer_tree_host_common.cc (right):

https://codereview.chromium.org/11534006/diff/3001/cc/layer_tree_host_common....
cc/layer_tree_host_common.cc:43: static inline gfx::Rect
calculateVisibleRectWithCachedLayerRect(const gfx::Rect& targetSurfaceRect,
const gfx::Rect& layerBoundRect, const gfx::Rect& layerRectInTargetSpace, const
gfx::Transform& transform)
i think the 'static' and 'inline' here are redundant - 'inline' implies static
linkage, no?

https://codereview.chromium.org/11534006/diff/3001/cc/layer_tree_host_common....
cc/layer_tree_host_common.cc:146: //gfx::Rect ancestorSurfaceClipRect =
gfx::ToEnclosingRect(MathUtil::projectClippedRect(MathUtil::inverse(layer->renderTarget()->renderSurface()->drawTransform()),
layer->renderTarget()->renderSurface()->clipRect()));
?

[shawnsingh, 2012-12-11 22:33:18]

Thanks for catching those, here's an updated version

https://codereview.chromium.org/11534006/diff/3001/cc/layer_tree_host_common.cc
File cc/layer_tree_host_common.cc (right):

https://codereview.chromium.org/11534006/diff/3001/cc/layer_tree_host_common....
cc/layer_tree_host_common.cc:43: static inline gfx::Rect
calculateVisibleRectWithCachedLayerRect(const gfx::Rect& targetSurfaceRect,
const gfx::Rect& layerBoundRect, const gfx::Rect& layerRectInTargetSpace, const
gfx::Transform& transform)
On 2012/12/11 19:13:21, jamesr wrote:
> i think the 'static' and 'inline' here are redundant - 'inline' implies static
> linkage, no?

Done.

https://codereview.chromium.org/11534006/diff/3001/cc/layer_tree_host_common....
cc/layer_tree_host_common.cc:146: //gfx::Rect ancestorSurfaceClipRect =
gfx::ToEnclosingRect(MathUtil::projectClippedRect(MathUtil::inverse(layer->renderTarget()->renderSurface()->drawTransform()),
layer->renderTarget()->renderSurface()->clipRect()));
On 2012/12/11 19:13:21, jamesr wrote:
> ?

residue from debugging =)   it's removed now

[jamesr, 2012-12-11 22:41:04]

lgtm