tree 9874118d2a2b35e17abc88e53c6dc3bb3ffe7926
parent 7394423a1e1e187918fd8e196fa84eccacc8a0c2
author commit-queue@webkit.org <commit-queue@webkit.org@268f45cc-cd09-0410-ab3c-d52691b4dbfc> 1571104837 +0000
committer commit-queue@webkit.org <commit-queue@webkit.org@268f45cc-cd09-0410-ab3c-d52691b4dbfc> 1571104837 +0000

Outsets for referenced SVG filters are always zero
https://bugs.webkit.org/show_bug.cgi?id=202826

Patch by Said Abou-Hallawa <sabouhallawa@apple.com> on 2019-10-14
Reviewed by Simon Fraser.

Source/WebCore:

Sometimes the filter is applied only to a part of the image, so we need
to enlarge the source rectangle such that the border of the result image
looks like as if the filter were applied to the whole image.

The filter outsets should only be calculated for the blur and the drop
shadow filters. The problem is FilterOperations::outsets() was returning
empty outsets always for the referenced filters.

Since the referenced filters must be software filters, the fix is to rely
on CSSFilter in calculating the filter outsets for software filters.

By adding a virtual function called outset() to the FilterEffect class,
we can loop through the CSSFilter::m_effects asking every FilterEffect
to return its outset(). This function is only overridden by FEDropShadow
and FEGaussianBlur.

This should work because RenderLayer builds the CSSFilter when the styleChanged()
happens through its updateFilterPaintingStrategy(). This will guarantee
that m_filters->filter()->outsets() will return the correct outsets for
the referenced and the non-referenced software filters.

We should keep FilterOperations::outsets() because it has be used for
the hardware non-referenced filters. In that case, RenderLayer does not
build the the filter effects. Therefore m_filters can't be used because
it is null in this case.

For accuracy, hasOutsets() implementation is deleted. Having a blur or
drop shadow filter effect is not enough to say hasOutsets() is true. We
need to calculate the outsets first and then ask if it isZero() or not.

Test: css3/filters/svg-blur-filter-clipped.html

* platform/graphics/IntRectExtent.h:
(WebCore::operator==):
(WebCore::operator+=):
(WebCore::IntRectExtent::expandRect const): Deleted.
IntRectExtent is only used as a filter outsets. So add the definition of
IntOutsets in IntRectExtent.h.

* platform/graphics/filters/FEDropShadow.cpp:
(WebCore::FEDropShadow::outsets const):
* platform/graphics/filters/FEDropShadow.h:
* platform/graphics/filters/FEGaussianBlur.cpp:
(WebCore::FEGaussianBlur::calculateOutsetSize):
(WebCore::FEGaussianBlur::outsets const):
* platform/graphics/filters/FEGaussianBlur.h:
* platform/graphics/filters/FilterEffect.h:
(WebCore::FilterEffect::outsets const):
* platform/graphics/filters/FilterOperations.cpp:
(WebCore::FilterOperations::outsets const):
(WebCore::outsetSizeForBlur): Deleted.
(WebCore::FilterOperations::hasOutsets const): Deleted.
* platform/graphics/filters/FilterOperations.h:
(WebCore::FilterOperations::hasOutsets const):
* platform/graphics/texmap/TextureMapperLayer.cpp:
(WebCore::TextureMapperLayer::computeOverlapRegions):

* rendering/CSSFilter.cpp:
(WebCore::CSSFilter::build):
(WebCore::CSSFilter::computeSourceImageRectForDirtyRect):
(WebCore::CSSFilter::outsets const):
Calculate m_outsets once and cache its value for later uses.

* rendering/CSSFilter.h:
* rendering/RenderLayer.cpp:
(WebCore::RenderLayer::setFilterBackendNeedsRepaintingInRect):
(WebCore::RenderLayer::hasAncestorWithFilterOutsets const):
(WebCore::transparencyClipBox):
(WebCore::RenderLayer::calculateClipRects const):
* rendering/RenderLayer.h:
* rendering/style/RenderStyle.h:
(WebCore::RenderStyle::filterOutsets const):
(WebCore::RenderStyle::hasFilterOutsets const): Deleted.

LayoutTests:

* css3/filters/svg-blur-filter-clipped-expected.html: Added.
* css3/filters/svg-blur-filter-clipped.html: Added.
* platform/ios/TestExpectations:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@251119 268f45cc-cd09-0410-ab3c-d52691b4dbfc