https://bugs.webkit.org/show_bug.cgi?id=44025

Patch by Ariya Hidayat <ariya@sencha.com> on 2010-08-16
Reviewed by Kenneth Rohde Christiansen.

WebCore:

The blur implementation follows the approximation of Gaussian blur
with three successive box blurs, working on the alpha channel only.
(see http://www.w3.org/TR/SVG/filters.html#feGaussianBlur).

* WebCore.pro: Refer to ContexShadow.* files.
* platform/graphics/qt/ContextShadow.cpp: Added.
(WebCore::ContextShadow::ContextShadow):
(WebCore::ContextShadow::clear):
(WebCore::blurHorizontal): Box blurs in horizontal direction, working
on QImage (in-place).
(WebCore::shadowBlur): Main blur function which just calls the
above blurHorizontal function twice, once with transposed image
(equivalent as it would have done vertical box blurs).
(WebCore::ContextShadow::drawShadowRect):
* platform/graphics/qt/ContextShadow.h: Added.
(WebCore::ContextShadow::):
* platform/graphics/qt/GraphicsContextQt.cpp:
(WebCore::GraphicsContextPlatformPrivate::hasShadow):
(WebCore::GraphicsContext::restorePlatformState):
(WebCore::GraphicsContext::fillRect): Use ContextShadow for the shadow.
(WebCore::GraphicsContext::setPlatformShadow):

LayoutTests:

Update pixel test reference after the blur support.

* platform/qt/fast/box-shadow/basic-shadows-expected.checksum:
* platform/qt/fast/box-shadow/basic-shadows-expected.png:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@65425 268f45cc-cd09-0410-ab3c-d52691b4dbfc