<rdar://problem/7647300> Incorrect client rects for blocks the span multiple columns and their descendants
https://bugs.webkit.org/show_bug.cgi?id=34923

Reviewed by Simon Fraser.

WebCore: 

Test: fast/multicol/client-rects.html

In column layout, a different transform applies to different points in
the block and its descendants, depending on their y coordinate within the
block. offsetFromContainer() used to return the offset that applied to
the origin. With this change, it returns the offset that applies to a
given reference point. When mapping a quad from local to absolute
coordinates, the top left of the quad’s bounding box is used as that
reference point.

* editing/SelectionController.cpp:
(WebCore::SelectionController::layout): Pass the caret’s origin as the
reference point to offsetFromContainer().
* rendering/RenderBlock.cpp:
(WebCore::RenderBlock::adjustForColumns): Adds the offset between the
given point and its image under the column paint-time transform to the
given offset. Used by offsetFromContainer() where it had previously used
adjustRectForColumns(), which takes a rect and operates less efficiently.
* rendering/RenderBlock.h:
* rendering/RenderBox.cpp:
(WebCore::RenderBox::mapLocalToContainer): Pass the transformed point as
the reference point to offsetFromContainer().
(WebCore::RenderBox::mapAbsoluteToLocalPoint): Pass a point to
offsetFromContainer().
(WebCore::RenderBox::offsetFromContainer): Use adjustForColumns() instead
of adjustRectForColumns(), and use the reference point to get the right
adjustment for the point of interest, instead of the origin, in case this
box spans multiple columns.
* rendering/RenderBox.h:
* rendering/RenderInline.cpp:
(WebCore::RenderInline::offsetFromContainer): Ditto. Actually apply the
column offset to the computation, which previously this function didn’t
do.
(WebCore::RenderInline::mapLocalToContainer): Pass the transformed point
as the reference point to offsetFromContainer().
(WebCore::RenderInline::mapAbsoluteToLocalPoint): Pass a point to
offsetFromContainer().
* rendering/RenderInline.h:
* rendering/RenderObject.cpp:
(WebCore::RenderObject::mapLocalToContainer): Apply column adjustment,
based on the reference point, to the transform if needed.
(WebCore::RenderObject::localToContainerQuad): Initialize the
TransformState with the top left corner of the quad’s bounding box. It
is later used as the reference point when deciding on which column to
base the calculations.
(WebCore::RenderObject::offsetFromContainer): Adjust for columns.
(WebCore::RenderObject::offsetFromAncestorContainer): Pass the origin
as the reference point to offsetFromContainer().
* rendering/RenderObject.h:
(WebCore::RenderObject::adjustForColumns): Added.
* rendering/RenderTableCell.cpp:
(WebCore::RenderTableCell::offsetFromContainer): Pass the reference
point through.
* rendering/RenderTableCell.h:
* rendering/RenderText.cpp:
(WebCore::RenderText::absoluteRectsForRange): Map (the origin of) each
rect to absolute coordinates individually.
* rendering/RenderThemeMac.mm:
(WebCore::RenderThemeMac::convertToPaintingRect): Pass a point to
offsetFromContainer().

LayoutTests: 

* fast/multicol/client-rects-expected.checksum: Added.
* fast/multicol/client-rects-expected.png: Added.
* fast/multicol/client-rects-expected.txt: Added.
* fast/multicol/client-rects.html: Added.



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@54784 268f45cc-cd09-0410-ab3c-d52691b4dbfc