[Webkit-unassigned] [Bug 51892] [Qt] QtTestBrowser renders only part of page when navigating back

[bugzilla-daemon at webkit.org]

https://bugs.webkit.org/show_bug.cgi?id=51892


Aparna Nandyal <aparna.nand at wipro.com> changed:

           What    |Removed                     |Added
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  Attachment #80809|                            |review?
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--- Comment #5 from Aparna Nandyal <aparna.nand at wipro.com>  2011-02-01 12:59:35 PST ---
Created an attachment (id=80809)
 --> (https://bugs.webkit.org/attachment.cgi?id=80809&action=review)
Patch of review

Analysis:
The bug is caused due to erroneous repaint region calculation. Earlier (before http://trac.webkit.org/changeset/73385 to fix https://bugs.webkit.org/show_bug.cgi?id=49220), visibleLayoutOverflow was returned in RenderBox::clippedOverflowRectForRepaint which was a union of layoutOverflow and visualOverflow. The layoutOverflow had the greater rect height as it is intended for scrolling.

If visualOverflow is returned in RenderBox::clippedOverflowRect  the height of the rect is from 0 to unscrolled visible area height.

When user decides to navigate back to a scrolled page in
FrameView::repaintContentRectangle (const IntRect& r, bool immediate)
{
.........

// The value of r is coming from RenderBox::clippedOverflowRect
InrtRect paintRect = r;

// The paintRect is becoming 0 as there is no common area,
// the height of paintRect represents unscrolled height and height in
// visibleContentRect() represents scrolled area height, hence
// painting is not happening
paintRect.intersect(visibleContentRect());

if (paintRect.isEmpty())
return;
...
}


Additional Info:
Bug also reproducible in arora

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