[webkit-reviews] review requested: [Bug 33150] Do not render the full frame when there is some elements with fixed positioning : [Attachment 48001] Repaint only the invalidated area after scrolling

Fri Feb 5 08:16:39 PST 2010

Benjamin Poulain <benjamin.poulain at nokia.com> has asked  for review:
Bug 33150: Do not render the full frame when there is some elements with fixed
positioning
https://bugs.webkit.org/show_bug.cgi?id=33150

Attachment 48001: Repaint only the invalidated area after scrolling
https://bugs.webkit.org/attachment.cgi?id=48001&action=review

------- Additional Comments from Benjamin Poulain <benjamin.poulain at nokia.com>
Put back to review, I think the problem is in paintingRootRect(), not in this
patch.

With the following HTML:
"<html>
<body style="height: 5000px;">
 <div style="width: 100px; height: 100px; background-color: green; opacity: .5;
position: fixed; top: 60px; left: 60px;"></div>
 <div style="width: 100px; height: 100px; background-color: green; opacity: .5;
position: fixed; top: 70px; left: 70px; -webkit-transform:
rotate(30deg);"></div>
</body>
</html>"

The rect returned by paintingRootRect() is empty for the second rect (the one
with a transformation).

The behavior for this case is also different between Safari and webkit trunk.
On Safari, the fixed element is not fixed if transformed. On trunk, it is. I
have absolutely no idea which behavior is the correct one.

Anyway, Dave Hyatt, any chance get a review and your opinion on the good
behavior for fixed transformed elements?