Bug 95776 - REGRESSION(r120832): RenderLayer::clampScrollOffset doesn't properly clamp
Summary: REGRESSION(r120832): RenderLayer::clampScrollOffset doesn't properly clamp
Status: RESOLVED FIXED
Alias: None
Product: WebKit
Classification: Unclassified
Component: Layout and Rendering (show other bugs)
Version: 528+ (Nightly build)
Hardware: All All
: P2 Normal
Assignee: Julien Chaffraix
URL:
Keywords: Regression
Depends on:
Blocks:
 
Reported: 2012-09-04 13:24 PDT by Julien Chaffraix
Modified: 2012-09-04 16:38 PDT (History)
3 users (show)

See Also:

Attachments
Manual test case (1.10 KB, text/html)
2012-09-04 13:24 PDT, Julien Chaffraix 		no flags Details
Proposed fix: Apply the max last to ensure positive offsets. (4.04 KB, patch)
2012-09-04 13:47 PDT, Julien Chaffraix 		no flags Details | Formatted Diff | Diff
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Description Julien Chaffraix 2012-09-04 13:24:58 PDT 
Created attachment 162092 [details]
Manual test case

When refactoring the clamping logic into clampScrollOffset as part of r120832, the different clipping logics were consolidated into the new function. Unfortunately the old code would wrongly clamp the values:

int x = min(max(scrollOffset.width(), 0), maxX);
int y = min(max(scrollOffset.height(), 0), maxY);

Note that because we apply the min last, we cannot guarantee that x and y are positive as nothing prevents maxX / maxY from being negative.

r120832 exposed the bug to RenderLayer::scrollRectToVisible which was doing the proper clamping.
Comment 1 Julien Chaffraix 2012-09-04 13:47:44 PDT 
Created attachment 162097 [details]
Proposed fix: Apply the max last to ensure positive offsets.
Comment 2 WebKit Review Bot 2012-09-04 16:38:37 PDT 
Comment on attachment 162097 [details]
Proposed fix: Apply the max last to ensure positive offsets.

Clearing flags on attachment: 162097

Committed r127520: <http://trac.webkit.org/changeset/127520>
Comment 3 WebKit Review Bot 2012-09-04 16:38:40 PDT 
All reviewed patches have been landed.  Closing bug.