Bug 17997

Summary:

Full Page Zoom: Artifacts in background images on mooseyard.com

Product:

WebKit

Reporter:

Frederik De Bleser <frederik>

Component:

Layout and Rendering

Assignee:

Dave Hyatt <hyatt>

Status:

RESOLVED FIXED

Severity:

Minor

CC:

ddkilzer, hyatt, marc

Priority:

Version:

528+ (Nightly build)

Hardware:

Mac

OS:

OS X 10.5

URL:

http://mooseyard.com/Jens/

Attachments:

Description	Flags
Screenshot of the site showing tearing artefacts	none
This is a workaround patch. Just recording it.	none
Patch	sullivan: review+

Frederik De Bleser

Reported 2008-03-21 17:26:41 PDT

Using the new full page zoom feature in Webkit r31201, zooming twice on the page http://mooseyard.com/Jens/ (command-+ command-+) shows tearing artefacts between repeating background images, manifested as black lines. See the screenshot for details. Note that this happens only at some zoom levels, notably zoomed in twice and five times. Zooming out also results in artefacts.

Attachments
Screenshot of the site showing tearing artefacts (662.95 KB, image/png) 2008-03-21 17:27 PDT, Frederik De Bleser	no flags	Details
This is a workaround patch. Just recording it. (1.27 KB, patch) 2008-03-24 19:41 PDT, Dave Hyatt	no flags	Details Formatted Diff Diff
Patch (2.12 KB, patch) 2008-11-11 11:28 PST, Dave Hyatt	sullivan: review+	Details Formatted Diff Diff
View All Add attachment proposed patch, testcase, etc.

Frederik De Bleser

Comment 1 2008-03-21 17:27:21 PDT

Created attachment 19947 [details] Screenshot of the site showing tearing artefacts

Dave Hyatt

Comment 2 2008-03-21 23:28:09 PDT

*** Bug 18003 has been marked as a duplicate of this bug. ***

Dave Hyatt

Comment 3 2008-03-21 23:28:52 PDT

*** Bug 17999 has been marked as a duplicate of this bug. ***

Dave Hyatt

Comment 4 2008-03-21 23:29:32 PDT

This bug appears to be Leopard-only, and it's an issue with CGContextDrawTiledImage The old Tiger code path (although slower) seems to be correct.

Dave Hyatt

Comment 5 2008-03-21 23:47:10 PDT

I can actually work around this, but it would mean taking the slow code path (and I think it would hurt performance way too much for zoomed pages to do this).

Dave Hyatt

Comment 6 2008-03-24 19:41:37 PDT

Created attachment 20018 [details] This is a workaround patch. Just recording it.

Dave Hyatt

Comment 7 2008-11-11 11:28:48 PST

Created attachment 25047 [details] Patch

John Sullivan

Comment 8 2008-11-11 11:41:56 PST

Comment on attachment 25047 [details] Patch Do you also want to check PLATFORM(MAC) anywhere? I see the existing #ifndef BUILDING_ON_TIGER does not do so, but maybe it should? John

Dave Hyatt

Comment 9 2008-11-11 11:51:56 PST

Fixed in r38309. Good question about PLATFORM(MAC). It depends on what version of CG ends up shipping with the next version of Safari on Windows whether or not the workaround will be needed for Windows.

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