Bug 36532

Summary: [Qt] Use integer pixel metric QFont API to fix rounding errors in text rendering on the Mac
Product: WebKit Reporter: Simon Hausmann <hausmann>
Component: Layout and RenderingAssignee: Simon Hausmann <hausmann>
Status: CLOSED FIXED    
Severity: Normal CC: allan.jensen, commit-queue, jesus, vestbo
Priority: P3 Keywords: Qt
Version: 528+ (Nightly build)   
Hardware: Other   
OS: OS X 10.5   
Bug Depends on: 93263    
Bug Blocks: 35784    
Attachments:
Description Flags
Turns off fractional metrics for fonts used in WebKit, since WebKit expects font engine to be integer-based
none
Patch
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Patch none

Simon Hausmann
Reported 2010-03-24 06:55:47 PDT
On Qt/Mac font metrics do have fractions. WebKit's text layouting is integer based, therefore visual rounding issues appear when using QtWebKit with Qt/Mac. Eskil is adding new API to Qt 4.7 to disable fractions in pixel metrics. We should use this API. Patch is coming soon.
Attachments
Turns off fractional metrics for fonts used in WebKit, since WebKit expects font engine to be integer-based (1.14 KB, patch)
2010-03-25 02:42 PDT, Eskil 		no flags
DetailsFormatted DiffDiff
Patch (1.70 KB, patch)
2010-04-13 07:54 PDT, Jesus Sanchez-Palencia 		no flags
DetailsFormatted DiffDiff
Patch (1.67 KB, patch)
2010-04-13 08:00 PDT, Jesus Sanchez-Palencia 		no flags
DetailsFormatted DiffDiff
Show Obsolete (2) View All Add attachment proposed patch, testcase, etc.
Eskil
Comment 1 2010-03-25 02:42:24 PDT
Created attachment 51612 [details] Turns off fractional metrics for fonts used in WebKit, since WebKit expects font engine to be integer-based Compiles against Qt 4.7 as soon as the Oslo2 staging branch integrates.
Tor Arne Vestbø
Comment 2 2010-03-29 09:27:49 PDT
I'll land this when the required changes in Qt have been integrated from oslo-staging-2
Jesus Sanchez-Palencia
Comment 3 2010-04-07 06:07:05 PDT
I think that oslo-staging-2 was integrated recently. Has this been landed yet?
Jesus Sanchez-Palencia
Comment 4 2010-04-13 07:54:40 PDT
Created attachment 53250 [details] Patch
Jesus Sanchez-Palencia
Comment 5 2010-04-13 08:00:16 PDT
Created attachment 53251 [details] Patch
WebKit Commit Bot
Comment 6 2010-04-13 08:21:45 PDT
Comment on attachment 53251 [details] Patch Clearing flags on attachment: 53251 Committed r57516: <http://trac.webkit.org/changeset/57516>
WebKit Commit Bot
Comment 7 2010-04-13 08:21:51 PDT
All reviewed patches have been landed. Closing bug.
Simon Hausmann
Comment 8 2010-04-20 13:03:42 PDT
Revision r57516 cherry-picked into qtwebkit-2.0 with commit 692f59b5496489f88a49b4af6749b9b45df090ab
Allan Sandfeld Jensen
Comment 9 2013-03-12 06:21:07 PDT
I am not sure this hack is necesary. While WebKit still uses integer coordinates for layout (until we enable SUBPIXEL_LAYOUT). Text is not layed out using integers, but using floats. Or maybe the bug is that advances are being rounded when they shouldn't be?
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