Bug 36532 - [Qt] Use integer pixel metric QFont API to fix rounding errors in text rendering on the Mac
Summary: [Qt] Use integer pixel metric QFont API to fix rounding errors in text render...
Status: CLOSED FIXED
Alias: None
Product: WebKit
Classification: Unclassified
Component: Layout and Rendering (show other bugs)
Version: 528+ (Nightly build)
Hardware: Other OS X 10.5
: P3 Normal
Assignee: Simon Hausmann
URL:
Keywords: Qt
Depends on: 93263
Blocks: 35784
  Show dependency tree / graph
 
Reported: 2010-03-24 06:55 PDT by Simon Hausmann
Modified: 2013-03-12 06:21 PDT (History)
4 users (show)

See Also:

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 Details | Formatted Diff | Diff
Patch (1.70 KB, patch)
2010-04-13 07:54 PDT, Jesus Sanchez-Palencia 		no flags Details | Formatted Diff | Diff
Patch (1.67 KB, patch)
2010-04-13 08:00 PDT, Jesus Sanchez-Palencia 		no flags Details | Formatted Diff | Diff
Show Obsolete (2) View All Add an attachment (proposed patch, testcase, etc.)

Note You need to log in before you can comment on or make changes to this bug.
Description Simon Hausmann 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.
Comment 1 Eskil 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.
Comment 2 Tor Arne Vestbø 2010-03-29 09:27:49 PDT 
I'll land this when the required changes in Qt have been integrated from oslo-staging-2
Comment 3 Jesus Sanchez-Palencia 2010-04-07 06:07:05 PDT 
I think that oslo-staging-2 was integrated recently.
Has this been landed yet?
Comment 4 Jesus Sanchez-Palencia 2010-04-13 07:54:40 PDT 
Created attachment 53250 [details]
Patch
Comment 5 Jesus Sanchez-Palencia 2010-04-13 08:00:16 PDT 
Created attachment 53251 [details]
Patch
Comment 6 WebKit Commit Bot 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>
Comment 7 WebKit Commit Bot 2010-04-13 08:21:51 PDT 
All reviewed patches have been landed.  Closing bug.
Comment 8 Simon Hausmann 2010-04-20 13:03:42 PDT 
Revision r57516 cherry-picked into qtwebkit-2.0 with commit 692f59b5496489f88a49b4af6749b9b45df090ab
Comment 9 Allan Sandfeld Jensen 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?