bugThe FreeType Project - Bugs: bug #31824, Too coarse subdivision of a cubic...

 
 

bug #31824: Too coarse subdivision of a cubic bezier curve in the gray rasterizer

Submitted by:  Samuel Rødal <capisce>
Submitted on:  Wed 08 Dec 2010 11:44:49 AM UTC  
 
Severity: 3 - NormalItem Group: Incorrect behaviour
Status: InvalidPrivacy: Public
Assigned to: Werner LEMBERG <wl>Open/Closed: Closed
Planned Release: None

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Wed 08 Dec 2010 12:17:52 PM UTC, comment #1:

I can't repeat this. Compiling the `TestBezier' demo program in the Nokia bug database with FreeType 2.4.4, I get the attached image which definitely isn't a straight line.

The problems you are talking about have been fixed meanwhile. Please test with the last FreeType release and reopen this bug if it still persists.

(file #22159)

Werner LEMBERG <wl>
Project AdministratorIn charge of this item.
Wed 08 Dec 2010 11:44:49 AM UTC, original submission:

These commits changed the logic on how much to subdivide a cubic bezier curve:

7fb3ef64a24489189113f693696eaf935f500c3f
e419f48b40a746465a6c8e1d446b407b8677bfed

We applied these changes downstream in Qt, which caused the following bug, so we chose to revert them: http://bugreports.qt.nokia.com/browse/QTBUG-15660

I guess they should be reverted or fixed in Freetype too.

The relevant cubic bezier has the following coordinates:

QPainterPath path;
path.moveTo(50, 150);
path.cubicTo(80, 150, 200, 40, 230, 40);

The 'level' variable in gray_render_cubic ends up being set to 0, which causes the bezier to be insufficiently approximated by two line segments.

Samuel Rødal <capisce>

 

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Attached Files
file #22159:  TestBezier.png added by wl (6KiB - image/png)

 

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Carbon-Copy List
  • -unavailable- added by wl (Updated the item)
  • -unavailable- added by capisce (Submitted the item)
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    Follow 5 latest changes.

    Date Changed By Updated Field Previous Value => Replaced By
    Wed 08 Dec 2010 12:17:52 PM UTCwlAttached File-=>Added TestBezier.png, #22159
      StatusNone=>Invalid
      Assigned toNone=>wl
      Open/ClosedOpen=>Closed
    Wed 08 Dec 2010 11:44:49 AM UTCcapisceCarbon-Copy-=>Added capisce

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