[cairo] (Grossly) Misplaced glyph(s) at certain font sizes

Peter Clifton pcjc2 at cam.ac.uk
Sat May 3 07:00:18 PDT 2008


I've been playing with Behdad's userfont branch (rebased onto git HEAD),
and encountered what I presumed to be a bug in that code..

I've been able to distill a small test-case, and it turns out that this
happens with the toy text API, without the userfont code. (git HEAD).

A screenshot of the bug, displaying the string "PA" at different sizes,
is here:


Testcase source code:


(And for those interested now, its also attached).

The bug manifests at slightly different font sizes, and depends on what
glyphs are being rendered. The string "OK" didn't manifest it for me,
"PK" did at some of the sizes I tried etc..

The four rendering sizes in the test-case correspond are on the
boundaries of what appears to be a working / non-working "region" for
the string "PA".

My display info:

  dimensions:    1400x1050 pixels (305x228 millimeters)
  resolution:    117x117 dots per inch


Peter Clifton

Electrical Engineering Division,
Engineering Department,
University of Cambridge,
9, JJ Thomson Avenue,

Tel: +44 (0)7729 980173 - (No signal in the lab!)
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