Re: Rounding problem in pango

[Behdad Esfahbod <behdad cs toronto edu>]

On Wed, 18 Jan 2006, Chia-I Wu wrote:

> Hi,
>
> The next release of freetype will not round the font metrics.
> (http://lists.gnu.org/archive/html/freetype-devel/2005-12/msg00027.html)
>
> As a result, the extents of layout will usually non-integral.  This can cause
> some problems.  For example, consider a layout with a single line which has
> ascent and descent 14.4 and 0 logically, 11 and 0 actually.
>
> When a GtkLabel is created with such a layout, it will have height round(14.4)
> and the layout will be paint at (0, 0).  Then if the glyphs are bitmaps, pango
> draws them with the baseline at round(14.4) and the top 1 pixel is clipped
> out.  I think outline glyphs also suffer from this, perhaps milder.
>
> In this image, comparision of GtkLabel rendering with freetype 2.1.10 (right)
> and cvs (left) is shown:
>
> http://www.olv.idv.tw/~olvaffe/tmp/freetype2/pango.rounding.png

Nice writup, can you cook a patch please?!

--behdad
http://behdad.org/

"Commandment Three says Do Not Kill, Amendment Two says Blood Will Spill"
	-- Dan Bern, "New American Language"