Bug#880407: xterm: font issue with FreeType 2.8; should not use the rounded ascender and descender
On 2017-10-31 16:21:58 -0400, Thomas Dickey wrote:
> On Tue, Oct 31, 2017 at 10:39:28AM +0100, Vincent Lefevre wrote:
> > Package: xterm
> > Version: 330-1
> > Severity: important
>
> wishlist or normal. Don't soapbox, if you want to have a constructive
> discussion.
No, this is really an important bug, with no workaround. This prevents
me from upgrading the FreeType packages and related.
> Following the discussion here, it's not xterm's bug.
>
> https://savannah.nongnu.org/bugs/index.php?52165
The fact is that xterm is based on a FreeType bug. The behavior of
xterm shouldn't have been changed by an upgrade of the library package.
> Lemberg's done this before. In a previous phase of breakage, I added
> this feature, which would let you do a workaround:
>
> scaleHeight (class ScaleHeight)
> Scale line-height values by the resource value, which is
> limited to “0.9” to “1.5”. The default value is “1.0”,
>
> While this resource applies to either bitmap or TrueType fonts,
> its main purpose is to help work around incompatible changes in
> the Xft library's font metrics. Xterm-dev checks the font
> metrics to find what the library claims are the bounding boxes
> for each glyph (character). However, some of Xft's features
> (such as the autohinter) can cause the glyphs to be scaled
> larger than the bounding boxes, and be partly overwritten by
> the next row.
>
> See useClipping for a related resource.
As I've said in
https://savannah.nongnu.org/bugs/index.php?52165
"*scaleHeight: 0.9" allows me to correct the window size, but
the rendering is buggy: the blank line is still there[*] and the
characters are not correctly erased.
[*] I assume that's because
(src->ascent + src->descent) > src->height
--
Vincent Lefèvre <vincent@vinc17.net> - Web: <https://www.vinc17.net/>
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Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)
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