Subject: 26.1; Effective font height is different from set value

From: Carlos Piat <[email-masked]>
Date: Mon, 04 Jun 2018 00:13:12 -0300

I'm setting the Hack Mono font for the default face with size 110:

  (set-face-attribute 'default nil :font "Hack" :height 110)

but I noticed that the result is slightly different from what
gnome-terminal renders for "Hack 11". Namely, in emacs the font looks
bigger. So I checked the attribute value in the customize-face
screen for the default face, which showed a height of 113.

Playing a bit with different heights I realized that the number I set is
never exactly the setting that ends up being effective, as if a rounding
error or something was happening somewhere.

Even if I set the font as "Hack 10" or set it from the standard dialog
that is available in the menu bar the result is the same.

Some relevant libraries in my system are:

  local/freetype2 2.9.1-1
    Font rasterization library
    
  local/libxft 2.3.2-1
    FreeType-based font drawing library for X

In GNU Emacs 26.1 (build 1, x86_64-pc-linux-gnu, GTK+ Version 3.22.30)
 of 2018-05-29 built on juergen
Windowing system distributor 'The X.Org Foundation', version 11.0.11906000
System Description:	Manjaro Linux

Recent messages:
nil
Creating customization items...
Creating customization items ...done
Resetting customization items...done
Creating customization setup...done
nil
Entering debugger...
previous-line: Beginning of buffer
nil
Auto-saving...

Configured using:
 'configure --prefix=/usr --sysconfdir=/etc --libexecdir=/usr/lib
 --localstatedir=/var --with-x-toolkit=gtk3 --with-xft --with-modules
 'CFLAGS=-march=x86-64 -mtune=generic -O2 -pipe -fstack-protector-strong
 -fno-plt' CPPFLAGS=-D_FORTIFY_SOURCE=2
 LDFLAGS=-Wl,-O1,--sort-common,--as-needed,-z,relro,-z,now'

Configured features:
XPM JPEG TIFF GIF PNG RSVG IMAGEMAGICK SOUND GPM DBUS GSETTINGS NOTIFY
ACL GNUTLS LIBXML2 FREETYPE M17N_FLT LIBOTF XFT ZLIB TOOLKIT_SCROLL_BARS
GTK3 X11 MODULES THREADS LIBSYSTEMD LCMS2

Important settings:
  value of $LC_MONETARY: en_US.UTF-8
  value of $LC_NUMERIC: en_US.UTF-8
  value of $LC_TIME: en_US.UTF-8
  value of $LANG: en_US.UTF-8
  locale-coding-system: utf-8-unix

Major mode: Emacs-Lisp

Minor modes in effect:
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  pyvenv-mode: t
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  tooltip-mode: t
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  eldoc-mode: t
  electric-indent-mode: t
  mouse-wheel-mode: t
  file-name-shadow-mode: t
  global-font-lock-mode: t
  font-lock-mode: t
  blink-cursor-mode: t
  auto-composition-mode: t
  auto-encryption-mode: t
  auto-compression-mode: t
  line-number-mode: t
  transient-mark-mode: t

Load-path shadows:
None found.

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esh-module esh-mode esh-util elpy-profile elpy-django s elpy-refactor
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ucs-normalize shell pcomplete parse-time format-spec advice json map ido
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