Add a request `.fzoom' and a number register `.zoom' to magnify

fonts.

* src/include/font.h (font): Add member variable `zoom'.
Add member functions `set_zoom' and `get_zoom'.
Remove `static' attribute from `scale' member function.

* src/libs/libgroff/font.cpp (font::font): Updated.
(scale_round): New version with three parameters to handle zoom
factor.
(font::scale, font::get_width): Handle zoom factor.
(font::set_zoom, font::get_zoom): New functions.
(font::load): Handle `zoom' while computing `space_width'.

* src/roff/troff/env.h: Declare `env_get_zoom'.
(environment): Add member function `get_zoom'.

* src/roff/troff/env.cpp (environment::get_zoom): New function.
(init_env_requests): Initialize `.zoom' register.

* src/roff/troff/node.cpp (font_info): New member functions
`set_zoom' and `get_zoom'.
(tfont): New member function `get_zoom'.
(env_get_zoom): New function.
(troff_output_file::set_font): Handle zoom factor.
(font_zoom_request): New function.
(init_node_requests): Initialize `fzoom' request.

* docs/groff.texinfo (Changing Fonts), man/groff.man,
man/groff_diff.man, NEWS: Document `fzoom' request and `.zoom'
register.

* src/roff/troff/TODO: Updated.

1 files changed, 36 insertions, 0 deletions

diff --git a/doc/groff.texinfo b/doc/groff.texinfo
index aae17d01..97b53473 100644
--- a/doc/groff.texinfo
+++ b/doc/groff.texinfo
@@ -8703,6 +8703,7 @@ the current environment.
 @endDefreq
 
 @Defreq {ftr, f [@Var{g}]}
+@cindex font translation (@code{ftr})
 @cindex @code{ft} request, and font translations
 @cindex @code{ul} request, and font translations
 @cindex @code{bd} request, and font translations
@@ -8725,6 +8726,41 @@ font@tie{}@var{g} is used.  If @var{g} is missing or equal to@tie{}@var{f}
 the translation is undone.
 @endDefreq
 
+@DefreqList {fzoom, f [@Var{zoom}]}
+@DefregListEnd {.zoom}
+@cindex magnification of a font (@code{fzoom})
+@cindex font, magnification (@code{fzoom})
+@cindex zoom factor of a font (@code{fzoom})
+@cindex factor, zoom, of a font (@code{fzoom})
+@cindex font, zoom factor (@code{fzoom})
+@cindex optical size of a font
+@cindex font, optical size
+@cindex size, optical, of a font
+Set magnification of font@tie{}@var{f} to factor @var{zoom}, which must be a
+non-negative integer multiple of 1/1000th.  This request is useful to adjust
+the optical size of a font in relation to the others.  In the example below,
+font @code{CR} is magnified by 10% (the zoom factor is thus 1.1).
+
+@Example
+.fam P
+.fzoom CR 1100
+.ps 12
+Palatino and \f[CR]Courier\f[]
+@endExample
+
+A missing or zero value of @var{zoom} is the same as a value of 1000, which
+means no magnification.  @var{f}@tie{}must be a real font name, not a style.
+
+Note that the magnification of a font is completely transparent to troff; a
+change of the zoom factor doesn't cause any effect except that the
+dimensions of glyphs, (word) spaces, kerns, etc., of the affected font are
+adjusted accordingly.
+
+The zoom factor of the current font is available in the read-only number
+register @samp{.zoom}, in multiples of 1/1000th.  It returns zero if there
+is no magnification.
+@endDefreq
+
 @c ---------------------------------------------------------------------
 
 @node Font Families, Font Positions, Changing Fonts, Fonts and Symbols