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Provide workaround for xftfont rendering problem

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* src/xftfont.c (syms_of_xftfont) <xft-font-ascent-descent-override>:
New variable.
(xftfont_open): Use it to work around problems with rendering some
fonts.  (Bug#23360)
This commit is contained in:
Eli Zaretskii 2016-05-22 19:20:28 +03:00
parent c9f7ec736b
commit 5ab083034c
1 changed files with 24 additions and 0 deletions
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24
src/xftfont.c
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@ -395,6 +395,24 @@ xftfont_open (struct frame *f, Lisp_Object entity, int pixel_size)
font->ascent = xftfont->ascent;
font->descent = xftfont->descent;
/* The following workaround is unnecessary on most systems, and
causes annoying differences in glyph height between regular and
bold fonts (see bug#22383). However, with some fonts, such as
monaco, removing the workaround results in overlapping vertical
space of a line, see bug#23360. As long as the way to reconcile
these opposites is not known, we provide a user option to work
around the problem. */
if (pixel_size >= 5
&& xft_font_ascent_descent_override)
{
/* The above condition is a dirty workaround because
XftTextExtents8 behaves strangely for some fonts
(e.g. "Dejavu Sans Mono") when pixel_size is less than 5. */
if (font->ascent < extents.y)
font->ascent = extents.y;
if (font->descent < extents.height - extents.y)
font->descent = extents.height - extents.y;
}
font->height = font->ascent + font->descent;
if (XINT (AREF (entity, FONT_SIZE_INDEX)) == 0)
@ -733,6 +751,12 @@ syms_of_xftfont (void)
DEFSYM (QCembolden, ":embolden");
DEFSYM (QClcdfilter, ":lcdfilter");
DEFVAR_BOOL ("xft-font-ascent-descent-override",
xft_font_ascent_descent_override,
doc: /* Non-nil means override the ascent and descent values for Xft font driver.
This is needed with some fonts to correct vertical overlap of glyphs. */);
xft_font_ascent_descent_override = 0;
ascii_printable[0] = 0;
xftfont_driver = ftfont_driver;