Support X core font driver on cairo (Bug#28236)

* configure.ac (HAVE_X_WINDOWS): Add xfont.o to FONT_OBJ if HAVE_CAIRO.

* doc/lispref/frames.texi (Font and Color Parameters): Mention X core font
driver with Cairo drawing.

* src/font.c (syms_of_font) [HAVE_X_WINDOWS && USE_CAIRO]: Call syms_of_xfont.

* src/xfns.c (x_create_tip_frame) [USE_CAIRO]: Register xfont_driver.

* src/xterm.c (x_cr_gc_clip) [USE_CAIRO]: New function extracted from
x_begin_cr_clip.
(x_begin_cr_clip) [USE_CAIRO]: Use it.
(xlib_surface_key, saved_drawable_key) [USE_CAIRO]: New variables.
(x_cr_destroy_xlib_surface, x_try_cr_xlib_drawable)
(x_end_cr_xlib_drawable) [USE_CAIRO]: New functions.
(x_draw_composite_glyph_string_foreground)
(x_draw_glyph_string_foreground) [USE_CAIRO]: Get Xlib surface when drawing
text with X core fonts into bitmap surfaces.  Add fallback code for drawing
into outline surfaces.

1 files changed, 5 insertions, 5 deletions

diff --git a/doc/lispref/frames.texi b/doc/lispref/frames.texi
index 336075a1ca2..629cec3c5fe 100644
--- a/doc/lispref/frames.texi
+++ b/doc/lispref/frames.texi
@@ -2282,11 +2282,11 @@ drawing characters on the frame, in order of priority.  In Emacs built
 without Cairo drawing on X, there are currently three available font
 backends: @code{x} (the X core font driver), @code{xft} (the Xft font
 driver), and @code{xfthb} (the Xft font driver with HarfBuzz text
-shaping).  If built with the Cairo drawing, there are two available
-font backends on X: @code{ftcr} (the FreeType font driver on Cairo)
-and @code{ftcrhb} (the FreeType font driver on Cairo with HarfBuzz
-text shaping).  On MS-Windows, there are currently three available
-font backends: @code{gdi} (the core MS-Windows font driver),
+shaping).  If built with the Cairo drawing, there are also three
+available font backends on X: @code{x}, @code{ftcr} (the FreeType font
+driver on Cairo), and @code{ftcrhb} (the FreeType font driver on Cairo
+with HarfBuzz text shaping).  On MS-Windows, there are currently three
+available font backends: @code{gdi} (the core MS-Windows font driver),
 @code{uniscribe} (font driver for OTF and TTF fonts with text shaping
 by the Uniscribe engine), and @code{harfbuzz} (font driver for OTF and
 TTF fonts with HarfBuzz text shaping) (@pxref{Windows Fonts,,, emacs,