WIP: Webrender graphic backend (GPU-accelerated Emacs)

configure.ac

@@ -399,6 +399,10 @@ otherwise for the first of 'inotify', 'kqueue' or 'gfile' that is usable.])
 OPTION_DEFAULT_OFF([xwidgets],
  [enable use of some gtk widgets in Emacs buffers (requires gtk3)])
 
+OPTION_DEFAULT_OFF([webrender],
+ [enable use of webrender(written in Rust) as GUI backend on
+multiple platforms(Linux, Windows and MacOS) (experimental)])
+
 ## For the times when you want to build Emacs but don't have
 ## a suitable makeinfo, and can live without the manuals.
 dnl https://lists.gnu.org/r/emacs-devel/2008-04/msg01844.html
@@ -2133,6 +2137,11 @@ if test "${HAVE_W32}" = "yes"; then
  with_xft=no
 fi
 
+
+if test "${with_webrender}" = "yes"; then
+ window_system=webrender
+fi
+
 ## $window_system is now set to the window system we will
 ## ultimately use.
 
@@ -2169,6 +2178,9 @@ dnl use the toolkit if we have gtk, or X11R5 or newer.
  w32 )
  term_header=w32term.h
  ;;
+ webrender )
+ term_header=wrterm.h
+ ;;
 esac
 
 if test "$window_system" = none && test "X$with_x" != "Xno"; then
@@ -4946,10 +4958,21 @@ if test "${HAVE_X_WINDOWS}" = "yes" ; then
  fi
  AC_SUBST(FONT_OBJ)
 fi
+
+if test "${window_system}" = "webrender" ; then
+ AC_DEFINE(USE_WEBRENDER, 1,
+ [Define to 1 if you want to use the webrender.])
+
+ EMACS_CHECK_MODULES([FONTCONFIG], [fontconfig >= 2.2.0])
+ test "$HAVE_FONTCONFIG" = "no" && AC_MSG_ERROR(webrender requires libfontconfig)
+
+fi
+
 AC_SUBST(XMENU_OBJ)
 AC_SUBST(XOBJ)
 AC_SUBST(FONT_OBJ)
 
+
 WIDGET_OBJ=
 MOTIF_LIBW=
 if test "${USE_X_TOOLKIT}" != "none" ; then
@@ -5360,6 +5383,7 @@ AS_ECHO([" Does Emacs use -lXpm? ${HAVE_XPM}
  Does Emacs have dynamic modules support? ${HAVE_MODULES}
  Does Emacs support Xwidgets (requires gtk3)? ${HAVE_XWIDGETS}
  Does Emacs have threading support in lisp? ${threads_enabled}
+ Does Emacs use webrender? ${with_webrender}
 "])
 
 if test -n "${EMACSDATA}"; then
@@ -5489,6 +5513,9 @@ case "$window_system" in
  w32)
  CARGO_DEFAULT_FEATURES="${CARGO_DEFAULT_FEATURES}\"window-system-w32\", "
  ;;
+ webrender)
+ CARGO_DEFAULT_FEATURES="${CARGO_DEFAULT_FEATURES}\"window-system-webrender\", "
+ ;;
 esac
 AC_SUBST(CARGO_DEFAULT_FEATURES)
 AC_CONFIG_FILES([rust_src/Cargo.toml])