build: require sassc and drop generated .css files

Instead of requiring sassc to be installed add meson subprojects
which build libsass and sassc (currently both forks of mine, tested
under linux/mingw/msvc) when needed.

This allows us to drop the generated .css files and build scripts from git.

See #1502

gtk/meson.build

@@ -767,16 +767,19 @@ gtk_gresources_xml = configure_file(output: 'gtk.gresources.xml',
                                       '@OUTPUT@'
                                     ])
 
-# Re-build the theme files if sassc is available
+# Build the theme files
 theme_deps = []
 sassc = find_program('sassc', required: false)
-if sassc.found()
-  sassc_opts = [ '-a', '-M', '-t', 'compact' ]
-
-  subdir('theme/Adwaita')
-  subdir('theme/HighContrast')
+if not sassc.found()
+  subproject('sassc')
+  sassc = find_program('sassc', required: true)
 endif
 
+sassc_opts = [ '-a', '-M', '-t', 'compact' ]
+
+subdir('theme/Adwaita')
+subdir('theme/HighContrast')
+
 gtkresources = gnome.compile_resources('gtkresources',
                                        gtk_gresources_xml,
                                        dependencies: theme_deps,

gtk/theme/Adwaita/README

@@ -1,13 +1,10 @@
 Summary
 -------
 
-* Do not edit the CSS directly, edit the source SCSS files
 * To be able to use the latest/adequate version of sass, install sassc
-* The configure script will detect whether or not you have sassc installed;
-  if you do, it will regenerate the CSS every time you modify the SCSS files.
+* meson will regenerate the CSS every time you modify the SCSS files.
 * Note that meson always builds out-of-tree, so the modified css files will
-  appear in your builddir, and you need to copy them back to the srcdir
-  to commit them.
+  appear in your builddir.
 
 How to tweak the theme
 ----------------------

gtk/theme/Adwaita/parse-sass.sh

@@ -1,13 +0,0 @@
-#! /bin/bash
-
-if [ ! "$(which sassc 2> /dev/null)" ]; then
-   echo sassc needs to be installed to generate the css.
-   exit 1
-fi
-
-SASSC_OPT="-M -t compact"
-
-echo Generating the css...
-
-sassc $SASSC_OPT gtk-contained.scss gtk-contained.css
-sassc $SASSC_OPT gtk-contained-dark.scss gtk-contained-dark.css

gtk/theme/HighContrast/parse-sass.sh

@@ -1,13 +0,0 @@
-#! /bin/bash
-
-if [ ! "$(which sassc 2> /dev/null)" ]; then
-   echo sassc needs to be installed to generate the css.
-   exit 1
-fi
-
-SASSC_OPT="-M -t compact"
-
-echo Generating the css...
-
-sassc $SASSC_OPT gtk-contained.scss gtk-contained.css
-sassc $SASSC_OPT gtk-contained-inverse.scss gtk-contained-inverse.css

subprojects/libsass.wrap

@@ -0,0 +1,4 @@
+[wrap-git]
+directory=libsass
+url=https://github.com/lazka/libsass.git
+revision=meson

subprojects/sassc.wrap

@@ -0,0 +1,4 @@
+[wrap-git]
+directory=sassc
+url=https://github.com/lazka/sassc.git
+revision=meson