build: Add Meson build system

Meson is a meta build system that is:

  - fast
  - simpler to understand and use
  - portable to multiple platforms through different backends
  - well integrated with the GNOME platform
  - well maintained

Using Meson allows us to build Pango much more quickly, and on all the
platforms we currently target, without any loss of functionality,
compared to Autotools.

Some timing comparisons with hot ccache for both build systems:

  * autogen.sh:                         * meson
    real	0m11.149s                 real          0m2.525s
    user	0m8.153s                  user	        0m1.609s
    sys	        0m2.363s                  sys	        0m1.206s
  * make -j$(($(nproc) + 2))            * ninja
    real	0m9.186s                  real	        0m3.387s
    user	0m16.295s                 user	        0m6.887s
    sys	        0m5.337s                  sys	        0m1.318s
  --------------------------------------------------------------
  * autotools                           * meson + ninja
    real	0m27.669s                 real	        0m5.772s
    user	0m45.622s                 user	        0m8.465s
    sys	        0m10.698s                 sys	        0m2.357s

System: Intel Core i7-7500U, SSD, 16GB of RAM

docs/meson.build

@@ -0,0 +1,108 @@
+subdir('xml')
+
+version_xml_conf = configuration_data()
+version_xml_conf.set('PANGO_VERSION', meson.project_version())
+configure_file(input: 'version.xml.in',
+               output: 'version.xml',
+               configuration: version_xml_conf)
+
+private_headers = [
+  'ftglue.h',
+  'modules.h',
+  'pangoatsui-private.h',
+  'pangocairo-private.h',
+  'pangocairo-fc.h',
+  'pangocairo-win32.h',
+  'pangocairo-atsui.h',
+  'pango-color-table.h',
+  'pango-engine-private.h',
+  'pango-impl-utils.h',
+  'pango-glyph-item-private.h',
+  'pango-layout-private.h',
+  'pango-script-table.h',
+  'pango-script-private.h',
+  'pangofc-private.h',
+  'pangoft2-private.h',
+  'pangowin32-private.h',
+  'pangoatsui-private.h',
+  'pangox-private.h',
+  'pangoxft-private.h',
+  'pango-ot-private.h',
+  'pango-script-lang-table.h',
+  'pango-language-sample-table.h',
+  'pangocoretext-private.h',
+  'pangoatsui-private.h',
+  'mini-fribidi',
+]
+
+if not host_system.contains('darwin')
+  private_headers += [
+    'pangocairo-coretextfont.h',
+    'pangocairo-coretext.h',
+    'pangocoretext.h',
+  ]
+endif
+
+if not host_system.contains('windows')
+  private_headers += [
+    'pangocairo-win32.h',
+    'pangowin32.h',
+  ]
+endif
+
+content_files = [
+  'pango_markup.sgml',
+  'version.xml',
+]
+
+html_images = [
+  'layout.gif',
+  'rotated-text.png',
+]
+
+docdeps = [ libpango_dep ]
+
+if freetype_dep.found()
+  docdeps += libpangoft2_dep
+endif
+
+if xft_dep.found()
+  docdeps += libpangoxft_dep
+endif
+
+if cairo_dep.found()
+  docdeps += libpangocairo_dep
+endif
+
+glib_prefix = dependency('glib-2.0').get_pkgconfig_variable('prefix')
+glib_docpath = join_paths(glib_prefix, 'share', 'gtk-doc', 'html')
+cairo_prefix = dependency('cairo').get_pkgconfig_variable('prefix')
+cairo_docpath = join_paths(cairo_prefix, 'share', 'gtk-doc', 'html')
+docpath = join_paths(pango_datadir, 'gtk-doc', 'html')
+
+gnome.gtkdoc('pango',
+             main_xml: 'pango-docs.sgml',
+             src_dir: [
+               join_paths(meson.source_root(), 'pango'),
+               join_paths(meson.build_root(), 'pango'),
+             ],
+             dependencies: docdeps,
+             gobject_typesfile: 'pango.types',
+             scan_args: [
+               '--rebuild-types',
+               '--deprecated-guards=PANGO_DISABLE_DEPRECATED',
+               '--ignore-decorators=_PANGO_EXTERN',
+               '--ignore-headers=' + ' '.join(private_headers),
+             ],
+             mkdb_args: [
+               '--sgml-mode',
+               '--output-format=xml',
+             ],
+             fixxref_args: [
+               '--html-dir=@0@'.format(docpath),
+               '--extra-dir=@0@'.format(join_paths(glib_docpath, 'glib')),
+               '--extra-dir=@0@'.format(join_paths(glib_docpath, 'gobject')),
+               '--extra-dir=@0@'.format(join_paths(cairo_docpath, 'cairo')),
+             ],
+             html_assets: html_images,
+             install: true)

docs/xml/gtkdocentities.ent.in

@@ -0,0 +1,8 @@
+<!ENTITY package "@PACKAGE@">
+<!ENTITY package_bugreport "@PACKAGE_BUGREPORT@">
+<!ENTITY package_name "@PACKAGE_NAME@">
+<!ENTITY package_string "@PACKAGE_STRING@">
+<!ENTITY package_tarname "@PACKAGE_TARNAME@">
+<!ENTITY package_url "@PACKAGE_URL@">
+<!ENTITY package_version "@PACKAGE_VERSION@">
+<!ENTITY package_api_version "@PACKAGE_API_VERSION@">

docs/xml/meson.build

@@ -0,0 +1,10 @@
+ent_conf = configuration_data()
+ent_conf.set('PACKAGE', meson.project_name())
+ent_conf.set('PACKAGE_BUGREPORT', 'https://bugzilla.gnome.org/enter_bug.cgi?product=pango')
+ent_conf.set('PACKAGE_NAME', meson.project_name())
+ent_conf.set('PACKAGE_STRING', meson.project_name())
+ent_conf.set('PACKAGE_TARNAME', '@0@-@1@'.format(meson.project_name(), meson.project_version()))
+ent_conf.set('PACKAGE_URL', 'https://developer.gnome.org/pango/stable')
+ent_conf.set('PACKAGE_VERSION', meson.project_version())
+ent_conf.set('PACKAGE_API_VERSION', pango_api_version)
+configure_file(input: 'gtkdocentities.ent.in', output: 'gtkdocentities.ent', configuration: ent_conf)

examples/meson.build

@@ -0,0 +1,22 @@
+examples = []
+
+if pango_cairo_backends.contains('png')
+  examples += [
+    'cairoshape',
+    'cairosimple',
+    'cairotwisted',
+  ]
+endif
+
+examples_deps = [ libpango_dep, libpangocairo_dep, ]
+
+if pango_font_backends.contains('freetype')
+  examples_deps += libpangoft2_dep
+endif
+
+foreach e: examples
+  executable(e, '@0@.c'.format(e),
+             dependencies: examples_deps + pango_deps,
+             include_directories: root_inc,
+             install: false)
+endforeach