[gtk: 4/6] meson: Use feature options for media and print backends

[Matthias Clasen <matthiasc src gnome org>]

commit a4aa6d79addfcc5f6b61a9aecd2b3a647e249622
Author: Xavier Claessens <xavier claessens collabora com>
Date:   Sat Oct 17 09:50:40 2020 -0400

    meson: Use feature options for media and print backends
    
    This gracefully disable ffmpeg, gstreamer, cups and cloudprint optional
    dependencies when they are not available, while still giving full
    control to distributors using -Dauto_features=enabled.

 meson_options.txt                 | 26 +++++++++----
 modules/media/meson.build         | 59 +++++++++++++---------------
 modules/printbackends/meson.build | 81 ++++++++++++---------------------------
 3 files changed, 69 insertions(+), 97 deletions(-)
---
diff --git a/meson_options.txt b/meson_options.txt
index ac50721ff8..24a61511d7 100644
--- a/meson_options.txt
+++ b/meson_options.txt
@@ -27,17 +27,27 @@ option('macos-backend',
 
 # Media backends
 
-option('media',
-       type: 'string',
-       value: 'gstreamer',
-       description : 'Build the specified media engines (comma-separated list, "all", or "none")')
+option('media-ffmpeg',
+       type: 'feature',
+       value: 'auto',
+       description : 'Build the ffmpeg media backend')
+
+option('media-gstreamer',
+       type: 'feature',
+       value: 'auto',
+       description : 'Build the gstreamer media backend')
 
 # Print backends
 
-option('print',
-       type: 'string',
-       value: 'cups,file',
-       description : 'Build the specified print backends (comma-separated list, "all", or "none")')
+option('print-cups',
+       type: 'feature',
+       value: 'auto',
+       description : 'Build the cups print backend')
+
+option('print-cloudprint',
+       type: 'feature',
+       value: 'auto',
+       description : 'Build the cloudprint print backend')
 
 # Optional features
 
diff --git a/modules/media/meson.build b/modules/media/meson.build
index 59124d3154..79df9c7769 100644
--- a/modules/media/meson.build
+++ b/modules/media/meson.build
@@ -1,27 +1,6 @@
-all_media_backends = [
-  'ffmpeg',
-  'gstreamer'
-]
-
-enabled_media_backends = get_option('media').split(',')
-
-if enabled_media_backends.contains('none')
-  media_backends = []
-elif enabled_media_backends.contains('all')
-  media_backends = all_media_backends
-else
-  media_backends = []
-  foreach b: enabled_media_backends
-    if all_media_backends.contains(b)
-      media_backends += b
-    else
-      error('No media backend named "@0@" exists.'.format (b))
-    endif
-  endforeach
-endif
-
 media_subdir = 'gtk-4.0/@0@/media'.format(gtk_binary_version)
 media_install_dir = join_paths(get_option('libdir'), media_subdir)
+media_backends = []
 
 extra_c_args = [
   '-DGTK_COMPILATION',
@@ -30,15 +9,28 @@ extra_c_args = [
 
 extra_c_args += common_cflags
 
-if media_backends.contains('ffmpeg')
-  libavfilter_dep = dependency('libavfilter', version: '>= 6.47.100', required: true)
-  libavformat_dep = dependency('libavformat', version: '>= 57.41.100', required: true)
-  libavcodec_dep = dependency('libavcodec', version: '>= 57.48.101', required: true)
-  libavutil_dep = dependency('libavutil', version: '>= 55.28.100', required: true)
-  libswscale_dep = dependency('libswscale', version: '>= 4.6.100', required: true)
-  ffmpeg_deps = [libavfilter_dep, libavformat_dep, libavcodec_dep, libavutil_dep, libswscale_dep]
+ffmpeg_opt = get_option('media-ffmpeg')
+ffmpeg_versions = {
+  'libavfilter': '>= 6.47.100',
+  'libavformat': '>= 57.41.100',
+  'libavcodec': '>= 57.48.101',
+  'libavutil': '>= 55.28.100',
+  'libswscale': '>= 4.6.100',
+}
+ffmpeg_deps = []
+ffmpeg_found = true
+foreach name, version : ffmpeg_versions
+  dep = dependency(name, version: version, required: ffmpeg_opt)
+  ffmpeg_deps += dep
+  if not dep.found()
+    ffmpeg_found = false
+    break
+  endif
+endforeach
+
+if ffmpeg_found
+  media_backends += 'ffmpeg'
   cdata.set('HAVE_FFMPEG', 1)
-
   shared_module('media-ffmpeg',
                 'gtkffmediafile.c',
                 c_args: extra_c_args,
@@ -47,10 +39,11 @@ if media_backends.contains('ffmpeg')
                 install : true)
 endif
 
-if media_backends.contains('gstreamer')
-  gstplayer_dep = dependency('gstreamer-player-1.0', version: '>= 1.12.3', required: true)
+gstplayer_dep = dependency('gstreamer-player-1.0', version: '>= 1.12.3',
+                           required: get_option('media-gstreamer'))
+if gstplayer_dep.found()
+  media_backends += 'gstreamer'
   cdata.set('HAVE_GSTREAMER', 1)
-
   shared_module('media-gstreamer',
                 'gtkgstmediafile.c',
                 'gtkgstpaintable.c',
diff --git a/modules/printbackends/meson.build b/modules/printbackends/meson.build
index 1cde173493..b60fdb202f 100644
--- a/modules/printbackends/meson.build
+++ b/modules/printbackends/meson.build
@@ -1,35 +1,4 @@
-all_print_backends = [
-  'cups',
-  'cloudprint',
-]
-
-enabled_print_backends = get_option('print').split(',')
-
-if enabled_print_backends.contains('none')
-  enabled_print_backends = []
-elif enabled_print_backends.contains('all')
-  enabled_print_backends = all_print_backends
-endif
-
-# The 'file' print backend cannot be disabled
-print_backends = ['file']
-
-# Checks to see if we should compile with CUPS backend for GTK
-enable_cups = enabled_print_backends.contains('cups')
-if enable_cups
-  cups_dep = dependency('cups', version : '>=2.0', required: true)
-  print_backends += ['cups']
-endif
-
-# Checks to see if we should compile with cloudprint backend for GTK
-enable_cloudprint = enabled_print_backends.contains('cloudprint')
-if enable_cloudprint
-  rest_dep = dependency('rest-0.7', required : true)
-  json_glib_dep = dependency('json-glib-1.0', required : true)
-  if rest_dep.found() and json_glib_dep.found()
-    print_backends += ['cloudprint']
-  endif
-endif
+print_backends = []
 
 if not cc.has_header('cairo-pdf.h', dependencies : cairo_dep)
   error('Cannot find cairo-pdf.h. You must build Cairo with the pdf backend enabled.')
@@ -44,11 +13,6 @@ if os_unix
   endif
 endif
 
-# Automatic fall-back to the lpr backend
-if not print_backends.contains('cups')
-  print_backends += ['lpr']
-endif
-
 printbackends_subdir = 'gtk-4.0/@0@/printbackends'.format(gtk_binary_version)
 printbackends_install_dir = join_paths(get_option('libdir'), printbackends_subdir)
 
@@ -61,7 +25,9 @@ printbackends_args = [
   '-D_GLIB_EXTERN=@0@'.format(visibility_define),
 ] + common_cflags
 
-if print_backends.contains('cups')
+cups_dep = dependency('cups', version : '>=2.0', required: get_option('print-cups'))
+if cups_dep.found()
+  print_backends += 'cups'
   shared_module('printbackend-cups',
                 'gtkprintbackendcups.c',
                 'gtkprintercups.c',
@@ -71,9 +37,21 @@ if print_backends.contains('cups')
                 dependencies: [libgtk_dep, cups_dep, colord_dep],
                 install_dir: printbackends_install_dir,
                 install : true)
+else
+  # Automatic fall-back to the lpr backend
+  print_backends += 'lpr'
+  shared_module('printbackend-lpr',
+                'gtkprintbackendlpr.c',
+                c_args: printbackends_args,
+                dependencies: libgtk_dep,
+                install_dir: printbackends_install_dir,
+                install : true)
 endif
 
-if print_backends.contains('cloudprint')
+rest_dep = dependency('rest-0.7', required : get_option('print-cloudprint'))
+json_glib_dep = dependency('json-glib-1.0', required : get_option('print-cloudprint'))
+if rest_dep.found() and json_glib_dep.found()
+  print_backends += ['cloudprint']
   shared_module('printbackend-cloudprint',
                 'gtkprintbackendcloudprint.c',
                 'gtkprintercloudprint.c',
@@ -84,20 +62,11 @@ if print_backends.contains('cloudprint')
                 install : true)
 endif
 
-if print_backends.contains('file')
-  shared_module('printbackend-file',
-                'gtkprintbackendfile.c',
-                c_args: printbackends_args,
-                dependencies: libgtk_dep,
-                install_dir: printbackends_install_dir,
-                install : true)
-endif
-
-if print_backends.contains('lpr')
-  shared_module('printbackend-lpr',
-                'gtkprintbackendlpr.c',
-                c_args: printbackends_args,
-                dependencies: libgtk_dep,
-                install_dir: printbackends_install_dir,
-                install : true)
-endif
+# The 'file' print backend cannot be disabled
+print_backends += 'file'
+shared_module('printbackend-file',
+              'gtkprintbackendfile.c',
+              c_args: printbackends_args,
+              dependencies: libgtk_dep,
+              install_dir: printbackends_install_dir,
+              install : true)