win32: add Media Control support

Add support for SystemMediaTransportControls interface. This allows to
control mpv from Windows media control ui.

meson.build

@@ -8,6 +8,8 @@ project('mpv',
             'buildtype=debugoptimized',
             'b_lundef=false',
             'c_std=c11',
+            'cpp_std=c++20',
+            'cpp_eh=default',
             'warning_level=2',
         ]
 )
@@ -383,7 +385,7 @@ if get_option('fuzzers')
     link_flags += ['-fsanitize=address,undefined,fuzzer', '-fno-omit-frame-pointer']
 endif
 
-add_project_arguments(flags, language: 'c')
+add_project_arguments(flags, language: ['c', 'cpp', 'objc'])
 add_project_arguments(['-Wno-unused-parameter'], language: 'objc')
 add_project_link_arguments(link_flags, language: ['c', 'cpp', 'objc'])
 
@@ -524,6 +526,10 @@ if not posix and not features['win32-desktop']
                      'osdep/terminal-dummy.c')
 endif
 
+if win32
+    subdir('osdep/win32')
+endif
+
 features += {'glob-posix': cc.has_function('glob', prefix: '#include <glob.h>')}
 
 features += {'glob-win32': win32 and not features['glob-posix']}

meson_options.txt

@@ -114,6 +114,9 @@ option('macos-touchbar', type: 'feature', value: 'auto', description: 'macOS Tou
 option('swift-build', type: 'feature', value: 'auto', description: 'macOS Swift build tools')
 option('swift-flags', type: 'string', description: 'Optional Swift compiler flags')
 
+# Windows features
+option('win32-smtc', type: 'feature', value: 'auto', description: 'Enable Media Control support')
+
 # manpages
 option('html-build', type: 'feature', value: 'disabled', description: 'HTML manual generation')
 option('manpage-build', type: 'feature', value: 'auto', description: 'manpage generation')

osdep/win32/meson.build

@@ -0,0 +1,9 @@
+add_languages('cpp')
+cpp = meson.get_compiler('cpp')
+
+smtc = cpp.has_header('winrt/base.h', required: get_option('win32-smtc'))
+features += {'smtc': smtc}
+if features['smtc']
+    dependencies += cpp.find_library('runtimeobject')
+    sources += meson.current_source_dir() / 'smtc.cc'
+endif