infra: add extra build options for flexible ThorVG composition

this commit introduces an additional build options:

- lottie expressions: this advanced feature in Lottie can
significantly increase binary size. Users now have the option
to enable or disable it based on their requirements.

Note that, this change introduces one config definitions:

- THORVG_LOTTIE_EXPRESSIONS_SUPPORT

meson.build

@@ -56,11 +56,6 @@ endif
 
 if all_loaders or get_option('loaders').contains('lottie') == true
     config_h.set10('THORVG_LOTTIE_LOADER_SUPPORT', true)
-    #Experimental feature, enable it manually
-    lottie_expressions = false
-    if lottie_expressions
-        config_h.set10('THORVG_LOTTIE_EXPRESSIONS_SUPPORT', false)
-    endif
 endif
 
 if all_loaders or get_option('loaders').contains('ttf') == true
@@ -124,6 +119,13 @@ if get_option('tools').contains('all') == true
     all_tools = true
 endif
 
+#Extra
+lottie_expressions = (get_option('loaders').contains('all') or get_option('loaders').contains('lottie')) and get_option('extra').contains('lottie_expressions')
+
+if lottie_expressions
+    config_h.set10('THORVG_LOTTIE_EXPRESSIONS_SUPPORT', true)
+endif
+
 #Miscellaneous
 config_h.set10('WIN32_LEAN_AND_MEAN', true)
 
@@ -173,6 +175,7 @@ Summary:
     Tool (Svg2Tvg):             @22@
     Tool (Svg2Png):             @23@
     Tool (Lottie2Gif):          @24@
+    Extra (Lottie Expressions): @25@
 
 '''.format(
         meson.project_version(),
@@ -200,6 +203,7 @@ Summary:
         all_tools or get_option('tools').contains('svg2tvg'),
         all_tools or get_option('tools').contains('svg2png'),
         all_tools or get_option('tools').contains('lottie2gif'),
+        lottie_expressions
     )
 
 message(summary)

meson_options.txt

@@ -57,3 +57,9 @@ option('static',
    type: 'boolean',
    value: false,
    description: 'Force to use static linking modules in thorvg')
+
+option('extra',
+   type: 'array',
+   choices: ['', 'lottie_expressions'],
+   value: ['lottie_expressions'],
+   description: '"Enable support for exceptionally advanced features')