servo: Merge #9781 - Allow user to choose between GL and ES2 (from jd…

…m:refactor_gle); r=glennw

Rebase of #8869. Requires servo/rust-layers#232.

Source-Repo: https://github.com/servo/servo
Source-Revision: f3a871ec3ded9efe5dfc07f8a3a39ddd6fb05856

UltraBlame original commit: a174eef4faed2e8280b7e4b5b896e56f6b270d07

servo/components/util/opts.rs

@@ -1396,6 +1396,18 @@ pub
 use_msaa
 :
 bool
+/
+/
+Which
+rendering
+API
+to
+use
+.
+pub
+render_api
+:
+RenderApi
 }
 fn
 print_usage
@@ -3110,6 +3122,35 @@ Desktop
 Android
 Gonk
 }
+#
+[
+derive
+(
+Clone
+Debug
+Eq
+Deserialize
+PartialEq
+Serialize
+)
+]
+pub
+enum
+RenderApi
+{
+GL
+ES2
+}
+const
+DEFAULT_RENDER_API
+:
+RenderApi
+=
+RenderApi
+:
+:
+GL
+;
 fn
 default_user_agent_string
 (
@@ -3837,6 +3878,9 @@ false
 use_msaa
 :
 false
+render_api
+:
+DEFAULT_RENDER_API
 }
 }
 pub
@@ -4567,6 +4611,31 @@ backend
 "
 )
 ;
+opts
+.
+optopt
+(
+"
+G
+"
+"
+graphics
+"
+"
+Select
+graphics
+backend
+(
+gl
+or
+es2
+)
+"
+"
+gl
+"
+)
+;
 let
 opt_match
 =
@@ -5866,6 +5935,84 @@ z
 )
 ;
 let
+render_api
+=
+match
+opt_match
+.
+opt_str
+(
+"
+G
+"
+)
+{
+Some
+(
+ref
+ga
+)
+if
+ga
+=
+=
+"
+gl
+"
+=
+>
+RenderApi
+:
+:
+GL
+Some
+(
+ref
+ga
+)
+if
+ga
+=
+=
+"
+es2
+"
+=
+>
+RenderApi
+:
+:
+ES2
+None
+=
+>
+DEFAULT_RENDER_API
+_
+=
+>
+args_fail
+(
+&
+format
+!
+(
+"
+error
+:
+graphics
+option
+must
+be
+gl
+or
+es2
+:
+"
+)
+)
+}
+;
+let
 opts
 =
 Opts
@@ -6013,6 +6160,9 @@ opt_present
 S
 "
 )
+render_api
+:
+render_api
 show_debug_borders
 :
 debug_options