support for special "help" value for both "encoding" and "encodings" …

…command line options

git-svn-id: https://xpra.org/svn/Xpra/trunk@12147 3bb7dfac-3a0b-4e04-842a-767bc560f471

src/xpra/scripts/main.py

@@ -1426,14 +1426,17 @@ def connect():
         except RuntimeError as e:
             #exceptions at this point are still initialization exceptions
             raise InitException(e.message)
+        ehelp = "help" in opts.encodings
+        if ehelp:
+            from xpra.codecs.loader import PREFERED_ENCODING_ORDER
+            opts.encodings = PREFERED_ENCODING_ORDER
         app.init(opts)
-        if opts.encoding:
-            #fix old encoding names if needed:
-            err = opts.encoding not in app.get_encodings()
+        if opts.encoding or ehelp:
+            err = opts.encoding and (opts.encoding not in app.get_encodings())
             info = ""
             if err and opts.encoding!="help":
                 info = "invalid encoding: %s\n" % opts.encoding
-            if opts.encoding=="help" or err:
+            if opts.encoding=="help" or ehelp or err:
                 from xpra.codecs.loader import encodings_help
                 raise InitInfo(info+"%s xpra client supports the following encodings:\n * %s" % (app.client_toolkit(), "\n * ".join(encodings_help(app.get_encodings()))))
         def handshake_complete(*args):

src/xpra/scripts/server.py

@@ -881,7 +881,7 @@ def run_server(error_cb, opts, mode, xpra_file, extra_args, desktop_display=None
     if opts.password_file and not (opts.auth or opts.tcp_auth):
         raise InitException("when specifying a password-file, you must use auth or tcp-auth")
     validate_encryption(opts)
-    if opts.encoding and opts.encoding=="help":
+    if opts.encoding=="help" or "help" in opts.encodings:
         #avoid errors and warnings:
         opts.encoding = ""
         opts.clipboard = False
@@ -898,13 +898,14 @@ def run_server(error_cb, opts, mode, xpra_file, extra_args, desktop_display=None
         from xpra.server.server_base import ServerBase
         sb = ServerBase()
         sb.init_options(opts)
-        #ensures that the threaded video helper init has completed
-        #(by running it again, which will block on the init lock)
+        from xpra.codecs.loader import PREFERED_ENCODING_ORDER, HELP_ORDER
+        if "help" in opts.encodings:
+            sb.allowed_encodings = PREFERED_ENCODING_ORDER
         from xpra.codecs.video_helper import getVideoHelper
         getVideoHelper().init()
         sb.init_encodings()
         from xpra.codecs.loader import encoding_help
-        for e in sb.encodings:
+        for e in (x for x in HELP_ORDER if x in sb.encodings):
             print(" * %s" % encoding_help(e))
         return 0