--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/libervia/frontends/tools/webrtc_screenshare.py	Sat Apr 06 13:43:09 2024 +0200
@@ -0,0 +1,207 @@
+#!/usr/bin/env python3
+
+# Libervia WebRTC implementation
+# Copyright (C) 2009-2024 Jérôme Poisson (goffi@goffi.org)
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU Affero General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU Affero General Public License for more details.
+
+# You should have received a copy of the GNU Affero General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+from libervia.backend.core import exceptions
+
+import asyncio
+import logging
+from random import randint
+
+
+log = logging.getLogger(__name__)
+
+
+SOURCES_AUTO = "auto"
+SOURCES_TEST = "test"
+SOURCES_DATACHANNEL = "datachannel"
+SINKS_APP = "app"
+SINKS_AUTO = "auto"
+SINKS_TEST = "test"
+SINKS_DATACHANNEL = "datachannel"
+
+
+class ScreenshareError(Exception):
+    pass
+
+
+class DesktopPortal:
+
+    def __init__(self, webrtc):
+        import dbus
+        from dbus.mainloop.glib import DBusGMainLoop
+        # we want monitors + windows, see https://flatpak.github.io/xdg-desktop-portal/docs/doc-org.freedesktop.portal.ScreenCast.html#org-freedesktop-portal-screencast-availablesourcetypes
+        self.dbus = dbus
+        self.webrtc = webrtc
+        self.sources_type = dbus.UInt32(7)
+        DBusGMainLoop(set_as_default=True)
+        self.session_bus = dbus.SessionBus()
+        portal_object = self.session_bus.get_object(
+            'org.freedesktop.portal.Desktop',
+            '/org/freedesktop/portal/desktop'
+        )
+        self.screencast_interface = dbus.Interface(
+            portal_object,
+            'org.freedesktop.portal.ScreenCast'
+        )
+        self.session_interface = None
+        self.session_signal = None
+        self.handle_counter = 0
+        self.session_handle = None
+        self.stream_data: dict|None = None
+
+    @property
+    def handle_token(self):
+        self.handle_counter += 1
+        return f"libervia{self.handle_counter}"
+
+    def on_session_closed(self, details: dict) -> None:
+        if self.session_interface is not None:
+            self.session_interface = None
+            self.webrtc.desktop_sharing = False
+            if self.session_signal is not None:
+                self.session_signal.remove()
+                self.session_signal = None
+
+
+    async def dbus_call(self, method_name: str, *args) -> dict:
+        """Call a screenshare portal method
+
+        This method handle the signal response.
+        @param method_name: method to call
+        @param args: extra args
+            `handle_token` will be automatically added to the last arg (option dict)
+        @return: method result
+        """
+        if self.session_handle is not None:
+            self.end_screenshare()
+        method = getattr(self.screencast_interface, method_name)
+        options = args[-1]
+        reply_fut = asyncio.Future()
+        signal_fut = asyncio.Future()
+        # cf. https://flatpak.github.io/xdg-desktop-portal/docs/doc-org.freedesktop.portal.Request.html
+        handle_token = self.handle_token
+        sender = self.session_bus.get_unique_name().replace(".", "_")[1:]
+        path = f"/org/freedesktop/portal/desktop/request/{sender}/{handle_token}"
+        signal_match = None
+
+        def on_signal(response, results):
+            assert signal_match is not None
+            signal_match.remove()
+            if response == 0:
+                signal_fut.set_result(results)
+            elif response == 1:
+                signal_fut.set_exception(
+                    exceptions.CancelError("Cancelled by user.")
+                )
+            else:
+                signal_fut.set_exception(ScreenshareError(
+                    f"Can't get signal result"
+                ))
+
+        signal_match = self.session_bus.add_signal_receiver(
+            on_signal,
+            signal_name="Response",
+            dbus_interface="org.freedesktop.portal.Request",
+            path=path
+        )
+
+        options["handle_token"] = handle_token
+
+        method(
+            *args,
+            reply_handler=reply_fut.set_result,
+            error_handler=reply_fut.set_exception
+        )
+        try:
+            await reply_fut
+        except Exception as e:
+            raise ScreenshareError(f"Can't ask screenshare permission: {e}")
+        return await signal_fut
+
+    async def request_screenshare(self) -> dict:
+        session_data = await self.dbus_call(
+            "CreateSession",
+            {
+                "session_handle_token": str(randint(1, 2**32)),
+            }
+        )
+        try:
+            session_handle = session_data["session_handle"]
+        except KeyError:
+            raise ScreenshareError("Can't get session handle")
+        self.session_handle = session_handle
+
+
+        await self.dbus_call(
+            "SelectSources",
+            session_handle,
+            {
+                "multiple": True,
+                "types": self.sources_type,
+                "modal": True
+            }
+        )
+        screenshare_data = await self.dbus_call(
+            "Start",
+            session_handle,
+            "",
+            {}
+        )
+
+        session_object = self.session_bus.get_object(
+            'org.freedesktop.portal.Desktop',
+            session_handle
+        )
+        self.session_interface = self.dbus.Interface(
+            session_object,
+            'org.freedesktop.portal.Session'
+        )
+
+        self.session_signal = self.session_bus.add_signal_receiver(
+            self.on_session_closed,
+            signal_name="Closed",
+            dbus_interface="org.freedesktop.portal.Session",
+            path=session_handle
+        )
+
+        try:
+            node_id, stream_data = screenshare_data["streams"][0]
+            source_type = int(stream_data["source_type"])
+        except (IndexError, KeyError):
+            raise ScreenshareError("Can't parse stream data")
+        self.stream_data = stream_data = {
+            "session_handle": session_handle,
+            "node_id": node_id,
+            "source_type": source_type
+        }
+        try:
+            height = int(stream_data["size"][0])
+            weight = int(stream_data["size"][1])
+        except (IndexError, KeyError):
+            pass
+        else:
+            stream_data["size"] = (height, weight)
+
+        return self.stream_data
+
+    def end_screenshare(self) -> None:
+        """Close a running screenshare session, if any."""
+        if self.session_interface is None:
+            return
+        self.session_interface.Close()
+        self.on_session_closed({})