add Friends.setRichPresence (#12)

* add Friends.setRichPresence
* Improve rich presence and add a small doc
---------
Co-authored-by: Yuxiao Mao <yuxiao.mao@outlook.com>

Author: RollinBarrel

native/friends.cpp

@@ -60,11 +60,20 @@ HL_PRIM void HL_NAME(activate_overlay_store)( int appid, int flag ) {
 	SteamFriends()->ActivateGameOverlayToStore((AppId_t)appid,(EOverlayToStoreFlag)flag);
 }
 
+HL_PRIM bool HL_NAME(set_rich_presence)( vbyte *pchKey, vbyte *pchValue ) {
+	return SteamFriends()->SetRichPresence((char*)pchKey, (char*)pchValue);
+}
+
+HL_PRIM void HL_NAME(clear_rich_presence)() {
+	SteamFriends()->ClearRichPresence();
+}
+
 DEFINE_PRIM(_BYTES, get_user_name, _UID);
 DEFINE_PRIM(_BYTES, get_user_avatar, _UID _I32 _REF(_I32) _REF(_I32));
 DEFINE_PRIM(_BOOL, request_user_information, _UID _BOOL);
 DEFINE_PRIM(_ARR, get_friends, _I32);
 DEFINE_PRIM(_BOOL, has_friend, _UID _I32);
 DEFINE_PRIM(_VOID, activate_overlay_user, _BYTES _UID);
 DEFINE_PRIM(_VOID, activate_overlay_store, _I32 _I32);
-
+DEFINE_PRIM(_BOOL, set_rich_presence, _BYTES _BYTES);
+DEFINE_PRIM(_VOID, clear_rich_presence, _NO_ARG);

steam/Friends.hx

@@ -92,11 +92,22 @@ class Friends {
 	public static function activateOverlay( overlay : OverlayKind, ?uid : UID ) {
 		activate_overlay_user( overlay == None ? null : @:privateAccess overlay.toString().toUtf8(), uid);
 	}
-	
+
 	public static function activateOverlayStore( appId : Int, flags : OverlayToStoreFlag ) : Void {}
 
+	/**
+		Key `steam_display` requires localized token as value, see https://partner.steamgames.com/doc/api/ISteamFriends#richpresencelocalization
+		Set `value` to empty or null to remove the key.
+	**/
+	public static function setRichPresence( key : String, value : Null<String> ) : Bool {
+		return @:privateAccess set_rich_presence(key.toUtf8(), value == null ? null : value.toUtf8());
+	}
+
+	public static function clearRichPresence() : Void {}
+
 	static function get_friends( flags : FriendFlags ) : hl.NativeArray<UID> { return null; }
 	static function has_friend( uid : UID, flags : FriendFlags ) : Bool { return false; }
 	static function activate_overlay_user( overlay : hl.Bytes, uid : UID ) : Void {}
+	static function set_rich_presence( pchKey : hl.Bytes, pchValue : hl.Bytes ) : Bool { return false; }
 
-}
+}