# HG changeset patch
# User nemo
# Date 1544211308 18000
# Node ID c3ae3cac8fba5ce135dd3bad8ccd5d4ce6ef44b9
# Parent  cc99f7c673c7dfa3a37d91d797b1998d293b5582# Parent  7f0166b01dc98c24082259030b5960b27cdf85cf
pull 0.9.25 changes into default

diff -r 7f0166b01dc9 -r c3ae3cac8fba gameServer2/src/protocol.rs
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gameServer2/src/protocol.rs	Fri Dec 07 14:35:08 2018 -0500
@@ -0,0 +1,47 @@
+use netbuf;
+use std::{
+    io::{Read, Result}
+};
+use nom::{
+    IResult, Err
+};
+
+pub mod messages;
+#[cfg(test)]
+pub mod test;
+mod parser;
+
+pub struct ProtocolDecoder {
+    buf: netbuf::Buf,
+    consumed: usize,
+}
+
+impl ProtocolDecoder {
+    pub fn new() -> ProtocolDecoder {
+        ProtocolDecoder {
+            buf: netbuf::Buf::new(),
+            consumed: 0,
+        }
+    }
+
+    pub fn read_from<R: Read>(&mut self, stream: &mut R) -> Result<usize> {
+        self.buf.read_from(stream)
+    }
+
+    pub fn extract_messages(&mut self) -> Vec<messages::HWProtocolMessage> {
+        let parse_result = parser::extract_messages(&self.buf[..]);
+        match parse_result {
+            Ok((tail, msgs)) => {
+                self.consumed = self.buf.len() - self.consumed - tail.len();
+                msgs
+            },
+            Err(Err::Incomplete(_)) => unreachable!(),
+            Err(Err::Error(_)) | Err(Err::Failure(_)) => unreachable!(),
+        }
+    }
+
+    pub fn sweep(&mut self) {
+        self.buf.consume(self.consumed);
+        self.consumed = 0;
+    }
+}
diff -r 7f0166b01dc9 -r c3ae3cac8fba gameServer2/src/protocol/mod.rs
--- a/gameServer2/src/protocol/mod.rs	Wed Dec 05 11:34:45 2018 -0500
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,47 +0,0 @@
-use netbuf;
-use std::{
-    io::{Read, Result}
-};
-use nom::{
-    IResult, Err
-};
-
-pub mod messages;
-#[cfg(test)]
-pub mod test;
-mod parser;
-
-pub struct ProtocolDecoder {
-    buf: netbuf::Buf,
-    consumed: usize,
-}
-
-impl ProtocolDecoder {
-    pub fn new() -> ProtocolDecoder {
-        ProtocolDecoder {
-            buf: netbuf::Buf::new(),
-            consumed: 0,
-        }
-    }
-
-    pub fn read_from<R: Read>(&mut self, stream: &mut R) -> Result<usize> {
-        self.buf.read_from(stream)
-    }
-
-    pub fn extract_messages(&mut self) -> Vec<messages::HWProtocolMessage> {
-        let parse_result = parser::extract_messages(&self.buf[..]);
-        match parse_result {
-            Ok((tail, msgs)) => {
-                self.consumed = self.buf.len() - self.consumed - tail.len();
-                msgs
-            },
-            Err(Err::Incomplete(_)) => unreachable!(),
-            Err(Err::Error(_)) | Err(Err::Failure(_)) => unreachable!(),
-        }
-    }
-
-    pub fn sweep(&mut self) {
-        self.buf.consume(self.consumed);
-        self.consumed = 0;
-    }
-}
diff -r 7f0166b01dc9 -r c3ae3cac8fba gameServer2/src/server.rs
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gameServer2/src/server.rs	Fri Dec 07 14:35:08 2018 -0500
@@ -0,0 +1,7 @@
+pub mod core;
+pub mod client;
+pub mod room;
+pub mod network;
+pub mod coretypes;
+mod actions;
+mod handlers;
diff -r 7f0166b01dc9 -r c3ae3cac8fba gameServer2/src/server/actions.rs
--- a/gameServer2/src/server/actions.rs	Wed Dec 05 11:34:45 2018 -0500
+++ b/gameServer2/src/server/actions.rs	Fri Dec 07 14:35:08 2018 -0500
@@ -4,7 +4,7 @@
     mem::replace
 };
 use super::{
-    server::HWServer,
+    core::HWServer,
     room::{GameInfo, RoomFlags},
     client::HWClient,
     coretypes::{ClientId, RoomId, GameCfg, VoteType},
diff -r 7f0166b01dc9 -r c3ae3cac8fba gameServer2/src/server/core.rs
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gameServer2/src/server/core.rs	Fri Dec 07 14:35:08 2018 -0500
@@ -0,0 +1,156 @@
+use slab;
+use crate::utils;
+use super::{
+    client::HWClient, room::HWRoom, actions, handlers,
+    coretypes::{ClientId, RoomId},
+    actions::{Destination, PendingMessage}
+};
+use crate::protocol::messages::*;
+use rand::{RngCore, thread_rng};
+use base64::{encode};
+use log::*;
+
+type Slab<T> = slab::Slab<T>;
+
+
+pub struct HWServer {
+    pub clients: Slab<HWClient>,
+    pub rooms: Slab<HWRoom>,
+    pub lobby_id: RoomId,
+    pub output: Vec<(Vec<ClientId>, HWServerMessage)>,
+    pub removed_clients: Vec<ClientId>,
+}
+
+impl HWServer {
+    pub fn new(clients_limit: usize, rooms_limit: usize) -> HWServer {
+        let rooms = Slab::with_capacity(rooms_limit);
+        let clients = Slab::with_capacity(clients_limit);
+        let mut server = HWServer {
+            clients, rooms,
+            lobby_id: 0,
+            output: vec![],
+            removed_clients: vec![]
+        };
+        server.lobby_id = server.add_room();
+        server
+    }
+
+    pub fn add_client(&mut self) -> ClientId {
+        let key: ClientId;
+        {
+            let entry = self.clients.vacant_entry();
+            key = entry.key();
+            let mut salt = [0u8; 18];
+            thread_rng().fill_bytes(&mut salt);
+
+            let client = HWClient::new(entry.key(), encode(&salt));
+            entry.insert(client);
+        }
+        self.send(key, &Destination::ToSelf, HWServerMessage::Connected(utils::PROTOCOL_VERSION));
+        key
+    }
+
+    pub fn client_lost(&mut self, client_id: ClientId) {
+        actions::run_action(self, client_id,
+                            actions::Action::ByeClient("Connection reset".to_string()));
+    }
+
+    pub fn add_room(&mut self) -> RoomId {
+        let entry = self.rooms.vacant_entry();
+        let key = entry.key();
+        let room = HWRoom::new(entry.key());
+        entry.insert(room);
+        key
+    }
+
+    pub fn handle_msg(&mut self, client_id: ClientId, msg: HWProtocolMessage) {
+        debug!("Handling message {:?} for client {}", msg, client_id);
+        if self.clients.contains(client_id) {
+            handlers::handle(self, client_id, msg);
+        }
+    }
+
+    fn get_recipients(&self, client_id: ClientId, destination: &Destination) -> Vec<ClientId> {
+        let mut ids = match *destination {
+            Destination::ToSelf => vec![client_id],
+            Destination::ToId(id) => vec![id],
+            Destination::ToAll {room_id: Some(id), ..} =>
+                self.room_clients(id),
+            Destination::ToAll {protocol: Some(proto), ..} =>
+                self.protocol_clients(proto),
+            Destination::ToAll {..} =>
+                self.clients.iter().map(|(id, _)| id).collect::<Vec<_>>()
+        };
+        if let Destination::ToAll {skip_self: true, ..} = destination {
+            if let Some(index) = ids.iter().position(|id| *id == client_id) {
+                ids.remove(index);
+            }
+        }
+        ids
+    }
+
+    pub fn send(&mut self, client_id: ClientId, destination: &Destination, message: HWServerMessage) {
+        let ids = self.get_recipients(client_id, &destination);
+        self.output.push((ids, message));
+    }
+
+    pub fn react(&mut self, client_id: ClientId, actions: Vec<actions::Action>) {
+        for action in actions {
+            actions::run_action(self, client_id, action);
+        }
+    }
+
+    pub fn lobby(&self) -> &HWRoom { &self.rooms[self.lobby_id] }
+
+    pub fn has_room(&self, name: &str) -> bool {
+        self.rooms.iter().any(|(_, r)| r.name == name)
+    }
+
+    pub fn find_room(&self, name: &str) -> Option<&HWRoom> {
+        self.rooms.iter().find_map(|(_, r)| Some(r).filter(|r| r.name == name))
+    }
+
+    pub fn find_room_mut(&mut self, name: &str) -> Option<&mut HWRoom> {
+        self.rooms.iter_mut().find_map(|(_, r)| Some(r).filter(|r| r.name == name))
+    }
+
+    pub fn find_client(&self, nick: &str) -> Option<&HWClient> {
+        self.clients.iter().find_map(|(_, c)| Some(c).filter(|c| c.nick == nick))
+    }
+
+    pub fn find_client_mut(&mut self, nick: &str) -> Option<&mut HWClient> {
+        self.clients.iter_mut().find_map(|(_, c)| Some(c).filter(|c| c.nick == nick))
+    }
+
+    pub fn select_clients<F>(&self, f: F) -> Vec<ClientId>
+        where F: Fn(&(usize, &HWClient)) -> bool {
+        self.clients.iter().filter(f)
+            .map(|(_, c)| c.id).collect()
+    }
+
+    pub fn room_clients(&self, room_id: RoomId) -> Vec<ClientId> {
+        self.select_clients(|(_, c)| c.room_id == Some(room_id))
+    }
+
+    pub fn protocol_clients(&self, protocol: u16) -> Vec<ClientId> {
+        self.select_clients(|(_, c)| c.protocol_number == protocol)
+    }
+
+    pub fn other_clients_in_room(&self, self_id: ClientId) -> Vec<ClientId> {
+        let room_id = self.clients[self_id].room_id;
+        self.select_clients(|(id, c)| *id != self_id && c.room_id == room_id )
+    }
+
+    pub fn client_and_room(&mut self, client_id: ClientId) -> (&mut HWClient, Option<&mut HWRoom>) {
+        let c = &mut self.clients[client_id];
+        if let Some(room_id) = c.room_id {
+            (c, Some(&mut self.rooms[room_id]))
+        } else {
+            (c, None)
+        }
+    }
+
+    pub fn room(&mut self, client_id: ClientId) -> Option<&mut HWRoom> {
+        self.client_and_room(client_id).1
+    }
+}
diff -r 7f0166b01dc9 -r c3ae3cac8fba gameServer2/src/server/handlers.rs
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/gameServer2/src/server/handlers.rs	Fri Dec 07 14:35:08 2018 -0500
@@ -0,0 +1,44 @@
+use mio;
+use std::{io, io::Write};
+
+use super::{
+    core::HWServer,
+    actions::{Action, Action::*},
+    coretypes::ClientId
+};
+use crate::{
+    protocol::messages::{
+        HWProtocolMessage,
+        HWServerMessage::*
+    }
+};
+use log::*;
+
+mod loggingin;
+mod lobby;
+mod inroom;
+mod common;
+mod checker;
+
+pub fn handle(server: &mut HWServer, client_id: ClientId, message: HWProtocolMessage) {
+    match message {
+        HWProtocolMessage::Ping =>
+            server.react(client_id, vec![Pong.send_self().action()]),
+        HWProtocolMessage::Quit(Some(msg)) =>
+            server.react(client_id, vec![ByeClient("User quit: ".to_string() + &msg)]),
+        HWProtocolMessage::Quit(None) =>
+            server.react(client_id, vec![ByeClient("User quit".to_string())]),
+        HWProtocolMessage::Malformed => warn!("Malformed/unknown message"),
+        HWProtocolMessage::Empty => warn!("Empty message"),
+        _ => {
+            match server.clients[client_id].room_id {
+                None =>
+                    loggingin::handle(server, client_id, message),
+                Some(id) if id == server.lobby_id =>
+                    lobby::handle(server, client_id, message),
+                Some(id) =>
+                    inroom::handle(server, client_id, id, message)
+            }
+        },
+    }
+}
diff -r 7f0166b01dc9 -r c3ae3cac8fba gameServer2/src/server/handlers/checker.rs
--- a/gameServer2/src/server/handlers/checker.rs	Wed Dec 05 11:34:45 2018 -0500
+++ b/gameServer2/src/server/handlers/checker.rs	Fri Dec 07 14:35:08 2018 -0500
@@ -3,7 +3,7 @@
 
 use crate::{
     server::{
-        server::HWServer,
+        core::HWServer,
         coretypes::ClientId,
     },
     protocol::messages::{
diff -r 7f0166b01dc9 -r c3ae3cac8fba gameServer2/src/server/handlers/common.rs
--- a/gameServer2/src/server/handlers/common.rs	Wed Dec 05 11:34:45 2018 -0500
+++ b/gameServer2/src/server/handlers/common.rs	Fri Dec 07 14:35:08 2018 -0500
@@ -1,5 +1,5 @@
 use crate::{
-    server::{actions::Action, server::HWServer},
+    server::{actions::Action, core::HWServer},
     protocol::messages::{
         HWProtocolMessage::{self, Rnd}, HWServerMessage::{self, ChatMsg},
     }
diff -r 7f0166b01dc9 -r c3ae3cac8fba gameServer2/src/server/handlers/inroom.rs
--- a/gameServer2/src/server/handlers/inroom.rs	Wed Dec 05 11:34:45 2018 -0500
+++ b/gameServer2/src/server/handlers/inroom.rs	Fri Dec 07 14:35:08 2018 -0500
@@ -6,7 +6,7 @@
             ClientId, RoomId, Voting, VoteType, GameCfg,
             MAX_HEDGEHOGS_PER_TEAM
         },
-        server::HWServer,
+        core::HWServer,
         room::{HWRoom, RoomFlags},
         actions::{Action, Action::*}
     },
diff -r 7f0166b01dc9 -r c3ae3cac8fba gameServer2/src/server/handlers/lobby.rs
--- a/gameServer2/src/server/handlers/lobby.rs	Wed Dec 05 11:34:45 2018 -0500
+++ b/gameServer2/src/server/handlers/lobby.rs	Fri Dec 07 14:35:08 2018 -0500
@@ -2,7 +2,7 @@
 
 use crate::{
     server::{
-        server::HWServer,
+        core::HWServer,
         coretypes::ClientId,
         actions::{Action, Action::*}
     },
diff -r 7f0166b01dc9 -r c3ae3cac8fba gameServer2/src/server/handlers/loggingin.rs
--- a/gameServer2/src/server/handlers/loggingin.rs	Wed Dec 05 11:34:45 2018 -0500
+++ b/gameServer2/src/server/handlers/loggingin.rs	Fri Dec 07 14:35:08 2018 -0500
@@ -3,7 +3,7 @@
 use crate::{
     server::{
         client::HWClient,
-        server::HWServer,
+        core::HWServer,
         coretypes::ClientId,
         actions::{Action, Action::*}
     },
diff -r 7f0166b01dc9 -r c3ae3cac8fba gameServer2/src/server/handlers/mod.rs
--- a/gameServer2/src/server/handlers/mod.rs	Wed Dec 05 11:34:45 2018 -0500
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,44 +0,0 @@
-use mio;
-use std::{io, io::Write};
-
-use super::{
-    server::HWServer,
-    actions::{Action, Action::*},
-    coretypes::ClientId
-};
-use crate::{
-    protocol::messages::{
-        HWProtocolMessage,
-        HWServerMessage::*
-    }
-};
-use log::*;
-
-mod loggingin;
-mod lobby;
-mod inroom;
-mod common;
-mod checker;
-
-pub fn handle(server: &mut HWServer, client_id: ClientId, message: HWProtocolMessage) {
-    match message {
-        HWProtocolMessage::Ping =>
-            server.react(client_id, vec![Pong.send_self().action()]),
-        HWProtocolMessage::Quit(Some(msg)) =>
-            server.react(client_id, vec![ByeClient("User quit: ".to_string() + &msg)]),
-        HWProtocolMessage::Quit(None) =>
-            server.react(client_id, vec![ByeClient("User quit".to_string())]),
-        HWProtocolMessage::Malformed => warn!("Malformed/unknown message"),
-        HWProtocolMessage::Empty => warn!("Empty message"),
-        _ => {
-            match server.clients[client_id].room_id {
-                None =>
-                    loggingin::handle(server, client_id, message),
-                Some(id) if id == server.lobby_id =>
-                    lobby::handle(server, client_id, message),
-                Some(id) =>
-                    inroom::handle(server, client_id, id, message)
-            }
-        },
-    }
-}
diff -r 7f0166b01dc9 -r c3ae3cac8fba gameServer2/src/server/mod.rs
--- a/gameServer2/src/server/mod.rs	Wed Dec 05 11:34:45 2018 -0500
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,7 +0,0 @@
-pub mod server;
-pub mod client;
-pub mod room;
-pub mod network;
-pub mod coretypes;
-mod actions;
-mod handlers;
diff -r 7f0166b01dc9 -r c3ae3cac8fba gameServer2/src/server/network.rs
--- a/gameServer2/src/server/network.rs	Wed Dec 05 11:34:45 2018 -0500
+++ b/gameServer2/src/server/network.rs	Fri Dec 07 14:35:08 2018 -0500
@@ -20,7 +20,7 @@
     protocol::{ProtocolDecoder, messages::*}
 };
 use super::{
-    server::{HWServer},
+    core::{HWServer},
     coretypes::ClientId
 };
 #[cfg(feature = "tls-connections")]
diff -r 7f0166b01dc9 -r c3ae3cac8fba gameServer2/src/server/server.rs
--- a/gameServer2/src/server/server.rs	Wed Dec 05 11:34:45 2018 -0500
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,156 +0,0 @@
-use slab;
-use crate::utils;
-use super::{
-    client::HWClient, room::HWRoom, actions, handlers,
-    coretypes::{ClientId, RoomId},
-    actions::{Destination, PendingMessage}
-};
-use crate::protocol::messages::*;
-use rand::{RngCore, thread_rng};
-use base64::{encode};
-use log::*;
-
-type Slab<T> = slab::Slab<T>;
-
-
-pub struct HWServer {
-    pub clients: Slab<HWClient>,
-    pub rooms: Slab<HWRoom>,
-    pub lobby_id: RoomId,
-    pub output: Vec<(Vec<ClientId>, HWServerMessage)>,
-    pub removed_clients: Vec<ClientId>,
-}
-
-impl HWServer {
-    pub fn new(clients_limit: usize, rooms_limit: usize) -> HWServer {
-        let rooms = Slab::with_capacity(rooms_limit);
-        let clients = Slab::with_capacity(clients_limit);
-        let mut server = HWServer {
-            clients, rooms,
-            lobby_id: 0,
-            output: vec![],
-            removed_clients: vec![]
-        };
-        server.lobby_id = server.add_room();
-        server
-    }
-
-    pub fn add_client(&mut self) -> ClientId {
-        let key: ClientId;
-        {
-            let entry = self.clients.vacant_entry();
-            key = entry.key();
-            let mut salt = [0u8; 18];
-            thread_rng().fill_bytes(&mut salt);
-
-            let client = HWClient::new(entry.key(), encode(&salt));
-            entry.insert(client);
-        }
-        self.send(key, &Destination::ToSelf, HWServerMessage::Connected(utils::PROTOCOL_VERSION));
-        key
-    }
-
-    pub fn client_lost(&mut self, client_id: ClientId) {
-        actions::run_action(self, client_id,
-                            actions::Action::ByeClient("Connection reset".to_string()));
-    }
-
-    pub fn add_room(&mut self) -> RoomId {
-        let entry = self.rooms.vacant_entry();
-        let key = entry.key();
-        let room = HWRoom::new(entry.key());
-        entry.insert(room);
-        key
-    }
-
-    pub fn handle_msg(&mut self, client_id: ClientId, msg: HWProtocolMessage) {
-        debug!("Handling message {:?} for client {}", msg, client_id);
-        if self.clients.contains(client_id) {
-            handlers::handle(self, client_id, msg);
-        }
-    }
-
-    fn get_recipients(&self, client_id: ClientId, destination: &Destination) -> Vec<ClientId> {
-        let mut ids = match *destination {
-            Destination::ToSelf => vec![client_id],
-            Destination::ToId(id) => vec![id],
-            Destination::ToAll {room_id: Some(id), ..} =>
-                self.room_clients(id),
-            Destination::ToAll {protocol: Some(proto), ..} =>
-                self.protocol_clients(proto),
-            Destination::ToAll {..} =>
-                self.clients.iter().map(|(id, _)| id).collect::<Vec<_>>()
-        };
-        if let Destination::ToAll {skip_self: true, ..} = destination {
-            if let Some(index) = ids.iter().position(|id| *id == client_id) {
-                ids.remove(index);
-            }
-        }
-        ids
-    }
-
-    pub fn send(&mut self, client_id: ClientId, destination: &Destination, message: HWServerMessage) {
-        let ids = self.get_recipients(client_id, &destination);
-        self.output.push((ids, message));
-    }
-
-    pub fn react(&mut self, client_id: ClientId, actions: Vec<actions::Action>) {
-        for action in actions {
-            actions::run_action(self, client_id, action);
-        }
-    }
-
-    pub fn lobby(&self) -> &HWRoom { &self.rooms[self.lobby_id] }
-
-    pub fn has_room(&self, name: &str) -> bool {
-        self.rooms.iter().any(|(_, r)| r.name == name)
-    }
-
-    pub fn find_room(&self, name: &str) -> Option<&HWRoom> {
-        self.rooms.iter().find_map(|(_, r)| Some(r).filter(|r| r.name == name))
-    }
-
-    pub fn find_room_mut(&mut self, name: &str) -> Option<&mut HWRoom> {
-        self.rooms.iter_mut().find_map(|(_, r)| Some(r).filter(|r| r.name == name))
-    }
-
-    pub fn find_client(&self, nick: &str) -> Option<&HWClient> {
-        self.clients.iter().find_map(|(_, c)| Some(c).filter(|c| c.nick == nick))
-    }
-
-    pub fn find_client_mut(&mut self, nick: &str) -> Option<&mut HWClient> {
-        self.clients.iter_mut().find_map(|(_, c)| Some(c).filter(|c| c.nick == nick))
-    }
-
-    pub fn select_clients<F>(&self, f: F) -> Vec<ClientId>
-        where F: Fn(&(usize, &HWClient)) -> bool {
-        self.clients.iter().filter(f)
-            .map(|(_, c)| c.id).collect()
-    }
-
-    pub fn room_clients(&self, room_id: RoomId) -> Vec<ClientId> {
-        self.select_clients(|(_, c)| c.room_id == Some(room_id))
-    }
-
-    pub fn protocol_clients(&self, protocol: u16) -> Vec<ClientId> {
-        self.select_clients(|(_, c)| c.protocol_number == protocol)
-    }
-
-    pub fn other_clients_in_room(&self, self_id: ClientId) -> Vec<ClientId> {
-        let room_id = self.clients[self_id].room_id;
-        self.select_clients(|(id, c)| *id != self_id && c.room_id == room_id )
-    }
-
-    pub fn client_and_room(&mut self, client_id: ClientId) -> (&mut HWClient, Option<&mut HWRoom>) {
-        let c = &mut self.clients[client_id];
-        if let Some(room_id) = c.room_id {
-            (c, Some(&mut self.rooms[room_id]))
-        } else {
-            (c, None)
-        }
-    }
-
-    pub fn room(&mut self, client_id: ClientId) -> Option<&mut HWRoom> {
-        self.client_and_room(client_id).1
-    }
-}
diff -r 7f0166b01dc9 -r c3ae3cac8fba qmlfrontend/CMakeLists.txt
--- a/qmlfrontend/CMakeLists.txt	Wed Dec 05 11:34:45 2018 -0500
+++ b/qmlfrontend/CMakeLists.txt	Fri Dec 07 14:35:08 2018 -0500
@@ -15,6 +15,8 @@
     "team.cpp" "team.h"
     "engine_instance.cpp" "engine_instance.h"
     "preview_image_provider.cpp" "preview_image_provider.h"
-    "engine_interface.h")
+    "engine_interface.h"
+    "preview_acceptor.cpp" "preview_acceptor.h"
+    )
 
 target_link_libraries(${PROJECT_NAME} Qt5::Core Qt5::Quick)
diff -r 7f0166b01dc9 -r c3ae3cac8fba qmlfrontend/Page1.qml
--- a/qmlfrontend/Page1.qml	Wed Dec 05 11:34:45 2018 -0500
+++ b/qmlfrontend/Page1.qml	Fri Dec 07 14:35:08 2018 -0500
@@ -2,24 +2,31 @@
 import Hedgewars.Engine 1.0
 
 Page1Form {
+  property var hwEngine
+
+  Component {
+    id: hwEngineComponent
+
+    HWEngine {
+      engineLibrary: "./libhedgewars_engine.so"
+      previewAcceptor: PreviewAcceptor
+      onPreviewImageChanged: previewImage.source = "image://preview/image"
+      onPreviewIsRendering: previewImage.source = "qrc:/res/iconTime.png"
+    }
+  }
+
+  Component.onCompleted: {
+    hwEngine = hwEngineComponent.createObject()
+  }
+
   tickButton.onClicked: {
     gameView.tick(100)
   }
   gameButton.onClicked: {
-    var engineInstance = HWEngine.runQuickGame()
+    var engineInstance = hwEngine.runQuickGame()
     gameView.engineInstance = engineInstance
   }
   button1.onClicked: {
-    HWEngine.getPreview()
-  }
-
-  Connections {
-    target: HWEngine
-    onPreviewImageChanged: {
-      previewImage.source = "image://preview/image"
-    }
-    onPreviewIsRendering: {
-      previewImage.source = "qrc:/res/iconTime.png"
-    }
+    hwEngine.getPreview()
   }
 }
diff -r 7f0166b01dc9 -r c3ae3cac8fba qmlfrontend/engine_instance.cpp
--- a/qmlfrontend/engine_instance.cpp	Wed Dec 05 11:34:45 2018 -0500
+++ b/qmlfrontend/engine_instance.cpp	Fri Dec 07 14:35:08 2018 -0500
@@ -1,6 +1,7 @@
 #include "engine_instance.h"
 
 #include <QDebug>
+#include <QLibrary>
 #include <QOpenGLFunctions>
 #include <QSurface>
 
@@ -12,37 +13,92 @@
     return currentOpenglContext->getProcAddress(fn);
 }
 
-EngineInstance::EngineInstance(QObject* parent)
-    : QObject(parent), m_instance(Engine::start_engine()) {}
+EngineInstance::EngineInstance(const QString& libraryPath, QObject* parent)
+    : QObject(parent) {
+  QLibrary hwlib(libraryPath);
+
+  if (!hwlib.load())
+    qWarning() << "Engine library not found" << hwlib.errorString();
+
+  hedgewars_engine_protocol_version =
+      reinterpret_cast<Engine::hedgewars_engine_protocol_version_t*>(
+          hwlib.resolve("hedgewars_engine_protocol_version"));
+  start_engine =
+      reinterpret_cast<Engine::start_engine_t*>(hwlib.resolve("start_engine"));
+  generate_preview = reinterpret_cast<Engine::generate_preview_t*>(
+      hwlib.resolve("generate_preview"));
+  dispose_preview = reinterpret_cast<Engine::dispose_preview_t*>(
+      hwlib.resolve("dispose_preview"));
+  cleanup = reinterpret_cast<Engine::cleanup_t*>(hwlib.resolve("cleanup"));
+
+  send_ipc = reinterpret_cast<Engine::send_ipc_t*>(hwlib.resolve("send_ipc"));
+  read_ipc = reinterpret_cast<Engine::read_ipc_t*>(hwlib.resolve("read_ipc"));
 
-EngineInstance::~EngineInstance() { Engine::cleanup(m_instance); }
+  setup_current_gl_context =
+      reinterpret_cast<Engine::setup_current_gl_context_t*>(
+          hwlib.resolve("setup_current_gl_context"));
+  render_frame =
+      reinterpret_cast<Engine::render_frame_t*>(hwlib.resolve("render_frame"));
+  advance_simulation = reinterpret_cast<Engine::advance_simulation_t*>(
+      hwlib.resolve("advance_simulation"));
+
+  m_isValid = hedgewars_engine_protocol_version && start_engine &&
+              generate_preview && dispose_preview && cleanup && send_ipc &&
+              read_ipc && setup_current_gl_context && render_frame &&
+              advance_simulation;
+  emit isValidChanged(m_isValid);
+
+  if (isValid()) {
+    qDebug() << "Loaded engine library with protocol version"
+             << hedgewars_engine_protocol_version();
+
+    m_instance = start_engine();
+  }
+}
+
+EngineInstance::~EngineInstance() {
+  if (m_isValid) cleanup(m_instance);
+}
 
 void EngineInstance::sendConfig(const GameConfig& config) {
   for (auto b : config.config()) {
-    Engine::send_ipc(m_instance, reinterpret_cast<uint8_t*>(b.data()),
-                     static_cast<size_t>(b.size()));
+    send_ipc(m_instance, reinterpret_cast<uint8_t*>(b.data()),
+             static_cast<size_t>(b.size()));
   }
 }
 
 void EngineInstance::advance(quint32 ticks) {
-  Engine::advance_simulation(m_instance, ticks);
+  advance_simulation(m_instance, ticks);
 }
 
-void EngineInstance::renderFrame() { Engine::render_frame(m_instance); }
+void EngineInstance::renderFrame() { render_frame(m_instance); }
 
 void EngineInstance::setOpenGLContext(QOpenGLContext* context) {
   currentOpenglContext = context;
 
   auto size = context->surface()->size();
-  Engine::setup_current_gl_context(
-      m_instance, static_cast<quint16>(size.width()),
-      static_cast<quint16>(size.height()), &getProcAddress);
+  setup_current_gl_context(m_instance, static_cast<quint16>(size.width()),
+                           static_cast<quint16>(size.height()),
+                           &getProcAddress);
 }
 
-Engine::PreviewInfo EngineInstance::generatePreview() {
+QImage EngineInstance::generatePreview() {
   Engine::PreviewInfo pinfo;
 
-  Engine::generate_preview(m_instance, &pinfo);
+  generate_preview(m_instance, &pinfo);
+
+  QVector<QRgb> colorTable;
+  colorTable.resize(256);
+  for (int i = 0; i < 256; ++i) colorTable[i] = qRgba(255, 255, 0, i);
 
-  return pinfo;
+  QImage previewImage(pinfo.land, static_cast<int>(pinfo.width),
+                      static_cast<int>(pinfo.height), QImage::Format_Indexed8);
+  previewImage.setColorTable(colorTable);
+
+  // Cannot use it here, since QImage refers to original bytes
+  // dispose_preview(m_instance);
+
+  return previewImage;
 }
+
+bool EngineInstance::isValid() const { return m_isValid; }
diff -r 7f0166b01dc9 -r c3ae3cac8fba qmlfrontend/engine_instance.h
--- a/qmlfrontend/engine_instance.h	Wed Dec 05 11:34:45 2018 -0500
+++ b/qmlfrontend/engine_instance.h	Fri Dec 07 14:35:08 2018 -0500
@@ -1,31 +1,50 @@
 #ifndef ENGINEINSTANCE_H
 #define ENGINEINSTANCE_H
 
-#include "engine_interface.h"
-
+#include <QImage>
 #include <QObject>
 #include <QOpenGLContext>
 
+#include "engine_interface.h"
 #include "game_config.h"
 
 class EngineInstance : public QObject {
   Q_OBJECT
  public:
-  explicit EngineInstance(QObject* parent = nullptr);
+  explicit EngineInstance(const QString& libraryPath,
+                          QObject* parent = nullptr);
   ~EngineInstance();
 
+  Q_PROPERTY(bool isValid READ isValid NOTIFY isValidChanged)
+
   void sendConfig(const GameConfig& config);
   void advance(quint32 ticks);
   void renderFrame();
   void setOpenGLContext(QOpenGLContext* context);
-  Engine::PreviewInfo generatePreview();
+  QImage generatePreview();
+
+  bool isValid() const;
 
  signals:
+  void isValidChanged(bool isValid);
 
  public slots:
 
  private:
   Engine::EngineInstance* m_instance;
+
+  Engine::hedgewars_engine_protocol_version_t*
+      hedgewars_engine_protocol_version;
+  Engine::start_engine_t* start_engine;
+  Engine::generate_preview_t* generate_preview;
+  Engine::dispose_preview_t* dispose_preview;
+  Engine::cleanup_t* cleanup;
+  Engine::send_ipc_t* send_ipc;
+  Engine::read_ipc_t* read_ipc;
+  Engine::setup_current_gl_context_t* setup_current_gl_context;
+  Engine::render_frame_t* render_frame;
+  Engine::advance_simulation_t* advance_simulation;
+  bool m_isValid;
 };
 
 #endif  // ENGINEINSTANCE_H
diff -r 7f0166b01dc9 -r c3ae3cac8fba qmlfrontend/engine_interface.h
--- a/qmlfrontend/engine_interface.h	Wed Dec 05 11:34:45 2018 -0500
+++ b/qmlfrontend/engine_interface.h	Fri Dec 07 14:35:08 2018 -0500
@@ -18,10 +18,11 @@
   unsigned char* land;
 } PreviewInfo;
 
-typedef uint32_t protocol_version_t();
+typedef uint32_t hedgewars_engine_protocol_version_t();
 typedef EngineInstance* start_engine_t();
 typedef void generate_preview_t(EngineInstance* engine_state,
                                 PreviewInfo* preview);
+typedef void dispose_preview_t(EngineInstance* engine_state);
 typedef void cleanup_t(EngineInstance* engine_state);
 
 typedef void send_ipc_t(EngineInstance* engine_state, uint8_t* buf,
@@ -36,18 +37,6 @@
 
 typedef bool advance_simulation_t(EngineInstance* engine_state, uint32_t ticks);
 
-extern protocol_version_t* protocol_version;
-extern start_engine_t* start_engine;
-extern generate_preview_t* generate_preview;
-extern cleanup_t* cleanup;
-
-extern send_ipc_t* send_ipc;
-extern read_ipc_t* read_ipc;
-
-extern setup_current_gl_context_t* setup_current_gl_context;
-extern render_frame_t* render_frame;
-extern advance_simulation_t* advance_simulation;
-
 #ifdef __cplusplus
 }
 };
diff -r 7f0166b01dc9 -r c3ae3cac8fba qmlfrontend/hwengine.cpp
--- a/qmlfrontend/hwengine.cpp	Wed Dec 05 11:34:45 2018 -0500
+++ b/qmlfrontend/hwengine.cpp	Fri Dec 07 14:35:08 2018 -0500
@@ -1,64 +1,33 @@
+#include "hwengine.h"
+
 #include <QDebug>
-#include <QLibrary>
-#include <QQmlEngine>
+#include <QImage>
 #include <QUuid>
 
 #include "engine_instance.h"
 #include "engine_interface.h"
 #include "game_view.h"
-#include "preview_image_provider.h"
-
-#include "hwengine.h"
+#include "preview_acceptor.h"
 
-HWEngine::HWEngine(QQmlEngine* engine, QObject* parent)
-    : QObject(parent),
-      m_engine(engine),
-      m_previewProvider(new PreviewImageProvider()) {
-  m_engine->addImageProvider(QLatin1String("preview"), m_previewProvider);
-}
+HWEngine::HWEngine(QObject* parent) : QObject(parent) {}
 
 HWEngine::~HWEngine() {}
 
-static QObject* hwengine_singletontype_provider(QQmlEngine* engine,
-                                                QJSEngine* scriptEngine) {
-  Q_UNUSED(scriptEngine)
-
-  HWEngine* hwengine = new HWEngine(engine);
-  return hwengine;
-}
-
-void HWEngine::exposeToQML() {
-  qDebug("HWEngine::exposeToQML");
-  qmlRegisterSingletonType<HWEngine>("Hedgewars.Engine", 1, 0, "HWEngine",
-                                     hwengine_singletontype_provider);
-  qmlRegisterType<GameView>("Hedgewars.Engine", 1, 0, "GameView");
-  qmlRegisterUncreatableType<EngineInstance>("Hedgewars.Engine", 1, 0,
-                                             "EngineInstance",
-                                             "Create by HWEngine run methods");
-}
-
 void HWEngine::getPreview() {
   emit previewIsRendering();
 
   m_gameConfig = GameConfig();
   m_gameConfig.cmdSeed(QUuid::createUuid().toByteArray());
 
-  EngineInstance engine;
+  EngineInstance engine(m_engineLibrary);
+  if (!engine.isValid())  // TODO: error notification
+    return;
+
   engine.sendConfig(m_gameConfig);
 
-  Engine::PreviewInfo preview = engine.generatePreview();
-
-  QVector<QRgb> colorTable;
-  colorTable.resize(256);
-  for (int i = 0; i < 256; ++i) colorTable[i] = qRgba(255, 255, 0, i);
+  QImage previewImage = engine.generatePreview();
 
-  QImage previewImage(preview.land, static_cast<int>(preview.width),
-                      static_cast<int>(preview.height),
-                      QImage::Format_Indexed8);
-  previewImage.setColorTable(colorTable);
-  previewImage.detach();
-
-  m_previewProvider->setImage(previewImage);
+  if (m_previewAcceptor) m_previewAcceptor->setImage(previewImage);
 
   emit previewImageChanged();
   // m_runQueue->queue(m_gameConfig);
@@ -74,9 +43,28 @@
   m_gameConfig.cmdTeam(team1);
   m_gameConfig.cmdTeam(team2);
 
-  EngineInstance* engine = new EngineInstance(this);
+  EngineInstance* engine = new EngineInstance(m_engineLibrary, this);
+
   return engine;
   // m_runQueue->queue(m_gameConfig);
 }
 
 int HWEngine::previewHedgehogsCount() const { return m_previewHedgehogsCount; }
+
+PreviewAcceptor* HWEngine::previewAcceptor() const { return m_previewAcceptor; }
+
+QString HWEngine::engineLibrary() const { return m_engineLibrary; }
+
+void HWEngine::setPreviewAcceptor(PreviewAcceptor* previewAcceptor) {
+  if (m_previewAcceptor == previewAcceptor) return;
+
+  m_previewAcceptor = previewAcceptor;
+  emit previewAcceptorChanged(m_previewAcceptor);
+}
+
+void HWEngine::setEngineLibrary(const QString& engineLibrary) {
+  if (m_engineLibrary == engineLibrary) return;
+
+  m_engineLibrary = engineLibrary;
+  emit engineLibraryChanged(m_engineLibrary);
+}
diff -r 7f0166b01dc9 -r c3ae3cac8fba qmlfrontend/hwengine.h
--- a/qmlfrontend/hwengine.h	Wed Dec 05 11:34:45 2018 -0500
+++ b/qmlfrontend/hwengine.h	Fri Dec 07 14:35:08 2018 -0500
@@ -8,25 +8,33 @@
 #include "game_config.h"
 
 class QQmlEngine;
-class PreviewImageProvider;
 class EngineInstance;
+class PreviewAcceptor;
 
 class HWEngine : public QObject {
   Q_OBJECT
 
   Q_PROPERTY(int previewHedgehogsCount READ previewHedgehogsCount NOTIFY
                  previewHedgehogsCountChanged)
+  Q_PROPERTY(PreviewAcceptor* previewAcceptor READ previewAcceptor WRITE
+                 setPreviewAcceptor NOTIFY previewAcceptorChanged)
+  Q_PROPERTY(QString engineLibrary READ engineLibrary WRITE setEngineLibrary
+                 NOTIFY engineLibraryChanged)
 
  public:
-  explicit HWEngine(QQmlEngine* engine, QObject* parent = nullptr);
+  explicit HWEngine(QObject* parent = nullptr);
   ~HWEngine();
 
-  static void exposeToQML();
-
   Q_INVOKABLE void getPreview();
   Q_INVOKABLE EngineInstance* runQuickGame();
 
   int previewHedgehogsCount() const;
+  PreviewAcceptor* previewAcceptor() const;
+  QString engineLibrary() const;
+
+ public slots:
+  void setPreviewAcceptor(PreviewAcceptor* previewAcceptor);
+  void setEngineLibrary(const QString& engineLibrary);
 
  signals:
   void previewIsRendering();
@@ -34,12 +42,15 @@
   void previewHogCountChanged(int count);
   void gameFinished();
   void previewHedgehogsCountChanged(int previewHedgehogsCount);
+  void previewAcceptorChanged(PreviewAcceptor* previewAcceptor);
+  void engineLibraryChanged(const QString& engineLibrary);
 
  private:
   QQmlEngine* m_engine;
-  PreviewImageProvider* m_previewProvider;
   GameConfig m_gameConfig;
   int m_previewHedgehogsCount;
+  PreviewAcceptor* m_previewAcceptor;
+  QString m_engineLibrary;
 };
 
 #endif  // HWENGINE_H
diff -r 7f0166b01dc9 -r c3ae3cac8fba qmlfrontend/main.cpp
--- a/qmlfrontend/main.cpp	Wed Dec 05 11:34:45 2018 -0500
+++ b/qmlfrontend/main.cpp	Fri Dec 07 14:35:08 2018 -0500
@@ -4,66 +4,34 @@
 #include <QQmlApplicationEngine>
 
 #include "engine_interface.h"
+#include "game_view.h"
 #include "hwengine.h"
+#include "preview_acceptor.h"
 
-namespace Engine {
-protocol_version_t* protocol_version;
-start_engine_t* start_engine;
-generate_preview_t* generate_preview;
-cleanup_t* cleanup;
-send_ipc_t* send_ipc;
-read_ipc_t* read_ipc;
-setup_current_gl_context_t* setup_current_gl_context;
-render_frame_t* render_frame;
-advance_simulation_t* advance_simulation;
-};  // namespace Engine
-
-void loadEngineLibrary() {
-#ifdef Q_OS_WIN
-  QLibrary hwlib("./libhedgewars_engine.dll");
-#else
-  QLibrary hwlib("./libhedgewars_engine.so");
-#endif
-
-  if (!hwlib.load())
-    qWarning() << "Engine library not found" << hwlib.errorString();
+namespace Engine {};  // namespace Engine
 
-  Engine::protocol_version = reinterpret_cast<Engine::protocol_version_t*>(
-      hwlib.resolve("protocol_version"));
-  Engine::start_engine =
-      reinterpret_cast<Engine::start_engine_t*>(hwlib.resolve("start_engine"));
-  Engine::generate_preview = reinterpret_cast<Engine::generate_preview_t*>(
-      hwlib.resolve("generate_preview"));
-  Engine::cleanup =
-      reinterpret_cast<Engine::cleanup_t*>(hwlib.resolve("cleanup"));
+static QObject* previewacceptor_singletontype_provider(
+    QQmlEngine* engine, QJSEngine* scriptEngine) {
+  Q_UNUSED(scriptEngine)
 
-  Engine::send_ipc =
-      reinterpret_cast<Engine::send_ipc_t*>(hwlib.resolve("send_ipc"));
-  Engine::read_ipc =
-      reinterpret_cast<Engine::read_ipc_t*>(hwlib.resolve("read_ipc"));
-
-  Engine::setup_current_gl_context =
-      reinterpret_cast<Engine::setup_current_gl_context_t*>(
-          hwlib.resolve("setup_current_gl_context"));
-  Engine::render_frame =
-      reinterpret_cast<Engine::render_frame_t*>(hwlib.resolve("render_frame"));
-  Engine::advance_simulation = reinterpret_cast<Engine::advance_simulation_t*>(
-      hwlib.resolve("advance_simulation"));
-
-  if (Engine::protocol_version)
-    qDebug() << "Loaded engine library with protocol version"
-             << Engine::protocol_version();
+  PreviewAcceptor* acceptor = new PreviewAcceptor(engine);
+  return acceptor;
 }
 
 int main(int argc, char* argv[]) {
   QCoreApplication::setAttribute(Qt::AA_EnableHighDpiScaling);
   QGuiApplication app(argc, argv);
 
-  loadEngineLibrary();
-
   QQmlApplicationEngine engine;
 
-  HWEngine::exposeToQML();
+  qmlRegisterSingletonType<PreviewAcceptor>(
+      "Hedgewars.Engine", 1, 0, "PreviewAcceptor",
+      previewacceptor_singletontype_provider);
+  qmlRegisterType<HWEngine>("Hedgewars.Engine", 1, 0, "HWEngine");
+  qmlRegisterType<GameView>("Hedgewars.Engine", 1, 0, "GameView");
+  qmlRegisterUncreatableType<EngineInstance>("Hedgewars.Engine", 1, 0,
+                                             "EngineInstance",
+                                             "Create by HWEngine run methods");
 
   engine.load(QUrl(QLatin1String("qrc:/main.qml")));
   if (engine.rootObjects().isEmpty()) return -1;
diff -r 7f0166b01dc9 -r c3ae3cac8fba qmlfrontend/preview_acceptor.cpp
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/qmlfrontend/preview_acceptor.cpp	Fri Dec 07 14:35:08 2018 -0500
@@ -0,0 +1,15 @@
+#include "preview_acceptor.h"
+
+#include <QImage>
+#include <QQmlEngine>
+
+#include "preview_image_provider.h"
+
+PreviewAcceptor::PreviewAcceptor(QQmlEngine *engine, QObject *parent)
+    : QObject(parent), m_previewProvider(new PreviewImageProvider()) {
+  engine->addImageProvider(QLatin1String("preview"), m_previewProvider);
+}
+
+void PreviewAcceptor::setImage(const QImage &preview) {
+  m_previewProvider->setImage(preview);
+}
diff -r 7f0166b01dc9 -r c3ae3cac8fba qmlfrontend/preview_acceptor.h
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/qmlfrontend/preview_acceptor.h	Fri Dec 07 14:35:08 2018 -0500
@@ -0,0 +1,21 @@
+#ifndef PREVIEW_ACCEPTOR_H
+#define PREVIEW_ACCEPTOR_H
+
+#include <QObject>
+
+class QQmlEngine;
+class PreviewImageProvider;
+
+class PreviewAcceptor : public QObject {
+  Q_OBJECT
+ public:
+  explicit PreviewAcceptor(QQmlEngine *engine, QObject *parent = nullptr);
+
+ public slots:
+  void setImage(const QImage &preview);
+
+ private:
+  PreviewImageProvider *m_previewProvider;
+};
+
+#endif  // PREVIEW_ACCEPTOR_H
diff -r 7f0166b01dc9 -r c3ae3cac8fba rust/lib-hedgewars-engine/src/lib.rs
--- a/rust/lib-hedgewars-engine/src/lib.rs	Wed Dec 05 11:34:45 2018 -0500
+++ b/rust/lib-hedgewars-engine/src/lib.rs	Fri Dec 07 14:35:08 2018 -0500
@@ -25,8 +25,8 @@
 }
 
 #[no_mangle]
-pub extern "C" fn protocol_version() -> u32 {
-    56
+pub extern "C" fn hedgewars_engine_protocol_version() -> u32 {
+    58
 }
 
 #[no_mangle]
@@ -42,14 +42,19 @@
 
     (*engine_state).world.generate_preview();
 
-    let land_preview = (*engine_state).world.preview();
+    if let Some(land_preview) = (*engine_state).world.preview() {
+        *preview = PreviewInfo {
+            width: land_preview.width() as u32,
+            height: land_preview.height() as u32,
+            hedgehogs_number: 0,
+            land: land_preview.raw_pixels().as_ptr(),
+        };
+    }
+}
 
-    *preview = PreviewInfo {
-        width: land_preview.width() as u32,
-        height: land_preview.height() as u32,
-        hedgehogs_number: 0,
-        land: land_preview.raw_pixels().as_ptr(),
-    };
+#[no_mangle]
+pub extern "C" fn dispose_preview(engine_state: &mut EngineInstance, preview: &mut PreviewInfo) {
+    (*engine_state).world.dispose_preview();
 }
 
 #[no_mangle]
diff -r 7f0166b01dc9 -r c3ae3cac8fba rust/lib-hedgewars-engine/src/world.rs
--- a/rust/lib-hedgewars-engine/src/world.rs	Wed Dec 05 11:34:45 2018 -0500
+++ b/rust/lib-hedgewars-engine/src/world.rs	Fri Dec 07 14:35:08 2018 -0500
@@ -26,7 +26,7 @@
 
 pub struct World {
     random_numbers_gen: LaggedFibonacciPRNG,
-    preview: Land2D<u8>,
+    preview: Option<Land2D<u8>>,
     game_state: Option<GameState>,
 }
 
@@ -34,7 +34,7 @@
     pub fn new() -> Self {
         Self {
             random_numbers_gen: LaggedFibonacciPRNG::new(&[]),
-            preview: Land2D::new(Size::new(0, 0), 0),
+            preview: None,
             game_state: None,
         }
     }
@@ -43,7 +43,7 @@
         self.random_numbers_gen = LaggedFibonacciPRNG::new(seed);
     }
 
-    pub fn preview(&self) -> &Land2D<u8> {
+    pub fn preview(&self) -> &Option<Land2D<u8>> {
         &self.preview
     }
 
@@ -63,7 +63,11 @@
 
         let params = LandGenerationParameters::new(0u8, u8::max_value(), 5, false, false);
         let landgen = TemplatedLandGenerator::new(template());
-        self.preview = landgen.generate_land(&params, &mut self.random_numbers_gen);
+        self.preview = Some(landgen.generate_land(&params, &mut self.random_numbers_gen));
+    }
+
+    pub fn dispose_preview(&mut self) {
+        self.preview = None
     }
 
     pub fn init(&mut self, template: OutlineTemplate) {