XEEN: Add Patcher class for doing on-the-fly map patches

The first patch is a script patch for Ellinger's Tower Level 2
on the Dark Side. It fixes an incorrect index for a wall item
of a curtain that's meant to be removed

7 files changed, 142 insertions, 2 deletions

diff --git a/engines/xeen/map.cpp b/engines/xeen/map.cpp
index 1fb5a9f73e..6e859e17ba 100644
--- a/engines/xeen/map.cpp
+++ b/engines/xeen/map.cpp
@@ -628,6 +628,7 @@ void Map::load(int mapId) {
 	FileManager &files = *g_vm->_files;
 	Interface &intf = *g_vm->_interface;
 	Party &party = *g_vm->_party;
+	Patcher &patcher = *g_vm->_patcher;
 	Sound &sound = *g_vm->_sound;
 	IndoorDrawList &indoorList = intf._indoorList;
 	OutdoorDrawList &outdoorList = intf._outdoorList;
@@ -982,6 +983,7 @@ void Map::load(int mapId) {
 		}
 	}
 
+	patcher.patch();
 	loadSky();
 
 	files.setGameCc(ccNum);
diff --git a/engines/xeen/module.mk b/engines/xeen/module.mk
index 9f6075b5f6..66091681b2 100644
--- a/engines/xeen/module.mk
+++ b/engines/xeen/module.mk
@@ -47,6 +47,7 @@ MODULE_OBJS := \
 	locations.o \
 	map.o \
 	party.o \
+	patcher.o \
 	resources.o \
 	saves.o \
 	screen.o \
diff --git a/engines/xeen/patcher.cpp b/engines/xeen/patcher.cpp
new file mode 100644
index 0000000000..384b90ee9a
--- /dev/null
+++ b/engines/xeen/patcher.cpp
@@ -0,0 +1,84 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#include "xeen/patcher.h"
+#include "xeen/xeen.h"
+#include "xeen/map.h"
+#include "xeen/party.h"
+#include "common/memstream.h"
+#include "common/serializer.h"
+
+namespace Xeen {
+
+struct ScriptEntry {
+	uint _gameId;
+	int _mapId;
+	const byte *_data;
+};
+
+const byte MAP54_LINE8[] = { 8, 10, 10, DIR_EAST, 8, OP_MoveWallObj, 20, 100, 100 };
+
+#define SCRIPT_PATCHES_COUNT 1
+static const ScriptEntry SCRIPT_PATCHES[] = {
+	{ GType_DarkSide, 54, MAP54_LINE8 }
+};
+
+/*------------------------------------------------------------------------*/
+
+void Patcher::patch() {
+	patchScripts();
+}
+
+void Patcher::patchScripts() {
+	FileManager &files = *g_vm->_files;
+	Map &map = *g_vm->_map;
+	Party &party = *g_vm->_party;
+	
+	uint gameId = g_vm->getGameID();
+	if (gameId == GType_WorldOfXeen)
+		gameId = files._ccNum ? GType_DarkSide : GType_Clouds;
+
+	for (int patchIdx = 0; patchIdx < SCRIPT_PATCHES_COUNT; ++patchIdx) {
+		const ScriptEntry &se = SCRIPT_PATCHES[patchIdx];
+		if (se._gameId != gameId || se._mapId != party._mazeId)
+			continue;
+		
+		MazeEvent evt;
+		Common::MemoryReadStream memStream(se._data, se._data[0] + 1);
+		Common::Serializer s(&memStream, nullptr);
+		evt.synchronize(s);
+
+		// Scan through the events to find a matching line
+		int idx = 0;
+		while (idx < (int)map._events.size() && (evt._position != map._events[idx]._position
+				|| evt._direction != map._events[idx]._direction || evt._line != map._events[idx]._line))
+			++idx;
+
+		// Set the event
+		if (idx == (int)map._events.size())
+			map._events.push_back(evt);
+		else
+			map._events[idx] = evt;
+	}
+}
+
+} // End of namespace Xeen
diff --git a/engines/xeen/patcher.h b/engines/xeen/patcher.h
new file mode 100644
index 0000000000..f0d4267320
--- /dev/null
+++ b/engines/xeen/patcher.h
@@ -0,0 +1,48 @@
+/* ScummVM - Graphic Adventure Engine
+ *
+ * ScummVM is the legal property of its developers, whose names
+ * are too numerous to list here. Please refer to the COPYRIGHT
+ * file distributed with this source distribution.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * 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 General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ */
+
+#ifndef XEEN_PATCHER_H
+#define XEEN_PATCHER_H
+
+namespace Xeen {
+
+class Patcher {
+private:
+	/**
+	 * Patches incorrect script lines
+	 */
+	void patchScripts();
+public:
+	/**
+	 * Constructor
+	 */
+	Patcher() {}
+
+	/**
+	 * Called after a map is loaded to patch any problems
+	 */
+	void patch();
+};
+
+} // End of namespace Xeen
+
+#endif	/* XEEN_PATCHER_H */
diff --git a/engines/xeen/scripts.cpp b/engines/xeen/scripts.cpp
index 464130be69..298dead111 100644
--- a/engines/xeen/scripts.cpp
+++ b/engines/xeen/scripts.cpp
@@ -1130,11 +1130,11 @@ bool Scripts::cmdRndDamage(ParamsIterator &params) {
 
 bool Scripts::cmdMoveWallObj(ParamsIterator &params) {
 	Map &map = *_vm->_map;
-	int itemNum = params.readByte();
+	int index = params.readByte();
 	int x = params.readShort();
 	int y = params.readShort();
 
-	map._mobData._wallItems[itemNum]._position = Common::Point(x, y);
+	map._mobData._wallItems[index]._position = Common::Point(x, y);
 	return true;
 }
 
diff --git a/engines/xeen/xeen.cpp b/engines/xeen/xeen.cpp
index f495f48a49..41de1d8565 100644
--- a/engines/xeen/xeen.cpp
+++ b/engines/xeen/xeen.cpp
@@ -49,6 +49,7 @@ XeenEngine::XeenEngine(OSystem *syst, const XeenGameDescription *gameDesc)
 	_locations = nullptr;
 	_map = nullptr;
 	_party = nullptr;
+	_patcher = nullptr;
 	_resources = nullptr;
 	_saves = nullptr;
 	_screen = nullptr;
@@ -75,6 +76,7 @@ XeenEngine::~XeenEngine() {
 	delete _locations;
 	delete _map;
 	delete _party;
+	delete _patcher;
 	delete _saves;
 	delete _screen;
 	delete _scripts;
@@ -100,6 +102,7 @@ bool XeenEngine::initialize() {
 	_locations = new LocationManager();
 	_map = new Map(this);
 	_party = new Party(this);
+	_patcher = new Patcher();
 	_saves = new SavesManager(_targetName);
 	_screen = new Screen(this);
 	_scripts = new Scripts(this);
diff --git a/engines/xeen/xeen.h b/engines/xeen/xeen.h
index 2cd42fdb0a..93be6d202f 100644
--- a/engines/xeen/xeen.h
+++ b/engines/xeen/xeen.h
@@ -39,6 +39,7 @@
 #include "xeen/locations.h"
 #include "xeen/map.h"
 #include "xeen/party.h"
+#include "xeen/patcher.h"
 #include "xeen/resources.h"
 #include "xeen/saves.h"
 #include "xeen/screen.h"
@@ -183,6 +184,7 @@ public:
 	LocationManager *_locations;
 	Map *_map;
 	Party *_party;
+	Patcher *_patcher;
 	Resources *_resources;
 	SavesManager *_saves;
 	Screen *_screen;