From e2b6ae9beb5dcfa6c470ff567ddcf191bdab76a4 Mon Sep 17 00:00:00 2001
From: lethosor <lethosor@gmail.com>
Date: Sat, 28 Mar 2015 11:27:47 -0400
Subject: [PATCH] Allocate Lua PenArray objects using an existing buffer

---
 library/LuaApi.cpp               |  3 ++-
 library/include/LuaTools.h       |  1 -
 library/include/modules/Screen.h |  2 ++
 library/modules/Screen.cpp       | 12 ++++++++++--
 4 files changed, 14 insertions(+), 4 deletions(-)

diff --git a/library/LuaApi.cpp b/library/LuaApi.cpp
index ff444013c..cccd8d88c 100644
--- a/library/LuaApi.cpp
+++ b/library/LuaApi.cpp
@@ -1064,7 +1064,8 @@ static int dfhack_penarray_new(lua_State *L)
 {
     int bufwidth = luaL_checkint(L, 1);
     int bufheight = luaL_checkint(L, 2);
-    new (L) PenArray(bufwidth, bufheight);
+    void *buf = lua_newuserdata(L, sizeof(PenArray) + (sizeof(Pen) * bufwidth * bufheight));
+    new (buf) PenArray(bufwidth, bufheight, buf);
 
     lua_rawgetp(L, LUA_REGISTRYINDEX, &DFHACK_PENARRAY_TOKEN);
     lua_setmetatable(L, -2);
diff --git a/library/include/LuaTools.h b/library/include/LuaTools.h
index cbcad7ccf..042870273 100644
--- a/library/include/LuaTools.h
+++ b/library/include/LuaTools.h
@@ -48,7 +48,6 @@ namespace DFHack {
     }
     namespace Screen {
         struct Pen;
-        struct PenArray;
     };
 }
 
diff --git a/library/include/modules/Screen.h b/library/include/modules/Screen.h
index bd87d416b..47bcdd0a6 100644
--- a/library/include/modules/Screen.h
+++ b/library/include/modules/Screen.h
@@ -118,8 +118,10 @@ namespace DFHack
             Pen *buffer;
             unsigned int dimx;
             unsigned int dimy;
+            bool static_alloc;
         public:
             PenArray(unsigned int bufwidth, unsigned int bufheight);
+            PenArray(unsigned int bufwidth, unsigned int bufheight, void *buf);
             ~PenArray();
             void clear();
             void set_tile(unsigned int x, unsigned int y, Screen::Pen pen);
diff --git a/library/modules/Screen.cpp b/library/modules/Screen.cpp
index f14068c47..e7fd2df04 100644
--- a/library/modules/Screen.cpp
+++ b/library/modules/Screen.cpp
@@ -442,15 +442,23 @@ df::interface_key Screen::charToKey(char code)
  */
 
 PenArray::PenArray(unsigned int bufwidth, unsigned int bufheight)
-    :dimx(bufwidth), dimy(bufheight)
+    :dimx(bufwidth), dimy(bufheight), static_alloc(false)
 {
     buffer = new Pen[bufwidth * bufheight];
     clear();
 }
 
+PenArray::PenArray(unsigned int bufwidth, unsigned int bufheight, void *buf)
+    :dimx(bufwidth), dimy(bufheight), static_alloc(true)
+{
+    buffer = (Pen*)((uint8_t*)buf + sizeof(PenArray));
+    clear();
+}
+
 PenArray::~PenArray()
 {
-    delete[] buffer;
+    if (!static_alloc)
+        delete[] buffer;
 }
 
 void PenArray::clear()