Expose PenArray dimensions and tiles to Lua

library/LuaApi.cpp

@@ -1080,6 +1080,31 @@ static int dfhack_penarray_clear(lua_State *L)
     return 0;
 }
 
+static int dfhack_penarray_get_dims(lua_State *L)
+{
+    PenArray *parr = check_penarray_native(L, 1);
+    lua_pushinteger(L, parr->get_dimx());
+    lua_pushinteger(L, parr->get_dimy());
+    return 2;
+}
+
+static int dfhack_penarray_get_tile(lua_State *L)
+{
+    PenArray *parr = check_penarray_native(L, 1);
+    unsigned int x = luaL_checkint(L, 2);
+    unsigned int y = luaL_checkint(L, 3);
+    if (x < parr->get_dimx() && y < parr->get_dimy())
+    {
+        Pen pen = parr->get_tile(x, y);
+        Lua::Push(L, pen);
+    }
+    else
+    {
+        lua_pushnil(L);
+    }
+    return 1;
+}
+
 static int dfhack_penarray_set_tile(lua_State *L)
 {
     PenArray *parr = check_penarray_native(L, 1);
@@ -1107,6 +1132,8 @@ static int dfhack_penarray_draw(lua_State *L)
 static const luaL_Reg dfhack_penarray_funcs[] = {
     { "new", dfhack_penarray_new },
     { "clear", dfhack_penarray_clear },
+    { "get_dims", dfhack_penarray_get_dims },
+    { "get_tile", dfhack_penarray_get_tile },
     { "set_tile", dfhack_penarray_set_tile },
     { "draw", dfhack_penarray_draw },
     { NULL, NULL }

library/include/modules/Screen.h

@@ -124,6 +124,9 @@ namespace DFHack
             PenArray(unsigned int bufwidth, unsigned int bufheight, void *buf);
             ~PenArray();
             void clear();
+            unsigned int get_dimx() { return dimx; }
+            unsigned int get_dimy() { return dimy; }
+            Pen get_tile(unsigned int x, unsigned int y);
             void set_tile(unsigned int x, unsigned int y, Screen::Pen pen);
             void draw(unsigned int x, unsigned int y, unsigned int width, unsigned int height,
                 unsigned int bufx = 0, unsigned int bufy = 0);

library/modules/Screen.cpp

@@ -451,7 +451,7 @@ PenArray::PenArray(unsigned int bufwidth, unsigned int bufheight)
 PenArray::PenArray(unsigned int bufwidth, unsigned int bufheight, void *buf)
     :dimx(bufwidth), dimy(bufheight), static_alloc(true)
 {
-    buffer = (Pen*)((uint8_t*)buf + sizeof(PenArray));
+    buffer = (Pen*)((PenArray*)buf + 1);
     clear();
 }
 
@@ -472,6 +472,13 @@ void PenArray::clear()
     }
 }
 
+Pen PenArray::get_tile(unsigned int x, unsigned int y)
+{
+    if (x < dimx && y < dimy)
+        return buffer[(y * dimx) + x];
+    return Pen(0, 0, 0, 0, false);
+}
+
 void PenArray::set_tile(unsigned int x, unsigned int y, Screen::Pen pen)
 {
     if (x < dimx && y < dimy)