detect extended tile properties and communicate them back to lua

docs/changelog.txt

@@ -79,6 +79,7 @@ Template for new versions:
 - ``dfhack.items.getValue()``: remove ``caravan_buying`` param as per C++ API change
 - ``widgets.BannerPanel``: panel with distinctive border for marking DFHack UI elements on otherwise vanilla screens
 - ``widgets.Panel``: new functions to override instead of setting corresponding properties (useful when subclassing instead of just setting attributes): ``onDragBegin``, ``onDragEnd``, ``onResizeBegin``, ``onResizeEnd``
+- ``dfhack.screen.readTile()``: now populates extended tile property fields (like top_of_text) in the returned Pen object
 
 ## Removed
 

library/LuaApi.cpp

@@ -844,6 +844,23 @@ static void make_pen_table(lua_State *L, Pen &pen)
                 lua_pushboolean(L, false); lua_setfield(L, -2, "tile_color");
                 break;
         }
+
+        if (pen.keep_lower) {
+            lua_pushboolean(L, true);
+            lua_setfield(L, -2, "keep_lower");
+        }
+        if (pen.write_to_lower) {
+            lua_pushboolean(L, true);
+            lua_setfield(L, -2, "write_to_lower");
+        }
+        if (pen.top_of_text) {
+            lua_pushboolean(L, true);
+            lua_setfield(L, -2, "top_of_text");
+        }
+        if (pen.bottom_of_text) {
+            lua_pushboolean(L, true);
+            lua_setfield(L, -2, "bottom_of_text");
+        }
     }
 }
 

library/modules/Screen.cpp

@@ -294,6 +294,7 @@ static Pen doGetTile_default(int x, int y, bool map) {
         return Pen(0, 0, 0, -1);
 
     long *texpos = &gps->screentexpos[index];
+    long *texpos_lower = &gps->screentexpos_lower[index];
     uint32_t *flag = &gps->screentexpos_flag[index];
 
     if (gps->top_in_use &&
@@ -301,6 +302,7 @@ static Pen doGetTile_default(int x, int y, bool map) {
              (use_graphics && gps->screentexpos_top[index]))) {
         screen = &gps->screen_top[index * 8];
         texpos = &gps->screentexpos_top[index];
+        texpos_lower = &gps->screentexpos_top_lower[index];
         flag = &gps->screentexpos_top_flag[index];
     }
 
@@ -308,19 +310,37 @@ static Pen doGetTile_default(int x, int y, bool map) {
     uint8_t fg = to_16_bit_color(&screen[1]);
     uint8_t bg = to_16_bit_color(&screen[4]);
     int tile = 0;
-    if (use_graphics)
+    bool write_to_lower = false;
+    bool top_of_text = false;
+    bool bottom_of_text = false;
+    if (use_graphics) {
         tile = *texpos;
+        if (!tile && *texpos_lower) {
+            tile = *texpos_lower;
+            write_to_lower = true;
+        }
+        if (*flag & 0x8)
+            top_of_text = true;
+        else if (*flag &0x10)
+            bottom_of_text = true;
+    }
 
+    Pen ret;
     if (*flag & 1) {
         // TileColor
-        return Pen(ch, fg&7, bg, !!(fg&8), tile, fg, bg);
+        ret = Pen(ch, fg&7, bg, !!(fg&8), tile, fg, bg);
     } else if (*flag & 2) {
         // CharColor
-        return Pen(ch, fg, bg, tile, true);
+        ret = Pen(ch, fg, bg, tile, true);
+    } else {
+        // AsIs
+        ret = Pen(ch, fg, bg, tile, false);
     }
 
-    // AsIs
-    return Pen(ch, fg, bg, tile, false);
+    ret.write_to_lower = write_to_lower;
+    ret.top_of_text = top_of_text;
+    ret.bottom_of_text = bottom_of_text;
+    return ret;
 }
 
 GUI_HOOK_DEFINE(Screen::Hooks::get_tile, doGetTile_default);