wesnoth.scroll_to_tile can now skip if onscreen

changelog

@@ -26,6 +26,8 @@ Version 1.13.6+dev:
      * New read-only keys: share_maps, share_view
        num_units, num_villages, total_upkeep, expenses, net_income
      * Existing keys made mutable: shroud, fog, flag, flag_icon
+   * wesnoth.scroll_to_tile now accepts a third boolean argument - if true, the scroll
+     is skipped when the tile is already visible onscreen.
  * WML Engine:
    * Removed LOW_MEM option when building.
    * Add color= attribute to [floating_text]

data/lua/wml/message.lua

@@ -354,7 +354,7 @@ function wesnoth.wml_actions.message(cfg)
 	else
 		-- Check ~= false, because the default if omitted should be true
 		if cfg.scroll ~= false then
-			wesnoth.scroll_to_tile(speaker.x, speaker.y)
+			wesnoth.scroll_to_tile(speaker.x, speaker.y, false, false, true)
 		end
 
 		wesnoth.highlight_hex(speaker.x, speaker.y)

src/scripting/game_lua_kernel.cpp

@@ -2371,15 +2371,22 @@ int game_lua_kernel::intf_play_sound(lua_State *L)
  * - Arg 1: location.
  * - Arg 2: boolean preventing scroll to fog.
  * - Arg 3: boolean specifying whether to warp instantly.
+ * - Arg 4: boolean specifying whether to skip if already onscreen
  */
 int game_lua_kernel::intf_scroll_to_tile(lua_State *L)
 {
 	map_location loc = luaW_checklocation(L, 1);
 	bool check_fogged = luaW_toboolean(L, 2);
-	bool immediate = luaW_toboolean(L, 3);
+	game_display::SCROLL_TYPE scroll = luaW_toboolean(L, 4)
+		? luaW_toboolean(L, 3)
+			? game_display::WARP
+			: game_display::SCROLL
+		: luaW_toboolean(L, 3)
+			? game_display::ONSCREEN_WARP
+			: game_display::ONSCREEN
+	;
 	if (game_display_) {
-		game_display_->scroll_to_tile(loc,
-			immediate ? game_display::WARP : game_display::SCROLL, check_fogged);
+		game_display_->scroll_to_tile(loc, scroll, check_fogged);
 	}
 	return 0;
 }