From 4a9974fda620633ed4c8bc7d9ee0d6801b00ca75 Mon Sep 17 00:00:00 2001
From: Richard Fine <richardf@unity3d.com>
Date: Sun, 13 Sep 2020 16:15:28 -0400
Subject: [PATCH] Introduce mechanism for configuring dropdown menu with static
 data

For menus with static content, provide a mechanism for building the menu items as a constexpr array, allowing developers to specify menus more concisely and to put the data into the .rodata section where it can be quickly copied through.
---
 src/openrct2-ui/interface/Dropdown.h | 51 ++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)

diff --git a/src/openrct2-ui/interface/Dropdown.h b/src/openrct2-ui/interface/Dropdown.h
index 8bc20503fb..83c7962aa9 100644
--- a/src/openrct2-ui/interface/Dropdown.h
+++ b/src/openrct2-ui/interface/Dropdown.h
@@ -11,6 +11,7 @@
 
 #include <openrct2-ui/interface/Window.h>
 #include <openrct2/common.h>
+#include <openrct2/localisation/StringIds.h>
 
 constexpr const rct_string_id DROPDOWN_SEPARATOR = 0;
 constexpr const rct_string_id DROPDOWN_FORMAT_COLOUR_PICKER = 0xFFFE;
@@ -50,3 +51,53 @@ void window_dropdown_show_colour(rct_window* w, rct_widget* widget, uint8_t drop
 void window_dropdown_show_colour_available(
     rct_window* w, rct_widget* widget, uint8_t dropdownColour, uint8_t selectedColour, uint32_t availableColours);
 uint32_t dropdown_get_appropriate_image_dropdown_items_per_row(uint32_t numItems);
+
+namespace Dropdown
+{
+    struct Item
+    {
+        constexpr Item(int32_t _expectedItemIndex, uint32_t _itemFormat, rct_string_id _stringId)
+            : expectedItemIndex(_expectedItemIndex)
+            , itemFormat(_itemFormat)
+            , stringId(_stringId)
+        {
+        }
+
+        int32_t expectedItemIndex;
+        uint32_t itemFormat;
+        rct_string_id stringId;
+    };
+
+    constexpr Item ToggleOption(int32_t _expectedItemIndex, rct_string_id _stringId)
+    {
+        return Item(_expectedItemIndex, STR_TOGGLE_OPTION, _stringId);
+    }
+
+    constexpr Item Separator()
+    {
+        return Item(-1, DROPDOWN_SEPARATOR, STR_EMPTY);
+    }
+
+    template<int N> void SetItems(const Dropdown::Item (&items)[N])
+    {
+        for (int i = 0; i < N; ++i)
+        {
+            const Item& item = items[i];
+            gDropdownItemsFormat[i] = item.itemFormat;
+            gDropdownItemsArgs[i] = item.stringId;
+        }
+    }
+
+    template<int N> constexpr bool ItemIDsMatchIndices(const Dropdown::Item (&items)[N])
+    {
+        for (int i = 0; i < N; ++i)
+        {
+            const Dropdown::Item& item = items[i];
+            if (item.expectedItemIndex >= 0 && item.expectedItemIndex != i)
+                return false;
+        }
+
+        return true;
+    }
+
+} // namespace Dropdown