Fix #18583: Land dropdown is incorrect if there are surface entry holes (#20035)

distribution/changelog.txt

@@ -21,6 +21,7 @@
 - Fix: [#13130] Android always defaulting to UK locale for language, currency and temperature.
 - Fix: [#13397] Ride simulation causes strange station behaviour and makes the ride unusable in some cases.
 - Fix: [#16791] Rotodrop top piece replicates when walls are placed around it and clearance checks are disabled (original bug).
+- Fix: [#18583] Land dropdown is incorrect if there are surface entry index holes.
 - Fix: [#18895] Responding mechanic blocked at level crossing.
 - Fix: [#19231] Crash due to null pointer to previously deleted banner in tile copy/paste functionality.
 - Fix: [#19296] Crash due to a race condition for parallel object loading.

src/openrct2-ui/interface/LandTool.cpp

@@ -89,6 +89,26 @@ void LandTool::ShowSurfaceStyleDropdown(WindowBase* w, Widget* widget, ObjectEnt
     gDropdownDefaultIndex = defaultIndex;
 }
 
+ObjectEntryIndex LandTool::GetSurfaceStyleFromDropdownIndex(size_t index)
+{
+    auto& objManager = GetContext()->GetObjectManager();
+    auto itemIndex = 0U;
+    for (size_t i = 0; i < MAX_TERRAIN_SURFACE_OBJECTS; i++)
+    {
+        const auto surfaceObj = static_cast<TerrainSurfaceObject*>(objManager.GetLoadedObject(ObjectType::TerrainSurface, i));
+        // If fallback images are loaded, the RCT1 styles will just look like copies of already existing styles, so hide them.
+        if (surfaceObj != nullptr && !surfaceObj->UsesFallbackImages())
+        {
+            if (itemIndex == index)
+            {
+                return static_cast<ObjectEntryIndex>(i);
+            }
+            itemIndex++;
+        }
+    }
+    return OBJECT_ENTRY_INDEX_NULL;
+}
+
 void LandTool::ShowEdgeStyleDropdown(WindowBase* w, Widget* widget, ObjectEntryIndex currentEdgeType)
 {
     auto& objManager = GetContext()->GetObjectManager();
@@ -119,3 +139,23 @@ void LandTool::ShowEdgeStyleDropdown(WindowBase* w, Widget* widget, ObjectEntryI
 
     gDropdownDefaultIndex = defaultIndex;
 }
+
+ObjectEntryIndex LandTool::GetEdgeStyleFromDropdownIndex(size_t index)
+{
+    auto& objManager = GetContext()->GetObjectManager();
+    auto itemIndex = 0U;
+    for (size_t i = 0; i < MAX_TERRAIN_EDGE_OBJECTS; i++)
+    {
+        const auto edgeObj = static_cast<TerrainEdgeObject*>(objManager.GetLoadedObject(ObjectType::TerrainEdge, i));
+        // If fallback images are loaded, the RCT1 styles will just look like copies of already existing styles, so hide them.
+        if (edgeObj != nullptr && !edgeObj->UsesFallbackImages())
+        {
+            if (itemIndex == index)
+            {
+                return static_cast<ObjectEntryIndex>(i);
+            }
+            itemIndex++;
+        }
+    }
+    return OBJECT_ENTRY_INDEX_NULL;
+}

src/openrct2-ui/interface/LandTool.h

@@ -30,5 +30,7 @@ namespace LandTool
 {
     uint32_t SizeToSpriteIndex(uint16_t size);
     void ShowSurfaceStyleDropdown(WindowBase* w, Widget* widget, ObjectEntryIndex currentSurfaceType);
+    ObjectEntryIndex GetSurfaceStyleFromDropdownIndex(size_t index);
     void ShowEdgeStyleDropdown(WindowBase* w, Widget* widget, ObjectEntryIndex currentEdgeType);
+    ObjectEntryIndex GetEdgeStyleFromDropdownIndex(size_t index);
 } // namespace LandTool

src/openrct2-ui/windows/Land.cpp

@@ -156,7 +156,8 @@ public:
                 if (dropdownIndex == -1)
                     dropdownIndex = gDropdownHighlightedIndex;
 
-                type = (dropdownIndex == -1) ? _selectedFloorTexture : dropdownIndex;
+                type = (dropdownIndex == -1) ? _selectedFloorTexture
+                                             : LandTool::GetSurfaceStyleFromDropdownIndex(static_cast<size_t>(dropdownIndex));
 
                 if (gLandToolTerrainSurface == type)
                 {
@@ -173,7 +174,8 @@ public:
                 if (dropdownIndex == -1)
                     dropdownIndex = gDropdownHighlightedIndex;
 
-                type = (dropdownIndex == -1) ? _selectedWallTexture : dropdownIndex;
+                type = (dropdownIndex == -1) ? _selectedWallTexture
+                                             : LandTool::GetEdgeStyleFromDropdownIndex(static_cast<size_t>(dropdownIndex));
 
                 if (gLandToolTerrainEdge == type)
                 {