implement a proper image list allocation

openrct2.vcxproj

@@ -68,6 +68,7 @@
     <ClCompile Include="src\drawing\engines\opengl\TextureCache.cpp" />
     <ClCompile Include="src\drawing\engines\SoftwareDrawingEngine.cpp" />
     <ClCompile Include="src\drawing\font.c" />
+    <ClCompile Include="src\drawing\Image.cpp" />
     <ClCompile Include="src\drawing\line.c" />
     <ClCompile Include="src\drawing\NewDrawing.cpp" />
     <ClCompile Include="src\drawing\Rain.cpp" />

src/drawing/Image.cpp

@@ -0,0 +1,100 @@
+#pragma region Copyright (c) 2014-2016 OpenRCT2 Developers
+/*****************************************************************************
+ * OpenRCT2, an open source clone of Roller Coaster Tycoon 2.
+ *
+ * OpenRCT2 is the work of many authors, a full list can be found in contributors.md
+ * For more information, visit https://github.com/OpenRCT2/OpenRCT2
+ *
+ * OpenRCT2 is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * A full copy of the GNU General Public License can be found in licence.txt
+ *****************************************************************************/
+#pragma endregion
+
+#include <list>
+#include "../core/Guard.hpp"
+
+extern "C"
+{
+    #include "drawing.h"
+}
+
+constexpr uint32 BASE_IMAGE_ID = 29294;
+constexpr uint32 MAX_IMAGES = 262144;
+constexpr uint32 INVALID_IMAGE_ID = UINT32_MAX;
+
+struct ImageList
+{
+    uint32 BaseId;
+    uint32 Count;
+};
+
+static bool                 _initialised = false;
+static std::list<ImageList> _freeLists;
+
+static uint32 AllocateImageList(uint32 count)
+{
+    if (!_initialised)
+    {
+        _initialised = true;
+        _freeLists.clear();
+        _freeLists.push_back({ BASE_IMAGE_ID, MAX_IMAGES });
+    }
+
+    for (auto it = _freeLists.begin(); it != _freeLists.end(); it++)
+    {
+        ImageList imageList = *it;
+        if (imageList.Count >= count)
+        {
+            _freeLists.erase(it);
+            if (imageList.Count > count)
+            {
+                ImageList remainder = { imageList.BaseId + count,
+                                        imageList.Count - count };
+                _freeLists.push_back(remainder);
+            }
+
+            return imageList.BaseId;
+        }
+    }
+    return INVALID_IMAGE_ID;
+}
+
+static void FreeImageList(uint32 baseImageId, uint32 count)
+{
+    Guard::Assert(_initialised);
+
+    // TODO validate that this was an allocated list
+    _freeLists.push_back({ baseImageId, count });
+}
+
+extern "C"
+{
+    uint32 gfx_object_allocate_images(const rct_g1_element * images, uint32 count)
+    {
+        uint32 baseImageId = AllocateImageList(count);
+        if (baseImageId == INVALID_IMAGE_ID)
+        {
+            log_error("Reached maximum image limit.");
+            return INVALID_IMAGE_ID;
+        }
+
+        uint32 imageId = baseImageId;
+        for (uint32 i = 0; i < count; i++)
+        {
+            g1Elements[imageId] = images[i];
+            drawing_engine_invalidate_image(imageId);
+            imageId++;
+        }
+
+        return baseImageId;
+    }
+
+    void gfx_object_free_images(uint32 baseImageId, uint32 count)
+    {
+        FreeImageList(baseImageId, count);
+    }
+}

src/drawing/sprite.c

@@ -173,30 +173,6 @@ int gfx_load_g2()
 	return 0;
 }
 
-static uint32 _nextImageId = 29294;
-
-uint32 gfx_object_allocate_images(const rct_g1_element * images, uint32 count)
-{
-	uint32 baseImageId = _nextImageId;
-	for (uint32 i = 0; i < count; i++) {
-		uint32 imageId = _nextImageId;
-		if (imageId >= 291438) {
-			log_error("Reached maximum image limit.");
-			break;
-		}
-
-		g1Elements[imageId] = images[i];
-		drawing_engine_invalidate_image(imageId);
-		_nextImageId++;
-	}
-	return baseImageId;
-}
-
-void gfx_object_free_images(uint32 baseImageId, uint32 count)
-{
-	_nextImageId = 29294;
-}
-
 /**
  * This function looks like it initialises the 0x009E3CE4 array which references sprites used for background / palette mixing or
  * something. Further investigation is needed.