Add notification for mismatched g2.dat entries size (#17496)

Added expected number of sprites to StringIds.h and a mismatch check upon loading g2.dat in Drawing.Sprite.cpp. If the mismatch catch fails, then an error is logged and a notification is displayed

* Add improper install warning

distribution/changelog.txt

@@ -22,6 +22,7 @@
 - Change: [#16952] Make “Object Selection” order more coherent.
 - Change: [#17002] Weather no longer resets when converting a save to scenario.
 - Change: [#17294] New ride window remembers scroll position per tab instead of highlighted ride.
+- Change: [#17496] Added warning for mismatched g2.dat entry size
 - Removed: [#16864] Title sequence editor (replaced by plug-in).
 - Removed: [#16911, #17411] Residual support for pre-Vista Windows systems.
 - Fix: [#13997] Placing a track design interferes with other players building a ride.

src/openrct2/drawing/Drawing.Sprite.cpp

@@ -282,6 +282,22 @@ bool gfx_load_g2()
         // Read element data
         _g2.data = fs.ReadArray<uint8_t>(_g2.header.total_size);
 
+        if (_g2.header.num_entries != G2_SPRITE_COUNT)
+        {
+            std::string errorMessage = "Mismatched g2.dat size.\nExpected: " + std::to_string(G2_SPRITE_COUNT) + "\nActual: "
+                + std::to_string(_g2.header.num_entries) + "\ng2.dat may be installed improperly.\nPath to g2.dat: " + path;
+
+            log_error(errorMessage.c_str());
+
+            if (!gOpenRCT2Headless)
+            {
+                auto uiContext = GetContext()->GetUiContext();
+                uiContext->ShowMessageBox(errorMessage);
+                uiContext->ShowMessageBox("Warning: You may experience graphical glitches if you continue. It's recommended "
+                                          "that you update g2.dat if you're seeing this message");
+            }
+        }
+
         // Fix entry data offsets
         for (uint32_t i = 0; i < _g2.header.num_entries; i++)
         {

src/openrct2/sprites.h

@@ -1158,6 +1158,8 @@ enum
     SPR_CSG_BEGIN = SPR_G2_END,
     SPR_CSG_END = SPR_CSG_BEGIN + RCT1::Limits::Num_LL_CSG_Entries,
 
+    G2_SPRITE_COUNT = SPR_G2_END - SPR_G2_BEGIN,
+
     SPR_SCROLLING_TEXT_START = SPR_CSG_END,
     SPR_SCROLLING_TEXT_END = SPR_SCROLLING_TEXT_START + OpenRCT2::MaxScrollingTextEntries,