Provide a default refresh rate when it cannot be queried

src/PowderToySDL.cpp

@@ -146,14 +146,14 @@ void blit(pixel *vid)
 
 void UpdateRefreshRate()
 {
-	std::optional<int> refreshRate;
+	RefreshRate refreshRate;
 	int displayIndex = SDL_GetWindowDisplayIndex(sdl_window);
 	if (displayIndex >= 0)
 	{
 		SDL_DisplayMode displayMode;
 		if (!SDL_GetCurrentDisplayMode(displayIndex, &displayMode) && displayMode.refresh_rate)
 		{
-			refreshRate = displayMode.refresh_rate;
+			refreshRate = RefreshRateQueried{ displayMode.refresh_rate };
 		}
 	}
 	ui::Engine::Ref().SetRefreshRate(refreshRate);

src/gui/game/GameView.cpp

@@ -2618,13 +2618,13 @@ void GameView::OnDraw()
 				fpsInfo << "hindered";
 			}
 			fpsInfo << "\n  Refresh rate: ";
-			if (auto refreshRate = ui::Engine::Ref().GetRefreshRate())
+			auto refreshRate = ui::Engine::Ref().GetRefreshRate();
+			fpsInfo << std::visit([](auto &refreshRate) {
+				return refreshRate.value;
+			}, refreshRate);
+			if (std::holds_alternative<RefreshRateDefault>(refreshRate))
 			{
-				fpsInfo << *refreshRate;
-			}
-			else
-			{
-				fpsInfo << "unknown";
+				fpsInfo << " (default)";
 			}
 		}
 

src/gui/interface/Engine.cpp

@@ -370,7 +370,9 @@ std::optional<int> Engine::GetEffectiveDrawCap() const
 	}
 	if (std::get_if<DrawLimitDisplay>(&drawLimit))
 	{
-		effectiveDrawCap = GetRefreshRate();
+		effectiveDrawCap = std::visit([](auto &&refreshRate) {
+			return refreshRate.value;
+		}, GetRefreshRate());
 	}
 	return effectiveDrawCap;
 }

src/gui/interface/Engine.h

@@ -2,6 +2,7 @@
 #include <memory>
 #include <optional>
 #include <stack>
+#include <variant>
 #include "common/String.h"
 #include "common/ExplicitSingleton.h"
 #include "graphics/Pixel.h"
@@ -10,6 +11,16 @@
 #include <climits>
 #include "FpsLimit.h"
 
+struct RefreshRateDefault
+{
+	int value = 60;
+};
+struct RefreshRateQueried
+{
+	int value;
+};
+using RefreshRate = std::variant<RefreshRateDefault, RefreshRateQueried>;
+
 class Graphics;
 namespace ui
 {
@@ -96,7 +107,7 @@ namespace ui
 		Window* state_;
 		Point windowTargetPosition;
 		bool ignoreEvents = false;
-		std::optional<int> refreshRate;
+		RefreshRate refreshRate;
 
 		// saved appearances of windows that are in the backround and
 		// thus are not currently being redrawn
@@ -140,12 +151,12 @@ namespace ui
 		bool GetResizable          () const { return windowFrameOps.resizable;           }
 		bool GetBlurryScaling      () const { return windowFrameOps.blurryScaling;       }
 
-		std::optional<int> GetRefreshRate() const
+		RefreshRate GetRefreshRate() const
 		{
 			return refreshRate;
 		}
 
-		void SetRefreshRate(std::optional<int> newRefreshRate)
+		void SetRefreshRate(RefreshRate newRefreshRate)
 		{
 			refreshRate = newRefreshRate;
 		}