feat: add support for stretching ImGui output to window and return to selector functionality

include/frontend_settings.hpp

@@ -28,6 +28,7 @@ struct FrontendSettings {
 	WindowIcon icon = WindowIcon::Rpog;
 	std::string language = "en";
 	bool showImGuiDebugPanel = true;
+	bool stretchImGuiOutputToWindow = false;
 
 	static Theme themeFromString(std::string inString);
 	static const char* themeToString(Theme theme);

include/panda_sdl/frontend_sdl.hpp

@@ -35,6 +35,9 @@ class FrontendSDL {
 	bool loadROM(const std::filesystem::path& path);
 	void run();
 	std::optional<std::filesystem::path> selectGame();
+	#ifdef IMGUI_FRONTEND
+	bool consumeReturnToSelector();
+	#endif
 	u32 getMapping(InputMappings::Scancode scancode) { return keyboardMappings.getMapping(scancode); }
 
 	SDL_Window* window = nullptr;
@@ -60,6 +63,7 @@ class FrontendSDL {
 	bool keyboardAnalogX = false;
 	bool keyboardAnalogY = false;
 	bool emuPaused = false;
+	bool returnToSelector = false;
 
   private:
 	void setupControllerSensors(SDL_GameController* controller);

include/panda_sdl/imgui_layer.hpp

@@ -26,6 +26,7 @@ class ImGuiLayer {
 	void setPaused(bool paused) { isPaused = paused; }
 	void setPauseCallback(std::function<void(bool)> callback) { onPauseChange = std::move(callback); }
 	void setVsyncCallback(std::function<void(bool)> callback) { onVsyncChange = std::move(callback); }
+	void setExitToSelectorCallback(std::function<void()> callback) { onExitToSelector = std::move(callback); }
 
   private:
 	void drawDebugPanel();
@@ -45,6 +46,7 @@ class ImGuiLayer {
 
 	std::function<void(bool)> onPauseChange;
 	std::function<void(bool)> onVsyncChange;
+	std::function<void()> onExitToSelector;
 };
 
 #endif

src/config.cpp

@@ -153,6 +153,7 @@ void EmulatorConfig::load() {
 			frontendSettings.icon = FrontendSettings::iconFromString(toml::find_or<std::string>(ui, "WindowIcon", "rpog"));
 			frontendSettings.language = toml::find_or<std::string>(ui, "Language", "en");
 			frontendSettings.showImGuiDebugPanel = toml::find_or<toml::boolean>(ui, "ShowImGuiDebugPanel", true);
+			frontendSettings.stretchImGuiOutputToWindow = toml::find_or<toml::boolean>(ui, "StretchImGuiOutputToWindow", false);
 		}
 	}
 }
@@ -222,6 +223,7 @@ void EmulatorConfig::save() {
 	data["UI"]["WindowIcon"] = std::string(FrontendSettings::iconToString(frontendSettings.icon));
 	data["UI"]["Language"] = frontendSettings.language;
 	data["UI"]["ShowImGuiDebugPanel"] = frontendSettings.showImGuiDebugPanel;
+	data["UI"]["StretchImGuiOutputToWindow"] = frontendSettings.stretchImGuiOutputToWindow;
 
 	std::ofstream file(path, std::ios::out);
 	file << data;

src/panda_sdl/frontend_sdl.cpp

@@ -124,6 +124,24 @@ void FrontendSDL::initialize(SDL_Window* existingWindow, SDL_GLContext existingC
 	ScreenLayout::calculateCoordinates(
 		screenCoordinates, u32(windowWidth), u32(windowHeight), emu.getConfig().topScreenSize, emu.getConfig().screenLayout
 	);
+	#ifdef IMGUI_FRONTEND
+	if (emu.getConfig().frontendSettings.stretchImGuiOutputToWindow) {
+		int drawableW = 0;
+		int drawableH = 0;
+		SDL_Window* currentWindow = existingWindow ? existingWindow : SDL_GL_GetCurrentWindow();
+		if (currentWindow) {
+			SDL_GL_GetDrawableSize(currentWindow, &drawableW, &drawableH);
+			if (drawableW > 0 && drawableH > 0) {
+				windowWidth = u32(drawableW);
+				windowHeight = u32(drawableH);
+				emu.setOutputSize(windowWidth, windowHeight);
+				ScreenLayout::calculateCoordinates(
+					screenCoordinates, windowWidth, windowHeight, emu.getConfig().topScreenSize, emu.getConfig().screenLayout
+				);
+			}
+		}
+	}
+	#endif
 
 	if (needOpenGL) {
 		#ifdef IMGUI_FRONTEND
@@ -266,6 +284,12 @@ void FrontendSDL::initialize(SDL_Window* existingWindow, SDL_GLContext existingC
 	imgui->init();
 	imgui->setPauseCallback([this](bool paused) { setPaused(paused); });
 	imgui->setVsyncCallback([this](bool enabled) { SDL_GL_SetSwapInterval(enabled ? 1 : 0); });
+	imgui->setExitToSelectorCallback([this]() {
+		returnToSelector = true;
+		programRunning = false;
+		emu.reset(Emulator::ReloadOption::NoReload);
+		emu.romType = ROMType::None;
+	});
 #endif
 }
 
@@ -287,6 +311,23 @@ void FrontendSDL::run() {
 	holdingRightClick = false;
 
 	while (programRunning) {
+		#ifdef IMGUI_FRONTEND
+		const auto& cfg = emu.getConfig();
+		if (cfg.frontendSettings.stretchImGuiOutputToWindow) {
+			int drawableW = 0;
+			int drawableH = 0;
+			SDL_GL_GetDrawableSize(window, &drawableW, &drawableH);
+			if (drawableW > 0 && drawableH > 0) {
+				windowWidth = u32(drawableW);
+				windowHeight = u32(drawableH);
+				emu.setOutputSize(windowWidth, windowHeight);
+				ScreenLayout::calculateCoordinates(
+					screenCoordinates, windowWidth, windowHeight, cfg.topScreenSize, cfg.screenLayout
+				);
+				glViewport(0, 0, drawableW, drawableH);
+			}
+		}
+		#endif
 #ifdef PANDA3DS_ENABLE_HTTP_SERVER
 		httpServer.processActions();
 #endif
@@ -559,12 +600,19 @@ void FrontendSDL::run() {
 				case SDL_WINDOWEVENT: {
 					auto type = event.window.event;
 					if (type == SDL_WINDOWEVENT_RESIZED) {
-						windowWidth = event.window.data1;
+						int drawableW = event.window.data1;
-						windowHeight = event.window.data2;
+						int drawableH = event.window.data2;
+						#ifdef IMGUI_FRONTEND
+						if (emu.getConfig().frontendSettings.stretchImGuiOutputToWindow) {
+							SDL_GL_GetDrawableSize(window, &drawableW, &drawableH);
+						}
+						#endif
+						windowWidth = u32(drawableW);
+						windowHeight = u32(drawableH);
 
 						const auto& config = emu.getConfig();
 						ScreenLayout::calculateCoordinates(
-							screenCoordinates, u32(windowWidth), u32(windowHeight), emu.getConfig().topScreenSize, emu.getConfig().screenLayout
+							screenCoordinates, windowWidth, windowHeight, config.topScreenSize, config.screenLayout
 						);
 
 						emu.setOutputSize(windowWidth, windowHeight);
@@ -640,13 +688,23 @@ void FrontendSDL::run() {
 	}
 
 	#ifdef IMGUI_FRONTEND
-	if (imgui) {
+	if (imgui && !returnToSelector) {
 		imgui->shutdown();
 		imgui.reset();
 	}
 	#endif
 }
 
+#ifdef IMGUI_FRONTEND
+bool FrontendSDL::consumeReturnToSelector() {
+	if (!returnToSelector) {
+		return false;
+	}
+	returnToSelector = false;
+	return true;
+}
+#endif
+
 void FrontendSDL::setupControllerSensors(SDL_GameController* controller) {
 	bool haveGyro = SDL_GameControllerHasSensor(controller, SDL_SENSOR_GYRO) == SDL_TRUE;
 	bool haveAccelerometer = SDL_GameControllerHasSensor(controller, SDL_SENSOR_ACCEL) == SDL_TRUE;

src/panda_sdl/imgui_layer.cpp

@@ -407,9 +407,13 @@ void ImGuiLayer::drawPausePanel() {
 		showSettings = true;
 	}
 	if (ImGui::Button("Quit", ImVec2(-1, 0))) {
-		SDL_Event quit{};
+		if (onExitToSelector) {
-		quit.type = SDL_QUIT;
+			onExitToSelector();
-		SDL_PushEvent(&quit);
+		} else {
+			SDL_Event quit{};
+			quit.type = SDL_QUIT;
+			SDL_PushEvent(&quit);
+		}
 	}
 
 	ImGui::End();
@@ -518,6 +522,7 @@ void ImGuiLayer::drawSettingsPanel() {
 			cfg.frontendSettings.showImGuiDebugPanel = showDebugPanel;
 			showDebug = showDebugPanel;
 		}
+		ImGui::Checkbox("Stretch Output To Window", &cfg.frontendSettings.stretchImGuiOutputToWindow);
 	}
 
 	if (ImGui::CollapsingHeader("Graphics")) {

src/panda_sdl/main.cpp

@@ -35,6 +35,30 @@ int emu_main(int argc, char *argv[]) {
 	FrontendSDL app;
 	#endif
 
+	#ifdef IMGUI_FRONTEND
+	std::optional<std::filesystem::path> forcedRom;
+	if (argc > 1) {
+		forcedRom = std::filesystem::current_path() / argv[1];
+	}
+
+	while (true) {
+		std::optional<std::filesystem::path> selected = forcedRom;
+		if (!selected.has_value()) {
+			selected = app.selectGame();
+			if (!selected.has_value()) {
+				return 0;
+			}
+		}
+		if (!app.loadROM(*selected)) {
+			Helpers::panic("Failed to load ROM file: %s", selected->string().c_str());
+		}
+		forcedRom.reset();
+		app.run();
+		if (!app.consumeReturnToSelector()) {
+			break;
+		}
+	}
+	#else
 	if (argc > 1) {
 		auto romPath = std::filesystem::current_path() / argv[1];
 		if (!app.loadROM(romPath)) {
@@ -42,20 +66,11 @@ int emu_main(int argc, char *argv[]) {
 			Helpers::panic("Failed to load ROM file: %s", romPath.string().c_str());
 		}
 	} else {
-		#ifdef IMGUI_FRONTEND
-		auto selected = app.selectGame();
-		if (!selected.has_value()) {
-			return 0;
-		}
-		if (!app.loadROM(*selected)) {
-			Helpers::panic("Failed to load ROM file: %s", selected->string().c_str());
-		}
-		#else
 		printf("No ROM inserted! Load a ROM by dragging and dropping it into the emulator window!\n");
-		#endif
 	}
 
 	app.run();
+	#endif
 	return 0;
 }