Add Metal support to Qt frontend and clean up renderer creation code (#795)

* Qt: Initial support for Metal renderer

* Clean up graphics context code

* Nits

* More nits

* Qt: Move screen-related stuff to own folder

* Qt: Make screen widget polymorphic

* Qt: Re-add Metal

* Add factory for screen widget

* Qt: Support compilation without Metal

* Qt: Fix build without Metal

* Oops

* oops

CMakeLists.txt

@@ -675,7 +675,7 @@ if(ENABLE_METAL AND APPLE)
 
     target_sources(AlberCore PRIVATE ${RENDERER_MTL_SOURCE_FILES})
     target_compile_definitions(AlberCore PUBLIC "PANDA3DS_ENABLE_METAL=1")
-    target_include_directories(AlberCore PRIVATE third_party/metal-cpp)
+    target_include_directories(AlberCore PUBLIC third_party/metal-cpp)
     # TODO: check if all of them are needed
     target_link_libraries(AlberCore PUBLIC "-framework Metal" "-framework Foundation" "-framework QuartzCore" resources_renderer_mtl)
 endif()
@@ -730,18 +730,25 @@ if(NOT BUILD_HYDRA_CORE AND NOT BUILD_LIBRETRO_CORE)
         option(GENERATE_QT_TRANSLATION "Generate Qt translation file" OFF)
         set(QT_LANGUAGES docs/translations)
 
-        set(FRONTEND_SOURCE_FILES src/panda_qt/main.cpp src/panda_qt/screen.cpp src/panda_qt/main_window.cpp src/panda_qt/about_window.cpp
+        set(FRONTEND_SOURCE_FILES src/panda_qt/main.cpp src/panda_qt/main_window.cpp src/panda_qt/about_window.cpp
             src/panda_qt/config_window.cpp src/panda_qt/zep.cpp src/panda_qt/text_editor.cpp src/panda_qt/cheats_window.cpp src/panda_qt/mappings.cpp
             src/panda_qt/patch_window.cpp src/panda_qt/elided_label.cpp src/panda_qt/shader_editor.cpp src/panda_qt/translations.cpp
             src/panda_qt/thread_debugger.cpp src/panda_qt/cpu_debugger.cpp src/panda_qt/dsp_debugger.cpp src/panda_qt/input_window.cpp
+            src/panda_qt/screen/screen.cpp src/panda_qt/screen/screen_gl.cpp src/panda_qt/screen/screen_mtl.cpp
         )
-        set(FRONTEND_HEADER_FILES include/panda_qt/screen.hpp include/panda_qt/main_window.hpp include/panda_qt/about_window.hpp
+
+        set(FRONTEND_HEADER_FILES include/panda_qt/main_window.hpp include/panda_qt/about_window.hpp
             include/panda_qt/config_window.hpp include/panda_qt/text_editor.hpp include/panda_qt/cheats_window.hpp
             include/panda_qt/patch_window.hpp include/panda_qt/elided_label.hpp include/panda_qt/shader_editor.hpp
             include/panda_qt/thread_debugger.hpp include/panda_qt/cpu_debugger.hpp include/panda_qt/dsp_debugger.hpp
-            include/panda_qt/disabled_widget_overlay.hpp include/panda_qt/input_window.hpp
+            include/panda_qt/disabled_widget_overlay.hpp include/panda_qt/input_window.hpp include/panda_qt/screen/screen.hpp
+            include/panda_qt/screen/screen_gl.hpp include/panda_qt/screen/screen_mtl.hpp
         )
 
+        if (APPLE AND ENABLE_METAL)
+            set(FRONTEND_SOURCE_FILES ${FRONTEND_SOURCE_FILES} src/panda_qt/screen/metal_context.mm)
+        endif()
+
         source_group("Source Files\\Qt" FILES ${FRONTEND_SOURCE_FILES})
         source_group("Header Files\\Qt" FILES ${FRONTEND_HEADER_FILES})
         include_directories(${Qt6Gui_PRIVATE_INCLUDE_DIRS})

include/PICA/gpu.hpp

@@ -109,11 +109,7 @@ class GPU {
 	void screenshot(const std::string& name) { renderer->screenshot(name); }
 	void deinitGraphicsContext() { renderer->deinitGraphicsContext(); }
 
-#if defined(PANDA3DS_FRONTEND_SDL)
+	void initGraphicsContext(void* context) { renderer->initGraphicsContext(context); }
-	void initGraphicsContext(SDL_Window* window) { renderer->initGraphicsContext(window); }
-#elif defined(PANDA3DS_FRONTEND_QT)
-	void initGraphicsContext(GL::Context* context) { renderer->initGraphicsContext(context); }
-#endif
 
 	void fireDMA(u32 dest, u32 source, u32 size);
 	void reset();

include/emulator.hpp

@@ -106,12 +106,8 @@ class Emulator {
 	bool loadELF(const std::filesystem::path& path);
 	bool loadELF(std::ifstream& file);
 
-#ifdef PANDA3DS_FRONTEND_QT
+	// For passing the SDL Window, GL context, etc from the frontend to the renderer
-	// For passing the GL context from Qt to the renderer
+	void initGraphicsContext(void* context) { gpu.initGraphicsContext(context); }
-	void initGraphicsContext(GL::Context* glContext) { gpu.initGraphicsContext(nullptr); }
-#else
-	void initGraphicsContext(SDL_Window* window) { gpu.initGraphicsContext(window); }
-#endif
 
 	RomFS::DumpingResult dumpRomFS(const std::filesystem::path& path);
 	void setOutputSize(u32 width, u32 height) { gpu.setOutputSize(width, height); }

include/panda_qt/main_window.hpp

@@ -20,7 +20,7 @@
 #include "panda_qt/cpu_debugger.hpp"
 #include "panda_qt/dsp_debugger.hpp"
 #include "panda_qt/patch_window.hpp"
-#include "panda_qt/screen.hpp"
+#include "panda_qt/screen/screen.hpp"
 #include "panda_qt/shader_editor.hpp"
 #include "panda_qt/text_editor.hpp"
 #include "panda_qt/thread_debugger.hpp"
@@ -136,7 +136,7 @@ class MainWindow : public QMainWindow {
 	void loadKeybindings();
 	void saveKeybindings();
 
-	// Tracks whether we are using an OpenGL-backed renderer or a Vulkan-backed renderer
+	// Tracks what graphics API is backing our renderer
 	bool usingGL = false;
 	bool usingVk = false;
 	bool usingMtl = false;

include/panda_qt/screen/screen.hpp

@@ -1,25 +1,27 @@
 #pragma once
 #include <QWidget>
 #include <functional>
-#include <memory>
 
 #include "gl/context.h"
 #include "screen_layout.hpp"
 #include "window_info.h"
 
-// OpenGL widget for drawing the 3DS screen
+// Abstract screen widget for drawing the 3DS screen. We've got a child class for each graphics API (ScreenWidgetGL, ScreenWidgetMTL, ...)
 class ScreenWidget : public QWidget {
 	Q_OBJECT
 
   public:
 	using ResizeCallback = std::function<void(u32, u32)>;
 
-	ScreenWidget(ResizeCallback resizeCallback, QWidget* parent = nullptr);
+	enum class API { OpenGL, Metal, Vulkan };
-	void resizeEvent(QResizeEvent* event) override;
-	// Called by the emulator thread for resizing the actual GL surface, since the emulator thread owns the GL context
-	void resizeSurface(u32 width, u32 height);
 
-	GL::Context* getGLContext() { return glContext.get(); }
+	ScreenWidget(API api, ResizeCallback resizeCallback, QWidget* parent = nullptr);
+	virtual ~ScreenWidget() {}
+
+	void resizeEvent(QResizeEvent* event) override;
+
+	virtual GL::Context* getGLContext() { return nullptr; }
+	virtual void* getMTKLayer() { return nullptr; }
 
 	// Dimensions of our output surface
 	u32 surfaceWidth = 0;
@@ -30,8 +32,9 @@ class ScreenWidget : public QWidget {
 	u32 previousWidth = 0;
 	u32 previousHeight = 0;
 
-	// Coordinates (x/y/width/height) for the two screens in window space, used for properly handling touchscreen regardless
+	API api = API::OpenGL;
-	// of layout or resizing
+
+	// Coordinates (x/y/width/height) for the two screens in window space, used for properly handling touchscreen
 	ScreenLayout::WindowCoordinates screenCoordinates;
 	// Screen layouts and sizes
 	ScreenLayout::Layout screenLayout = ScreenLayout::Layout::Default;
@@ -39,16 +42,23 @@ class ScreenWidget : public QWidget {
 
 	void reloadScreenLayout(ScreenLayout::Layout newLayout, float newTopScreenSize);
 
-  private:
+	// Creates a screen widget depending on the graphics API we're using
-	std::unique_ptr<GL::Context> glContext = nullptr;
+	static ScreenWidget* getWidget(API api, ResizeCallback resizeCallback, QWidget* parent = nullptr);
+
+	// Called by the emulator thread on OpenGL for resizing the actual GL surface, since the emulator thread owns the GL context
+	virtual void resizeSurface(u32 width, u32 height) {};
+
+  protected:
 	ResizeCallback resizeCallback;
 
-	bool createGLContext();
+	virtual bool createContext() = 0;
+	virtual void resizeDisplay() = 0;
+	std::optional<WindowInfo> getWindowInfo();
 
+  private:
 	qreal devicePixelRatioFromScreen() const;
 	int scaledWindowWidth() const;
 	int scaledWindowHeight() const;
-	std::optional<WindowInfo> getWindowInfo();
 
 	void reloadScreenCoordinates();
 };

include/panda_qt/screen/screen_gl.hpp

@@ -0,0 +1,18 @@
+#pragma once
+#include <memory>
+
+#include "gl/context.h"
+#include "panda_qt/screen/screen.hpp"
+
+class ScreenWidgetGL : public ScreenWidget {
+	std::unique_ptr<GL::Context> glContext = nullptr;
+
+  public:
+	ScreenWidgetGL(API api, ResizeCallback resizeCallback, QWidget* parent = nullptr);
+
+	virtual GL::Context* getGLContext() override;
+	virtual bool createContext() override;
+
+	virtual void resizeDisplay() override;
+	virtual void resizeSurface(u32 width, u32 height) override;
+};

include/panda_qt/screen/screen_mtl.hpp

@@ -0,0 +1,18 @@
+#pragma once
+#include "panda_qt/screen/screen.hpp"
+
+class ScreenWidgetMTL : public ScreenWidget {
+	void* mtkLayer = nullptr;
+
+	// Objective-C++ functions for handling the Metal context
+	bool createMetalContext();
+	void resizeMetalView();
+
+  public:
+	ScreenWidgetMTL(API api, ResizeCallback resizeCallback, QWidget* parent = nullptr);
+	~ScreenWidgetMTL() override;
+
+	virtual void* getMTKLayer() override;
+	virtual bool createContext() override;
+	virtual void resizeDisplay() override;
+};

include/renderer.hpp

@@ -69,7 +69,7 @@ class Renderer {
 
 	virtual void reset() = 0;
 	virtual void display() = 0;                                                              // Display the 3DS screen contents to the window
-	virtual void initGraphicsContext(SDL_Window* window) = 0;                                // Initialize graphics context
+	virtual void initGraphicsContext(void* context) = 0;                                     // Initialize graphics context
 	virtual void clearBuffer(u32 startAddress, u32 endAddress, u32 value, u32 control) = 0;  // Clear a GPU buffer in VRAM
 	virtual void displayTransfer(u32 inputAddr, u32 outputAddr, u32 inputSize, u32 outputSize, u32 flags) = 0;  // Perform display transfer
 	virtual void textureCopy(u32 inputAddr, u32 outputAddr, u32 totalBytes, u32 inputSize, u32 outputSize, u32 flags) = 0;
@@ -91,9 +91,9 @@ class Renderer {
 	// Called to notify the core to use OpenGL ES and not desktop GL
 	virtual void setupGLES() {}
 
-	// Only relevant for Metal renderer on iOS
+	// Used for Metal renderer on Qt and iOS
-	// Passes a SwiftUI MTKView's layer (CAMetalLayer) to the renderer
+	// Passes an NSView's backing layer (CAMetalLayer) to the renderer
-	virtual void setMTKLayer(void* layer) {};
+	virtual void setMTKLayer(void* layer) { Helpers::panic("Renderer doesn't support MTK Layer"); };
 
 	// This function is called on every draw call before parsing vertex data.
 	// It is responsible for things like looking up which vertex/fragment shaders to use, recompiling them if they don't exist, choosing between
@@ -101,11 +101,6 @@ class Renderer {
 	// Returns whether this draw is eligible for using hardware-accelerated shaders or if shaders should run on the CPU
 	virtual bool prepareForDraw(ShaderUnit& shaderUnit, PICA::DrawAcceleration* accel) { return false; }
 
-	// Functions for initializing the graphics context for the Qt frontend, where we don't have the convenience of SDL_Window
-#ifdef PANDA3DS_FRONTEND_QT
-	virtual void initGraphicsContext(GL::Context* context) { Helpers::panic("Tried to initialize incompatible renderer with GL context"); }
-#endif
-
 	void setFBSize(u32 width, u32 height) {
 		fbSize[0] = width;
 		fbSize[1] = height;

include/renderer_gl/renderer_gl.hpp

@@ -191,7 +191,7 @@ class RendererGL final : public Renderer {
 
 	void reset() override;
 	void display() override;                                                              // Display the 3DS screen contents to the window
-	void initGraphicsContext(SDL_Window* window) override;                                // Initialize graphics context
+	void initGraphicsContext(void* context) override;                                     // Initialize graphics context
 	void clearBuffer(u32 startAddress, u32 endAddress, u32 value, u32 control) override;  // Clear a GPU buffer in VRAM
 	void displayTransfer(u32 inputAddr, u32 outputAddr, u32 inputSize, u32 outputSize, u32 flags) override;  // Perform display transfer
 	void textureCopy(u32 inputAddr, u32 outputAddr, u32 totalBytes, u32 inputSize, u32 outputSize, u32 flags) override;
@@ -211,10 +211,6 @@ class RendererGL final : public Renderer {
 	void resetStateManager() { gl.reset(); }
 	void initUbershader(OpenGL::Program& program);
 
-#ifdef PANDA3DS_FRONTEND_QT
-	virtual void initGraphicsContext([[maybe_unused]] GL::Context* context) override { initGraphicsContextInternal(); }
-#endif
-
 	// Take a screenshot of the screen and store it in a file
 	void screenshot(const std::string& name) override;
 };

include/renderer_mtl/renderer_mtl.hpp

@@ -13,7 +13,6 @@
 #include "mtl_vertex_buffer_cache.hpp"
 #include "renderer.hpp"
 
-
 // HACK: use the OpenGL cache
 #include "../renderer_gl/surface_cache.hpp"
 
@@ -30,7 +29,7 @@ class RendererMTL final : public Renderer {
 
 	void reset() override;
 	void display() override;
-	void initGraphicsContext(SDL_Window* window) override;
+	void initGraphicsContext(void* context) override;
 	void clearBuffer(u32 startAddress, u32 endAddress, u32 value, u32 control) override;
 	void displayTransfer(u32 inputAddr, u32 outputAddr, u32 inputSize, u32 outputSize, u32 flags) override;
 	void textureCopy(u32 inputAddr, u32 outputAddr, u32 totalBytes, u32 inputSize, u32 outputSize, u32 flags) override;
@@ -38,10 +37,6 @@ class RendererMTL final : public Renderer {
 	void screenshot(const std::string& name) override;
 	void deinitGraphicsContext() override;
 
-#ifdef PANDA3DS_FRONTEND_QT
-	virtual void initGraphicsContext([[maybe_unused]] GL::Context* context) override {}
-#endif
-
 	virtual void setMTKLayer(void* layer) override;
 
   private:

include/renderer_null/renderer_null.hpp

@@ -9,7 +9,7 @@ class RendererNull final : public Renderer {
 
 	void reset() override;
 	void display() override;
-	void initGraphicsContext(SDL_Window* window) override;
+	void initGraphicsContext(void* context) override;
 	void clearBuffer(u32 startAddress, u32 endAddress, u32 value, u32 control) override;
 	void displayTransfer(u32 inputAddr, u32 outputAddr, u32 inputSize, u32 outputSize, u32 flags) override;
 	void textureCopy(u32 inputAddr, u32 outputAddr, u32 totalBytes, u32 inputSize, u32 outputSize, u32 flags) override;
@@ -20,8 +20,4 @@ class RendererNull final : public Renderer {
 	// Tell the GPU core that we'll handle vertex fetch & shader execution in the renderer in order to speed up execution.
 	// Of course, we don't do this and geometry is never actually processed, since this is the null renderer.
 	virtual bool prepareForDraw(ShaderUnit& shaderUnit, PICA::DrawAcceleration* accel) override { return true; };
-
-#ifdef PANDA3DS_FRONTEND_QT
-	virtual void initGraphicsContext([[maybe_unused]] GL::Context* context) override {}
-#endif
 };

include/renderer_sw/renderer_sw.hpp

@@ -9,15 +9,11 @@ class RendererSw final : public Renderer {
 
 	void reset() override;
 	void display() override;
-	void initGraphicsContext(SDL_Window* window) override;
+	void initGraphicsContext(void* context) override;
 	void clearBuffer(u32 startAddress, u32 endAddress, u32 value, u32 control) override;
 	void displayTransfer(u32 inputAddr, u32 outputAddr, u32 inputSize, u32 outputSize, u32 flags) override;
 	void textureCopy(u32 inputAddr, u32 outputAddr, u32 totalBytes, u32 inputSize, u32 outputSize, u32 flags) override;
 	void drawVertices(PICA::PrimType primType, std::span<const PICA::Vertex> vertices) override;
 	void screenshot(const std::string& name) override;
 	void deinitGraphicsContext() override;
-
-#ifdef PANDA3DS_FRONTEND_QT
-	virtual void initGraphicsContext([[maybe_unused]] GL::Context* context) override {}
-#endif
 };

include/renderer_vk/renderer_vk.hpp

@@ -113,7 +113,7 @@ class RendererVK final : public Renderer {
 
 	void reset() override;
 	void display() override;
-	void initGraphicsContext(SDL_Window* window) override;
+	void initGraphicsContext(void* context) override;
 	void clearBuffer(u32 startAddress, u32 endAddress, u32 value, u32 control) override;
 	void displayTransfer(u32 inputAddr, u32 outputAddr, u32 inputSize, u32 outputSize, u32 flags) override;
 	void textureCopy(u32 inputAddr, u32 outputAddr, u32 totalBytes, u32 inputSize, u32 outputSize, u32 flags) override;

src/core/renderer_gl/renderer_gl.cpp

@@ -191,7 +191,7 @@ void RendererGL::initGraphicsContextInternal() {
 
 // The OpenGL renderer doesn't need to do anything with the GL context (For Qt frontend) or the SDL window (For SDL frontend)
 // So we just call initGraphicsContextInternal for both
-void RendererGL::initGraphicsContext([[maybe_unused]] SDL_Window* window) { initGraphicsContextInternal(); }
+void RendererGL::initGraphicsContext([[maybe_unused]] void* context) { initGraphicsContextInternal(); }
 
 // Set up the OpenGL blending context to match the emulated PICA
 void RendererGL::setupBlending() {

src/core/renderer_mtl/renderer_mtl.cpp

@@ -10,8 +10,8 @@
 
 #include "PICA/gpu.hpp"
 #include "PICA/pica_hash.hpp"
-#include "screen_layout.hpp"
 #include "SDL_metal.h"
+#include "screen_layout.hpp"
 
 using namespace PICA;
 
@@ -57,9 +57,7 @@ void RendererMTL::reset() {
 	colorRenderTargetCache.reset();
 }
 
-void RendererMTL::setMTKLayer(void* layer) {
+void RendererMTL::setMTKLayer(void* layer) { metalLayer = (CA::MetalLayer*)layer; }
-	metalLayer = (CA::MetalLayer*)layer;
-}
 
 void RendererMTL::display() {
 	CA::MetalDrawable* drawable = metalLayer->nextDrawable();
@@ -151,13 +149,13 @@ void RendererMTL::display() {
 	drawable->release();
 }
 
-void RendererMTL::initGraphicsContext(SDL_Window* window) {
+void RendererMTL::initGraphicsContext(void* window) {
-	// On iOS, the SwiftUI side handles the MetalLayer
+	// On Qt and IOS, the frontend handles the MetalLayer
-#ifdef PANDA3DS_IOS
+#if defined(PANDA3DS_FRONTEND_QT) || defined(PANDA3DS_IOS)
 	device = MTL::CreateSystemDefaultDevice();
 #else
 	// TODO: what should be the type of the view?
-	void* view = SDL_Metal_CreateView(window);
+	void* view = SDL_Metal_CreateView((SDL_Window*)window);
 	metalLayer = (CA::MetalLayer*)SDL_Metal_GetLayer(view);
 	device = MTL::CreateSystemDefaultDevice();
 	metalLayer->setDevice(device);

src/core/renderer_null/renderer_null.cpp

@@ -6,7 +6,7 @@ RendererNull::~RendererNull() {}
 
 void RendererNull::reset() {}
 void RendererNull::display() {}
-void RendererNull::initGraphicsContext(SDL_Window* window) {}
+void RendererNull::initGraphicsContext(void* context) {}
 void RendererNull::clearBuffer(u32 startAddress, u32 endAddress, u32 value, u32 control) {}
 void RendererNull::displayTransfer(u32 inputAddr, u32 outputAddr, u32 inputSize, u32 outputSize, u32 flags) {}
 void RendererNull::textureCopy(u32 inputAddr, u32 outputAddr, u32 totalBytes, u32 inputSize, u32 outputSize, u32 flags) {}

src/core/renderer_sw/renderer_sw.cpp

@@ -7,7 +7,7 @@ RendererSw::~RendererSw() {}
 void RendererSw::reset() { printf("RendererSW: Unimplemented reset call\n"); }
 void RendererSw::display() { printf("RendererSW: Unimplemented display call\n"); }
 
-void RendererSw::initGraphicsContext(SDL_Window* window) { printf("RendererSW: Unimplemented initGraphicsContext call\n"); }
+void RendererSw::initGraphicsContext(void* context) { printf("RendererSW: Unimplemented initGraphicsContext call\n"); }
 void RendererSw::clearBuffer(u32 startAddress, u32 endAddress, u32 value, u32 control) { printf("RendererSW: Unimplemented clearBuffer call\n"); }
 
 void RendererSw::displayTransfer(u32 inputAddr, u32 outputAddr, u32 inputSize, u32 outputSize, u32 flags) {

src/core/renderer_vk/renderer_vk.cpp

@@ -173,7 +173,8 @@ std::tuple<vk::UniquePipeline, vk::UniquePipelineLayout> createGraphicsPipeline(
 	vk::PipelineDynamicStateCreateInfo dynamicState = {};
 	static vk::DynamicState dynamicStates[] = {// The viewport and scissor of the framebuffer will be dynamic at
 											   // run-time
-											   vk::DynamicState::eViewport, vk::DynamicState::eScissor};
+											   vk::DynamicState::eViewport, vk::DynamicState::eScissor
+	};
 	dynamicState.dynamicStateCount = std::size(dynamicStates);
 	dynamicState.pDynamicStates = dynamicStates;
 
@@ -469,7 +470,8 @@ vk::RenderPass RendererVK::getRenderPass(vk::Format colorFormat, std::optional<v
 		vk::SubpassDependency(
 			0, VK_SUBPASS_EXTERNAL, vk::PipelineStageFlagBits::eAllGraphics, vk::PipelineStageFlagBits::eAllGraphics,
 			vk::AccessFlagBits::eColorAttachmentWrite, vk::AccessFlagBits::eColorAttachmentWrite, vk::DependencyFlagBits::eByRegion
-		)};
+		)
+	};
 
 	renderPassInfo.setDependencies(subpassDependencies);
 
@@ -892,8 +894,8 @@ using VulkanDynamicLoader = vk::detail::DynamicLoader;
 using VulkanDynamicLoader = vk::DynamicLoader;
 #endif
 
-void RendererVK::initGraphicsContext(SDL_Window* window) {
+void RendererVK::initGraphicsContext(void* windowPointer) {
-	targetWindow = window;
+	targetWindow = (SDL_Window*)windowPointer;
 	// Resolve all instance function pointers
 	static VulkanDynamicLoader dl;
 	VULKAN_HPP_DEFAULT_DISPATCHER.init(dl.getProcAddress<PFN_vkGetInstanceProcAddr>("vkGetInstanceProcAddr"));
@@ -978,8 +980,8 @@ void RendererVK::initGraphicsContext(SDL_Window* window) {
 	}
 
 	// Create surface
-	if (window) {
+	if (targetWindow) {
-		if (VkSurfaceKHR newSurface; SDL_Vulkan_CreateSurface(window, instance.get(), &newSurface)) {
+		if (VkSurfaceKHR newSurface; SDL_Vulkan_CreateSurface(targetWindow, instance.get(), &newSurface)) {
 			swapchainSurface = newSurface;
 		} else {
 			Helpers::warn("Error creating Vulkan surface");
@@ -1127,7 +1129,7 @@ void RendererVK::initGraphicsContext(SDL_Window* window) {
 		vk::Extent2D swapchainExtent;
 		{
 			int windowWidth, windowHeight;
-			SDL_Vulkan_GetDrawableSize(window, &windowWidth, &windowHeight);
+			SDL_Vulkan_GetDrawableSize(targetWindow, &windowWidth, &windowHeight);
 			swapchainExtent.width = windowWidth;
 			swapchainExtent.height = windowHeight;
 		}
@@ -1275,7 +1277,8 @@ void RendererVK::initGraphicsContext(SDL_Window* window) {
 
 	static vk::DescriptorSetLayoutBinding displayShaderLayout[] = {
 		{// Just a singular texture slot
-		 0, vk::DescriptorType::eCombinedImageSampler, 1, vk::ShaderStageFlagBits::eFragment},
+		 0, vk::DescriptorType::eCombinedImageSampler, 1, vk::ShaderStageFlagBits::eFragment
+		},
 	};
 
 	if (auto createResult = Vulkan::DescriptorUpdateBatch::create(device.get()); createResult.has_value()) {
@@ -1407,7 +1410,8 @@ void RendererVK::clearBuffer(u32 startAddress, u32 endAddress, u32 value, u32 co
 
 		static vk::ImageSubresourceRange depthStencilRanges[2] = {
 			vk::ImageSubresourceRange(vk::ImageAspectFlagBits::eDepth, 0, 1, 0, 1),
-			vk::ImageSubresourceRange(vk::ImageAspectFlagBits::eStencil, 0, 1, 0, 1)};
+			vk::ImageSubresourceRange(vk::ImageAspectFlagBits::eStencil, 0, 1, 0, 1)
+		};
 
 		// Clear RenderTarget
 		getCurrentCommandBuffer().clearDepthStencilImage(

src/panda_qt/main_window.cpp

@@ -10,6 +10,7 @@
 #include "cheats.hpp"
 #include "input_mappings.hpp"
 #include "panda_qt/dsp_debugger.hpp"
+#include "panda_qt/screen/screen.hpp"
 #include "sdl_sensors.hpp"
 #include "services/dsp.hpp"
 #include "version.hpp"
@@ -25,8 +26,19 @@ MainWindow::MainWindow(QApplication* app, QWidget* parent) : QMainWindow(parent)
 	resize(800, 240 * 4);
 	show();
 
+	const RendererType rendererType = emu->getConfig().rendererType;
+	usingGL = (rendererType == RendererType::OpenGL || rendererType == RendererType::Software || rendererType == RendererType::Null);
+	usingVk = (rendererType == RendererType::Vulkan);
+	usingMtl = (rendererType == RendererType::Metal);
+
+	ScreenWidget::API api = ScreenWidget::API::OpenGL;
+	if (usingVk)
+		api = ScreenWidget::API::Vulkan;
+	else if (usingMtl)
+		api = ScreenWidget::API::Metal;
+
 	// We pass a callback to the screen widget that will be triggered every time we resize the screen
-	screen = new ScreenWidget([this](u32 width, u32 height) { handleScreenResize(width, height); }, this);
+	screen = ScreenWidget::getWidget(api, [this](u32 width, u32 height) { handleScreenResize(width, height); }, this);
 	setCentralWidget(screen);
 
 	appRunning = true;
@@ -149,28 +161,29 @@ MainWindow::MainWindow(QApplication* app, QWidget* parent) : QMainWindow(parent)
 
 	// The emulator graphics context for the thread should be initialized in the emulator thread due to how GL contexts work
 	emuThread = std::thread([this]() {
-		const RendererType rendererType = emu->getConfig().rendererType;
+		switch (screen->api) {
-		usingGL = (rendererType == RendererType::OpenGL || rendererType == RendererType::Software || rendererType == RendererType::Null);
+			case ScreenWidget::API::OpenGL: {
-		usingVk = (rendererType == RendererType::Vulkan);
+				// Make GL context current for this thread, enable VSync
-		usingMtl = (rendererType == RendererType::Metal);
+				GL::Context* glContext = screen->getGLContext();
+				glContext->MakeCurrent();
+				glContext->SetSwapInterval(emu->getConfig().vsyncEnabled ? 1 : 0);
 
-		if (usingGL) {
+				if (glContext->IsGLES()) {
-			// Make GL context current for this thread, enable VSync
+					emu->getRenderer()->setupGLES();
-			GL::Context* glContext = screen->getGLContext();
+				}
-			glContext->MakeCurrent();
-			glContext->SetSwapInterval(emu->getConfig().vsyncEnabled ? 1 : 0);
 
-			if (glContext->IsGLES()) {
+				emu->initGraphicsContext(glContext);
-				emu->getRenderer()->setupGLES();
+				break;
 			}
 
-			emu->initGraphicsContext(glContext);
+			case ScreenWidget::API::Metal: {
-		} else if (usingVk) {
+				emu->initGraphicsContext(nullptr);
-			Helpers::panic("Vulkan on Qt is currently WIP, try the SDL frontend instead!");
+				emu->getRenderer()->setMTKLayer(screen->getMTKLayer());
-		} else if (usingMtl) {
+				break;
-			Helpers::panic("Metal on Qt currently doesn't work, try the SDL frontend instead!");
+			}
-		} else {
+
-			Helpers::panic("Unsupported graphics backend for Qt frontend!");
+			case ScreenWidget::API::Vulkan: Helpers::panic("Vulkan on Qt is currently WIP, try the SDL frontend instead!"); break;
+			default: Helpers::panic("Unsupported graphics backend for Qt frontend!"); break;
 		}
 
 		// We have to initialize controllers on the same thread they'll be polled in
@@ -213,6 +226,8 @@ void MainWindow::emuThreadMainLoop() {
 void MainWindow::swapEmuBuffer() {
 	if (usingGL) {
 		screen->getGLContext()->SwapBuffers();
+	} else if (usingMtl) {
+		// The renderer itself calls presentDrawable to swap buffers on Metal
 	} else {
 		Helpers::panic("[Qt] Don't know how to swap buffers for the current rendering backend :(");
 	}
@@ -290,6 +305,7 @@ MainWindow::~MainWindow() {
 	delete aboutWindow;
 	delete configWindow;
 	delete cheatsEditor;
+	delete screen;
 	delete luaEditor;
 }
 

src/panda_qt/screen/metal_context.mm

@@ -0,0 +1,71 @@
+#import <AppKit/AppKit.h>
+#import <Metal/Metal.h>
+#import <QuartzCore/CAMetalLayer.h>
+#import <Metal/Metal.hpp>
+#import <QWindow>
+#import <QuartzCore/QuartzCore.hpp>
+
+#import "panda_qt/screen/screen_mtl.hpp"
+
+id<MTLDevice> metalDevice = nil;
+
+bool ScreenWidgetMTL::createMetalContext() {
+	NSView* nativeView = (NSView*)this->winId();
+	// Retain the layer so that we can manually memory manage it.
+	CAMetalLayer* metalLayer = [[CAMetalLayer layer] retain];
+
+	if (!metalLayer) {
+		return false;
+	}
+
+	metalDevice = MTLCreateSystemDefaultDevice();
+
+	if (!metalDevice) {
+		NSLog(@"Failed to create metal device");
+		return false;
+	}
+
+	metalLayer.device = metalDevice;
+	metalLayer.framebufferOnly = NO;
+	metalLayer.pixelFormat = MTLPixelFormatBGRA8Unorm;
+
+	CGFloat scale = [nativeView window].backingScaleFactor;
+	CGSize pointSize = nativeView.bounds.size;
+
+	metalLayer.contentsScale = scale;
+	metalLayer.drawableSize = CGSizeMake(pointSize.width * scale, pointSize.height * scale);
+
+	[nativeView setLayer:metalLayer];
+	[nativeView setWantsLayer:YES];
+
+	CA::MetalLayer* cppLayer = (CA::MetalLayer*)metalLayer;
+	mtkLayer = static_cast<void*>(cppLayer);
+
+	return true;
+}
+
+void ScreenWidgetMTL::resizeMetalView() {
+	NSView* view = (NSView*)this->windowHandle()->winId();
+	CAMetalLayer* metalLayer = (CAMetalLayer*)[view layer];
+
+	if (metalLayer) {
+		metalLayer.drawableSize = CGSizeMake(surfaceWidth, surfaceHeight);
+	}
+}
+
+ScreenWidgetMTL::~ScreenWidgetMTL() {
+	if (mtkLayer) {
+		CAMetalLayer* metalLayer = (__bridge CAMetalLayer*)static_cast<CA::MetalLayer*>(mtkLayer);
+
+		NSView* view = (NSView*)this->winId();
+		[view setLayer:nil];
+		[view setWantsLayer:NO];
+
+		// Release Metal device and layer
+		metalLayer.device = nil;
+		[metalLayer release];
+		[metalDevice release];
+
+		mtkLayer = nullptr;
+	}
+}

src/panda_qt/screen/screen.cpp

@@ -1,10 +1,12 @@
+#ifdef PANDA3DS_ENABLE_OPENGL
 #include "opengl.hpp"
+#endif
 // opengl.hpp must be included at the very top. This comment exists to make clang-format not reorder it :p
+
 #include <QGuiApplication>
 #include <QScreen>
 #include <QWindow>
 #include <algorithm>
-#include <array>
 #include <cmath>
 #include <optional>
 
@@ -12,16 +14,16 @@
 #include <qpa/qplatformnativeinterface.h>
 #endif
 
-#include "panda_qt/screen.hpp"
+#include "panda_qt/screen/screen.hpp"
+#include "panda_qt/screen/screen_gl.hpp"
+#include "panda_qt/screen/screen_mtl.hpp"
 
-// OpenGL screen widget, based on https://github.com/stenzek/duckstation/blob/master/src/duckstation-qt/displaywidget.cpp
+// Screen widget, based on https://github.com/stenzek/duckstation/blob/master/src/duckstation-qt/displaywidget.cpp
 // and https://github.com/melonDS-emu/melonDS/blob/master/src/frontend/qt_sdl/main.cpp
 
 #ifdef PANDA3DS_ENABLE_OPENGL
-ScreenWidget::ScreenWidget(ResizeCallback resizeCallback, QWidget* parent) : QWidget(parent), resizeCallback(resizeCallback) {
+ScreenWidget::ScreenWidget(API api, ResizeCallback resizeCallback, QWidget* parent) : api(api), QWidget(parent), resizeCallback(resizeCallback) {
 	// Create a native window for use with our graphics API of choice
-	resize(800, 240 * 4);
-
 	setAutoFillBackground(false);
 	setAttribute(Qt::WA_NativeWindow, true);
 	setAttribute(Qt::WA_NoSystemBackground, true);
@@ -29,11 +31,8 @@ ScreenWidget::ScreenWidget(ResizeCallback resizeCallback, QWidget* parent) : QWi
 	setAttribute(Qt::WA_KeyCompression, false);
 	setFocusPolicy(Qt::StrongFocus);
 	setMouseTracking(true);
-	show();
 
-	if (!createGLContext()) {
+	// The graphics context, as well as resizing and showing the widget, is handled by the screen backend
-		Helpers::panic("Failed to create GL context for display");
-	}
 }
 
 void ScreenWidget::resizeEvent(QResizeEvent* event) {
@@ -48,18 +47,7 @@ void ScreenWidget::resizeEvent(QResizeEvent* event) {
 	}
 
 	reloadScreenCoordinates();
-
+	resizeDisplay();
-	// This will call take care of calling resizeSurface from the emulator thread
-	resizeCallback(surfaceWidth, surfaceHeight);
-}
-
-// Note: This will run on the emulator thread, we don't want any Qt calls happening there.
-void ScreenWidget::resizeSurface(u32 width, u32 height) {
-	if (previousWidth != width || previousHeight != height) {
-		if (glContext) {
-			glContext->ResizeSurface(width, height);
-		}
-	}
 }
 
 void ScreenWidget::reloadScreenCoordinates() {
@@ -73,30 +61,6 @@ void ScreenWidget::reloadScreenLayout(ScreenLayout::Layout newLayout, float newT
 	reloadScreenCoordinates();
 }
 
-bool ScreenWidget::createGLContext() {
-	// List of GL context versions we will try. Anything 4.1+ is good for desktop OpenGL, and 3.1+ for OpenGL ES
-	static constexpr std::array<GL::Context::Version, 8> versionsToTry = {
-		GL::Context::Version{GL::Context::Profile::Core, 4, 6}, GL::Context::Version{GL::Context::Profile::Core, 4, 5},
-		GL::Context::Version{GL::Context::Profile::Core, 4, 4}, GL::Context::Version{GL::Context::Profile::Core, 4, 3},
-		GL::Context::Version{GL::Context::Profile::Core, 4, 2}, GL::Context::Version{GL::Context::Profile::Core, 4, 1},
-		GL::Context::Version{GL::Context::Profile::ES, 3, 2},   GL::Context::Version{GL::Context::Profile::ES, 3, 1},
-	};
-
-	std::optional<WindowInfo> windowInfo = getWindowInfo();
-	if (windowInfo.has_value()) {
-		this->windowInfo = *windowInfo;
-
-		glContext = GL::Context::Create(*getWindowInfo(), versionsToTry);
-		if (glContext == nullptr) {
-			return false;
-		}
-
-		glContext->DoneCurrent();
-	}
-
-	return glContext != nullptr;
-}
-
 qreal ScreenWidget::devicePixelRatioFromScreen() const {
 	const QScreen* screenForRatio = windowHandle()->screen();
 	if (!screenForRatio) {
@@ -156,3 +120,15 @@ std::optional<WindowInfo> ScreenWidget::getWindowInfo() {
 	return wi;
 }
 #endif
+
+ScreenWidget* ScreenWidget::getWidget(API api, ResizeCallback resizeCallback, QWidget* parent) {
+	if (api == API::OpenGL) {
+		return new ScreenWidgetGL(api, resizeCallback, parent);
+	} else if (api == API::Metal) {
+		return new ScreenWidgetMTL(api, resizeCallback, parent);
+	} else if (api == API::Vulkan) {
+		Helpers::panic("Vulkan is not yet supported on Panda3DS-Qt. Try SDL instead");
+	} else {
+		Helpers::panic("ScreenWidget::getWidget: Unimplemented graphics API");
+	}
+}

src/panda_qt/screen/screen_gl.cpp

@@ -0,0 +1,64 @@
+#include "panda_qt/screen/screen_gl.hpp"
+
+#include <array>
+
+#ifdef PANDA3DS_ENABLE_OPENGL
+ScreenWidgetGL::ScreenWidgetGL(API api, ResizeCallback resizeCallback, QWidget* parent) : ScreenWidget(api, resizeCallback, parent) {
+	// On Wayland + OpenGL, we have to show the window before we can create a graphics context.
+	resize(800, 240 * 4);
+	show();
+
+	if (!createContext()) {
+		Helpers::panic("Failed to create GL context for display");
+	}
+}
+
+bool ScreenWidgetGL::createContext() {
+	// List of GL context versions we will try. Anything 4.1+ is good for desktop OpenGL, and 3.1+ for OpenGL ES
+	static constexpr std::array<GL::Context::Version, 8> versionsToTry = {
+		GL::Context::Version{GL::Context::Profile::Core, 4, 6}, GL::Context::Version{GL::Context::Profile::Core, 4, 5},
+		GL::Context::Version{GL::Context::Profile::Core, 4, 4}, GL::Context::Version{GL::Context::Profile::Core, 4, 3},
+		GL::Context::Version{GL::Context::Profile::Core, 4, 2}, GL::Context::Version{GL::Context::Profile::Core, 4, 1},
+		GL::Context::Version{GL::Context::Profile::ES, 3, 2},   GL::Context::Version{GL::Context::Profile::ES, 3, 1},
+	};
+
+	std::optional<WindowInfo> windowInfo = getWindowInfo();
+	if (windowInfo.has_value()) {
+		this->windowInfo = *windowInfo;
+
+		glContext = GL::Context::Create(*getWindowInfo(), versionsToTry);
+		if (glContext == nullptr) {
+			return false;
+		}
+
+		glContext->DoneCurrent();
+	}
+
+	return glContext != nullptr;
+}
+
+void ScreenWidgetGL::resizeDisplay() {
+	// This will call take care of calling resizeSurface from the emulator thread, as the GL renderer must resize from the emu thread
+	resizeCallback(surfaceWidth, surfaceHeight);
+}
+
+// Note: This will run on the emulator thread, we don't want any Qt calls happening there.
+void ScreenWidgetGL::resizeSurface(u32 width, u32 height) {
+	if (previousWidth != width || previousHeight != height) {
+		if (glContext) {
+			glContext->ResizeSurface(width, height);
+		}
+	}
+}
+
+GL::Context* ScreenWidgetGL::getGLContext() { return glContext.get(); }
+#else
+ScreenWidgetGL::ScreenWidgetGL(API api, ResizeCallback resizeCallback, QWidget* parent) : ScreenWidget(api, resizeCallback, parent) {
+	Helpers::panic("OpenGL renderer not supported. Make sure you've compiled with OpenGL support and that you're on a compatible platform");
+}
+
+GL::Context* ScreenWidgetGL::getGLContext() { nullptr; }
+bool ScreenWidgetGL::createContext() { return false; }
+void ScreenWidgetGL::resizeDisplay() {}
+void ScreenWidgetGL::resizeSurface(u32 width, u32 height) {}
+#endif

src/panda_qt/screen/screen_mtl.cpp

@@ -0,0 +1,33 @@
+#include "panda_qt/screen/screen_mtl.hpp"
+
+#ifdef PANDA3DS_ENABLE_METAL
+ScreenWidgetMTL::ScreenWidgetMTL(API api, ResizeCallback resizeCallback, QWidget* parent) : ScreenWidget(api, resizeCallback, parent) {
+	if (!createContext()) {
+		Helpers::panic("Failed to create Metal context for display");
+	}
+
+	resize(800, 240 * 4);
+	show();
+}
+
+void ScreenWidgetMTL::resizeDisplay() {
+	resizeMetalView();
+	resizeCallback(surfaceWidth, surfaceHeight);
+}
+
+bool ScreenWidgetMTL::createContext() { return createMetalContext(); }
+void* ScreenWidgetMTL::getMTKLayer() { return mtkLayer; }
+
+#else
+ScreenWidgetMTL::ScreenWidgetMTL(API api, ResizeCallback resizeCallback, QWidget* parent) : ScreenWidget(api, resizeCallback, parent) {
+	Helpers::panic("Metal renderer not supported. Make sure you've compiled with Metal support and that you're on a compatible platform");
+}
+
+ScreenWidgetMTL::~ScreenWidgetMTL() {}
+bool ScreenWidgetMTL::createContext() { return false; }
+bool ScreenWidgetMTL::createMetalContext() { return false; }
+void* ScreenWidgetMTL::getMTKLayer() { return nullptr; }
+
+void ScreenWidgetMTL::resizeDisplay() {}
+void ScreenWidgetMTL::resizeMetalView() {}
+#endif