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

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);
-	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);
+	enum class API { OpenGL, Metal, Vulkan };
 
-	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
-	// of layout or resizing
+	API api = API::OpenGL;
+
+	// 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:
-	std::unique_ptr<GL::Context> glContext = nullptr;
+	// Creates a screen widget depending on the graphics API we're using
+	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;
+};