Add Qt screen widget

CMakeLists.txt

@@ -63,7 +63,7 @@ if(ENABLE_DISCORD_RPC AND NOT ANDROID)
     include_directories(third_party/discord-rpc/include)
 endif()
 
-if (ENABLE_QT_GUI)
+if(ENABLE_QT_GUI)
     find_package(Qt6 REQUIRED COMPONENTS Widgets)
 
     # We can't use qt_standard_project_setup since it's Qt 6.3+ and we don't need to set the minimum that high
@@ -179,9 +179,14 @@ set(RENDERER_SW_SOURCE_FILES src/core/renderer_sw/renderer_sw.cpp)
 
 # Frontend source files
 if(ENABLE_QT_GUI)
-    set(FRONTEND_SOURCE_FILES src/panda_qt/main.cpp)
+    set(FRONTEND_SOURCE_FILES src/panda_qt/main.cpp src/panda_qt/screen.cpp)
+    set(FRONTEND_HEADER_FILES include/panda_qt/screen.hpp)
+    
+    source_group("Source Files\\Qt" FILES ${FRONTEND_SOURCE_FILES})
+    source_group("Header Files\\Qt" FILES ${FRONTEND_HEADER_FILES})
 else()
     set(FRONTEND_SOURCE_FILES src/panda_sdl/main.cpp)
+    set(FRONTEND_HEADER_FILES "")
 endif()
 
 set(HEADER_FILES include/emulator.hpp include/helpers.hpp include/termcolor.hpp
@@ -353,7 +358,8 @@ endif()
 
 source_group("Header Files\\Core" FILES ${HEADER_FILES})
 set(ALL_SOURCES ${SOURCE_FILES} ${FRONTEND_SOURCE_FILES} ${FS_SOURCE_FILES} ${CRYPTO_SOURCE_FILES} ${KERNEL_SOURCE_FILES} 
-    ${LOADER_SOURCE_FILES} ${SERVICE_SOURCE_FILES} ${APPLET_SOURCE_FILES} ${RENDERER_SW_SOURCE_FILES} ${PICA_SOURCE_FILES} ${THIRD_PARTY_SOURCE_FILES} ${HEADER_FILES})
+    ${LOADER_SOURCE_FILES} ${SERVICE_SOURCE_FILES} ${APPLET_SOURCE_FILES} ${RENDERER_SW_SOURCE_FILES} ${PICA_SOURCE_FILES} ${THIRD_PARTY_SOURCE_FILES}
+    ${HEADER_FILES} ${FRONTEND_HEADER_FILES})
 
 if(ENABLE_OPENGL)
     # Add the OpenGL source files to ALL_SOURCES

include/panda_qt/screen.hpp

@@ -0,0 +1,36 @@
+#pragma once
+#include <QWidget>
+#include <memory>
+
+#include "gl/context.h"
+#include "window_info.h"
+
+// OpenGL widget for drawing the 3DS screen
+class ScreenWidget : public QWidget {
+	Q_OBJECT
+
+  public:
+	ScreenWidget(QWidget* parent = nullptr) : QWidget(parent) {
+		// Create a native window for use with our graphics API of choice
+		setAutoFillBackground(false);
+		setAttribute(Qt::WA_NativeWindow, true);
+		setAttribute(Qt::WA_NoSystemBackground, true);
+		setAttribute(Qt::WA_PaintOnScreen, true);
+		setAttribute(Qt::WA_KeyCompression, false);
+		setFocusPolicy(Qt::StrongFocus);
+		setMouseTracking(true);
+
+		if (!createGLContext()) {
+			Helpers::panic("Failed to create GL context for display");
+		}
+	}
+
+  private:
+	std::unique_ptr<GL::Context> glContext = nullptr;
+	bool createGLContext();
+
+	qreal devicePixelRatioFromScreen() const;
+	int scaledWindowWidth() const;
+	int scaledWindowHeight() const;
+	std::optional<WindowInfo> getWindowInfo();
+};

src/panda_qt/main.cpp

@@ -1,12 +1,17 @@
 #include <QApplication>
 #include <QtWidgets>
 
+#include "panda_qt/screen.hpp"
+
 int main(int argc, char *argv[]) {
-    QApplication app(argc, argv);
-    QWidget window;
-    
-    window.resize(320, 240);
-    window.show();
-    window.setWindowTitle("Alber");
-    return app.exec();
+	QApplication app(argc, argv);
+	QWidget window;
+
+	window.resize(320, 240);
+	window.show();
+	window.setWindowTitle("Alber");
+	ScreenWidget screen(&window);
+	screen.show();
+
+	return app.exec();
 }

src/panda_qt/screen.cpp

@@ -0,0 +1,86 @@
+#include "panda_qt/screen.hpp"
+
+#include <algorithm>
+#include <array>
+#include <cmath>
+#include <optional>
+#include <QGuiApplication>
+#include <QScreen>
+#include <QWindow>
+
+// OpenGL screen widget, based on https://github.com/melonDS-emu/melonDS/blob/master/src/frontend/qt_sdl/main.cpp
+
+#ifdef PANDA3DS_ENABLE_OPENGL
+bool ScreenWidget::createGLContext() {
+	// List of GL context versions we will try. Anything 4.1+ is good
+	static constexpr std::array<GL::Context::Version, 6> 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},
+	};
+
+	std::optional<WindowInfo> windowInfo = getWindowInfo();
+	if (windowInfo.has_value()) {
+		glContext = GL::Context::Create(*getWindowInfo(), versionsToTry);
+		glContext->DoneCurrent();
+	}
+
+	return glContext != nullptr;
+}
+
+qreal ScreenWidget::devicePixelRatioFromScreen() const {
+	const QScreen* screenForRatio = window()->windowHandle()->screen();
+	if (!screenForRatio) {
+		screenForRatio = QGuiApplication::primaryScreen();
+	}
+
+	return screenForRatio ? screenForRatio->devicePixelRatio() : static_cast<qreal>(1);
+}
+
+int ScreenWidget::scaledWindowWidth() const {
+	return std::max(static_cast<int>(std::ceil(static_cast<qreal>(width()) * devicePixelRatioFromScreen())), 1);
+}
+
+int ScreenWidget::scaledWindowHeight() const {
+	return std::max(static_cast<int>(std::ceil(static_cast<qreal>(height()) * devicePixelRatioFromScreen())), 1);
+}
+
+std::optional<WindowInfo> ScreenWidget::getWindowInfo() {
+	WindowInfo wi;
+
+// Windows and Apple are easy here since there's no display connection.
+#if defined(_WIN32)
+	wi.type = WindowInfo::Type::Win32;
+	wi.window_handle = reinterpret_cast<void*>(winId());
+#elif defined(__APPLE__)
+	wi.type = WindowInfo::Type::MacOS;
+	wi.window_handle = reinterpret_cast<void*>(winId());
+#else
+	QPlatformNativeInterface* pni = QGuiApplication::platformNativeInterface();
+	const QString platform_name = QGuiApplication::platformName();
+	if (platform_name == QStringLiteral("xcb")) {
+		wi.type = WindowInfo::Type::X11;
+		wi.display_connection = pni->nativeResourceForWindow("display", windowHandle());
+		wi.window_handle = reinterpret_cast<void*>(winId());
+	} else if (platform_name == QStringLiteral("wayland")) {
+		wi.type = WindowInfo::Type::Wayland;
+		QWindow* handle = windowHandle();
+		if (handle == nullptr) {
+			return std::nullopt;
+		}
+
+		wi.display_connection = pni->nativeResourceForWindow("display", handle);
+		wi.window_handle = pni->nativeResourceForWindow("surface", handle);
+	} else {
+		qCritical() << "Unknown PNI platform " << platform_name;
+		return std::nullopt;
+	}
+#endif
+
+	wi.surface_width = static_cast<u32>(scaledWindowWidth());
+	wi.surface_height = static_cast<u32>(scaledWindowHeight());
+	wi.surface_scale = static_cast<float>(devicePixelRatioFromScreen());
+
+	return wi;
+}
+#endif