[qt] refactor: qt_common lib (#94)

This is part of a series of PRs made in preparation for the QML rewrite. this PR specifically moves a bunch of utility functions from main.cpp into qt_common, with the biggest benefit being that QML can reuse the exact same code through ctx passthrough.

Also, QtCommon::Frontend is an abstraction layer over several previously Widgets-specific stuff like QMessageBox that gets used everywhere. The idea is that once QML is implemented, these functions can have a Quick version implemented for systems that don't work well with Widgets (sun) or for those on Plasma 6+ (reduces memory usage w/o Widgets linkage) although Quick from C++ is actually anal, but whatever.

Other than that this should also just kinda reduce the size of main.cpp which is a 6000-line behemoth rn, and clangd straight up gives up with it for me (likely caused by the massive amount of headers, which this DOES reduce).

In the future, I probably want to create a common strings lookup table that both Qt and QML can reference--though I'm not sure how much linguist likes that--which should give us a way to keep language consistent (use frozen-map).

TODO: Docs for Qt stuff

Co-authored-by: MaranBr <maranbr@outlook.com>
Reviewed-on: eden-emu/eden#94
Reviewed-by: MaranBr <maranbr@eden-emu.dev>
Reviewed-by: Shinmegumi <shinmegumi@eden-emu.dev>

src/qt_common/qt_common.cpp

@@ -0,0 +1,122 @@
+// SPDX-FileCopyrightText: Copyright 2025 Eden Emulator Project
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "qt_common.h"
+#include "common/fs/fs.h"
+
+#include <QGuiApplication>
+#include <QStringLiteral>
+#include "common/logging/log.h"
+#include "core/frontend/emu_window.h"
+
+#include <QFile>
+
+#include <QMessageBox>
+
+#include <JlCompress.h>
+
+#if !defined(WIN32) && !defined(__APPLE__)
+#include <qpa/qplatformnativeinterface.h>
+#elif defined(__APPLE__)
+#include <objc/message.h>
+#endif
+
+namespace QtCommon {
+
+#ifdef YUZU_QT_WIDGETS
+QWidget* rootObject = nullptr;
+#else
+QObject* rootObject = nullptr;
+#endif
+
+std::unique_ptr<Core::System> system = nullptr;
+std::shared_ptr<FileSys::RealVfsFilesystem> vfs = nullptr;
+std::unique_ptr<FileSys::ManualContentProvider> provider = nullptr;
+
+Core::Frontend::WindowSystemType GetWindowSystemType()
+{
+    // Determine WSI type based on Qt platform.
+    QString platform_name = QGuiApplication::platformName();
+    if (platform_name == QStringLiteral("windows"))
+        return Core::Frontend::WindowSystemType::Windows;
+    else if (platform_name == QStringLiteral("xcb"))
+        return Core::Frontend::WindowSystemType::X11;
+    else if (platform_name == QStringLiteral("wayland"))
+        return Core::Frontend::WindowSystemType::Wayland;
+    else if (platform_name == QStringLiteral("wayland-egl"))
+        return Core::Frontend::WindowSystemType::Wayland;
+    else if (platform_name == QStringLiteral("cocoa"))
+        return Core::Frontend::WindowSystemType::Cocoa;
+    else if (platform_name == QStringLiteral("android"))
+        return Core::Frontend::WindowSystemType::Android;
+
+    LOG_CRITICAL(Frontend, "Unknown Qt platform {}!", platform_name.toStdString());
+    return Core::Frontend::WindowSystemType::Windows;
+} // namespace Core::Frontend::WindowSystemType
+
+Core::Frontend::EmuWindow::WindowSystemInfo GetWindowSystemInfo(QWindow* window)
+{
+    Core::Frontend::EmuWindow::WindowSystemInfo wsi;
+    wsi.type = GetWindowSystemType();
+
+#if defined(WIN32)
+    // Our Win32 Qt external doesn't have the private API.
+    wsi.render_surface = reinterpret_cast<void*>(window->winId());
+#elif defined(__APPLE__)
+    wsi.render_surface = reinterpret_cast<void* (*) (id, SEL)>(
+        objc_msgSend)(reinterpret_cast<id>(window->winId()), sel_registerName("layer"));
+#else
+    QPlatformNativeInterface* pni = QGuiApplication::platformNativeInterface();
+    wsi.display_connection = pni->nativeResourceForWindow("display", window);
+    if (wsi.type == Core::Frontend::WindowSystemType::Wayland)
+        wsi.render_surface = window ? pni->nativeResourceForWindow("surface", window) : nullptr;
+    else
+        wsi.render_surface = window ? reinterpret_cast<void*>(window->winId()) : nullptr;
+#endif
+    wsi.render_surface_scale = window ? static_cast<float>(window->devicePixelRatio()) : 1.0f;
+
+    return wsi;
+}
+
+const QString tr(const char* str)
+{
+    return QGuiApplication::tr(str);
+}
+
+const QString tr(const std::string& str)
+{
+    return QGuiApplication::tr(str.c_str());
+}
+
+#ifdef YUZU_QT_WIDGETS
+void Init(QWidget* root)
+#else
+void Init(QObject* root)
+#endif
+{
+    system = std::make_unique<Core::System>();
+    rootObject = root;
+    vfs = std::make_unique<FileSys::RealVfsFilesystem>();
+    provider = std::make_unique<FileSys::ManualContentProvider>();
+}
+
+std::filesystem::path GetEdenCommand() {
+    std::filesystem::path command;
+
+    QString appimage = QString::fromLocal8Bit(getenv("APPIMAGE"));
+    if (!appimage.isEmpty()) {
+        command = std::filesystem::path{appimage.toStdString()};
+    } else {
+        const QStringList args = QGuiApplication::arguments();
+        command = args[0].toStdString();
+    }
+
+    // If relative path, make it an absolute path
+    if (command.c_str()[0] == '.') {
+        command = Common::FS::GetCurrentDir() / command;
+    }
+
+    return command;
+}
+
+} // namespace QtCommon