[desktop] Bump minimum Qt to 6.6 (#4628)

Signed-off-by: crueter <crueter@eden-emu.dev>

- [x] I have read and followed the [Contribution Guidelines](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/CONTRIBUTING.md#code-contributions).
- [x] I have read and followed the [Coding Guidelines](https://git.eden-emu.dev/eden-emu/eden/src/branch/master/docs/policies/Coding.md) to the best of my ability.
- [x] I have read and followed the [website policy](https://git.eden-emu.dev/eden-emu/site-policy).
- [x] I affirm that the content of this pull request body was written and submitted entirely by me, in my own words, and not by an AI agent or LLM.
- [ ] I affirm that I did not read any of this, and understand that my pull request will be closed if I check this box.
- [x] I affirm that, by submitting this pull request, I am responsible for all of the changes contained within these commits.

-------------------

Reviewed-on: https://git.eden-emu.dev/eden-emu/eden/pulls/4628
Reviewed-by: lizzie <lizzie@eden-emu.dev>

CMakeLists.txt

@@ -594,7 +594,7 @@ if (ENABLE_QT)
         list(APPEND CMAKE_PREFIX_PATH "${Qt6_DIR}")
     endif()
 
-    find_package(Qt6 REQUIRED COMPONENTS Core)
+    find_package(Qt6 6.5 REQUIRED COMPONENTS Core)
 
     if (NOT DEFINED QT_TARGET_PATH)
         get_target_property(qtcore_path Qt6::Core LOCATION_Release)

docs/Deps.md

@@ -25,7 +25,7 @@ The following additional tools are also required:
     * `tools/windows/install-vulkan-sdk.ps1` (for PowerShell 5+)
     * `tools/windows/install-vulkan-sdk.sh` (for Git Bash, etc)
 
-If you are on desktop and plan to use the Qt frontend, you *must* install Qt 6, and optionally Qt Creator (the **RECOMMENDED** IDE for building)
+If you are on desktop and plan to use the Qt frontend, you *must* install Qt >=6.6, and optionally Qt Creator (the **RECOMMENDED** IDE for building)
 
 * On Linux, *BSD and macOS, this can be done by the package manager
   * If you wish to use Qt Creator, append `qtcreator` or `qt-creator` to the commands seen below.

src/qt_common/qt_common.cpp

@@ -332,10 +332,10 @@ QPixmap CreateCirclePixmapFromColor(const QColor& color) {
 }
 
 #ifdef _WIN32
-// TODO(crueter): Does this affect Qt 6 at all?
 static void OverrideWindowsFont() {
-    // Qt5 chooses these fonts on Windows and they have fairly ugly alphanumeric/cyrillic characters
+    // Qt chooses these fonts on Windows and they have fairly ugly alphanumeric/cyrillic characters
     // Asking to use "MS Shell Dlg 2" gives better other chars while leaving the Chinese Characters.
+    // https://github.com/qt/qtbase/blob/v6.12.0/src/gui/text/windows/qwindowsfontdatabasebase.cpp#L970-L1020
     const QString startup_font = QGuiApplication::font().family();
     const QStringList ugly_fonts = {QStringLiteral("SimSun"), QStringLiteral("PMingLiU")};
     if (ugly_fonts.contains(startup_font)) {

src/yuzu/bootmanager.cpp

@@ -179,11 +179,6 @@ bool GRenderWindow::IsShown() const {
     return !isMinimized();
 }
 
-// On Qt 5.0+, this correctly gets the size of the framebuffer (pixels).
-//
-// Older versions get the window size (density independent pixels),
-// and hence, do not support DPI scaling ("retina" displays).
-// The result will be a viewport that is smaller than the extent of the window.
 void GRenderWindow::OnFramebufferSizeChanged() {
     // Screen changes potentially incur a change in screen DPI, hence we should update the
     // framebuffer size

src/yuzu/loading_screen.h

@@ -12,6 +12,8 @@
 #include <QWidget>
 #include <QtGlobal>
 
+#include "common/container/unordered_map.h"
+
 #if !QT_CONFIG(movie)
 #define YUZU_QT_MOVIE_MISSING 1
 #endif
@@ -91,7 +93,3 @@ private:
     std::chrono::steady_clock::time_point previous_time;
     std::size_t slow_shader_first_value = 0;
 };
-
-#if QT_VERSION < QT_VERSION_CHECK(6, 0, 0)
-Q_DECLARE_METATYPE(VideoCore::LoadCallbackStage);
-#endif

src/yuzu/main_window.cpp

@@ -64,9 +64,7 @@
 // Qt Stuff //
 #define QT_NO_OPENGL
 
-#if QT_VERSION >= QT_VERSION_CHECK(6, 5, 0)
 #include <QStyleHints>
-#endif
 
 #include <QActionGroup>
 #include <QCheckBox>
@@ -345,17 +343,9 @@ QString GetTranslatedGameIconSize(size_t index) {
 } // namespace
 
 #ifndef _WIN32
-// TODO(crueter): carboxyl does this, is it needed in qml?
 inline static bool isDarkMode() {
-#if QT_VERSION >= QT_VERSION_CHECK(6, 5, 0)
     const auto scheme = QGuiApplication::styleHints()->colorScheme();
     return scheme == Qt::ColorScheme::Dark;
-#else
-    const QPalette defaultPalette;
-    const auto text = defaultPalette.color(QPalette::WindowText);
-    const auto window = defaultPalette.color(QPalette::Window);
-    return text.lightness() > window.lightness();
-#endif // QT_VERSION
 }
 #endif // _WIN32