Take advantage of RHI

Use Metal with Qt 6.4+ and macOS 10.14+, OpenGL for Wayland whenever enabled

ui/gl/gl_window.cpp

@@ -23,6 +23,16 @@ namespace Ui::GL {
 namespace {
 
 constexpr auto kUseNativeChild = false;// ::Platform::IsWindows();
+
+class RpWindowNoRhi : public RpWindow {
+protected:
+#if QT_VERSION >= QT_VERSION_CHECK(6, 4, 0)
+	std::optional<QPlatformBackingStoreRhiConfig> rhiConfig() const override {
+		return QPlatformBackingStoreRhiConfig();
+	}
+#endif // Qt >= 6.4.0
+};
+
 [[nodiscard]] Fn<Backend(Capabilities)> ChooseBackendWrap(
 		Fn<Backend(Capabilities)> chooseBackend) {
 	return [=](Capabilities capabilities) {
@@ -60,7 +70,7 @@ not_null<RpWidget*> Window::widget() const {
 
 std::unique_ptr<RpWindow> Window::createWindow(
 		const Fn<Backend(Capabilities)> &chooseBackend) {
-	auto result = std::make_unique<RpWindow>();
+	std::unique_ptr<RpWindow> result = std::make_unique<RpWindowNoRhi>();
 	if constexpr (!kUseNativeChild) {
 		_backend = chooseBackend(CheckCapabilities(result.get()));
 		if (_backend != Backend::OpenGL) {

ui/platform/mac/ui_window_mac.mm

@@ -270,7 +270,9 @@ void WindowHelper::Private::enforceStyle() {
 }
 
 void WindowHelper::Private::initOpenGL() {
+#if QT_VERSION < QT_VERSION_CHECK(6, 4, 0)
 	auto forceOpenGL = std::make_unique<QOpenGLWidget>(_owner->window());
+#endif // Qt < 6.4.0
 }
 
 void WindowHelper::Private::resolveWeakPointers() {

ui/rp_widget.cpp

@@ -6,10 +6,45 @@
 //
 #include "ui/rp_widget.h"
 
+#include "base/platform/base_platform_info.h"
 #include "base/qt_signal_producer.h"
+#include "ui/gl/gl_detection.h"
 
 #include <QtGui/QWindow>
 #include <QtGui/QtEvents>
+#include <private/qwidget_p.h>
+
+class TWidgetPrivate : public QWidgetPrivate {
+public:
+#if QT_VERSION >= QT_VERSION_CHECK(6, 4, 0)
+	QPlatformBackingStoreRhiConfig rhiConfig() const override {
+		const auto q = static_cast<TWidget*>(q_ptr);
+		if (!q->testAttribute(Qt::WA_WState_Created)) {
+			return QWidgetPrivate::rhiConfig();
+		}
+		if (const auto config = q->rhiConfig()) {
+			return *config;
+		}
+		if (::Platform::IsMac10_14OrGreater()) {
+			return { QPlatformBackingStoreRhiConfig::Metal };
+		}
+		// We can't specify the widget here as q_evaluateRhiConfig is called
+		// in QWidgetWindow constructor, while windowHandle is set right after
+		// the constructor is completed
+		if (::Platform::IsWayland() // old versions of mutter produce flicker without OpenGL
+			&& Ui::GL::ChooseBackendDefault(
+					Ui::GL::CheckCapabilities(nullptr))
+				== Ui::GL::Backend::OpenGL) {
+			return { QPlatformBackingStoreRhiConfig::OpenGL };
+		}
+		return QWidgetPrivate::rhiConfig();
+	}
+#endif // Qt >= 6.4.0
+};
+
+TWidget::TWidget(QWidget *parent)
+: TWidgetHelper<QWidget>(*(new TWidgetPrivate), parent, {}) {
+}
 
 namespace Ui {
 namespace {

ui/rp_widget.h

@@ -18,6 +18,10 @@
 #include <QtCore/QPointer>
 #include <QtGui/QtEvents>
 
+#if QT_VERSION >= QT_VERSION_CHECK(6, 4, 0)
+#include <qpa/qplatformbackingstore.h>
+#endif // Qt >= 6.4.0
+
 namespace Ui {
 
 void ToggleChildrenVisibility(not_null<QWidget*> widget, bool visible);
@@ -25,6 +29,7 @@ void ToggleChildrenVisibility(not_null<QWidget*> widget, bool visible);
 } // namespace Ui
 
 class TWidget;
+class TWidgetPrivate;
 
 template <typename Base>
 class TWidgetHelper : public Base {
@@ -146,6 +151,12 @@ protected:
 	virtual void enterFromChildEvent(QEvent *e, QWidget *child) {
 	}
 
+#if QT_VERSION >= QT_VERSION_CHECK(6, 4, 0)
+	virtual std::optional<QPlatformBackingStoreRhiConfig> rhiConfig() const {
+		return std::nullopt;
+	}
+#endif // Qt >= 6.4.0
+
 private:
 	TWidget *tparent() {
 		return qobject_cast<TWidget*>(Base::parentWidget());
@@ -157,6 +168,8 @@ private:
 	template <typename OtherBase>
 	friend class TWidgetHelper;
 
+	friend class TWidgetPrivate;
+
 };
 
 class TWidget : public TWidgetHelper<QWidget> {
@@ -164,8 +177,7 @@ class TWidget : public TWidgetHelper<QWidget> {
 	Q_OBJECT
 
 public:
-	TWidget(QWidget *parent = nullptr) : TWidgetHelper<QWidget>(parent) {
-	}
+	TWidget(QWidget *parent = nullptr);
 
 	// Get the size of the widget as it should be.
 	// Negative return value means no default width.