core/window: handle graphics context loss

src/window/proxywindow.cpp

@@ -1,6 +1,7 @@
 #include "proxywindow.hpp"
 
 #include <private/qquickwindow_p.h>
+#include <qcontainerfwd.h>
 #include <qcoreevent.h>
 #include <qevent.h>
 #include <qguiapplication.h>
@@ -112,6 +113,8 @@ void ProxyWindowBase::ensureQWindow() {
 		auto opaque = this->qsSurfaceFormat.opaqueModified ? this->qsSurfaceFormat.opaque
 		                                                   : this->mColor.alpha() >= 255;
 
+		format.setOption(QSurfaceFormat::ResetNotification);
+
 		if (opaque) format.setAlphaBufferSize(0);
 		else format.setAlphaBufferSize(8);
 
@@ -195,6 +198,7 @@ void ProxyWindowBase::connectWindow() {
 	QObject::connect(this->window, &QWindow::heightChanged, this, &ProxyWindowBase::heightChanged);
 	QObject::connect(this->window, &QWindow::screenChanged, this, &ProxyWindowBase::screenChanged);
 	QObject::connect(this->window, &QQuickWindow::colorChanged, this, &ProxyWindowBase::colorChanged);
+	QObject::connect(this->window, &QQuickWindow::sceneGraphError, this, &ProxyWindowBase::onSceneGraphError);
 	QObject::connect(this->window, &ProxiedWindow::exposed, this, &ProxyWindowBase::onExposed);
 	QObject::connect(this->window, &ProxiedWindow::devicePixelRatioChanged, this, &ProxyWindowBase::devicePixelRatioChanged);
 	// clang-format on
@@ -226,6 +230,22 @@ void ProxyWindowBase::completeWindow() {
 	emit this->screenChanged();
 }
 
+void ProxyWindowBase::onSceneGraphError(
+    QQuickWindow::SceneGraphError error,
+    const QString& message
+) {
+	if (error == QQuickWindow::ContextNotAvailable) {
+		qCritical().nospace() << "Failed to create graphics context for " << this << ": " << message;
+	} else {
+		qCritical().nospace() << "Scene graph error " << error << " occurred for " << this << ": "
+		                      << message;
+	}
+
+	emit this->resourcesLost();
+	this->mVisible = false;
+	this->setVisibleDirect(false);
+}
+
 void ProxyWindowBase::onVisibleChanged() {
 	if (this->mVisible && !this->window->isVisible()) {
 		this->mVisible = false;

src/window/proxywindow.hpp

@@ -142,6 +142,7 @@ public:
 
 signals:
 	void closed();
+	void resourcesLost();
 	void windowConnected();
 	void windowDestroyed();
 	void visibleChanged();
@@ -161,13 +162,16 @@ signals:
 	void polished();
 
 protected slots:
-	void onVisibleChanged();
 	virtual void onWidthChanged();
 	virtual void onHeightChanged();
+	virtual void onPolished();
+
+private slots:
+	void onSceneGraphError(QQuickWindow::SceneGraphError error, const QString& message);
+	void onVisibleChanged();
 	void onMaskChanged();
 	void onMaskDestroyed();
 	void onScreenDestroyed();
-	virtual void onPolished();
 	void onExposed();
 
 protected:

src/window/windowinterface.cpp

@@ -134,6 +134,7 @@ void WindowInterface::connectSignals() const {
 	auto* window = this->proxyWindow();
 	// clang-format off
 	QObject::connect(window, &ProxyWindowBase::closed, this, &WindowInterface::closed);
+	QObject::connect(window, &ProxyWindowBase::resourcesLost, this, &WindowInterface::resourcesLost);
 	QObject::connect(window, &ProxyWindowBase::windowConnected, this, &WindowInterface::windowConnected);
 	QObject::connect(window, &ProxyWindowBase::visibleChanged, this, &WindowInterface::visibleChanged);
 	QObject::connect(window, &ProxyWindowBase::backerVisibilityChanged, this, &WindowInterface::backingWindowVisibleChanged);

src/window/windowinterface.hpp

@@ -239,6 +239,12 @@ signals:
 	/// This signal is emitted when the window is closed by the user, the display server,
 	/// or an error. It is not emitted when @@visible is set to false.
 	void closed();
+	/// This signal is emitted when resources a window depends on to display are lost,
+	/// or could not be acquired during window creation. The most common trigger for
+	/// this signal is a lack of VRAM when creating or resizing a window.
+	///
+	/// Following this signal, @@closed(s) will be sent.
+	void resourcesLost();
 	void windowConnected();
 	void visibleChanged();
 	void backingWindowVisibleChanged();