core: switch to custom incubation controller

This change requires more QtPrivate usage but eliminates generation or
cleanup related window incubation controller bugs. Additionally it
enables async loads prior to rendering windows.

src/core/incubator.cpp

@@ -1,7 +1,16 @@
 #include "incubator.hpp"
 
+#include <private/qsgrenderloop_p.h>
+#include <qabstractanimation.h>
+#include <qguiapplication.h>
 #include <qlogging.h>
+#include <qloggingcategory.h>
+#include <qminmax.h>
+#include <qnamespace.h>
+#include <qobject.h>
+#include <qobjectdefs.h>
 #include <qqmlincubator.h>
+#include <qscreen.h>
 #include <qtmetamacros.h>
 
 #include "logcat.hpp"
@@ -15,3 +24,112 @@ void QsQmlIncubator::statusChanged(QQmlIncubator::Status status) {
 	default: break;
 	}
 }
+
+void QsIncubationController::initLoop() {
+	auto* app = static_cast<QGuiApplication*>(QGuiApplication::instance()); // NOLINT
+	this->renderLoop = QSGRenderLoop::instance();
+
+	QObject::connect(
+	    app,
+	    &QGuiApplication::screenAdded,
+	    this,
+	    &QsIncubationController::updateIncubationTime
+	);
+
+	QObject::connect(
+	    app,
+	    &QGuiApplication::screenRemoved,
+	    this,
+	    &QsIncubationController::updateIncubationTime
+	);
+
+	this->updateIncubationTime();
+
+	QObject::connect(
+	    this->renderLoop,
+	    &QSGRenderLoop::timeToIncubate,
+	    this,
+	    &QsIncubationController::incubate
+	);
+
+	QAnimationDriver* animationDriver = this->renderLoop->animationDriver();
+	if (animationDriver) {
+		QObject::connect(
+		    animationDriver,
+		    &QAnimationDriver::stopped,
+		    this,
+		    &QsIncubationController::animationStopped
+		);
+	} else {
+		qCInfo(logIncubator) << "Render loop does not have animation driver, animationStopped cannot "
+		                        "be used to trigger incubation.";
+	}
+}
+
+void QsIncubationController::setIncubationMode(bool render) {
+	if (render == this->followRenderloop) return;
+	this->followRenderloop = render;
+
+	if (render) {
+		qCDebug(logIncubator) << "Incubation mode changed: render loop driven";
+	} else {
+		qCDebug(logIncubator) << "Incubation mode changed: event loop driven";
+	}
+
+	if (!render && this->incubatingObjectCount()) this->incubateLater();
+}
+
+void QsIncubationController::timerEvent(QTimerEvent* /*event*/) {
+	this->killTimer(this->timerId);
+	this->timerId = 0;
+	this->incubate();
+}
+
+void QsIncubationController::incubateLater() {
+	if (this->followRenderloop) {
+		if (this->timerId != 0) {
+			this->killTimer(this->timerId);
+			this->timerId = 0;
+		}
+
+		// Incubate again at the end of the event processing queue
+		QMetaObject::invokeMethod(this, &QsIncubationController::incubate, Qt::QueuedConnection);
+	} else if (this->timerId == 0) {
+		// Wait for a while before processing the next batch. Using a
+		// timer to avoid starvation of system events.
+		this->timerId = this->startTimer(this->incubationTime);
+	}
+}
+
+void QsIncubationController::incubate() {
+	if ((!this->followRenderloop || this->renderLoop) && this->incubatingObjectCount()) {
+		if (!this->followRenderloop) {
+			this->incubateFor(10);
+			if (this->incubatingObjectCount()) this->incubateLater();
+		} else if (this->renderLoop->interleaveIncubation()) {
+			this->incubateFor(this->incubationTime);
+		} else {
+			this->incubateFor(this->incubationTime * 2);
+			if (this->incubatingObjectCount()) this->incubateLater();
+		}
+	}
+}
+
+void QsIncubationController::animationStopped() { this->incubate(); }
+
+void QsIncubationController::incubatingObjectCountChanged(int count) {
+	if (count
+	    && (!this->followRenderloop
+	        || (this->renderLoop && !this->renderLoop->interleaveIncubation())))
+	{
+		this->incubateLater();
+	}
+}
+
+void QsIncubationController::updateIncubationTime() {
+	auto* screen = QGuiApplication::primaryScreen();
+	if (!screen) return;
+
+	// 1/3 frame on primary screen
+	this->incubationTime = qMax(1, static_cast<int>(1000 / screen->refreshRate() / 3));
+}