move carouselview to standalone c++ component, fix crash due to memory leak in wallpaper object creation

Plugins/ZShell/Internal/wallpaperimage.cpp

@@ -4,14 +4,31 @@
 #include <QCryptographicHash>
 #include <QDir>
 #include <QFileInfo>
+#include <QImageReader>
 #include <QtConcurrent>
-#include <QSGImageNode>
 #include <QQuickWindow>
 
 namespace ZShell::internal {
 
+QThreadPool* WallpaperImage::loadPool() {
+	static QThreadPool* pool = [] {
+		auto* p = new QThreadPool();
+		p->setMaxThreadCount(4);
+		return p;
+	}();
+	return pool;
+}
+
 WallpaperImage::WallpaperImage(QQuickItem* parent) : QQuickItem(parent) {
 	setFlag(ItemHasContents, true);
+
+	m_loadDebounceTimer.setSingleShot(true);
+	connect(
+		&m_loadDebounceTimer,
+		&QTimer::timeout,
+		this,
+		&WallpaperImage::beginLoad);
+
 	connect(
 		&m_imageWatcher,
 		&QFutureWatcher<QImage>::finished,
@@ -20,12 +37,15 @@ WallpaperImage::WallpaperImage(QQuickItem* parent) : QQuickItem(parent) {
 }
 
 WallpaperImage::~WallpaperImage() {
+	m_requestGeneration->fetch_add(1, std::memory_order_relaxed);
+	m_imageWatcher.disconnect();
+
 	if (m_texture) delete m_texture;
+	if (m_previousTexture) delete m_previousTexture;
 }
 
 void WallpaperImage::setStatus(const Status s) {
 	if (m_status == s) return;
-
 	m_status = s;
 	emit statusChanged();
 }
@@ -36,14 +56,14 @@ void WallpaperImage::setSource(const QUrl& source) {
 	emit sourceChanged();
 
 	setStatus(Loading);
-	loadImage();
+	m_loadDebounceTimer.start(80);
 }
 
 void WallpaperImage::setScreenResolution(const QSize& screenResolution) {
 	if (m_screenResolution == screenResolution) return;
 	m_screenResolution = screenResolution;
 	emit screenResolutionChanged();
-	loadImage();
+	beginLoad();
 }
 
 void WallpaperImage::setZoom(qreal zoom) {
@@ -53,6 +73,13 @@ void WallpaperImage::setZoom(qreal zoom) {
 	update();
 }
 
+void WallpaperImage::setFadeDuration(int ms) {
+	if (ms < 0) ms = 0;
+	if (m_fadeDuration == ms) return;
+	m_fadeDuration = ms;
+	emit fadeDurationChanged();
+}
+
 void WallpaperImage::setCropX(qreal x) {
 	if (qFuzzyCompare(m_cropX, x)) return;
 	m_cropX = x;
@@ -100,143 +127,227 @@ QString WallpaperImage::getCacheFilePath() const {
 	return cachePath + "/" + hash + ".png";
 }
 
-void WallpaperImage::loadImage() {
+void WallpaperImage::beginLoad() {
 	if (m_source.isEmpty()) {
 		setStatus(Null);
 		return;
 	}
 
+	const quint64 requestId =
+		m_requestGeneration->fetch_add(1, std::memory_order_relaxed) + 1;
+
 	QString cacheFile = getCacheFilePath();
 	QString sourceFile = m_source.isLocalFile() ? m_source.toLocalFile()
 												: m_source.toString();
-
-	if (sourceFile.startsWith("qrc:/")) {
-		sourceFile = sourceFile.mid(3);
-	}
+	if (sourceFile.startsWith("qrc:/")) sourceFile = sourceFile.mid(3);
 
 	QSize targetRes = m_screenResolution;
+	auto generation = m_requestGeneration;
+
+	QFuture<QImage> future = QtConcurrent::run(
+		loadPool(),
+		[sourceFile, cacheFile, targetRes, requestId, generation]() -> QImage {
+			auto stale = [&] {
+				return generation->load(std::memory_order_relaxed) != requestId;
+			};
+
+			if (stale()) return QImage();
 
-	QFuture<QImage> future =
-		QtConcurrent::run([sourceFile, cacheFile, targetRes]() -> QImage {
 			if (!targetRes.isEmpty() && !cacheFile.isEmpty() &&
 				QFileInfo::exists(cacheFile)) {
 				QImage cached(cacheFile);
 				if (!cached.isNull()) return cached;
 			}
 
-			QImage original(sourceFile);
+			if (stale()) return QImage();
+
+			QImage original;
+			QImageReader reader(sourceFile);
+			if (!targetRes.isEmpty() &&
+				reader.supportsOption(QImageIOHandler::Size)) {
+				QSize actual = reader.size();
+				if (actual.isValid() &&
+					(actual.width() > targetRes.width() ||
+					 actual.height() > targetRes.height())) {
+					QSize scaledSize =
+						actual.scaled(targetRes, Qt::KeepAspectRatioByExpanding);
+					reader.setScaledSize(scaledSize);
+				}
+				original = reader.read();
+			} else {
+				original = QImage(sourceFile);
+			}
 			if (original.isNull()) return QImage();
 
-			if (targetRes.isEmpty()) {
-				return original;
-			}
+			if (stale()) return QImage();
 
-			if (original.width() > targetRes.width() ||
-				original.height() > targetRes.height()) {
-				QImage scaled = original.scaled(
-					targetRes,
-					Qt::KeepAspectRatioByExpanding,
-					Qt::SmoothTransformation);
-				if (!cacheFile.isEmpty()) scaled.save(cacheFile, "PNG");
-				return scaled;
-			}
+			if (targetRes.isEmpty()) return original;
 
-			if (!cacheFile.isEmpty()) original.save(cacheFile, "PNG");
-			return original;
+			QImage scaled = (original.width() > targetRes.width() ||
+							 original.height() > targetRes.height())
+								? original.scaled(
+									  targetRes,
+									  Qt::KeepAspectRatioByExpanding,
+									  Qt::SmoothTransformation)
+								: original;
+
+			if (stale()) return scaled;
+
+			if (!cacheFile.isEmpty()) scaled.save(cacheFile, "PNG");
+			return scaled;
 		});
 
 	m_imageWatcher.setFuture(future);
 }
 
 void WallpaperImage::handleImageLoaded() {
-	m_image = m_imageWatcher.result();
+	QImage result = m_imageWatcher.result();
+	if (result.isNull()) {
+		setStatus(Error);
+		return;
+	}
 
-	setStatus(m_image.isNull() ? Error : Ready);
-
-	m_textureDirty = true;
+	m_pendingImage = result;
+	m_hasPending = true;
+	setStatus(Ready);
 	update();
 }
 
-QSGNode* WallpaperImage::updatePaintNode(
-	QSGNode* oldNode, UpdatePaintNodeData*) {
-	auto* node = static_cast<QSGImageNode*>(oldNode);
+QRectF WallpaperImage::computeSourceRect(QSGTexture* texture) const {
+	QSize texSize = texture->textureSize();
 
-	if (m_image.isNull()) {
-		delete node;
-		return nullptr;
+	qreal cW = m_cropWidth / m_zoom;
+	qreal cH = m_cropHeight / m_zoom;
+
+	QRectF reqRect(
+		m_cropX * texSize.width(),
+		m_cropY * texSize.height(),
+		cW * texSize.width(),
+		cH * texSize.height());
+
+	QRectF bounds = boundingRect();
+	if (bounds.isEmpty() || reqRect.isEmpty()) return reqRect;
+
+	qreal targetRatio = bounds.width() / bounds.height();
+	qreal reqRatio = reqRect.width() / reqRect.height();
+
+	QRectF sourceRect = reqRect;
+
+	if (reqRatio > targetRatio) {
+		qreal newWidth = reqRect.height() * targetRatio;
+		qreal xOffset = (reqRect.width() - newWidth) / 2.0;
+		sourceRect.setX(reqRect.x() + xOffset);
+		sourceRect.setWidth(newWidth);
+	} else if (reqRatio < targetRatio) {
+		qreal newHeight = reqRect.width() / targetRatio;
+		qreal yOffset = (reqRect.height() - newHeight) / 2.0;
+		sourceRect.setY(reqRect.y() + yOffset);
+		sourceRect.setHeight(newHeight);
 	}
 
-	if (!node) {
-		node = window()->createImageNode();
-	}
+	return sourceRect;
+}
 
-	if (m_textureDirty) {
-		if (m_texture) delete m_texture;
-		m_texture = window()->createTextureFromImage(
-			m_image, QQuickWindow::TextureHasAlphaChannel);
-		m_textureDirty = false;
-	}
+void WallpaperImage::configureImageNode(
+	QSGImageNode* node, QSGTexture* texture) {
+	node->setTexture(texture);
+	node->setRect(boundingRect());
+	node->setFiltering(QSGTexture::Linear);
 
-	if (m_texture) {
-		node->setTexture(m_texture);
-		node->setRect(boundingRect());
-		node->setFiltering(QSGTexture::Linear);
-
-		qreal cW = m_cropWidth / m_zoom;
-		qreal cH = m_cropHeight / m_zoom;
-
-		QRectF reqRect(
-			m_cropX * m_texture->textureSize().width(),
-			m_cropY * m_texture->textureSize().height(),
-			cW * m_texture->textureSize().width(),
-			cH * m_texture->textureSize().height());
-
-		QRectF bounds = boundingRect();
-		if (bounds.isEmpty() || reqRect.isEmpty()) return node;
-
-		qreal targetRatio = bounds.width() / bounds.height();
-		qreal reqRatio = reqRect.width() / reqRect.height();
-
-		QRectF sourceRect = reqRect;
-
-		if (reqRatio > targetRatio) {
-			qreal newWidth = reqRect.height() * targetRatio;
-			qreal xOffset = (reqRect.width() - newWidth) / 2.0;
-			sourceRect.setX(reqRect.x() + xOffset);
-			sourceRect.setWidth(newWidth);
-		} else if (reqRatio < targetRatio) {
-			qreal newHeight = reqRect.width() / targetRatio;
-			qreal yOffset = (reqRect.height() - newHeight) / 2.0;
-			sourceRect.setY(reqRect.y() + yOffset);
-			sourceRect.setHeight(newHeight);
-		}
+	QRectF sourceRect = computeSourceRect(texture);
+	node->setSourceRect(sourceRect);
 
+	if (texture == m_texture) {
+		QSize texSize = texture->textureSize();
 		QRectF normalizedActual(
-			sourceRect.x() / m_texture->textureSize().width(),
-			sourceRect.y() / m_texture->textureSize().height(),
-			sourceRect.width() / m_texture->textureSize().width(),
-			sourceRect.height() / m_texture->textureSize().height());
+			sourceRect.x() / texSize.width(),
+			sourceRect.y() / texSize.height(),
+			sourceRect.width() / texSize.width(),
+			sourceRect.height() / texSize.height());
 
 		bool changed = false;
-
 		auto updateIfChanged = [&](qreal& dst, qreal value) {
 			if (!qFuzzyCompare(dst, value)) {
 				dst = value;
 				changed = true;
 			}
 		};
-
 		updateIfChanged(m_actualCropX, normalizedActual.x());
 		updateIfChanged(m_actualCropY, normalizedActual.y());
 		updateIfChanged(m_actualCropWidth, normalizedActual.width());
 		updateIfChanged(m_actualCropHeight, normalizedActual.height());
-
 		if (changed) emit actualCropChanged();
+	}
+}
 
-		node->setSourceRect(sourceRect);
+QSGNode* WallpaperImage::updatePaintNode(
+	QSGNode* oldNode, UpdatePaintNodeData*) {
+	Q_UNUSED(oldNode);
+
+	if (m_hasPending) {
+		if (m_previousTexture) {
+			delete m_previousTexture;
+			m_previousTexture = nullptr;
+		}
+		m_previousTexture = m_texture;
+		m_texture = window()->createTextureFromImage(
+			m_pendingImage, QQuickWindow::TextureHasAlphaChannel);
+		m_pendingImage = QImage();
+		m_hasPending = false;
+
+		if (m_previousTexture && m_fadeDuration > 0) {
+			m_fading = true;
+			m_fadeTimer.restart();
+		} else {
+			if (m_previousTexture) {
+				delete m_previousTexture;
+				m_previousTexture = nullptr;
+			}
+			m_fading = false;
+		}
 	}
 
-	return node;
+	if (!m_texture) {
+		return m_rootNode;
+	}
+
+	if (!m_rootNode) {
+		m_rootNode = new QSGNode();
+
+		m_newOpacityNode = new QSGOpacityNode();
+		m_newImageNode = window()->createImageNode();
+		m_newOpacityNode->appendChildNode(m_newImageNode);
+		m_rootNode->appendChildNode(m_newOpacityNode);
+
+		m_oldOpacityNode = new QSGOpacityNode();
+		m_oldImageNode = window()->createImageNode();
+		m_oldOpacityNode->appendChildNode(m_oldImageNode);
+		m_rootNode->appendChildNode(m_oldOpacityNode);
+	}
+
+	configureImageNode(m_newImageNode, m_texture);
+	m_newOpacityNode->setOpacity(1.0);
+
+	if (m_fading && m_previousTexture) {
+		qreal progress =
+			qBound(0.0, qreal(m_fadeTimer.elapsed()) / m_fadeDuration, 1.0);
+
+		configureImageNode(m_oldImageNode, m_previousTexture);
+		m_oldOpacityNode->setOpacity(1.0 - progress);
+
+		if (progress >= 1.0) {
+			m_fading = false;
+			delete m_previousTexture;
+			m_previousTexture = nullptr;
+			m_oldOpacityNode->setOpacity(0.0);
+		} else {
+			update();
+		}
+	} else {
+		m_oldOpacityNode->setOpacity(0.0);
+	}
+
+	return m_rootNode;
 }
 
 } // namespace ZShell::internal