4 files changed, 49 insertions, 36 deletions

diff --git a/stats/chartitem.cpp b/stats/chartitem.cpp
index 6fef5e44f..aeb395d41 100644
--- a/stats/chartitem.cpp
+++ b/stats/chartitem.cpp
@@ -14,13 +14,15 @@ static int round_up(double f)
 }
 
 ChartItem::ChartItem(StatsView &v, ChartZValue z) :
-	dirty(false), zValue(z), view(v)
+	dirty(false), dirtyPrev(nullptr), dirtyNext(nullptr),
+	zValue(z), view(v)
 {
 }
 
 ChartItem::~ChartItem()
 {
-	view.unregisterChartItem(this);
+	if (dirty)
+		view.unregisterDirtyChartItem(*this);
 }
 
 QSizeF ChartItem::sceneSize() const
@@ -41,19 +43,17 @@ ChartPixmapItem::~ChartPixmapItem()
 void ChartPixmapItem::setTextureDirty()
 {
 	textureDirty = true;
-	dirty = true;
+	view.registerDirtyChartItem(*this);
 }
 
 void ChartPixmapItem::setPositionDirty()
 {
 	positionDirty = true;
-	dirty = true;
+	view.registerDirtyChartItem(*this);
 }
 
 void ChartPixmapItem::render()
 {
-	if (!dirty)
-		return;
 	if (!node) {
 		node.reset(view.w()->createImageNode());
 		view.addQSGNode(node.get(), zValue);
@@ -71,7 +71,6 @@ void ChartPixmapItem::render()
 		node->setRect(rect);
 		positionDirty = false;
 	}
-	dirty = false;
 }
 
 void ChartPixmapItem::resize(QSizeF size)
@@ -161,5 +160,5 @@ void ChartLineItem::setLine(QPointF fromIn, QPointF toIn)
 	from = fromIn;
 	to = toIn;
 	positionDirty = true;
-	dirty = true;
+	view.registerDirtyChartItem(*this);
 }
diff --git a/stats/chartitem.h b/stats/chartitem.h
index 5dab8d1ea..f13cb3bc4 100644
--- a/stats/chartitem.h
+++ b/stats/chartitem.h
@@ -19,9 +19,10 @@ class ChartItem {
 public:
 	ChartItem(StatsView &v, ChartZValue z);
 	virtual ~ChartItem();
-	virtual void render() = 0;	// Only call on render thread!
+	virtual void render() = 0;		// Only call on render thread!
 	QRectF getRect() const;
-	bool dirty;			// If true, call render() when rebuilding the scene
+	bool dirty;				// If true, call render() when rebuilding the scene
+	ChartItem *dirtyPrev, *dirtyNext;	// Double linked list of dirty items
 	const ChartZValue zValue;
 protected:
 	QSizeF sceneSize() const;
diff --git a/stats/statsview.cpp b/stats/statsview.cpp
index e893c3ebb..40d23eed3 100644
--- a/stats/statsview.cpp
+++ b/stats/statsview.cpp
@@ -36,9 +36,10 @@ StatsView::StatsView(QQuickItem *parent) : QQuickItem(parent),
 	xAxis(nullptr),
 	yAxis(nullptr),
 	draggedItem(nullptr),
-	rootNode(nullptr)
+	rootNode(nullptr),
+	firstDirtyChartItem(nullptr),
+	lastDirtyChartItem(nullptr)
 {
-	chartItems.reset(new std::vector<ChartItem *>[(size_t)ChartZValue::Count]);
 	setFlag(ItemHasContents, true);
 
 	connect(&diveListNotifier, &DiveListNotifier::numShownChanged, this, &StatsView::replotIfVisible);
@@ -124,11 +125,11 @@ QSGNode *StatsView::updatePaintNode(QSGNode *oldNode, QQuickItem::UpdatePaintNod
 		plotAreaChanged(plotRect.size());
 	}
 
-	for (int i = 0; i < (int)ChartZValue::Count; ++i) {
-		for (ChartItem *item: chartItems[i]) {
-			if (item->dirty)
-				item->render();
-		}
+	for (ChartItem *item = std::exchange(firstDirtyChartItem, nullptr); item;
+	     item = std::exchange(item->dirtyNext, nullptr)) {
+		item->render();
+		item->dirty = false;
+		item->dirtyPrev = nullptr;
 	}
 
 	img->fill(Qt::transparent);
@@ -145,22 +146,34 @@ void StatsView::addQSGNode(QSGNode *node, ChartZValue z)
 	rootNode->zNodes[idx]->appendChildNode(node);
 }
 
-// Currently this does an inefficient linear search in the chart-item vector.
-// However, we entertain one vector of items per Z-value and currently
-// only the infobox is explicitly deleted, which has a unique Z-value.
-void StatsView::unregisterChartItem(const ChartItem *item)
+void StatsView::unregisterDirtyChartItem(ChartItem &item)
 {
-	int idx = std::clamp((int)item->zValue, 0, (int)ChartZValue::Count - 1);
-	std::vector<ChartItem *> &v = chartItems[idx];
-	auto it = std::find(v.begin(), v.end(), item);
-	if (it != v.end())
-		v.erase(it);
+	if (!item.dirty)
+		return;
+	if (item.dirtyNext)
+		item.dirtyNext->dirtyPrev = item.dirtyPrev;
+	else
+		lastDirtyChartItem = item.dirtyPrev;
+	if (item.dirtyPrev)
+		item.dirtyPrev->dirtyNext = item.dirtyNext;
+	else
+		firstDirtyChartItem = item.dirtyNext;
+	item.dirtyPrev = item.dirtyNext = nullptr;
+	item.dirty = false;
 }
 
-void StatsView::registerChartItem(ChartItem *item)
+void StatsView::registerDirtyChartItem(ChartItem &item)
 {
-	int idx = std::clamp((int)item->zValue, 0, (int)ChartZValue::Count - 1);
-	chartItems[idx].push_back(item);
+	if (item.dirty)
+		return;
+	if (!firstDirtyChartItem) {
+		firstDirtyChartItem = &item;
+	} else {
+		item.dirtyPrev = lastDirtyChartItem;
+		lastDirtyChartItem->dirtyNext = &item;
+	}
+	lastDirtyChartItem = &item;
+	item.dirty = true;
 }
 
 QQuickWindow *StatsView::w() const
@@ -326,9 +339,10 @@ void StatsView::reset()
 	highlightedSeries = nullptr;
 	xAxis = yAxis = nullptr;
 	draggedItem = nullptr;
-	if (rootNode) {
-		for (int i = 0; i < (int)ChartZValue::Count; ++i)
-			chartItems[i].clear(); // non-owning pointers
+	for (ChartItem *item = std::exchange(firstDirtyChartItem, nullptr); item;
+	     item = std::exchange(item->dirtyNext, nullptr)) {
+		item->dirty = false;
+		item->dirtyPrev = nullptr;
 	}
 	legend.reset();
 	series.clear();
diff --git a/stats/statsview.h b/stats/statsview.h
index c8e850d9b..f472e1e16 100644
--- a/stats/statsview.h
+++ b/stats/statsview.h
@@ -54,8 +54,8 @@ public:
 	QQuickWindow *w() const;		// Make window available to items
 	QSizeF size() const;
 	void addQSGNode(QSGNode *node, ChartZValue z);	// Must only be called in render thread!
-	void registerChartItem(ChartItem *item);
-	void unregisterChartItem(const ChartItem *item);
+	void registerDirtyChartItem(ChartItem &item);
+	void unregisterDirtyChartItem(ChartItem &item);
 	template <typename T, class... Args>
 	std::unique_ptr<T> createChartItem(Args&&... args);
 
@@ -142,7 +142,6 @@ private:
 
 	StatsState state;
 	QFont titleFont;
-	std::unique_ptr<std::vector<ChartItem *>[]> chartItems;
 	std::vector<std::unique_ptr<StatsAxis>> axes;
 	std::unique_ptr<StatsGrid> grid;
 	std::vector<std::unique_ptr<StatsSeries>> series;
@@ -162,6 +161,7 @@ private:
 	void mouseReleaseEvent(QMouseEvent *event) override;
 	void mouseMoveEvent(QMouseEvent *event) override;
 	RootNode *rootNode;
+	ChartItem *firstDirtyChartItem, *lastDirtyChartItem;
 };
 
 // This implementation detail must be known to users of the class.
@@ -170,7 +170,6 @@ template <typename T, class... Args>
 std::unique_ptr<T> StatsView::createChartItem(Args&&... args)
 {
 	std::unique_ptr<T> res(new T(*this, std::forward<Args>(args)...));
-	registerChartItem(res.get());
 	return res;
 }