statistics: turn axes into QSGNode

Render the labels and the title into a pixmap and render
the ticks and the base line using individual QSGNodes.
Attempting to render the ticks likewise into the pixmap
gave horrible results, because (quite obviously) rendering
with QPainter and the QSG shader gives non-matching ticks
and grid lines.

The memory management had to be changed a bit: The ChartItems
were collected in the root QSGNode. However, the axes are added
before the first plotting, so this node might not exist.
Therefore, store the axes in the StatsView object.

Signed-off-by: Berthold Stoeger <bstoeger@mail.tuwien.ac.at>

1 files changed, 10 insertions, 9 deletions

diff --git a/stats/statsview.cpp b/stats/statsview.cpp
index 83a586456..e893c3ebb 100644
--- a/stats/statsview.cpp
+++ b/stats/statsview.cpp
@@ -38,6 +38,7 @@ StatsView::StatsView(QQuickItem *parent) : QQuickItem(parent),
 	draggedItem(nullptr),
 	rootNode(nullptr)
 {
+	chartItems.reset(new std::vector<ChartItem *>[(size_t)ChartZValue::Count]);
 	setFlag(ItemHasContents, true);
 
 	connect(&diveListNotifier, &DiveListNotifier::numShownChanged, this, &StatsView::replotIfVisible);
@@ -89,7 +90,6 @@ public:
 	QSGImageNode *imageNode; // imageNode to plot QGRaphicsScene on. Remove in due course.
 	// We entertain one node per Z-level.
 	std::array<QSGNode *, (size_t)ChartZValue::Count> zNodes;
-	std::array<std::vector<ChartItem *>, (size_t)ChartZValue::Count> items;
 };
 
 RootNode::RootNode(QQuickWindow *w)
@@ -124,8 +124,8 @@ QSGNode *StatsView::updatePaintNode(QSGNode *oldNode, QQuickItem::UpdatePaintNod
 		plotAreaChanged(plotRect.size());
 	}
 
-	for (auto &v: n->items) {
-		for (ChartItem *item: v) {
+	for (int i = 0; i < (int)ChartZValue::Count; ++i) {
+		for (ChartItem *item: chartItems[i]) {
 			if (item->dirty)
 				item->render();
 		}
@@ -151,7 +151,7 @@ void StatsView::addQSGNode(QSGNode *node, ChartZValue z)
 void StatsView::unregisterChartItem(const ChartItem *item)
 {
 	int idx = std::clamp((int)item->zValue, 0, (int)ChartZValue::Count - 1);
-	std::vector<ChartItem *> &v = rootNode->items[idx];
+	std::vector<ChartItem *> &v = chartItems[idx];
 	auto it = std::find(v.begin(), v.end(), item);
 	if (it != v.end())
 		v.erase(it);
@@ -160,7 +160,7 @@ void StatsView::unregisterChartItem(const ChartItem *item)
 void StatsView::registerChartItem(ChartItem *item)
 {
 	int idx = std::clamp((int)item->zValue, 0, (int)ChartZValue::Count - 1);
-	rootNode->items[idx].push_back(item);
+	chartItems[idx].push_back(item);
 }
 
 QQuickWindow *StatsView::w() const
@@ -307,8 +307,9 @@ void StatsView::updateTitlePos()
 template <typename T, class... Args>
 T *StatsView::createAxis(const QString &title, Args&&... args)
 {
-	T *res = createItem<T>(&scene, title, std::forward<Args>(args)...);
-	axes.emplace_back(res);
+	std::unique_ptr<T> ptr = createChartItem<T>(title, std::forward<Args>(args)...);
+	T *res = ptr.get();
+	axes.push_back(std::move(ptr));
 	return res;
 }
 
@@ -326,8 +327,8 @@ void StatsView::reset()
 	xAxis = yAxis = nullptr;
 	draggedItem = nullptr;
 	if (rootNode) {
-		for (auto &v: rootNode->items)
-			v.clear(); // non-owning pointers
+		for (int i = 0; i < (int)ChartZValue::Count; ++i)
+			chartItems[i].clear(); // non-owning pointers
 	}
 	legend.reset();
 	series.clear();