statistics: keep track of dirty items in double-linked list

So far the items to be recalculated in the drawing thread
had a "dirty" flag and were kept in one array par z-level.

Once the series are implemented in terms of QSGNodes, there
may lots of these items. To make this more efficient when
only one or two of these items change (e.g. highlighting due
to mouseover), keep the dirty items in a linked list.

Of course, this makes the draw first version of the chart
less efficient.

There are more fancy ways of implementing the double-linked
list, but the few ns gained in the render thread are hardly
worth it.

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

1 files changed, 7 insertions, 8 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);
 }