statistics: replace PieSeries by QSG nodes

Since there are no disk-segment QSG primitives (one could draw
a triangle fan, but that doesn't seem optimal), this draws
into a pixmap and blits that as a QSG node.

Since this is the only series without axis, it needs a function
that returns the size of the plot area. This didn't exist, so
add it.

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

1 files changed, 30 insertions, 0 deletions

diff --git a/stats/chartitem.cpp b/stats/chartitem.cpp
index b8bf0f189..be2b3d635 100644
--- a/stats/chartitem.cpp
+++ b/stats/chartitem.cpp
@@ -224,6 +224,11 @@ ChartTextItem::ChartTextItem(StatsView &v, ChartZValue z, const QFont &f, const
 	resize(QSizeF(totalWidth, totalHeight));
 }
 
+ChartTextItem::ChartTextItem(StatsView &v, ChartZValue z, const QFont &f, const QString &text) :
+	ChartTextItem(v, z, f, std::vector<QString>({ text }), true)
+{
+}
+
 void ChartTextItem::setColor(const QColor &c)
 {
 	img->fill(Qt::transparent);
@@ -240,6 +245,31 @@ void ChartTextItem::setColor(const QColor &c)
 	setTextureDirty();
 }
 
+ChartPieItem::ChartPieItem(StatsView &v, ChartZValue z, double borderWidth) : ChartPixmapItem(v, z),
+	borderWidth(borderWidth)
+{
+}
+
+void ChartPieItem::drawSegment(double from, double to, QColor fill, QColor border)
+{
+	painter->setPen(QPen(border, borderWidth));
+	painter->setBrush(QBrush(fill));
+	// For whatever obscure reason, angles of pie pieces are given as 16th of a degree...?
+	// Angles increase CCW, whereas pie charts usually are read CW. Therfore, startAngle
+	// is dervied from "from" and subtracted from the origin angle at 12:00.
+	int startAngle = 90 * 16 - static_cast<int>(round(to * 360.0 * 16.0));
+	int spanAngle = static_cast<int>(round((to - from) * 360.0 * 16.0));
+	QRectF drawRect(QPointF(0.0, 0.0), rect.size());
+	painter->drawPie(drawRect, startAngle, spanAngle);
+	setTextureDirty();
+}
+
+void ChartPieItem::resize(QSizeF size)
+{
+	ChartPixmapItem::resize(size);
+	img->fill(Qt::transparent);
+}
+
 ChartLineItem::ChartLineItem(StatsView &v, ChartZValue z, QColor color, double width) : HideableChartItem(v, z),
 	color(color), width(width), positionDirty(false), materialDirty(false)
 {